The Mystery of Flight

The Mystery of Flight provides the reader with a clear and concise understanding of aviation. The book portrays the excitement and wonder of flight through the use of descriptive paragraphs. These excerpts convey to the reader a sense of what it is like to fly various types of aircraft. The theme of the book focuses on how man is capable of flight. In addition, the book describes many of the specific skills and techniques that are necessary in order to fly safely. The Mystery of Flight is designed to stir a reader's interest in aviation and provide them with a better understanding of a very challenging profession.

TABLE OF CONTENTS

INTRODUCTION - A Prelude

CHAPTER 1 - The Mystery of Flight

CHAPTER 2 - Proper Preparation

CHAPTER 3 - Launch Time

CHAPTER 4 - The Enroute Phase

CHAPTER 5 - The Landing Phase

CHAPTER 6 - The Sky Above

CHAPTER 7 - Flying Opportunities

CHAPTER 8 - Military Tactical Flying

CHAPTER 9 - Watch the Weather

CHAPTER 10 - Rotary Wing Flight

CHAPTER 11 - Unconventional Flight

CONCLUSION - What the Future Holds

INTRODUCTION - A PRELUDE

Aviation is an expression of man's adventurous spirit. Grace, beauty and the mystery of flight are the driving force behind an age old quest to soar free from the gravitational constraints of earth. Throughout history man has been driven to discover the elusive secret of how to fly. Numerous attempts led to that one defining moment at Kitty Hawk, North Carolina on December 17, 1903. The focused persistence and ingenuity of two brothers named Orville and Wilbur Wright helped to bring about a century of aviation that has been marked by impressive growth and amazing accomplishments. From its humble beginnings on a flight that lasted less than a minute, to the present day where man can now race around the world and fly well beyond the speed of sound. The cutting edge of aviation has moved from the sandy slopes of a North Carolina beach to the lofty and spacious heights of outer space. The thrill, the challenge and the excitement of flight are an irresistible lure to the adventurous at heart. Unforgettable experiences are the fringe benefits that can be derived from a lifetime of flying.

Climb aboard a high performance tactical jet aircraft. Strap into the narrow seat and start two powerful turbine engines that will carry you swiftly skyward. Power up, as you begin a slow taxi to the duty runway. Complete the Takeoff Checklist and call for your clearance as you taxi out onto the runway. Stand on the brakes while you push both throttles full forward to their military power settings. Feel the plane squat lurch forward against the brakes as you two engines begin to howl with a raging fury. Check all of your instruments prior to brake release and commence your takeoff roll.

To a casual observer watching from a vantage point on the ground, the takeoff sequence is an impressive event.

"The sleek jet fighter roared loudly as high pressure fuel was driven forcefully into the fiery core of two straining engines. The dart shaped fuselage leapt forward, accelerating as it rolled down the sloped concrete surface of a sun bleached runway. In seconds the jet achieved its takeoff airspeed and rose effortlessly above the ground. Passing a few hundred feet in the climb, the landing gear disappeared into the jet's underbelly and the plane surged forward. Crossing the departure end of the runway, the nose of the jet pivoted sharply upward and commenced a steep vertical climb. Unbridled thrust from two, powerful turbine engines rendered the persistent pull of gravity ineffective. The sound of the engines crackled in the cool morning air. Over time the jet grew smaller and smaller in size, until it disappeared in the grasp of a hazy summer sky."

The excitement of flight can also be experienced in the high altitude world of air combat maneuvering.

"Carving aggressively through an aquamarine sky, two fighter jets maneuvered inbound for a high speed pass. Hurling past one another, the opposing jets commenced a climbing, high angle of bank turn. Each pilot fought to gain the advantage by flying with a smooth and knowing hand. Preserving lift and energy, the engagement became an orchestrated and fact paced duel performed in a three dimensional world. Engines roared powerfully, sending torrid plumes of hot gas from their tailpipes. Each pilot maneuvered for the kill as the fighting grew more intense. The two planes became entwined in a tight, high angle of bank engagement. The tight turns intensified gravitational force on both pilot and aircraft. As quickly as it began, the adrenaline filled engagement came to a decisive end. Victory was achieved with by conserving energy, anticipating an opponents next move and drawing from years of experience in the aircraft."

The thrill and excitement of flight is not necessarily confined to a high altitude, supersonic experience. The helicopter by contrast offers a unique, low level, seat of the pants ride.

"The agile helicopter raced swiftly over the brine encrusted soil of a dry desert lake bed. Banking gently to the right, the pilot steered toward a distant mountain range that rose majestically over the sun scorched valley. Beneath the fuselage an elongated shadow danced in reckless pursuit, bouncing lightly along the rocky floor of a barren desert. Two whirling rotor blades flickered brightly in the midday sun. Desert heat poured relentlessly into the helicopter, through the wide expanse of open cargo doors."

Aviation can also be defined by contrast. For example the quiet, serene experience of being in a glider as it soars silently above sun baked terrain.

"Lifting free from the runway, the glider rose steadily. The persistent tug of a long tow line helped the sleek craft climb to altitude and its operating area.

As the tow rope fell free, the glider sailed on outstretched wings, rising rapidly on an invisible current of air. The wind slipped softly around the contoured surface of a bubbled canopy as the maneuvering glider floated majestically in the clear desert air."

An even more sedate way to fly is onboard a hot air balloon. The balloon was man's earliest mode of successful flight. In this example we observe an early morning launch from a distance as the ground crew busily prepares a hot air balloon.

"A sea of unfurled fabric covered the wide expanse of a dew drenched field. Scampering urgently about, the crew worked knowingly in the dawn's meager light. Preparations to set sail were well underway. The pulsating roar of fiery propane roared loudly, as it pierced the serene morning air. Turbulent plumes of amber raced into the balloon's gaping mouth, swelling a sea of fabric. Slowly, the distended belly of a slumbering giant began to rise, fed with a diet of superheated air.

Large crescent shaped panels appeared from an ocean of rumpled fabric. Each hot burst of fire from the propone unit served as the catalyst for lift, pulling the balloon's pliant fabric higher and higher into the air. Silhouetted against the glimmering backdrop of a morning sky, the half filled balloon resembled the sloping contour of a giant tortoise shell.

In time, the canopy assumed a more discernible form. The bulbous shaped sphere grew larger and larger as it dancing with an airy fullness above the grassy field. Lifting free from the ground, the sphere swayed with a luminescent glow, tugging impatiently at straining tethers.

Three passengers quickly boarded a wicker gondola. In unison the ground crew freed all ropes, and the craft soared majestically upward into the morning sky, driven south by a gentle breeze."

In contrast to a hot air balloon, we return to the helicopter, the best example of a complex flying machine. The helicopter is a sophisticated aircraft that relies on a variety of moving parts to sustain flight. The aerodynamic components of a helicopter move at furiously high speeds, rotating in close proximity to one another. An example of a helicopter's agility and maneuverability is described below.

"A faint, almost imperceptible vibration floated through the cool morning air. Driven by shifting winds, the sensation dissipated and then grew in random intensity. Soon a noise resembling the light tap of a big drum became perceptible.

Over time, these muffled compressions became more intense, penetrating the outstretched arms of oak tree branches. The high pitched whine of rotating turbines grew stronger and stronger until the surrounding air was saturated with an ear spitting shriek.

In unison, the dense forest echoed the hammering sound of rotor blades slapping the air with contempt. Suddenly, the shadow of a helicopter appeared, dancing swiftly across the ground as it traversed a leave covered clearing. The silhouette of a helicopter appeared, descending between the outstretched branches of two large oak trees.

During its descent, the helicopter flared slightly, achieving a ten foot high hover. Without delay, the nose of the aircraft dropped and the machine accelerated rapidly, dashing across the clearing toward a distant tree line. As the craft approached the dense foliage, the pilot pulled aggressively back on the stick and commenced a nose high climb. The aircraft decelerated rapidly, exchanging airspeed for altitude. Soon, the sleek craft reached the apex of its climb, suspended motionless in space like a bird on a perch.

Like a sailfish after leaping from the sea, the helicopter began to settle while the nose of the aircraft sliced downward and passed through the horizon to a nose low attitude. Accelerating rapidly the pilot pulled back on the stick, leveling the helicopter in a high speed hover above a patch of swirling rye grass.

Momentum carried the ship across the clearing until it reached an adjacent tree line. The nose of the aircraft rose again and the narrow fuselage swung directly overhead. Without effort the agile machine cleared the tree tops, rolled sharply to the left and disappeared behind a thrashing curtain of pine boughs."

Aviation - An Overview

Aviation is the sum of man's aeronautical knowledge and skill. It is visible expression of man's adventurous spirit as he takes to the skies. Skill and success in the air is measured by how well a pilot flies an aircraft. "Air Sense" is a critical part of this equation. Air sense is the measure of a pilot's ability to perceive and grasp the subtle but important nuances relating to flight. "Air Sense" is a God given skill that can be refined and enhanced through experience.

A critical part of flying is the ability of a pilot to "feel" the aircraft on the ground and in the air. The hum of the engine, the rush of the wind and the tug of the seat are all essential external cues that provide the pilot with a better awareness in flight. A good pilot does not ignore these signals. They are a useful way to assess flight conditions, the performance of the aircraft, and the potential for any problems. Air Sense is a pilot's ability to stay mentally ahead of a fast moving aircraft.

Exceptional pilots are gifted with the ability to fly an aircraft as though it was a physical extension of their body. Flying is not a tense, rigid, or rotely sequential activity. On the contrary, good flying involves the smooth and precise application of flight controls in a timely manner. The ability to integrate these higher level aviation skills is a true measure of an aviator's talent.

In concert with skill, flying demands vigilance and discipline. Aviation by its nature is brutally unforgiving. Complacency is insidious and ever-present threat. One neglectful moment in the air can lead to the rapid termination of a pilot's life. Fatigue coupled with complacency is an even more deadly combination. To help minimize this risk, limitations are placed on how long a pilot can fly. Factors leading to aircrew fatigue must be minimized to protect both the crew and the passengers from unnecessary risk.

This book was written to provide the reader with a broad base of knowledge about aviation. The goal is to motivate and encourage individuals who possess a desire and a yearning for flight. Modern day aviation is growing at a phenomenal pace. Each year more and more people personally experience the wonders of aviation. The lure and the excitement of flight can be expressed in a variety of ways. For the earthbound, it may be as simple as watching an airplane as it races across the sky into the evening twilight.

"The setting sun flickered brightly along the silvery fuselage of a high altitude jet. Feathery contrails poured relentlessly from the depths of each engine. Cottony plumes stretched for miles across the wide expanse of a darkening sky. The underside of each contrail was painted fiery red with the uneven brushstrokes of a setting sun. As dusk approaches the jet hastens west. Slowly, the outline of its fuselage grows faint, consumed by the surreal glow of a crimson blazing sky."

Aviation for many is a way of life. Those who choose it as a profession will enjoy many memorable experiences in the air. The following chapters are designed to encourage and kindle an individual's interested. The goal is to expand the reader's knowledge and impart a better understanding of what flying is really all about. So let's strap in and enjoy the flight! It is guaranteed to be quite a ride.

CHAPTER 1 - THE MYSTERY OF FLIGHT

How an Airplane Flies

Have you ever wondered how an airplane flies? Do you often watch in amazement as a commercial jet pass overhead in a slow descent for landing? Have you ever gazed at a large widebody jet maneuvering through the air as it maintains an impressively slow airspeed?

The image of a high performance jet aircraft flying low over the ground is an awe inspiring sight. So too is the thunderous roar of a jumbo jet as it lumbers down the runway in an amazing display of power. To the casual observer a question that is often asked is how can such a large aircraft climb free of the captive forces of gravity and fly? How do the wings of an airplane create enough lift to carry an object that is so large and so heavy into the air?

Aerodynamics

To explain how an airplane flies, it is important to understand a few aerodynamic concepts. The wings of an airplane are built to create lift. Lift is the force that is necessary in order to overcome the weight of the airplane. Lift is formed when air passes over the top and bottom of a wing. The flow of air creates a pressure differential on the wing and allows the airplane to fly.

In order for an airplane to be able to fly, it must generate sufficient lift. The lift required must be equal to or greater than the weight of the airplane. Airflow over the wings is created by the power of a rotating propeller or the thrust of a turbine engine. The airplane is either pushed or pulled through the air, in order to create lift and sustain flight.

A simple way to envision how an airplane flies, is to imagine that it is being supported by a sea of molecules. These air molecules flow at different rates as they pass above and below the wings of the plane. The secret of flight is directly related to this flow of air. Let's take a closer and more detailed look at these aerodynamic concepts before our takeoff.

Relative Wind

Relative Wind is a critical component that must be present for the production of lift. "Relative Wind," is a measure of wind in relation to the leading edge of a wing. The flight path of a wing combined with the direction of the Relative Wind helps to determine the amount of lift that is being generated by the wing. As an aircraft flies through the atmosphere, it creates Relative Wind. Relative wind can be experienced on the ground for example when riding in a car as a passenger. Wind is formed as the car moves down the highway. Simply extend an arm out into the slipstream to feel that wind. On a calm day, the strength of the wind is proportional to the speed of the car.

Relative Wind is an essential part of flight and critical for the production of lift. During takeoff and landing, it is important to maximize the aerodynamic benefits of wind. That is why pilots always strive to take off and land into a headwind. Headwinds provide additional aerodynamic lift as they pass over the wing. The additional lift is not produced at the expense of fuel. Just as a headwind is beneficial for takeoff and landing, a tail wind is detrimental. Tailwinds adversely affect the efficiency of a wing during critical phases of flight, extending takeoff and landing distances.

A tailwind increases the distance that an airplane must travel down the runway before achieving takeoff airspeed. If a pilot elects to takeoff with a tailwind, the increase in takeoff distance will be directly proportional to the intensity of the tailwind. A headwind on the other hand, increases the aerodynamic performance of a wing and reduces the distance an aircraft must travel before getting airborne.

Chord Line and Angle of Attack

To further understand how an airplane stays airborne, it is important to tie the concept of Relative Wind to other aerodynamic principles that critical for the production of lift. Two of these factors include the wing's Chord Line and the wing's Angle of Attack. Refer to Figure (1), for a depiction of these concepts. The chord line of a wing is an imaginary line that runs from the center of the wing's leading edge to the very tip of its trailing edge.

Angle of Attack is the angle that is formed between the Chord Line of the wing and the Relative Wind. The Angle of Attack on a wing will vary significantly throughout a flight because of the way the aircraft is flown and how it is configured.

Weight

An airplane's weight includes its basic weight plus fuel, passengers and cargo. An aircraft is restricted by its maximum gross weight for takeoffs and landings. It can be loaded with passengers and cargo up to a certain point. The maximum gross weight of an aircraft is tied to structural limitations. Takeoff and landing weights must be computed by the pilot for each takeoff and landing. As you can see, takeoffs are not always the same. For example, if a pilot takes off using a constant power setting in a heavier aircraft, it will require a longer takeoff roll to get airborne. The reason for this is the fact that a heavier aircraft accelerates at a much slower rate. Heavier aircraft must remain on the ground longer in order to generate a sufficient airspeed/airflow over the wings before lifting off the ground.

Thrust

Thrust is a force produced by jet engines or propellers. It is necessary to overcome drag on the airplane. Thrust can be produced in a variety of ways. For example, a glider takes advantage of the thrust that is provided by another aircraft. In contrast, the thrust created by a helicopter is formed from the rotation of its rotor blades.

The pitch angle of a helicopter's rotor blades is altered during flight. As the pitch angle of the blades increases the Angle of Attack is increased. The main rotor system takes a bigger "bite" out of the air, causing the aircraft to climb or fly more rapidly.

In the case of a jet aircraft, thrust is formed when air is drawn into the intakes of a jet engine, compressed, heated under pressure and violently propelled out the back of the engine and into the atmosphere. The rapid expansion of gasses pushes the aircraft forward through the atmosphere.

Drag

Drag is a retarding force that is created as a by-product of thrust. There are two basic types of drag, induced drag and parasite drag. Induced drag is formed when a wing produces lift. As the Angle of Attack of a wing increases, induced drag grows proportionally, all the way up to the point where the aircraft stalls.

Parasite drag originates from the exposed portions of an aircraft. These surfaces include the fuselage, the engine intakes, exposed cowlings and the landing gear. Friction is created as these components are pushed through the atmosphere. The decelerating force of parasite drag varies considerably during a flight. For example, when an aircraft is configured for landing, the wing flaps are lowered along with the landing gear. A significant amount of power must be added in order to overcome resistance and the combined effects of parasite and induced drag.

Lift Revisited

As the Relative Wind strikes the leading edge of a wing, the flow of air is divided. A wing is aerodynamically designed so that as air flows over the top of a wing it must travel a greater distance than the air passing underneath the wing. This is a very important concept. Two separate streams of air must travel different distances in order to reach the trailing edge of the wing. Due to the physical properties of air, molecules in both air streams will arrive at the trailing edge of the wing, at the same time. In order for this to occur, the flow of air above the wing must travel at a faster rate than the flow of air below the wing.

As the air is accelerated, the molecules within the airmass are spread further apart. Greater distance between air molecules in the atmosphere results in lower air pressure. So, "How does an aircraft fly"? The answer to this question is based on the pressure differential that is created between the top of the wing and the bottom of the wing.

Lift occurs when the higher air pressure located beneath the wing pushes the wing upward into the low pressure region above the wing. The secret of lift is an essential part of being able to understand how an aircraft as large, heavy aircraft like the Boeing 747 is able to fly.

The amount of lift a wing can create is based on several things. These factors include the wing's Angle of Attack, the wing's rate of travel through the atmosphere, the density of the air, the wings shape and the wings area.

Angle of Attack, as previously discussed, is a measure of the angle formed by the chord line of the wing and the Relative Wind. Angle of Attack can be increased by raising the nose of an aircraft or by altering the direction of the Relative Wind.

There are limitations associated with the production of lift and how large the Angle of Attack can be. A line of demarcation is created when the wing of an aircraft is raised to the point of stall. When this angle is exceeded, lift is no longer generated, due to a degraded aerodynamic condition. As a result, the aircraft stalls. A stall occurs when the airflow over the wing becomes disturbed. Any disturbance above the wing will reduce the size and the effectiveness of its low pressure region. As a result, a wing with an excessively high Angle of Attack will quickly lose lift and cease to fly.

Angle of Attack is also be increased by modifying the shape of the wing. A unique way to accomplish this is to temporarily change the shape of the wing by lowering the flaps. As the flaps are lowered, the trailing edge of the wing pivots downward. The chordline of the wing is shifted upward and the Angle of Attack is increased, even though the nose of the aircraft has not moved.

To better understand how lift is created, it is important to realize that air behaves very much like a liquid. Both the flow of air and the flow of water possess similar physical properties. Imagine that an airplane is flying (i.e. swimming) through a large ocean of water.

A passenger onboard a moving ship for example can easily observe the ocean as it drifts past the bow. The flow of water is also visible as it swirls across a ship's rudder and provides the necessary pressure for steerage. The flow of air over and under a wing however is invisible. Because we cannot see airflow, we cannot understand it as readily, hence the term "Mystery of Flight". By take a closer look at the ocean we can visualize the flow of air. Winds shift in many directions and vary in speed, just like the currents in an ocean. Air turbulence is similar to the pitching surface of an unsettled ocean.

"Plunging steadily into the aquamarine sea, the bow of the ship thrust a mound of pristine water gracefully upward. Misty plumes of brine rose high on the wings of a swirling breeze. Hardened steel carved cleanly into a cresting wave. The bow plunged deeper, lifting translucent sheets of water upward and casting a watery curtain in a frothy rage onto the gnarled face of the sea.

The bow recoils quickly, rising high above the swells in anticipation of another powerful stroke. As it rises the sea clings tenaciously to the concave surface of a ferrous hull. Foamy white waves slap lightly against the unyielding surface of cold black steel. Lured innocently astern, the sea darkens. Strong currents lurking beneath the surface pull retreating waves into the iron grip of a swirling maelstrom. Massive whirlpools suck the ocean chaotically downward into the surging grasp of a ship's propellers. Spiral screws compress water into tightly packed vortices which are tossed violently aft. Each water contrail dissipates quickly, floating slowly toward the surface and forming the ship's wake."

Unlike our vivid picture which is depicted above, the flow of air across a wing is invisible. To see and understand aerodynamic principles, we must rely on some demonstrations that will help us understand how lift is produced.

Airflow Demonstration

To help visually display how the wind affects the performance of an aerodynamic surface, refer to the following demonstrations outlined below. These two practical examples will help you understand how lift is formed.

Begin the first demonstration by grasping a piece of typing paper with both hands. Roll the page downward and place the curled portion of the paper up against your chin. The longer portion of the paper should hang down below your lips. Now, take a deep breath and blow a steady stream of air over the top of the paper. Observe what happens. Did you expect the force of air to push the paper down? What actually happened to the paper? Why did the paper float up in response to the wind?

A man by the name of Daniel Bernoulli can help us understand the answers to many of our aerodynamic questions. Hs was a Swiss scientist who discovered Bernoulli's Principle in 1738. Mr. Bernoulli developed a theory based on the fluid properties of air. He stated that the total energy of a fluid in motion (i.e. air) must be constant at all points in a steady path. Additionally, as the velocity of the air increases, the pressure of the fluid (air) must decrease proportionately. Simply stated, faster flowing air over the top of a cambered wing has a lower air pressure than slower moving air that travels beneath it.

Due to Daniel Bernoulli's persistence and his enlightening research relating to these physical properties, he received notoriety and fame. Unfortunately for him, this came many years after his death. The ultimate compliment however is the fact that a scientific principle is named after him. The Bernoulli Principle describes how lift is produced on a wing.

Another experiment designed to help understand how lift is formed is begun by holding two sheets of notebook paper vertically. Place them approximately three to four inches apart. Lean over and blow a steady stream of air between these two pages. Note what happens. You might expect the breeze to push both sheets further apart. What actually happened? Why did the two pages move closer together?

It is necessary to refer back to the efforts of Daniel Bernoulli in order to understand these results. Air pressure differences can effect a wing in both the vertical and the horizontal plane. A low pressure area is created between both sheets of paper as the air is accelerated through the gap. High pressure air on the outside pushes the two sheets of paper together, into the low pressure region.

Maneuvering Flight

The two previous experiments help us to visually understand how lift is a byproduct of the Relative Wind. The focus of our discussion will now shift to an aircraft's flight control system and how flight controls are used to coordinate the movement of an aircraft through the air. Before an aircraft becomes airborne, it must be taxied from the flight line to the runway. Ground taxi resembles the act of driving a car down the highway. The weight of the aircraft rides on each wheel as the plane moves about in two dimensions. When an aircraft becomes airborne however, a three dimensional world is encountered and the flight controls are used to coordinate the movement of the aircraft through all three axis.

Flight control systems vary by type of aircraft. Most commercial airplanes have flight control systems consisting of a yoke, a throttle quadrant and rudder pedals. Military aircraft, utilize a stick, a throttle and rudder pedals. Flight controls in the cockpit are connected to external control surfaces by direct mechanical linkages or by electronic "fly-by-wire" systems. Flight controls are designed to physically move all of the aerodynamic surfaces on an airplane. They are assisted by the power of motors and hydraulic actuators.

Hydraulic systems and hydraulic actuators are necessary because of the high forces that are generated by the wind. The control surfaces must overcome extreme pressure while they are being forced out into the wind stream. The power that a hydraulic system produces counters this pressure and provides control. Flaps, ailerons and rudders are moved with the assistance of hydraulic pressure.

After an aircraft becomes airborne it is flown about three dimensions consisting of the lateral, longitudinal and vertical planes of rotation. They correspond to pitch, roll and yaw in an aircraft. Refer to Figure (2) for a pictorial of these control surfaces and information about each axis of rotation.

Pitch

Pitch is the movement of an airplane about its lateral axis. The stick or yoke controls the fore and aft movement of the helicopter. The primary control surface responsible for pitch is the elevator. An elevator is located on the tail along the trailing edge of the horizontal stabilizer. It is one of two moveable parts mounted on the tail.

The elevator is an aerodynamic surface that is used to alter the shape of the tail. The purpose of the elevator is to create lift and move the tail either up or down. The nose attitude of an aircraft is controlled by the vertical movement of the tail. When a pilot wishes to lower the nose of the aircraft, the stick is pushed forward. Elevator control tubes in the fuselage are connected to hydraulic actuators and the elevator is lowered in response to the stick's movement. The Angle of Attack is increased on the horizontal stabilizer, creating additional lift. The lift causes the tail to rises and the nose of the aircraft to pitch down.

The opposite occurs when the stick or yoke is pulled back. The elevator is raised and the Angle of Attack on the tail is decreased. As a result, the tail will settle and cause the nose of the aircraft to pitch upward.

Roll

Roll is the movement of an aircraft about its longitudinal axis. The lateral movement of the stick or yoke controls roll. The control surfaces responsible for roll are the ailerons. Ailerons are located on the outer edge of the wing, along the trailing edge. A mechanical or electronic linkage is used to connect the ailerons to the stick or the yoke. Both ailerons are interconnected and are designed to move in opposite directions. During a turn, the lift on one wing is increased and decreased proportionally on the other wing.

For example, if an airplane is rolled to the left, the left aileron is raised, decreasing lift on the left wing. The aileron on the right wing is simultaneously lowered, increasing lift on the right wing. The two opposing forces create roll in an airplane. The roll rate is determined by the rate of stick displacement.

Yaw

Yaw is the movement of an aircraft about its vertical axis. Yaw is controlled by inputs to the rudder pedals. The primary function of the rudder pedals is to move the tail laterally and balance the aircraft. The rudder is a control surface that is mounted on the tail. It is attached to the trailing edge of the vertical stabilizer. The rudder pedals are mechanically or electronically connected to servos that move the rudder. A rudder functions in the same capacity as an elevator. The difference is that the force of lift is horizontal instead of vertical.

For example, a pilot who wishes to move the nose of the aircraft to the left simply depresses the left rudder pedal in the cockpit. The rudder then moves to the left, creating lift on the left side of the vertical stabilizer. In response, the tail of the aircraft pivots to the right while the nose of the aircraft yaws left, in the desired direction of travel.

When an aircraft is flown through the air, the pilot rarely uses only one axis of rotation. Maneuvering flight requires the coordinated integration of pitch, roll and yaw. Flight control adjustments are all interrelated. If one control surface is moved, the other two must be changed in order to maintain the stability of the aircraft.

Slow Flight

The ability to fly an aircraft at a slow airspeed while maintaining complete control is essential. The importance of slow flight can be appreciated by watching a large airplane on final approach for landing. As the aircraft descends on the glide path it appears to be suspended in space, barely moving in relation to the ground. These amazingly slow airspeeds are conducive to a safe and more comfortable landing. A slower approach provides a pilot with many benefits such as a shorter stopping distance, reduced braking requirements and the availability of additional runway for contingencies. To fly at these significantly slower airspeeds, a physical modification of the wing must take place.

Slow flight is possible by altering the aerodynamic characteristics of a wing. Wing flaps are located along the trailing edge of each wing, near the wing root. When wing flaps are lowered, the Angle of Attack on the wing is increased creating additional lift. On some aircraft wing flaps actually increase the area of the wing. In all cases, the chord line of the wing is shifted upward by lowering flaps. Remember that the chord line is measured from the leading edge of the wing to the trailing edge. By lowering flaps on a wing, the wing's trailing edge is lowered. Because of this movement, the angle between the relative wind and the chord line is increased. So is the amount of lift generated by the wings.

An unfortunate by-product of an increase in lift is an increase in induced drag. As a result higher power settings are required to overcome the increase in drag. When wing flaps are rotated to the down and locked position, power adjustments must be anticipated in order to maintain the proper airspeed and desired rate of descent.

The aerodynamic changes that occur when wing flaps are lowered, permits an aircraft to fly at slower airspeeds without the likelihood of stall. Flaps are used for both takeoffs and landings. A half flap configuration is normally set for takeoff while a full flap setting is selected during the landing phase.

Stalls

One of the more potentially dangerous hazards associated with aviation is the possibility of stalling an aircraft in flight. Stalls are the result of excessive Angle of Attack on a wing. There are three basic types of stall, the basic stall, the accelerated stall and the approach turn stall. Pilots regularly practice entering and recovering from stalls at higher altitudes where there is ample room for less than perfect recoveries. In order for a pilot to enter a stall, the pilot reduces the power on the engines to idle while maintaining the nose attitude of the aircraft with back stick. The basic stall is the first type of stall. It is encountered when an airplane decelerates below its normal slow flight airspeed.

The aerodynamic characteristics of a basic stall result from disturbed airflow over the top of the wing. Many aircraft are designed to provide a pilot with sufficient cues when a stall is impending. The turbulence associated with a pre-stall condition often reverberates throughout an airframe. It varies in degree from very mild to extremely violent. These vibrations are known as "buffet". Buffet is a tangible warning that the aircraft is approaching a stalled flight condition. If an aircraft continues to decelerate, the leading edge of the wing will continue to rise and the Angle of Attack will increase to a point where the airplane passes through buffet and into stall.

In a stalled flight condition, the Angle of Attack on the wing has reached an extreme angle. The wing actually functions more like a barricade than an aerodynamic surface. As the flow of air over the wing becomes disturbed and separates from the wing. The end result is a reduction in the valuable low pressure region above the wing. The aerodynamic limits of the wing have been exceeded and the wing is no longer able to create the lift necessary for flight.

When a wing is stalled the nose of the aircraft will pitch forward. The wing may roll to the right or the left as the nose falls through the horizon. The most significant feature of a stall is the fact that the pilot is no longer in complete control of the aircraft. In this case he will not be able to maintain an assigned altitude. A stalled flight condition is extremely critical when flying close to the ground since altitude must be sacrificed in order to effect a successful recovery.

To recover from a stall the pilot must lower the nose of the aircraft and add power. Lift is restored by decreasing the Angle of Attack of the wing and by increasing airflow across the upper surface of the wing. A pilot quickly learns that ailerons should not be used to level an aircraft during stall recoveries. Any erratic flight control movements may further degrade the wing's ability to generate lift. Extensive aileron movement in deep stall condition will hinder the recovery. During a stall the rudder can be used for directional control since it is not stalled. It continues to be an effective control surface. Figure (3) depicts how the airflow on a wing appears when the wing is stalled.

Many tactical military aircraft are built with a critical wing. A critical wing is designed to enhance airspeed and performance on a jet. As a tradeoff, there is very little warning of stall in these types of aircraft. If these aircraft are flown to the limits of stall, they may depart controlled flight unexpectedly and tumble violently through the air, in a series of post stall gyrations.

To counter or minimize the negative effects of a stall, many aircraft are engineered so that a stall will commence at the wing root. On an aircraft, the wingroot is located at the base of the wing, the area closest to the fuselage. As you recall, the ailerons are control surfaces which control the longitudinal axis of flight. For this reason, the ailerons should be the last part of the wing that stalls.

Aerodynamic twist is a feature that is integrated into many wings to ensure that the wing root stalls first Angle of Attack on a wing with aerodynamic twist is actually greater at the wing root than at the wing tip. As a result, when a stall is encountered, the base of the wing will stall first while the outer portion of a wing continues fly in a stream of undisturbed air.

The second type of stall is an accelerated stall. The accelerated stall is not always encountered at slower airspeeds. Even under normal flying conditions an aircraft can be accelerated quickly into a stall. For example, the rapid application of back stick during a high angle of bank turn will place a greater load on the wings. Stall occurs as centrifugal forces are combined with the sudden movement of the wing into a high Angle of Attack condition.

During steep turns, power must be added to counter the effect of high wing load. The aft movement of the stick increases the Angle of Attack on the wing, which may lead to buffet or stall. An accelerated stall may occur despite the fact that the aircraft is flying at a very high airspeed. To recover from an accelerated stall the pilot simply eases the back pressure on the stick and decreases angle of bank. Erratic movements of the flight controls during a stalled flight condition will aggravate the stall and delay recovery.

A third type of stall is the approach turn stall. The approach turn stall occurs when an aircraft is "dirty", or in the landing configuration. In preparation for landing, the gear and flaps of an airplane are lowered. Induced and the parasite drag are both significantly increased. Therefore the power requirements on the airplane are much greater. When a "dirty" airplane is in a high angle of bank turn, additional power is necessary due to wing loading. The potential for an approach turn stall is favorable under a low power, high angle of bank flight condition. The approach turn stall is a particularly dangerous since it occurs when the aircraft is in the landing pattern and close to the ground.

Approach Turn Stalls occur when flight control inputs are improperly applied to an aircraft at low energy states. If an aircraft in the landing pattern is placed into a sharp turn without sufficient power, the aircraft will slow down below its recommended maneuvering speed and it will begin to descend. If the pilot attempts to compensate for a loss of altitude by raising the nose and not adding power, it will only worsen the condition.

In this case, the Angle of Attack on the high wing can increase significantly to the point of a full stall. By raising the nose of the aircraft in a slow flight condition, the higher wing will stall first and stop flying. As a result, the high wing drops from a loss of lift and the airplane rolls over on its back. Fortunately most modern aircraft are equipped with electronic warning devices that emit an aural tone when a stalled flight condition is impending. A pilot also learns to recognize the conditions associated with stall by practicing them and becoming familiar with the proper recovery procedures.

CHAPTER II - PROPER PREPARATION

Flight Planning

Before takeoff a pilot must conduct thorough flight planning. One of the first steps is to prepare a detailed flight plan. A flight plan provides a controlling agency with a detailed description of where the pilot intends to fly and what route he or she plans to take while enroute to their destination. Flight plans are filed with the Federal Aviation Administration. A flight plan includes essential information that relates specifically to the flight. Information required on a flight plan includes the type of aircraft that is being flown, the aircraft's call sign, the planned airspeed, altitude, and desired route of flight. All enroute stops are listed along with the final destination. An alternate airfield is identified if required by weather. The estimated time enroute, fuel required to destination and the total fuel onboard is also provided.

Additional administrative requirements include: the name of the pilot, the number of personnel onboard and the color of the aircraft. Figure (4) is a copy of an actual flight plan that is used by a pilot to file with the FAA. Before departure a pilot must call or visit an approved FAA facility in order to obtain weather information for the filed route of flight. The weather must also be checked for the planned destination and any alternate airfields that are required. FAA locations are called Flight Service Stations. Weather information can be accessed by computer or by telephone. Flight Service is responsible for inputting a pilot's flight plan into the FAA computer and providing pilots with applicable Notices to Airmen or NOTAMS. A NOTAM identifies any procedural changes that might affect operations at a departure, destination or alternate airfield.

Flight Service Stations are located regionally around the country and can be reached in flight by transmitting on a designated radio frequency. Flight Service Stations activate and modify flight plans and also provide enroute and destination weather updates. When a pilot calls a Flight Service Station, the call is prefaced by the name of the Station followed by the word "Radio". For example "Macon Radio" is the call sign for the Flight Service Station located in Macon, Georgia. Various Flight Service Stations monitor the same radio frequency.

VFR Flight

Before flight, there are two types of flight plans that a pilot generally files. They are the Visual Flight Rules, Flight Plan (VFR) and Instrument Flight Rules, Flight Plan (IFR). Visual Meteorological Conditions are required for VFR flight. A pilot must be able to see and avoid both the ground and other aircraft during VFR flight. For a pilot to fly under VFR, the bottoms of the cloud layer must be at least three thousand feet above the ground and there must be a horizontal visibility of three miles or better. Marginal VFR conditions exist when the base of a cloud layer are between one thousand and three thousand feet above the ground.

Some aircraft are not properly equipped with the essential instruments for IFR flight. Many civilian aircraft have rudimentary instruments that are intended for situations where a pilot inadvertently flies into the clouds. These instruments are not rated for IFR flight and are only intended for use in the event of an emergency. A pilot on a VFR flight plan should always remain clear of clouds and any instrument flight conditions.

In the event that a pilot inadvertently enters the clouds on a VFR flight, he or she must focus their complete attention on the instruments that are available in the cockpit. The attitude gyro is the primary instrument for a pilot to watch in this situation. An attitude gyro continuously displays the attitude of the aircraft in relation to the horizon.

If a pilot has inadvertently entered the clouds, they must immediately begin using an instrument scan, in order to remain oriented. The ideal next step is to reverse course and fly back out of the clouds. To do so, the pilot commences a stable, standard rate turn for one hundred and eighty degrees of heading change.

In the event that the does aircraft break out of the clouds, the pilot may elect to continue with VFR flight and circumvent any adverse weather along the course of flight. If the weather deteriorates however, a wise pilot will opt to land and wait for better flying conditions.

IFR Flight

The second type of flight plan is called an IFR flight plan. Instrument Flight Rules apply when an aircraft is flown in conditions with cloud bases less than one thousand feet AGL, and/or the horizontal visibility is less than one mile. An aircraft that is certified for instrument flight contains all of the appropriate navigational instruments that are needed to safely fly in the clouds. In order to fly in Instrument Meteorological Conditions a pilot must also have an instrument flight rating before initiating a flight in IMC flight conditions. An instrument rating is obtained by completing a certified ground school course followed by instrument flight training in a flight simulator and an aircraft. At the completion of ground training a pilot must successful complete an evaluation by flying in an instrument rated aircraft, with an FAA flight examiner onboard.

Fuel Planning

Accurate fuel management is an essential part of flying. Fuel preservation is a top priority for all pilots. To determine how much fuel is required for a flight, the pilot must make several preflight computations. The first planning step is to measure the distance that the airplane must travel to reach its filed destination. Utilizing the basic principles of time, distance and fuel flow, a fuel plan can be prepared for each leg of the flight. The following sample fuel problem is provided to help understand how a pilot computes fuel burn and determines what proper fuel load is required.

In our sample problem, an aircraft must fly 900 nautical miles to its destination. The true airspeed for the flight is computed to be 300 miles per hour and the aircraft will be flown at an altitude of 16,000 feet. The aircraft is forecast to burn 300 pounds of fuel per hour at this assigned altitude. In this example there is no wind. As a result, the aircraft is scheduled to arrive at its destination in three hours. (900 miles divided by 300 mph equals three hrs.). To compute how much fuel is required for the enroute portion of the flight, the pilot multiplies the fuel burn rate of 300 pounds per hour, by the enroute time of three hours. The total fuel required for the cruise portion of the flight is 900 pounds.

Looks pretty simple, but fuel planning is more than a single computation. The pilot must also incorporate the fuel that is necessary for start, taxi, takeoff. The higher fuel flow associated with a climb to altitude must also be factored in to the fuel plan so that the appropriate amount of fuel is carried onboard the aircraft.

For example, a commercial airliner taking off from Kennedy International Airport in New York on a Friday evening will experience extensive delays before reaching the runway. Gate holds, departure sequencing, deicing requirements are several factors that can contribute to delays. Therefore, additional fuel must be carried in order to properly account for those delays.

During takeoff and climb out, fuel consumption is significantly higher. Throttle settings in the climb are much greater and these large power demands contribute to sizable fuel burn rates. Therefore, a large amount of fuel can be burned in a relatively short period of time. Certain flight configurations can worsen this situation. The use of an afterburner on a jet engine causes fuel flow to increase astronomically. Heavily loaded aircraft use more fuel since they take longer to climb to altitude. As a precaution, pilots must take a very detailed look at all aspects of a flight and plan for the worst case scenario when estimating fuel.

Jet engines perform more economically at higher altitudes. The optimum cruise altitude for a large jet aircraft is based on its weight at level off. Air is less dense at higher altitude. Parasite drag is significantly less when compared with conditions at a lower altitude. The outside air temperature at high altitudes is extremely cold. Fuel savings are an added benefit. In contrast, extended flight at low altitudes will increase fuel consumption and adversely affect the fuel plan.

In some cases an aircraft may be flown above its optimum cruise altitude. Fuel consumption will be higher in this scenario because of higher power settings and less favorable aerodynamic conditions. It is important to understand that carrying an excessive amount of fuel in large commercial aircraft can be wasteful. Due to the added weight of this fuel, the fuel flow to the engines will be higher. The increased weight will adversely affect fuel efficiency.

Now, let's return to our fuel planning problem. But in this case we will factor in the effects of wind on fuel performance. When making fuel computations, it is very important for a pilot to use ground speed. As the name implies, ground speed is the rate that an airplane travels over the ground. In our previous scenario, we used a "no wind" computation and based our calculations on a true airspeed of 300 nautical miles per hour. Without a headwind or tailwind component, the progress of the airplane over the ground is neither impeded nor improved.

Ride the Wind

To appreciate the effect of wind on fuel consumption, let's imagine that an airplane must fly to its destination with a 100 nautical mile per hour headwind. The ground speed of the aircraft at cruise altitude will now only be 200 nautical miles per hour, instead of 300 nautical miles per hour.

True airspeed is a measure of the actual speed of the airplane as it flies through the air. The reading on the airspeed indicator is the indicated airspeed. Indicated airspeed is a measure of the dynamic pressure of the aircraft as it flies through the air. True airspeed is the plane's indicated airspeed, corrected for any variations in the density of the atmosphere and calibration errors in the gage. It is very important to note that true airspeed is not a measure of how fast an aircraft is traveling over the ground. True airspeed is an indicator of how fast the aircraft is flying through an "ocean" of air that we call the atmosphere.

When a 100 nautical mile per hour headwind is pushing against the airplane, it is slowing the aircraft's physical progress over the ground. Aerodynamically however, the wings of the aircraft are still experiencing 300 knots of dynamic pressure.

A headwind is beneficial when it comes to increasing airflow over a wing but it is detrimental when measuring progress over the ground. True airspeed and groundspeed are independent of one another and are rarely equal.

When an aircraft is flying into a headwind, the fuel plan and the estimated time of arrival must be adjusted to compensate for the negative effects of the headwind. More fuel is required to safely reach a filed destination.

We must re-compute our time enroute based on our new headwind. So, let's take the total distance to destination (900 miles) and divide it by the groundspeed. Remember that the groundspeed is now 200 miles per hour vice 300 mile per hour with our 100 knot headwind. The flight will take an additional hour and a half to reach its destination. Therefore the time of flight will now increase from 3 hours to 4 and one half hour.

To determine how much additional fuel should be carried on the aircraft to compensate for a forecast headwind, the pilot must multiply the fuel burn per hour by the additional time enroute. A fuel burn of 300 pounds per hour multiplied by an additional hour and a half of flight time is equal to 450 pounds. Our planned fuel consumption at altitude has increased from 900 pounds to 1,350 pounds due to the extra 450 pounds of fuel burn.

During the flight, actual fuel burn must be compared against the projected fuel consumption that is depicted on the fuel plan. The task must be done at regular intervals throughout the flight, to determine if a fuel surplus or a fuel deficit exists. The difference between planned fuel consumption and actual fuel consumption may vary in either direction. Contributing factors to a fuel deficit include ground delays, headwinds, alternate routing, holding and prolonged approach times.

On the positive side, fuel requirements can actually be reduced if an aircraft can takeoff quickly or an enroute tailwind component exists. Pilots do not always count on the benefits of a tailwind during flight planning however. A tailwind cannot be used in flight planning to get you to your destination. The reason for this is that the tailwind may dissipate during the course of the flight. If a pilot relies on a tail wind to get to a destination, he or she may be left "high and dry" if the wind dies down, with a lot less fuel than planned.

Pilots are required to carry a fuel reserve on each flight. The purpose for carrying reserve fuel is to provide a buffer and to compensate for unexpected fuel deficits. A fuel reserve is increased if the weather is marginal at the filed destination. Additional fuel must be carried as a contingency. If the pilot must divert to an alternate airfield for landing there will be sufficient fuel available to reach the alternate and shoot an instrument approach.

The winds actually encountered at altitude are the truth teller. It is reflected in the aircraft's progress over the ground. If a headwind is not as strong as forecast or a tailwind is stronger than anticipated, the pilot will have the luxury of a more fuel at touchdown. Refer to an example of a sample fuel plan located in Figure (5).

Refueling

Aircraft are fueled utilizing three different methods, gravity fueling, high pressure fueling and in-flight refueling. Gravity fueling is similar to putting gas in a car. The pilot simply removes the fuel cap from the top of a wing or the side of the fuselage. The fuel nozzle is placed inside the aircraft and fueling commences. Gravity fueling is also known as "Over the Wing" fueling. It is a suitable way to transfer small amounts of fuel. The preferred method for refueling an aircraft that requires a large amount of fuel is through the use of a pressure refueling system.

Pressure refueling as its name implies, involves fueling aircraft with a forced flow of fuel. The fueling hose is configured with a special fitting that attaches directly to a refueling port on the side of the aircraft. The closed system relies on a one way, high pressure valve that opens while fuel is pumped directly into the tank. The valve closes automatically after fueling is complete. Fuel pressure can be adjusted at the fuel truck in order to suit the type of aircraft that is being refueled. Pressure refueling can be conducted safely even when the engines on an aircraft are running. Military airfields have pressure refueling facilities called "Hot Pits." The "Hot Pits" are located near a taxiway so that aircraft can be quickly refueled before takeoff or after landing.

To "Hot Pit," a pilot taxies the aircraft into the fuel pits and completes the hot refueling checklist. The ground crew attaches a high pressure hose to the receptacle and refueling is initiated. An indication of positive fuel transfer is noted when the cockpit fuel quantity gage begins to increase.

Fuel is transferred into internal storage tanks that are located in various parts of the aircraft. In smaller aircraft, the fuel tanks are located inside the wings. In larger aircraft the fuel is also stored in the wings and in fuel cells located above and below the cabin. Certain military and civilian aircraft are configured with fuel tip tanks that are mounted at the end of each wing. Auxiliary fuel tanks can also be suspended from wing store stations located below the wings. Auxiliary fuel provides the pilot with the capability to fly longer distances or remain on station for longer periods of time.

The third type of refueling is in-flight refueling. In-flight refueling is used by the military to extend the flight time of aircraft after they have launched. Large refueling aircraft with extra fuel are utilized to refuel tactical aircraft. Aircraft requiring fuel must rendezvous with the "Tanker". Refueling takes place along a prescribed route called a "Track". Aircraft to be refueled are configured with fuel probes. The fuel probe is designed to plug into a long fuel hose that is suspended behind the refueling aircraft. In some cases a refueling boom is used. A crewman in the refueling aircraft flies the refueling boom down to a receptacle in the aircraft that requires fuel. In either case once the connection has been made, the fuel is transferred at a very high rate.

Fuel in an aircraft is measured by weight instead of volume. Weight is a more reliable indicator and provides a more accurate fuel reading. During maneuvering flight, fuel in an aircraft's fuel tanks will slosh around. If total fuel was measured by volume there would be erratic fuel quantity indications displayed on the fuel gage in the cockpit. Weight is a more accurate and consistent way to measure fuel in an aircraft. The gross weight of fuel is not affected by any sloshing that occurs in the tank. Therefore, it can be displayed more accurately on a fuel gage.

While on the ground, fuel levels can be measured externally. The pilot uses a dipstick to determine how much fuel is in each tank. Measurements in smaller aircraft are accomplished by inserting a dipstick into the tank via a wing refueling port. The dipstick is removed and the total amount of fuel is displayed on a graduated scale engraved on the side of the dip stick. In larger aircraft fuel is measured by using separate fuel gages located in the cockpit. During refueling the amount of fuel that is put into the aircraft is recorded and compared with the amount of fuel that is on the gage and on the fuel plan.

The Aircraft Preflight

Before each flight, a pilot must conduct a thorough preflight. The preflight checklist is used to guide a pilot and to ensure that important things on the aircraft are checked. Areas to be inspected are delineated on the checklist. For example prior to takeoff, an airplane must be checked for loose cowlings, loose or missing service caps and unfastened access panels. The condition of the landing gear is checked along with all aerodynamic surfaces, and various engine systems. Other critical areas include fuel and oil quantities, tire pressures, unrestricted movement of the flight controls, and the engine intakes, propellers and cockpit systems.

The obvious reason for a preflight is to deal with any problems that may exist before the aircraft is flown. A preflight also extends well beyond a physical inspection of the aircraft. It encompasses a detailed analysis of factors such as weather, service facilities at the destination and a proper review of all flight notices (NOTAMS). Night operations also require special preparation. At night attention must be paid to aircraft lighting, local taxi procedures and obstacle avoidance. During tactical military operations, very thorough mission planning must be conducted well in advance of the flight. A proper preflight is essential to help minimize any surprises in the air. If preflight procedures are not conducted properly or ignored altogether, dire consequences may result.

CHAPTER III - LAUNCH TIME

The Start

Before starting an aircraft, a pilot must complete the pre-start checklist. The pre-start checklist is a tool that is used to make sure that the appropriate cockpit switches are in the proper position for start. The copilot begins the process by reading a checklist item out loud to the pilot. Checklist items are visually checked by the pilot to ensure that they are configured properly. All switches are inspected to verify that they are in the correct position. After a visual confirmation, the pilot announces to the copilot the appropriate response from the checklist. The copilot monitors the pilot's response and visually cross-checks to ensure that the switch has in fact been placed in the appropriate position.

An example of a challenge and response checklist is provided. As the copilot announces "Fuel Switches," the pilot places his hand on both fuel switches and physically moves them to the on position. The pilot then reports "Number 1 and 2 - On." The copilot crosschecks to verify the fuel switches are in the correct position and then proceeds on to the next checklist item.

When the pre-start checklist is complete, the pilot starts the engine or engines. Due to the rapid succession of procedures associated with an engine start, the start procedures are done from memory. The engine is started when a starter motor is energized. The starter physically rotates the engine until a specific rate RPM is achieved. Fuel is then introduced into the combustion section of the engine and it is ignited electrically. When the engine has achieved a self sustaining RPM the starter motor is disengaged. The Post Start Checklist is then performed following engine start.

Taxi

Before taxing for takeoff, a pilot must obtain a clearance from ground control. The clearance provides the pilot with specific departure and enroute instructions. Clearance information is generated from the pilot's filed flight plan. To activate a clearance, the pilot must contact a ground controller. The ground controller will read the pilot the complete clearance. After receipt of the clearance, the pilot must resolved any questions or issues before accepting the assigned routing.

When the crew is ready for taxi, a call is made to ground control. The pilot requests clearance to taxi and is given taxi instructions along a specified route. To aid the pilot, there are detailed diagrams of all the major airports included in their flight publications. A bird's eye view of the airfield is presented in the drawing. Runway locations, taxiway designations, ramp areas and terminal buildings are all depicted based on their size and location. Refer to Figure (6) for an example of an airfield diagram. All airport runways are numbered based on their magnetic heading. Taxiways are identified by designated by using letters of the alphabet. Buildings are depicted in black and drawn according to their shape.

When a taxi clearance is issued, the controller will specify a particular route for the pilot to take to the active runway. For example, "Lobo 14, taxi to runway 19 via "A" taxiway (pronounced "Alpha"). Pilots unfamiliar with the airfield can request progressive taxi instructions from Ground Control. When progressive taxi instructions are requested, the Ground Controller provides the pilot with a series of directions as the pilot is taxiing to the runway. A pilot must remain oriented at all times during ground taxi. Frequently there is a requirement to cross active runways enroute to an assigned takeoff runway. The airfield diagram serves as an excellent road map in order to avoid any conflicts and maintain the assigned taxi route.

Taxi signs are located strategically along sides of each taxiway. Taxi signs identify the location of all runways, taxiways and parking gates. They are lit at night for easy viewing. Under darkness, taxiways are identified by blue edge lighting while all runways are marked with white edge lighting. The last 2000 feet of the runway is marked with amber lights.

To begin taxiing, the pilot must add power to the engines so that the propeller or the jet engine can begin to physically move the aircraft down the taxiway. Taxi speeds are controlled by throttle setting and brake application. Aircraft are steered using either differential braking or nose wheel steering. Small airplanes use differential braking to control direction. With differential braking, a turn is performed by applying pressure to one of the brakes. Brakes on an airplane are employed by pressing down on the rudder pedals. For example, in order to turn an aircraft to the right, the pilot must press down on the right rudder pedal. Friction created on the right brake disk causes the nose of the aircraft to pull to the right.

Larger commercial aircraft are equipped with nose wheel steering systems. A nose wheel steering system allows a pilot to manually control the direction that the nose wheel turns. A small steering wheel located in the cockpit is used to physically move the nose wheel in the desired direction of turn.

When a large commercial aircraft is parked at the gate and is ready for taxi, it is either pushed back by a ground crew using a tractor or it is powered out of the gate using thrust reversers. During "pushback" or "powerback", the taxi director signals a pilot for all movement in and around the gate area. Ground support personnel are also positioned around the aircraft to ensure that all sides of the aircraft are clear of any obstacles while the aircraft is moved. The taxi director stands where the pilot can clearly observe all of the signals that are used to direct the movement of the aircraft. A taxi director normally uses taxi wands with reflective material on them for use during the day. At night the wands are illuminated. "Wing Walkers" assist the taxi director by monitoring wingtip clearance and tail movement when an aircraft is pivoted about in a turn.

During taxi from the ramp to the runway, a taxi checklist is completed. The taxi checklist is used to prepare an aircraft for takeoff. Examples of things required on a taxi checklist include lowering wing flaps, checking flight controls for freedom of movement and preparing all cockpit systems for takeoff.

Takeoff

Approaching the runway, the pilot must complete the Before Takeoff Checklist after the aircraft is brought to a stop at the "Hold Short Line." The hold short line is a yellow line that is painted across the width of the taxiway. The pilot must stop the aircraft behind the hold short line unless clearance has been given by the tower to taxi out onto the runway. The hold short line is designed to keep aircraft a safe distance away from the active runway and landing traffic.

When the cockpit crew is ready for takeoff, the copilot contacts the tower and requests a takeoff clearance. The tower will issue one of the following clearances: "Position and Hold" which means that the pilot is cleared to taxi onto the runway and wait for a takeoff clearance. Or the pilot may be instructed "Cleared for Takeoff". In this case the pilot is cleared to taxi onto the runway and takeoff. The pilot may also be told to "Hold Short". In this case, the pilot must remain behind the hold short line until clearance to taxi onto the runway is received.

After a takeoff clearance is received, the pilot must verbally accept/repeat the clearance back to the tower, smoothly add power and taxi out onto the runway. Out of the turn, the aircraft must be aligned with the runway centerline. During the takeoff, the throttles for each engine are increased to their takeoff power setting. Several gages are monitored to ensure that the indications are in limits and the flight controls are checked for any feedback. If all of systems are "in the green," the pilot releases the brakes and begins the takeoff roll.

As the aircraft accelerates down the runway, brakes are initially used to maintain runway heading. After sufficient airspeed has been obtained the rudder becomes aerodynamically effective and nose alignment is coordinated through the use of the rudder pedals.

A Copilot's Duties

The role of the copilot during takeoff in a commercial aircraft is to back the pilot up with the appropriate takeoff calls. The copilot also monitors the cockpit gages and makes sure that the correct takeoff power is set on each one of the throttles. Takeoff power settings are determined during preflight planning. These values are calculated based on the takeoff weight of the aircraft, the ambient air temperature, the flap settings on the aircraft and the airfield elevation.

Two important airspeeds are also computed for takeoff. The first critical airspeed is called V1 or takeoff "refusal speed." Prior to V1, if there are any problems with the aircraft, the pilot will abort the takeoff by pulling the power back to idle and immediately applying the brakes and the thrust reversers. After V1 speed is reached, the pilot will no longer consider aborting a takeoff. The crew will continue with the takeoff and concentrate on getting the aircraft airborne. In cases of emergency where the aircraft must return to the field for a landing, the pilot must climb to altitude, dump fuel, turn downwind and obtain an emergency clearance for an immediate landing. Within the cockpit, a checklist delineates the appropriate steps that are to be used. The specific emergency is reviewed and the appropriate procedures initiated in order to prepare the aircraft for landing.

In terms of the takeoff sequence, the next speed of importance to a pilot is "Vr", or "rotation airspeed." When Vr is attained, the pilot pulls back on the yolk or the stick and lifts the nose of the aircraft off of the runway. As the nose pivots skyward the aircraft follows suit and flys gracefully off the runway and into the air.

Takeoff procedures may vary based on the type of aircraft being flown. Smaller airplanes and helicopters use different cockpit procedures for takeoff but the takeoff clearance and any abort criteria must be clearly defined. The following scenario is provided so that the reader can envision a complete takeoff sequence:

"A light cool breeze blew gently across the runway. The first rays of morning light poured brightly through a row of pine tree in the distance. "Turbo one five, you are cleared for takeoff on runway one nine." "Roger, Turbo one five, cleared for takeoff on runway one nine."

Viewed from the Control Tower, a growing plume of hot gas could be seen pouring from the back of two tail mounted engines. A whirlwind of heat and dust arose, racing angrily over the surface of the taxiway. The fuel laden aircraft responded begrudgingly. Laboring for a moment the aircraft wheels broke free from a persistent grasp of summer softened asphalt and the airplane rolled out onto the runway.

As the aircraft moved, bright sunlight danced along the length of its silvery fuselage. Brilliant flashes flickered intermittently from the mirrored surface of each passenger window.

The pilot pulled the throttles back to idle as weight and momentum carried the airplane through the turn. The jet pivoted about in a wide sweeping arc. Out of the turn, the aircraft continued its taxi down the runway for a short distance and coasted to a gentle stop, poised for takeoff.

Suddenly, the peaceful serenity of the morning was shattered by a harsh, earsplitting roar. Torrid plumes of hot gas spewed violently from the tapered exhaust nozzles of both engines. Intense, unrelenting heat swirled furiously backward, out over the grass covered approach end of the runway. Awakened from its slumber, the aircraft lurched forward, nose down, like a wild bronco trying to throw a hapless rider.

At brake release, the craft began rolling steadily down the runway. The pilot steadily added power, expanding the profile of the exhaust plume and driving it even higher into the air.

Slowly and deliberately the speed of the airplane began to increase. Rate of acceleration was indicated inside the cockpit by a rising airspeed indicator and the rhythmic pounding of a nose wheel rolling over expansion joints in the concrete runway. As groundspeed increased a slight shudder filled the cabin. The fuselage began rocking gently from side to side, until the nose of the aircraft pivoted slowly upward. Lifting free from the runway, the jet bounced slightly and began its upward climb."

CHAPTER IV - THE ENROUTE PHASE

Flight Following

As we have seen, a flight plan is a detailed account of a pilot's intended route of flight. It also provides both the pilot and the passengers onboard with a measure of safety. On a VFR flight, if an aircraft should have to execute a precautionary landing at a remote airfield, the flight plan would serve as a valuable starting point for any search and rescue efforts.

"Flight Following" is a very helpful method that is used to track a pilot's progress over the ground. When a flight plan is filed the pilot lists the estimated time of arrival for the flight. Shortly after takeoff the pilot activates the flight plan by calling Flight Service on an assigned radio frequency. The Flight Service representative is provided with the pilot's call sign, take off time, and filed destination. Based on this information, the flight plan is activated. After arriving at the destination airfield a pilot MUST remember to call Flight Service and close out the flight plan. The call to Flight Service may be made on the radio just prior to landing or on the ground via telephone after the flight.

Flight following ensures that an aircraft has safely reached it's filed destination. When a pilot fails to close out a flight plan, the FAA will contact the destination airport to see if the aircraft is on the ground. If the status of the aircraft cannot be determined, a search and rescue plan is initiated to help locate the overdue aircraft.

In the process of filing a flight plan a pilot must receive a thorough weather brief that covers the enroute and destination portion of the flight. If marginal weather is forecast during the scheduled arrival time, an alternate airport must be identified on the flight plan. Additional fuel must also be carried in order for the pilot to safely reach the alternate airfield.

Weather briefings can be obtained over the telephone or by visiting a meteorological facility. Automated weather stations provide briefings and weather can also be pulled up on the Internet. Weather stations are located at designated regional airports and military airfields around the country. These facilities provide face to face briefing services for pilots and aircrew.

Enroute to a Destination

When an aircraft lifts free of the runway and climbs into the sky, the pilot must concentrate on a variety of tasks. After the landing gear is raised and the flaps are retracted, the pilot must fly the assigned departure heading. When the aircraft is clear of the airport traffic area a pilot is instructed by tower to contact departure control on a radio frequency that is provided in the clearance. During the initial climb, the focus of attention must be dedicated to collision avoidance. The entire crew is tasked with the important task of searching for any conflicting aircraft.

After reaching the assigned enroute cruising altitude, the pilot's attention is focused on enroute navigation and cockpit systems. The fuel plan must be compared with the actual fuel consumption to determine whether the crew is ahead or behind on fuel.

Navigation

Proper navigation is essential for the safe conduct of flight. A pilot can utilize several navigation techniques in order to proceed to a desired destination. There are two primary methods of navigation: visual navigation and instrument navigation. Both methods are not mutually exclusive. For example, flight instruments are frequently used in conjunction with a map to crosscheck and verify the location of an aircraft.

VFR Navigation

Pilots who fly under VFR flight rules, navigate by using a map, much like a driver does as they travel down the highway. A VFR Sectional is one of many maps that a pilot uses for VFR navigation. A pilot can reference a VFR Sectional and compare distinguishing features on the ground with their symbolic representation on the map. The VFR Sectional has a map on both sides. Each side represents an area equivalent to 42,500 square miles. The VFR Sectional derives its name from the largest city depicted on the map. For example, a Phoenix Sectional covers several large populated areas but the biggest of these is the city of Phoenix.

A VFR Sectional provides a pilot with a bird's eye view of an entire area. Colors are an important aid to navigation on the map. They signify a variety of things to a pilot. For example, different shades of brown and orange are used to depict ground elevation in mountainous regions. Blue is used to display water and yellow depicts large populated areas such as cities and towns. Both man made and natural objects are represented on a VFR Sectional map. Cities, airports, roads, railroad tracks, power lines, factories, towers, quarries, lakes, rivers and restricted airspace are all depicted.

During preparation for a VFR flight, it is worthwhile for a pilot to draw the route of flight on a navigational chart. A yellow highlighter is useful for making a clear distinct line from checkpoint to checkpoint. The line helps to clearly delineate a path that should be flown over the ground. Once airborne, the route is an excellent point of reference. The pilot can use it to compare the actual position of the aircraft to where it should be along the preplanned route of flight. While navigating, a pilot will often orient the map in the direction of flight. With a map properly oriented, the objects depicted on the map are in the same relative position as they are on the ground. The pilot can tell immediately if the aircraft is off course by noting the position of the aircraft in relation to the highlighted course line.

Navigation information should also be written on the map. It is helpful to place the information in a box next to the course line, for each segment of the trip. The information that is written in the box includes the aircraft's heading corrected for the wind, the total distance of each segment, the time enroute and how much fuel is required for each leg. To be useful, this data must be readily accessible and clearly displayed. An example of a navigation route on a VFR Sectional is depicted in Figure (7).

It is important for a pilot to conduct a thorough map study before takeoff. A map study allows a pilot to become familiar with the elevation of the surrounding terrain and note if there are any significant man made obstacles that may affect the flight. The location of each checkpoint is noted along the route of flight. For a pilot, the navigation task begins immediately after takeoff. It is very important to remain oriented and maintain a high level of situational awareness. The aircraft must be flown on course and remain clear of restricted airspace.

On occasion, a pilot may be unsure of an aircraft's exact position. The first step is to make note of any discernible checkpoints on the ground. These features can be cross-referenced with those what are depicted on the map. The position of an aircraft can be determined based on heading and distance from these known points. To fly safely a pilot must be an efficient and an effective navigator.

While enroute the aircraft is flown at one of the established VFR cruising altitudes. These altitudes are designed to preclude any conflicts with IFR traffic. VFR cruising altitudes begin at three thousand five hundred feet above the ground and are measured in thousand foot increments. When flying from east to west, pilots can choose even altitudes plus five hundred feet. When flying from west to east, the pilot can choose odd altitudes plus five hundred feet.

For example, a pilot flying VFR on a westerly course from Saint Louis, Missouri to Kansas City, Missouri, can select a VFR cruise altitude of: four thousand five hundred feet MSL, six thousand five hundred feet MSL, eight thousand five hundred feet MSL, and so forth. On the return trip the appropriate choice of altitudes are: three thousand five hundred feet MSL, five thousand five hundred feet MSL, seven thousand five hundred feet MSL and above. VFR cruising rules do not apply when flying below three thousand feet AGL.

When planning for a VFR flight it is important to take into consideration, the direction and the intensity of the wind. Wind direction and intensity can vary considerably at different altitudes. A pilot can obtain wind information from the Winds Aloft Chart. Winds Aloft Charts are provided by the National Weather Service. They symbolically depict the direction and the intensity of the wind at various altitudes around the country.

Night Operations

Night operations are a unique experience. Visual acuity and depth perception are significantly reduced under nighttime conditions. The ability to distinguish form, shape, definition and detail is degraded when flying in the evening twilight or total darkness. Or eyes use different receptors to see in the dark. The rods of the eye are sensory receptors that are suited for the night. These receptors are physically located in a circular fashion around the retina. Good night vision requires an active scan. Due to the physical location of the rods in the eye a pilot must move his head and eyes continuously when flying at night.

Under low ambient conditions it is very easy to misjudge distance. One important precaution that a pilot can take before flying at night is to dark adapt. During dark adaptation, the pupils of both eyes will open wider, allowing more light to pass through the lens and into the eyes. Rods in the eyes are more sensitive and responsive to lower light thresholds.

If a pilot does not dark adapt before flying at night, both eyes will be adjusted for daytime vision. Their overall capability to see will be considerably reduced. Until their eyes dark adapt, they will not work very efficiently. An excellent example of the failure to dark adapt can be seen in a movie theater. Impatient moviegoers often enter a dark theater and set out in quick pursuit of an empty seat. The rapid transition from daylight to darkness makes it very difficult to see. The end result is a banged shin or an embarrassing fall. One easy solution is to wait a few minutes so that the eyes can adapt.

A pilot must utilize different navigation techniques at night. The ability to read a map in a dark cockpit and remain oriented requires practice. Pilots must also develop an eye for recognizing specific night navigation checkpoints. Additional preflight requirements for night flight include a properly working flashlight, a well prepared map and a close eye on the weather. The location of adverse weather and its projected course is essential information for a pilot. Fog, low level stratus clouds and reduced visibility are all contributing factors to potentially hazardous flight conditions.

A pilot flying in a remote location on a VFR flight plan should check ambient light levels to verify the amount of illumination that the moon and the stars will be providing. It is important to know what time the moon rises and sets. The moon's size and its elevation above the horizon is valuable information as well. Many times the bright light of a full moon provides illumination that rivals daytime conditions. In contrast, a night without a moon or stars may result in very dark flying conditions. It may require an instrument scan and the use of night vision devices. Cloud cover can degrade an already poor situation by blocking any ambient light from above. On the plus side, city lights do reflect brightly off the bottom of a cloud layer. These same clouds help to disburse this artificial form of light a great distance.

At night, thunderstorms are a dangerous proposition for an aviator. These large cloud formations provide a colorful display of lightning. An unwanted side effect associated with thunderstorms is the possibility of severe turbulence. A sudden jolt coupled with a rapid rate of descent is risky proposition when flying too close to a storm. Large frontal systems often contain imbedded thunderstorms. High winds associated with cold fronts move rapidly as they pass over the ground. Unrelenting rains that are released from these storms may catch an unsuspecting pilot by surprise. It is possible for aircraft damage to occur due to hail, wind shear or lightening strikes. These are some of the more serious consequences that can result if a pilot inadvertently penetrates a thunderstorm. Therefore, it is wise for a pilot to circumvent bad weather by giving it a wide berth.

Night Navigation

Night navigation requires special preflight preparation. Many terrain features and checkpoints that are utilized during daytime navigation are not visible in the dark. Therefore other techniques must be incorporated into night navigation. A pilot must also learn to recognize how the environment affects the ability to navigate at night.

For example, it is important to be sensitive to lighting and contrasts in lighting. The ability of a pilot to clearly see terrain features and navigation checkpoints is significantly influenced by the ambient light levels and the checkpoint's features. For example, when a pilot approaches an airfield located within the heart if a large city, it can be very difficult locate the runway at night. The lights of a runway are easily lost in wide expanse of bright city lights. Street lights, building lights and parking lot lights can easily outshine runway lights and make them very difficult to pick out. The pilot must continue flying toward the airfield until the outline of the runway is visible.

In a similar situation, it is equally as difficult to spot an unlit, rural airstrip at dusk. The dark black earth that surrounds the airfield closely matches the black asphalt of a single unlit runway. The pilot must use known terrain features and navigational aids in order to get the airfield in sight. The lighting system for many runways can be enabled remotely by selecting a designated frequency on the radio. To turn the lights on the pilot simply clicks the radio switch a specified number of times. The intensity of the lights can be adjusted by using clicking the microphone.

Airport Beacons

As an aid to night navigation, many airports have a rotating beacon located at the airfield. An airfield beacon is normally situated on top of a tall building or a high tower. It is comprised of two powerful lights that serve as a lone sentinel in the night. The steady flashing of an airfield beacon is an open invitation for a pilot in search of a runway. It also serves as an excellent navigation feature for pilots who are flying to a far away destination.

Civilian and military airfields are equipped with rotating beacons that operate from sunset to sunrise. The beacon is also turned on when IFR weather conditions are encountered at an airfield. Airport beacons contain a white light and a green light offset by one hundred and eighty degrees. As the beacon rotates, it emanates a flash of bright white light, followed by the flicker of a green light. Military fields utilize the same lighting system. The difference between a military airfield and a civilian airfield is the white beam. Military airfields have a split white beacon with two distinct flashes instead of one. The split white beacon helps a pilot to differentiate between civilian and military airfields.

As discussed earlier, man made features are useful checkpoints for navigating at night. The lights from the cities and nearby towns will emanate brightly into the night sky. The limits of a city are distinguished by light from the streets, moving cars and large buildings. When viewed from above, a winding road often resembles a string of lights on a Christmas tree. In contrast, a large open field reflects very little light. Dark clearings appear as a black hole surrounded by an irregular outline of lights. Successful night navigation is enhanced by the use of several techniques. For example, one way to distinguish water at night is to note how moonlight shimmers on the surface of a lake. When viewed from above, the reflected light appears to be racing across the water as though it was flying in formation with the aircraft.

Tall TV towers and high antennas are of great concern to a pilot during day and night flying periods. At night, these man made hazards are marked with bright red lights that are installed vertically on each side of these towers. Radio and TV towers higher than 1000 feet are often equipped with a large white flashing strobe light that is mounted on top of the tower.

Moonlight and More Night Flying Techniques

The moon is a important factor to consider when planning a night navigation route. The bright light emanating from a full moon can enhance the pilot's ability to navigate. On bright moon lit nights, there is sufficient light to navigate visually. Most of the objects on the ground are clearly visible.

In contrast, the brightness of a low angle setting sun has an adverse effect on a pilot's forward visibility. It can significantly hinder the ability to see clearly and to navigate. A bright sun shining in a pilot's eyes is also an annoyance. A good pair of sunglasses can be used to protect the eyes when it is necessary to navigate into the brightness of a setting sun.

Shadowing is another unique problem associated with a low sun angle. In mountainous regions, shadowing is a potentially dangerous problem. High terrain in the distance can block the low angle lighting of the sun. As a result dark shadowy regions are created, making navigation difficult in terms of obstacle avoidance.

Another dangerous scenario associated with shadowing is a case where a distant ridgeline can mask in its shadow a ridgeline that is closer and less prominent. A pilot who is unaware of this phenomenon may experience an unexpected and potentially close encounter with the ground while flying over the hidden ridgeline. Bright lights on the horizon are detrimental to the preservation of night vision. When flying at night pilots should avoid looking directly at bright lights for an extended period of time.

When flying at night it is essential for a pilot to have a flashlight in the cockpit that is easily accessible. A flashlight is essential in the event of an electrical malfunction. In the rare instances where an electrical failure occurs in an aircraft, darkness will envelop the cockpit. Many crucial instruments will be lost due to the lack of power. A flashlight is an important contingency for this unlikely occurrence.

Many daytime navigation techniques are useful at night. Prior to departure it is important to compute and plot flight information on a navigation chart for the route of flight. Data such as an estimated time enroute, the magnetic heading and distance between checkpoints is essential for accurate navigation. Night navigation routes must be planned to take advantage of "limiting features" on each leg of the flight. "Limiting features" are distinctive landmarks and recognizable terrain features that are clearly visible from the air. They are selected based on ease of use. A limiting feature is ideally linear in nature. Two lane highways and irrigation canals make excellent limiting features.

A limiting feature is a distinctive landmark that is located just beyond a designated checkpoint on the route of flight. In the event that the checkpoint is inadvertently overflown, the "limiting feature" serves as a valuable warning to the pilot. Limiting features alert a pilot when a course reversal should be initiated or if a course correction must be made, in the event that the pilot opts to continue on to the next checkpoint.

Special Use Airspace

An important part of navigation is the ability to avoid areas that have restrictions to flight. Controlled airspace is depicted on both VFR and IFR charts. The various types of controlled airspace include Restricted Areas, Prohibited Areas, Warning Areas, Military Operating Areas and Wildlife Areas. Controlled airspace exists for a variety of reasons. Many of the operations that are conducted within these areas involve dangerous activities that are potentially harmful to non-participating aircraft.

Restricted Areas

A restricted area is a designated airspace where aviation weapons delivery missions, air combat engagements and missile test firings take place. Ground based weapon systems may also fire at targets in a Restricted Area. The trajectory of the munitions passing through the air creates a dangerous situation for any unsuspecting pilot. As a result the airspace is restricted from use by general aviation. Aircraft not under positive radar control in a restricted area are not authorized to fly within a restricted area. A restricted airspace protects an aircraft from physical harm. It is a pilot's responsibility to remain clear of all active restricted areas.

Prohibited Areas

A prohibited area consists of airspace where flight is strictly forbidden. A high level clearance is required to enter prohibited airspace. Prohibited areas are designed to protect installations that are essential for national security such as the Congress, the White House and select industrial production facilities.

Warning Areas

Warning areas are located offshore. A warning area like a restricted area protects pilots from potentially dangerous activities. For example, naval vessels or military aircraft may be firing weapon systems within the confines of a Warning Area. The difference between a Restricted Area and a Warning Area is that Warning Areas extend out over international waters and their use cannot be as strictly controlled.

Military Operating Areas (MOA's)

A Military Operating Areas or MOA is a designated airspace where extensive military flight activities are conducted. See and avoid rules apply to participating aircraft and they are responsible for their own separation. Non-participating aircraft are highly encouraged to remain clear of MOA's due to the high concentration of military aircraft. The fast pace of Air Combat Maneuvering is an unfriendly environment for an unsuspecting pilot who flies into the middle of a high speed, high angle of bank, engagement. Locations adjacent to sites where a large number of military aircraft train are often designated as Alert Areas. A pilot who elects to fly through an Alert Area must be vigilant and aware. A high volume of traffic transits through an Alert Area, on their way to and from an operating MOA.

Wildlife Areas

Pilots are restricted from flying at low level altitudes over designated Wildlife Areas. Wildlife Areas should be flown over with a vertical distance of two thousand feet AGL. The airspace serves as a buffer and it is designed to protect wildlife. Wildlife Areas are typically found along coastal and flyway regions where migratory birds are prevalent. The airspace protects nesting sites and locations where rare species are present.

Restricted areas, Prohibited areas, MOA's and Warning areas are all depicted on the VFR Sectional charts. A discreet radio frequency is assigned for pilots to determine the status of these areas and to obtain a clearance for flight within this airspace.

Global Positioning Systems (GPS)

Navigating with a map by referencing key terrain features on the ground is a skill that all pilots must master. It is essential for a pilot to keep up with the exact position of their aircraft as it moves over the ground. In many cases cockpit instruments are very beneficial in providing detailed navigation and present position information to the pilot. A navigational system of great value to a pilot is the Global Positioning System or GPS.

The Global Positioning System is a satellite based navigation system designed and launched by the United States military. GPS satellites are situated in outer space and they provide pilots with very accurate, continuously updated, latitude and longitude information. The GPS system was launched in the 80's and a variety of these satellites were put into space. These satellites are capable of transmitting a continuous, discreet signal that can be detected by a functional GPS receiver.

A GPS receiver receives discreet signals from every GPS satellite that is in range of the receiver. In order for a GPS receiver to function properly, it must receive a signal from a minimum of three satellites. Using this information, the GPS can determine its exact location by processing the signals and computing the direction and distance they came from. GPS receivers are used to provide a pilot with a current latitude/longitude position and to compute heading and distance to other locations.

For example, a pilot can program the coordinates of a destination airfield into the GPS receiver. While enroute, heading and distance information will be continuously updated and displayed on the GPS screen. In addition to heading and distance information, ground speed and time enroute information is also computed.

A pilot can obtain crucial navigation information from a GPS receiver by selecting the "present position" setting. In this configuration, it provides the pilot with a continuously updated listing of the aircraft's current latitude and longitude.

Certain types of aircraft have moving map display systems installed in their cockpit. A moving map display combines map symbology with an aircraft icon that is superimposed over a map. To navigate, the pilot simply notes the position of the icon in relation to a map that moves.

GPS technology reduces pilot workload and provides a variety of important benefits. The GPS can compute and display a crosswind component. The receiver provides corrected headings for a pilot to fly in order to maintain a proper track across the ground. The accuracy of GPS is invaluable for eliminating navigation errors and saving fuel. With a GPS receiver, a pilot can fly on a direct course over a very long distance and still stay on course.

A GPS in the cockpit can be programmed with the location of a variety of airfields. These pre-programmed airfields can serve as valuable diverts in the event of bad weather at a destination airfield. Precise heading and distance information to an alternate is crucial when a missed approach must be executed. The estimated time enroute and ground speed to the designated alternate airfield is automatically computed by the GPS system. Precise ground speed computations are very important when determining fuel requirements to the alternate. A GPS lets pilots quickly evaluate the feasibility of several alternates and choose the one that is best suited for their current situation.

GPS is a technology that came of age and quickly matured during the Gulf War in Kuwait. Many ground and aviation units utilized GPS as a reliable source of information to determine present position, avoid obstacles, generate targeting information and establish rendezvous points. During desert operations there are few distinct terrain features of any significance. Navigation is very difficult and GPS systems helped to fill a void. They created a reliable way of generating definitive electronic checkpoints and they provide for more reliable methods of navigation.

GPS systems are also available to civilians. Some of the more recent GPS systems for sale include moving map displays for automobiles and navigational guidance systems for ships on the open seas. Hand held GPS receivers are available for outdoorsmen who frequently go on fishing, hunting and boating excursions.

Instrument Flight Navigation

IFR flight involves the use of different systems for navigation. When flying in the clouds a pilot cannot reference the terrain for navigation purposes. Therefore navigation must be conducted by using various flight instruments in the cockpit. The Federal Airways System was designed for this purpose. An airway resembles a highway in the sky. Pilots can navigate safely along an airway under IFR flight conditions by utilizing published IFR navigation charts.

The Federal Airways System originated in the early 1920's, when a visual navigation system was designed for pilots who were required to fly over remote stretches of land at night. Large bonfires were built along the way in order to illuminate the proper route of flight. Through the darkness a bright flame was visible by the pilot. These fiery markers served as welcome reference points that lead the pilots to their destination. Extended flights at night became a safer proposition once this system was put into place.

Over a period of time fires were replaced by light beacons, and the beacons were eventually replaced by an electronic navigation system. The advantage that an electronic system has over a visual one is the fact that the pilot can fly and navigate without any ground reference. The difference is that a radio beacon emits an electronic signal instead of visible light.

Instrument equipped aircraft flying at altitude use these navigation signals to navigate accurately. Modern day electronic stations are called navigational aids or NAVAIDs. The function of a NAVAID is to transmit three hundred and sixty discreet signals. Each signal is called a "radial". Radials are equivalent to the headings on a compass and the signal pattern created by a NAVAID station resembles the spokes on a wheel. The 360 radials that scribe a full circle around the station can serve as a potential highway on the modern day airways system. IFR aircraft navigate on radials by proceeding from one NAVAID station to the next. The ability of an aircraft to receive a specific navigation signal is based on several factors that include, the height of the terrain surrounding the NAVAID and the height of an aircraft above the ground, the type of electronic equipment installed in the aircraft and the signal strength.

Various instruments are used in the cockpit when navigating on an IFR flight. These instruments provide important information about the relative position of the aircraft from a NAVAID. An aircraft's position is determined in the cockpit with a gage that depicts what radial the aircraft is on. In some cases, the same instrument reveals how far the airplane is from the NAVAID station.

One type of instrument that is used to express this information is called an RMI or Radio Magnetic Indicator. The RMI is designed with a rotating compass disc mounted on the face of the gage. The disc is marked on its outer edge with 360 degrees of compass headings. The RMI card has a rotating compass indicating system that continuously displays the aircraft's magnetic heading.

The heading of the aircraft is indicated by a fixed indexer that is located at the top of the RMI gage. The fixed indexer indicates present heading when the aircraft is straight and level. When the aircraft is in a turn the RMI card turns spins beneath the fixed indexer. The rate that the compass card spins is based on the aircraft's angle of bank. At a greater angle of bank the compass card will turn faster. Refer to Figure (8) for an illustration of an RMI gage.

The navigation needle is another important component of the RMI gage. The navigation needle is mounted directly above the RMI compass card. The navigation needle is designed to continuously points toward any NAVAID that is tuned into the receiver. In order for a pilot to fly directly to a NAVAID, the pilot turns the aircraft so that the head of the needle is aligned with the fixed indexer on the top of the gage.

The basis for IFR navigation is built on this concept. In terms of a real world example, a pilot may be instructed by approach control to proceed directly to an assigned NAVAID. The aircraft is turned in the shortest direction so that the head of the needle is positioned underneath the fixed indexer. When the two are aligned the aircraft will be proceeding toward the selected NAVAID station. Keep in mind that this heading is a "no wind" heading and there are no corrections for wind. A crosswind component will affect the course of the aircraft as it flies toward the NAVAID. The movement is detected when the navigation needle drifts out and moves away from the fixed indexer.

Wind affects the track of an aircraft over the ground. In the case of a crosswind the pilot must compensate by flying the aircraft into the wind. This correction is known as a "crab". A crab is designed to keep the aircraft on course. To initiate a crab the aircraft is turned into the wind so that an offset heading can be flown. The proper ground track is maintained by pointing the nose of the aircraft into the force of the crosswind.

To determine what radial the aircraft is on, simply references the tail of the navigation needle. The tail of the needle represents the actual position of the aircraft in relation to the station. The following is an example of how a pilot will use the tail of the needle to accurately navigate. Let's assume that an aircraft is located southeast of a NAVAID on the one five zero degree (150) radial. In this example, we will say that the pilot is flying from south to north and will pass the NAVAID to the east. As you can see, the aircraft is not heading directly toward the NAVAID. The RMI gage will indicate a northerly heading of three six zero degrees (360). As the aircraft flies north, the tail of the needle will rise and move through the one five zero degree (150) radial, past the zero nine zero (090)degree radial and up through the zero three zero (030) degree radial and so forth.

Refer to Figure (9) to help alleviate any confusion that may arise from these examples. The tail of the needle indicates an aircraft's present position. The head of the needle indicates where the NAVAID station is located in relation to the aircraft. There are many moving parts to an RMI gage. All of the moving parts in an RMI gage provides a pilot with essential information that helps to make navigation easier.

A Crosswinds Effect on Navigation

A crosswind is a lateral force that influences the heading of an aircraft. To determine if a crosswind component exists, a pilot maintains a no wind heading and notes any drift on the navigation needle. Drift occurs when the tail of the needle moves away from a designated radial. Wind may exist but it may not affect the aircraft laterally. A direct headwind or tailwind will increase or decrease an aircraft's rate of travel over the ground but it will not cause any lateral drift.

A crosswind component is displayed when the navigation needle drifts away from the desired radial. The rate of displacement is used to determine the strength of the crosswind component. Corrections for drift are intended to place the aircraft back on the designated radial. Once the aircraft is back on track some of the initial crab must be taken out. If it is not reduced, the airplane will fly through the radial and overshoot to the other side of the course line.

For example, if the pilot is instructed to fly inbound to the NAVAID, on the zero nine zero (090) degree radial and the tail of the needle begins drifting upward toward the zero eight five (085) degree radial, a crosswind is blowing from the south. The wind is pushing the aircraft sideways, from south to north.

In another example, the pilot notes that the tail of the needle is moving from the zero nine zero (090) degree radial toward the zero nine five (095) degree radial. In this case the crosswind is blowing from north to south.

Refer to Figure (10) to review how a crosswind effects the ground track of the aircraft and how a crab is used to overcome unwanted drift.

IFR navigation is conducted by employing instrument flight techniques. Navigation stations located around the world serve as the foundation for this method of travel. After takeoff, a pilot intercepts an assigned radial and flies outbound to a specific point along the route. At that point, the next NAVAID station is tuned in. The needle on the RMI swings around and begins pointing to the new NAVAID station that is located in front of the aircraft. The head of the needle is used to navigate along that radial and to maintain a proper ground track. When the aircraft passes over the next NAVAID station, the navigation needle spins around for 180 degrees and the pilot navigates outbound, using the tail of the needle.

In addition to heading (azimuth) information, several navigation receivers are capable of providing distance information. Distance is displayed on the RMI gage as well. Distance Measuring Equipment, known as DME works by transmitting a signal from the aircraft to a NAVAID station. The station immediately responds to the query by sending a return signal back to the aircraft. Distance from the station is determined by measuring the time that it takes for the signal to travel from the aircraft to the NAVAID and back to the aircraft. DME is expressed in nautical miles. A nautical miles is eight hundred feet longer than a statute mile (6080 feet vice 5,280 feet). DME is a very useful way to determine the exact position of an aircraft in relation to a NAVAID station.

IFR Charts

The Federal Airways System uses radials to connect one NAVAID station with another. IFR enroute charts and pilot Jepson Manuals depict published airways segments along with pertinent information such as NAVAID frequencies, minimum enroute altitudes, intersections and divert airfields. Refer to Figure (11) for a sample IFR chart.

Information provided on IFR charts is useful during preflight planning and while airborne. An IFR chart displays mileage for each flight segment. Total mileage between NAVAIDs is depicted in a box that is located next to the radial that defines the airway. An airway is the segment between two NAVAID stations. Intersections are also depicted on IFR charts. An intersection is a point in space where two or more airways cross. Intersections are labeled with five letter names. An example of the name of an intersection is "RAVEN" intersection.

Civilian and military IFR Charts depict separate high and a low altitude route structures. The low altitude IFR enroute charts are more detailed and depict a much smaller area over the ground. More airfields and NAVAIDS are also displayed on a low altitude chart. The Federal Airways System is divided into two parts. The first part is the Low Altitude Airways System. Altitudes in the Low Altitude Airways System are separated in increments of one thousand feet. For example, aircraft flying west to east are expected to file at odd altitudes, such as five thousand feet MSL, seven thousand feet MSL and so forth. Aircraft flying east to west are expected to file for even altitudes such as six thousand feet MSL or eight thousand feet MSL.

The low altitude Federal Airway System is contained within the airspace that extends from twelve hundred feet above the ground to eighteen thousand feet above sea level. Each route is labeled by with single letter followed by a one to three digit number. Low Altitude routes begin with the letter "V," followed by the route number, such as V123. The low altitude route structure is also referred to as the "Victor" airways.

Jet routes on the other hand are designed for high altitude operations. A typical route segment is longer and more direct. Jet routes are depicted on IFR High Altitude Charts. The high altitude route structure begins at eighteen thousand feet MSL and extends up to forty-five thousand feet MSL. Jet routes are labeled just like the low altitude system only the letter "J" replaces the letter "V". As an example, "J32" represents jet route 32. Assigned altitudes are called "Flight Levels".

IFR Clearance

Prior to taxiing, a pilot must request an enroute clearance. The clearance defines the expected route of flight based on information provided in the filed flight plan. A pilot is instructed by Air Traffic Control to fly a route specified in the enroute clearance. Clearances are built based on a computer analysis of the projected traffic along a route of flight. When Clearance Delivery reads the clearance information to the pilot, the pilot writes the information down and compares it with the filed flight plan. If the routing has changed, the pilot must reevaluate the effect of these changes and determine how they will impact fuel consumption and total time enroute. If there is a problem or there is insufficient fuel onboard the aircraft, the pilot must request an amended route of flight or the aircraft must be shut down in order to take on additional fuel. When a pilot is unsure of any portion of the clearance, the clearance must be read back so that any misunderstandings can be clarified.

Instrument Approaches

IFR instrument charts, instrument approach plates and navigation publications are carried by pilots during each flight. These navigation publications are updated regularly and provide detailed information on the procedures required to fly safely in IFR flight conditions. An instrument approach plate is like a road map in the sky. It depicts the altitudes that the pilot must fly and the courses that must be flown to get down to the runway.

Approaches are named after the navigational aid that is used during the approach. The magnetic heading of the runway is also included. For example, the VOR approach to runway 12 Right at Steamy Acres airfield utilizes a VOR as the navigational aid and terminates with a landing on runway 12 Right. The name of the approach is the "VOR12R" approach. The number 12 represents a magnetic heading of one hundred and twenty (120) degrees. The R represents the right runway at a 2 parallel runway airfield.

To minimize confusion, there are large white numbers painted on the approach end of each operational runway. These numbers indicate the magnetic heading of the runway and help a pilot verify from the air which one is the correct runway for landing. Closed runways have a series of large yellow X's painted down the center of the runway. These X's are painted along the entire length of the runway so that there can be no doubt that a landing should not be attempted unless the pilot is experiencing an emergency.

Approach plates depict important information in order for a pilot to make a safe letdown to a landing. The information is presented in a variety of ways. A birds eye view and a cross sectional view of the approach are both on the approach plate. The pilot uses these two profiles to navigate the aircraft along a winding, descending, invisible path to a safe landing. Occasionally an instrument approach must be flown in the clouds, down to approach minimums for the runway in use. Information such as segment altitudes, authorized descent points, the final approach course and the missed approach point are all included on the approach plate. Refer to Figure (12) for an example of an actual approach plate.

Additional information normally displayed on an approach plate includes the airport elevation, runway length, weather minimums and the runway layout. Before commencing an approach, a pilot must be very familiar with the entire procedure. Deviation from any published altitudes or headings must be carefully avoided unless these variances are approved by approach control.

During periods of inclement weather it is even more essential for a pilot to comply with the published approach instructions. When aircraft are flying in clouds the pilots are unable to see and avoid other aircraft. Therefore air traffic controllers must provide sequencing and separation in a high density traffic area. The air traffic controller must constantly monitor all activity within their assigned sector and manage the flow of aircraft through their designated airspace. Controllers assist pilots by providing crucial navigational information and recommendations for severe weather avoidance.

Many large commercial aircraft have sophisticated navigation and instrument landing systems that provide for the capability to land in thick fog. Vertical and horizontal visibility is a critical consideration during the landing phase of a flight. On the final portion of an instrument approach, the pilot must be able to break out of the clouds and visually acquire the runway. Sometimes, this has to be accomplished in a relatively short period of time. Runway centerline lights are helpful for a pilot. They serve as a reference in order to help keep the aircraft properly aligned with the middle of the runway. Large white center line stripes are also painted down the runway. During periods of low visibility and at night, the white centerline lights are lit. They also help a pilot properly distinguish a runway from other visual illusions such as a brightly lit highway.

Sophisticated onboard computers and navigation equipment provide a pilot with the capability to land a large commercial aircraft without touching the flight controls. During a coupled approach, the flight controls are moved by the autopilot. An autopilot relieves the pilot of excessive workload during certain phases of flight. When an aircraft is under the control of an autopilot, it will maintain an assigned heading, airspeed and altitude. The autopilot provides aural and visual warning during climbs and descents as the aircraft approaches an assigned altitude. An autopilot automatically adjusts power in order to level the aircraft at an assigned altitude.

Many commercial and military aircraft can be flown by an autopilot to touchdown. Category 1, 2 and 3 approaches are conducted utilizing an Instrument Landing System (ILS). An ILS is a type of instrument approach that is designed to bring an aircraft down on a glidepath to landing. The ILS approach equipment is physically located at the approach end of the runway. The ILS emits an electronic glidepath signal that is aligned with the intended point of landing. The electronic signal is detected by a receiver in the aircraft. The signal is interpreted and the navigation information is displayed on a gage in the cockpit. The gage has two crosshairs that are used to depict whether an aircraft is above or below the glidepath and right or left of the final approach course.

Figure (13) is an example of what a basic ILS display looks like in the cockpit. An ILS approach is very sensitive to corrections, particularity when in close to the runway. The reason for this is the fact that an ILS signal resembles a very large flashlight beam. As the electronic beam travels further away from its source, the signal gets wider. The beam narrows in close to the landing area. It is more sensitive to heading or altitude deviations. Deliberate and timely flight control inputs are necessary in order to remain on course all the way to touchdown.

In many cases, the autopilot is used to keep the aircraft on the glidepath. During the final phase of a coupled instrument approach, all of the flight controls are managed by a computer. The airplane is flown down the glidepath and across the approach end of the runway. During the landing phase, the nose of the aircraft is raised and a flare is established. In quick succession, the throttles are reduced to idle and the aircraft touches down on the runway.

As the aircraft rolls out on the runway it decelerates to a complete stop. For the majority of instrument approaches that are flown, the pilot retains control of the aircraft throughout the entire approach and landing. In a case where weather conditions are poor an automatic approach is a useful option.

Poor weather will usually cause significant delays at major airports. Under IFR flight conditions, a pilot is not able to reference the ground for navigation purposes. Instead, the flight instruments must be used to position the aircraft for an approach. Air traffic controllers provide assistance by sequencing each aircraft so that they are properly established on the final approach course. Added separation between aircraft is necessary when the weather is poor. Increased distance between aircraft and longer time intervals between each landing are major reasons for these types of delays.

Cockpit Instruments

A variety of cockpit instruments are utilized when flying under instrument flight conditions. These instruments provide important information that is used by the pilot to obtain a more complete picture. Many instruments work in unison with one another and convey similar data. For example, a climb or a descent is depicted on both the altimeter and on a gage called the VSI while the altimeter measures an aircraft's altitude above mean sea level. The more sensitive VSI is used to detect subtle altitude deviations.

The VSI detects vertical movement of an aircraft in feet per minute. The gage contains a horizontal needle that pivots above and below a horizontal index line. A graduated scale is used to indicate the rate of a climb or descent. Both the VSI and the altimeter provide the same information but the VSI is very sensitive and more responsive to vertical movement. Therefore the first indication of a climb or a descent will be detected by the VSI.

Another valuable instrument that is used more frequently than any other is the artificial horizon. The artificial horizon is also referred to as an attitude gyro. This gage provides a real time display of an aircraft's nose attitude and angle of bank in relation to the horizon. When a pilot is flying on instruments the attitude gyro will indicate if an aircraft is climbing, descending, turning left or turning right. Any changes associated with maneuvering flight are immediately displayed on an attitude gyro.

Cockpit instruments must be used in conjunction with one another. Deviations are detected by cross referencing several gages and analyzing all of the information. By itself, an airspeed indicator will show how fast an aircraft is traveling and whether or not it is accelerating or decelerating. If a pilot detects an increase in airspeed, it may be caused by one of two things, an addition of power or a nose low descent. To differentiate between the two, the pilot must cross-reference other gages in the cockpit. In the case of a level acceleration, the pilot would notice a higher power setting on the engine RPM gage and a stable altimeter reading. In the case of a nose low descent, power on the engines would be constant but the altimeter and the VSI would reveal an altitude loss. A good instrument scan combined with an understanding of what each instrument is saying is an essential part of what it takes to fly an aircraft in IFR conditions.

Pitot Static System

A variety of instruments in the cockpit display information based on inputs from the pitot static system. The pitot static system compares dynamic air pressure with the static air pressure of the atmosphere. Ram air is taken into the pitot system through a long pipe called a "pitot tube." The hollow tapered probe extends out into the windstream and scoops the air in for measurement. An air port located along side the aircraft measures static air pressure. The pressure differential is expressed in the cockpit on the airspeed indicator, the VSI and the barometric altimeter.

Holding

When weather around a major airport deteriorates, arriving and departing aircraft experience delays. The vectoring and sequencing requirements for an instrument approach are extensive and the elapsed time between landings may be significantly increased. As a result, many pilots are often required to hold enroute to their destination airport. Holding is a way for ATC to manage a high volume of traffic when many aircraft are converging on the same location from several directions. If instructed to hold, each pilot is assigned an altitude and a block of airspace where the holding turns can be conducted. The holding pattern is shaped like an elongated oval that resembles a racetrack in the sky. Figure (14) depicts and example of a holding pattern on an IFR Enroute Navigational Chart.

Before entering holding, a pilot must slow the aircraft to an appropriate holding airspeed. Excessive airspeed creates a wider pattern and increases the radius of turn. Slower airspeeds keep the aircraft within the confines of the assigned holding airspace and help to conserve fuel.

Holding is not a common occurrence. On most flights, the pilot will takeoff, climb, proceed directly to the destination airfield, descend and land. As the aircraft approaches the intended point of landing, the pilot descends with the guidance of radar vectors from approach control. Nearing the airport, the final controller provides heading information and traffic avoidance calls to the pilot. The pilot is given vectors to the final approach course for a self contained ILS final approach. If the weather is marginal, holding may be required in order to establish the proper sequence for arriving aircraft. When a pilot is assigned a holding clearance, fuel consumption must be closely monitored to ensure that sufficient fuel is available for an instrument approach and landing. A pilot must also have a contingency plan for proceeding to an alternate airport if the weather is close to approach minimums. When holding is assigned, a pilot should check the weather at the destination and alternate airfields in order to get a better perspective of the situation and to request priority handling if required.

CHAPTER V - THE LANDING PHASE

Automated Terminal Information System(ATIS)

The Automated Terminal Information System or (ATIS) is a continuous loop recording that gives the pilot a concise summary of the weather and the runway conditions at an airport. ATIS information is usually broadcast on either a VHF and/or UHF frequency. The recording is updated hourly. Rapidly changing weather conditions dictate more frequent updates. After a pilot selects the ATIS frequency, information such as wind direction, altimeter settings, temperature, dew point, pressure altitude and the active runway can be heard over the radio. Additional information includes special conditions at the airfield such as a closed taxiway, an alternate taxi route or any temporary obstacles located on the airfield.

An ATIS broadcast is identified by a sequentially assigned letter that can be heard on each recording. Ceiling and visibility information is provided so that existing conditions can be compared with allowable approach minimums. ATIS information also gives a pilot the current landing and departure runways. ATIS reduces the amount of talking that a controller is required to do over the approach control frequency. Another advantage derived by listening to ATIS while airborne is the fact that a pilot has sufficient time to study the approach procedures for the runway in use.

Landing

A successful flight must always be culminated with a safe landing. Prior to the landing however, a pilot must properly configure the aircraft. The type of landing that can be made is limited by the structural capabilities of the aircraft. For example, a Navy carrier pilot can land an aircraft on the pitching deck of an aircraft carrier. The approach dictates a sustained five hundred foot per minute rate of descent all the way to touchdown. As the tailhook of the aircraft engages the cable, the aircraft is jerked to a violent stop. In contrast, this landing technique is ill advised in a commercial airliner. A five hundred foot per minute rate of descent would provide for a very colorful landing. The pilot of that ill-fated aircraft would surely face the wrath of many distraught passengers as they exit the aircraft. In addition, the embarrassed pilot would have to explain to the chief pilot how four flat tires and two scraped wing tips appeared on one of his aircraft. It is obvious that large passenger aircraft are designed for gentle landings on long runways.

No matter what type of landing a pilot decides to use, the most important factor is a precise and stable descent on the glidepath all the way down to landing. The aircraft must also be properly configured well in advance of the landing. The landing gear must be down and locked, the flaps must be set in their proper position and the spoilers must be armed for deployment. (Spoilers are large metal panels located on the top of each wing. They are hydraulically raised into the wind stream after the main landing gear has come in contact with the runway. Spoilers are designed to dissipate lift on a wing).

Speed Brake Employment

Tactical jet aircraft have speed brakes incorporated into their design. Speed brakes are large metal panels that are extended in flight. Speed brakes are hydraulically operated and they are designed to create additional drag on an airplane. As a result of this drag, a much higher power setting is required on the engines in order to maintain the same rate of descent during an approach. Jet engines are more responsive at higher power settings therefore speed brakes help to keep these engines "spooled up" and ready to respond quickly to power demands.

A speed brake significantly increases parasite drag on an aircraft. When an engine runs at a higher RPM it is ready in the event that a waveoff is required. When a pilot is instructed by the control tower to "Go Around", the speed brakes are immediately retracted and full power is applied to the engines. The immediate reduction in parasite drag combined with the added thrust generated by engines is a very effective way to lift an aircraft off of the runway, away from a potentially dangerous situation.

Landing Checklists

Prior to landing, a pilot must complete the landing checklist. A landing checklist contains important items that must be verified before touchdown. Several items found on a landing checklist include: landing gear position, flap settings, a landing clearance and a final check of the flight instruments. Of obvious importance to a pilot is the landing gear. The landing gear must be lowered and cross-checked to ensure that it is actually "down and locked". A gear position indicator is located on the instrument console. It is used to verify whether the main landing gear and the nose gear are up, in transit, or down.

Several different methods are used to display gear position. For example, red and green lights are used or picture symbols can be used to represent the physical location of the wheels. The word "UP" is used to indicate when the landing gear is up and locked. A "barber pole" symbol means that the gear is in transit or it is unsafe. A tire tread symbolically represents a "down and locked" condition.

Another important checklist item is the requirement to verify the position of the flaps. A flap handle is used to raise and lower the flaps. The flap position gage indicates the degree of flap extension. Half flaps are normally used for takeoff while full flaps are selected for landing. In the event that an electrical problem occurs, the flap indicating system may be inoperative. In this case, a pilot can visually inspect the position of the flaps and the landing gear. If the pilot is unable to observe gear and flaps due to cockpit design the other option is to make a low pass down the runway so that someone on the ground can visual inspect their position.

Engine and flight instruments are also checked for abnormalities prior to landing. System problems must be identified early in the landing sequence. A problem discovered during the final phase of flight is more difficult to deal with because of the many things that must be accomplished just prior to landing.

The aircraft's final approach airspeed must be computed and set on an airspeed indicator. This is done by rotating a knob that moves a pointer called the "bug" around the edge of the airspeed indicator. An aircraft's final approach speed is calculated based on variables that include the weight of the aircraft, the outside air temperature, and the specific flap setting that is used for the approach.

Military pilots often use an Angle of Attack system for landing. The Angle of Attack system consists of an Angle of Attack gage and an Angle of Attack Indexer. The Angle of Attack Gage displays the aircraft's Angle of Attack in terms of "units". The AOA indexer is a vertical display of three lights that represent three airspeed conditions. The AOA indexer is mounted on the dash of the aircraft in plain view of the pilots scan.

Prior to landing, the pilot computes the proper AOA in units based on the plane's weight and the flap setting of the aircraft. The AOA Indexer is also used to determine if an aircraft is fast, onspeed or slow during an approach to landing. An amber colored circle illuminates when the aircraft is flying "onspeed". Mounted above the onspeed donut is an inverted chevron that is red in color. If the aircraft is slow it will illuminate. In contrast, a green chevron is mounted below the onspeed symbol. If the green chevron is illuminated, the pilot is flying a fast approach.

The AOA system is used when practicing or executing carrier landings. Angle of Attack is a very critical factor during shipboard landings. An extremely nose high approach prior to touchdown can inadvertently cause the tailhook to engage the arresting wire while the aircraft is still airborne. At another extreme, a nose low attitude or a "flat" approach can contribute to a hook skip. When a tail hook skips, it simply bounces off the flight deck. A "bolter" usually follows since the tailhook has failed to engage the wire. In the event of a bolter, a pilot's proper response is to immediately retract the speed brakes and push the throttles to military power. This critical response will ensure that the aircraft continues to fly as it races off the end of the flight deck and out over the water.

Another important checklist item is the landing light. Landing lights are used for collision avoidance during the day and are essential at night in order to observe the runway environment. Landing lights are also an important asset when taxiing around in the dark. They can be used to identify any obstacles and check the condition of the taxiway.

During final approach, the pilot must line the aircraft up with the runway centerline. In the process, it is important for the pilot to maintain the proper approach speed and rate of descent. A straight in approach begins by reducing power with the throttles. The rate of descent is controlled with power and any airspeed deviations are corrected by adjusting the nose attitude. The glide path is flown all the way to touchdown and the pilot should seek to land on the first thousand feet of the runway.

A proper approach speed is critical for landing. Approaches that are flown below "onspeed" may experience flight control problems. At slower airspeeds the airflow across the ailerons, elevator and rudder is reduced. On a slow approach the control surfaces must be displaced further into the wind stream in order to create the necessary aerodynamic changes. Large aileron inputs near stall speed have an adverse effect on controllability. On the other hand, an approach that is flown at higher than normal speeds carries with it surplus energy that must be dissipated on the runway. A longer rollout and warm brakes are symptomatic of a "hot approach". A firmer landing is also likely during a fast approach since the pilot must get the aircraft on the ground expeditiously in order to begin braking.

Hot brakes are dangerous since they can damage the wheels and in some instances can lead to a fire. In a worse case scenario, an excessively fast approach while landing can result in an even more exciting scenario. The pilot may not be able to stop the airplane before it reaches the end of the runway. In this case, there are few options left for a pilot but to watch helplessly as the aircraft rolls off the runway and onto the grassy overrun.

Of particular concern to a pilot during landing is the condition of the runway. A wet or icy runway can significantly increase landing distance. Braking action is dramatically reduced on an icy surface. In heavy rains hydroplaning tires have little or no contact with the ground. A tire will ride up on top of pooled water, much like a water skier as they ski across the surface of a lake. In this situation, the tire tread cannot grip the runway and insufficient braking action is available. In preparation for landing under adverse conditions, a pilot must plan to fly an approach that is not excessively fast. The use of judicious braking is also essential on a wet runway.

One unique and effective way to minimize landing rollout while landing an aircraft is through the use of an arresting system. A tailhook provides a pilot with a safe and effective way to stop a tactical aircraft in a very short distance. The thick arresting cable is deployed across the approach end of a runway. The "wire" is scooped up by an extended tailhook and is dragged down the runway. It is deployed from a spool and causes the aircraft to come to a very abrupt stop.

In contrast to a tactical jet a tail hook is not a practical device for a large commercial airliner. The rapid deceleration associated with an arrested landing would dramatically affect the physical well-being of each passenger. In addition the airline would have to pay many dry cleaning bills and deal with numerous cancellations for the return flight.

Commercial airplanes however have been designed with a system that will expeditiously decelerate the aircraft after it has landed on the runway. Thrust reversers are incorporated into the engines of large and midsize aircraft. The purpose of the thrust reverser is to redirect the flow of hot exhaust gasses forward so that the energy can be used to slow the airplane quickly during the landing rollout. When the thrust reverser system is activated, large clamshell doors swing open, blocking the exhaust pipes on each engine. The redirected energy creates a powerful decelerating force. Thrust reversers minimize the requirement for heavy brake application during rollout.

Snow or slush on a runway requires special attention during the landing phase. Actuators for the landing gear and the wing flaps can become frozen if sleet or moist snow accumulates up in these recessed compartments. When an airplane has landed in deep snow or heavy slush it must be inspected for frozen deposits prior to the next takeoff.

Certain aircraft are designed to land in unique environments. As we have seen, a pilot landing on an aircraft carrier must land with precision. The aircraft is not flared or decelerated at the bottom of the approach. Instead, it is driven onto the flight deck by maintaining a proper attitude and a constant rate of descent. A carrier approach requires precise control inputs all the way to touchdown. There is little margin for error during the landing phase due to the close quarters associated with a flight deck. A carrier landing becomes even more exciting when combined with an inflight emergency on a dark and stormy night.

Another example of extreme landing conditions is a situation where a pilot must land a large aircraft on a short runway in a mountainous region. This process can be challenging and requires excellent flying skills so that a safe and expeditious landing can be achieved. The combination of three adverse conditions can significantly extend both landing and takeoff distances in this environment.

High altitude, high temperatures and high humidity are all detrimental to the performance of any aircraft. At higher altitudes, the atmosphere is thinner and there are fewer air molecules available to generate thrust. Hot temperatures and very humid weather can make the situation even worse. Warm moist air is less dense and less capable of generating lift. Higher temperatures increase the molecular activity in the atmosphere and decrease the density of the air. The end result is a diminished aerodynamic state. Many commercial airports located in higher elevations must compensate for "high, hot and humid" conditions in the summer by maintaining longer runways and limiting takeoff weight.

Landing on short runways at high altitudes provides little margin for error. An expeditious touchdown is important. The first priority for a pilot is to land the aircraft in the first thousand feet of runway. By landing in a timely manner a pilot can take full advantage of plenty of runway. If an aircraft floats down the runway, consideration should be given for a "Go Around." An early waveoff is prudent to ensure that there is sufficient runway available to become safely airborne again. The pilot may pay an expensive price if indecision is a part of the equation. Failure to execute a timely waveoff can lead to a rough ride through a field of dark green alfalfa.

The Wave Off

In some instances an aircraft on final approach must execute a "wave off" or a "go around." A waveoff must be initiated if a conflict exists that could possibly prevent a safe landing. There are many reasons why a pilot should waveoff. In the first instance a pilot may elect to add power and go around because the runway is not clear for landing. Or, the controller may instruct the pilot to initiate a wave off due to conflicting traffic. For example, an aircraft may be behind another aircraft that is on short final for landing. An insufficient interval may exist between the two airplanes.

In either case a pilot who is instructed to wave off must respond by adding power and climbing to an assigned altitude. Additional factors that contribute to a decision to waveoff include animals on the runway, unexpected conditions such as ice or rain. Strong crosswinds and an excessive rate of descent on final approach are other reasons why a pilot may opt to initiate a waveoff.

The Missed Approach

A waveoff during an instrument approach is called a missed approach. Published approach minimums for a runway determine how low a pilot can descend toward the runway. If the pilot flies down to the approach minimums and the runway environment is not in sight, or when a pilot breaks out of the clouds and discovers that the aircraft is not properly lined up with the landing runway a missed approach must be executed. The options are to attempt another approach or proceed directly to the alternate airfield for landing.

CHAPTER VI - THE SKY ABOVE

Aerobatic Flight

One of the more exciting aspects of aviation is the ability to conduct acrobatic maneuvers in an airplane. Aerobatic flight dates back to the early years of military aviation. Pilots who flew in combat developed certain strategies to improve their survivability. Air to air combat and low level, ordnance delivery missions required a series of techniques that helped a pilot to minimize his exposure to enemy fire. The pilot was expected to maneuver an aircraft in a precise manner, so as to accurately place bombs on target. During dogfights the successful pilot was the one who saw the enemy aircraft first and maneuvered his machine to gain the tactical advantage.

Aerobatic flight is comprised of a series of horizontal and vertical movements throughout a three dimensional world of space. Acrobatic maneuvers are either performed individually or tied together through the use of graceful transitions. The following information about acrobatics is provided so that the reader to can feel the tug of the shoulder straps, the grip of the seat and the swirling panorama of ground and sky.

Preparation for Aerobatics

Aerobatic aircraft must be structurally designed to withstand an inordinate amount of stress. The airplane must be capable of sustaining both positive and negative "g" forces. Many aircraft however are not designed to handle the rigors of aerobatic flight. For example, a large commercial airplane is built to fly in an upright attitude. All airplanes handle stress better while wings level. In this case all loads on the aircraft are imposed vertically. The pressure is more evenly distributed throughout the structure. Commercial aircraft rarely exceed forty-five degrees angle of bank in a turn, and the nose of these large planes are rarely raised more than thirty degrees above the horizon. Aerobatic maneuvers are rarely employed by commercial aircraft. They are used only when a pilot must respond immediately to a potentially dangerous situation.

A fully aerobatic airplane is manufactured to withstand the pressures associated with gravity and centrifugal force. The constant twisting and pulling of the fuselage demonstrates the need for strong structural components. To perform acrobatics an aircraft must be equipped with special equipment such as a reinforced shoulder harness, an inverted fuel tank system, an auto ignition system along with a great paint job. A properly fitted shoulder harness is essential in order to keep a pilot securely in position at all times. A strong, comfortable restraining system is important due to the unusual attitudes and the radical "g" forces that a pilot experiences during aerobatic maneuvering.

An inverted fuel tank provides a continuous and steady flow of fuel to the engine, even when the aircraft is being flown upside down. An inverted fuel tank prevents engine flameout caused by fuel starvation. With an inverted fuel system, the fuel is extracted from the top of the tank when the airplane is inverted and from the bottom of the tank when it is upright. A constant flow of fuel is assured regardless of the aircraft's attitude.

An aerobatic aircraft should also have an automatic ignition system that is activated before aerobatic maneuvers are performed. When the auto ignition system is turned on, it sends a series of electrical sparks to the combustion section of the engine. If a flameout occurs, sparks automatically ignite the fuel and restart the engine. Acrobatic airplanes must have wings that are structurally designed to withstand a large amount of lateral and vertical stress. The rapid transition from a high gravitational flight condition to an airy weightless is commonly experienced during an aerobatic sequence. Maneuvers performed by aerobatic airplanes are often practiced at higher altitudes and flown closer to the ground during air shows or flight demonstrations.

Before initiating an aerobatic maneuver, the acrobatic checklist must be completed. This checklist is unique to each aircraft. However, some of the more common checklist items include: "Loose Gear - Stowed," "Harness - Locked," "Engine Instruments - Normal," "Operating Area - Clear of Traffic."

A variety of aerobatic maneuvers can be flown by a pilot. Refer to the drawings in Figure (15) for each maneuver sequence. The following is a description and a summary of how these maneuvers are flown.

The Wingover

A wingover is an aerobatic maneuver designed to quickly reverse the course of an aircraft. On hundred and eighty degrees of heading change is accomplished during the wing over. A pilot starts a wingover by completing the acrobatic checklist and establishing the proper entry airspeed. A wingover is commenced with a nose high climb followed by a high angle of bank in the desired direction of turn. In the climb, the aircraft scribes a ninety degree arc through the horizon until accomplishing ninety degrees of heading change with ninety degrees angle of bank. The nose of the aircraft then passes through the horizon and the aircraft begins a descending turn back to its original entry altitude.

The following word picture helps visualize the smooth and flowing nature of a wing over.

"Soaring steadily upward, the aircraft arced gracefully in the summer air. Rising intently, the sleek machine was silhouetted against the backdrop of white billowy clouds. As the plane rose higher and higher it gradually succumbed to the steady pull gravitational force. Floating gracefully at the apex of its climb, the plane hung weightlessly as its nose rotated downward, slicing through the horizon. On the back side of the maneuver, the pilot pulled steadily on the stick as the aircraft simultaneously level its wings and rolled out a reciprocal heading."

The Aileron Roll

An aileron role is a basic acrobatic maneuver that allows a pilot to observe what is happening beneath the aircraft. The aileron roll is performed by initiating a three hundred and sixty degree roll about the aircraft's longitudinal axis. Before the maneuver is conducted, the pilot must complete the acrobatic checklist then raise the nose of the aircraft above the horizon. The control stick is pushed sharply to the left or right in order to establish a roll rate. As the aircraft rotates through the inverted position, the weight of the airplane and a corresponding loss of lift will cause the nose of the aircraft to drop back down toward the horizon. The aileron roll is complete when the aircraft is established in an upright, wings level attitude.

The Loop

A loop is a high "g" maneuver that is used to reverse course in a vertical climb. A loop is initiated after completing the acrobatic checklist. When the aircraft has achieved its prescribed entry airspeed, the pilot pulls firmly back on the stick and maintains a six "g" climbing attitude. During the early stages of a loop, it is important for the pilot to cross reference heading, airspeed and altitude. As the airplane climbs, it decelerates. The additional backstick pressure is required in order to maintain a constant six "g" pull. A "g" meter located in the cockpit is a useful gage that lets the pilot know how many "g's" are exerted on an aircraft. One "g" is equivalent to the weight that a pilot experiences while standing on the earth. Two "g's" are twice a man's weight and so forth.

Approaching the top of the climb, the aircraft assumes an inverted flight attitude. The pilot experiences both weightlessness and a great view of the world below. In order to remain visually oriented the pilot must drop his head backward and observe the ground beneath the aircraft. Small corrections should be made throughout the maneuver, by fine tuning the aircraft's attitude with stick and rudder deflections. As the aircraft rolls through the back side of the loop, it accelerates in a steep descent and races back toward the initial entry altitude. "G" loading increases as the pilot pulls back on the stick, trading altitude for airspeed in the descent.

High "g" forces can cause adverse physical effects on the human body. Some of the symptoms include difficulty in breathing, tunnel vision and in extreme cases a complete blackout. Under high "g" states, blood in the body is forced downward toward the lower extremities. The blood tends to pool in the legs and feet, creating a noticeable deficit as it rushes out of the brain. A "g" suit is designed to counter the negative effect of the high "g" forces. Pilots assigned to fly tactical military aircraft must wear "g" suits when they fly.

The "g" suit resembles long leggings that a cowboy uses when riding a horse. Large rubber bladders are installed within the fabric of the "G suit". These bladders are inflated by pressurized air, any time a pilot is subject to strong "g" forces. The pressure helps to push the blood that is pooled in the legs back up into the torso and the brain. To help minimize the adverse effects of "g" loading on the body, a pilot can also contract various stomach muscles by grunting. The additional muscle contractions help to minimize blood pooling and augment the positive effects of a "g" suit.

The Immelman

The Immelman was devised during the early stages of air combat maneuvering and it is an expeditious way to gain altitude. An Immelman is commenced by executing the first half of a loop. When the nose of the aircraft reaches a point that is twenty degrees above the horizon, a roll is initiated to an upright attitude. The Immelman is complete after the aircraft has gained several thousand feet of altitude and is wings level. The Immelman is used to quickly reverse course and climb swiftly away from any ground threat.

The One Half Cuban Eight

The One Half Cuban Eight is another maneuver that begins with the same entry procedures as a loop. The One Half Cuban Eight was developed during the early days of ordnance delivery. It was used to properly position an aircraft for bomb release over a target. The One Half Cuban Eight is also used to minimize an aircraft's exposure to small arms fire. It helps to protect the pilot and the aircraft during the entry into and latter stages of a bombing run. After completing the first half of a loop, the aircraft is flown through the inverted position and pulled backwards into a forty-five degree nose low descent. Once established, the aircraft is rolled upright and the dive is continued to the bomb release point.

The Barrel Roll

A Barrel Roll is a slow graceful maneuver that resembles its name. During a Barrel Roll, a pilot rolls and loops the aircraft as if it is being flown around the inside of a barrel. The pilot initiates a Barrel Roll by raising the nose of the aircraft in a climbing turn. The airplane is flown to an inverted position that is 90 degrees from the initial entry heading. The soaring climb carries the aircraft from level flight to a lofty inverted perch. Climb rate and roll rate are adjusted to ensure a smooth coordinated maneuver.

At the top of the Barrel Roll the pilot must pause in order to let the nose of the aircraft fall through the horizon. The maneuver is completed with a arcing descending turn as the aircraft returns to its original entry heading and altitude. A pilot can easily become disoriented during a barrel roll. Simultaneous movements about the vertical and the horizontal axis are very vertigo inducing.

In order to minimize the disorienting aspects of acrobatic flight, pilots frequently use the ground as a reference. Working areas with distinctive terrain features are selected so that a pilot can stay oriented throughout the maneuver. For example, a uniform row of fields bordered by dirt roads running north/south and east/west are excellent compass indicators. These linear terrain features are called "section lines" and they help a pilot to discern direction.

Acrobatic maneuvers are initiated by paralleling a section line. An aircraft's rate of turn is measured by the use of section lines. The nose of the aircraft is pulled across the horizon and measured against these linear checkpoints.

The Spin

A spin is caused by excessive flight control inputs during a stalled flight condition. To intentionally enter a spin a pilot commences a nose high climb and reduces the throttles to idle. As the airspeed decelerates through buffet and into a fully stalled flight condition, the rudder pedal is completely deflected in one direction while the stick is pulled aft and displaced laterally in the opposite direction. The end result is an aircraft that departs controlled flight in a yawing, spinning, high rate of descent.

Spins also occur unintentionally. During slow flight, an aircraft is always susceptible to loss of control. If excessive flight control inputs are applied at high Angle of Attack states, the aircraft may lose critical lifting forces and depart. Air Combat Maneuvering for example, involves a series of extreme flight attitudes. A smooth hand and a knowing eye are essential for success in this flight regime. Excessive aileron inputs during slow airspeed, nose high attitudes can quickly dissipate lift and propel an aircraft into a violent spin. As the aircraft departs controlled flight, it tumbles wildly until it has stabilized in a steady state spin.

Recovery procedures for the spin vary by the type of aircraft. The initial steps for spin recovery are to neutralize the flight controls, reduce the throttles to idle and analyze the spin. Flight controls are neutralized by centering the stick and the rudders. This is done so that the control surfaces are not extended into the wind. The throttles must be reduced to idle in order to eliminate unnecessary thrust. After an aircraft has entered a spin, it is no longer flying. In this situation, any thrust is a liability instead of an asset.

A pilot should never attempt to interpret spin direction or initiate a recovery utilizing "seat of the pants" techniques. Visual references can easily result in erroneous interpretations and extended the recovery time. A spin must be analyzed by looking at specific flight instruments in the cockpit. These instruments will provide accurate and reliable information, even as the aircraft is spiraling uncontrollably toward the ground.

The turn needle is an essential flight instrument that is used to determine spin direction. A turn needle consists of a vertical indicator that pivots to the left or to the right of a fixed reference line. Displacement of the turn needle confirms the direction of turn while the degree of deflection indicates the rate of turn. A turn needle is a valuable instrument and an essential tool that must be used when determining spin direction.

The Angle of Attack gage is another important instrument that is used for spin assessment. Pilots flying aircraft equipped with an Angle of Attack gage can determine if the aircraft is stalled. The Angle of Attack gage provides a pilot with a current readout of the angle that exists between the wing's chord line and the relative wind. Angle of Attack is measured in increments called "Units." The Angle of Attack indexer can vary from zero units to thirty units. In an upright spin the AOA gage is pegged at its highest value of thirty units. On the flip side, if an aircraft is in an inverted spin it will indicate zero units of AOA. The AOA needle is pegged at the bottom of the gage.

Airspeed is a very important factor when conducting spin analysis. In some cases the aircraft may not be completely stalled. Airspeed readings well above stall speed are a key indicator that the aircraft is still flying and is most likely established in a high speed spiral. A high speed spiral closely resembles a spin and the two are easily confused.

When an aircraft is established in a steady state spin, the airspeed indicator fluctuates near its stall speed. During a high speed spiral however, the airspeed indicator may display airspeeds in excess of two hundred and fifty knots. AOA is another effective way to differentiate between a high speed spiral and a spin. The AOA during a high speed spiral will fluctuate and is not pegged like that of a spin.

As we discussed previously, the first step in spin recovery is to center the flight controls. By physically moving the control surfaces to the neutral position, the aircraft is more streamlined. The pilot must pull the throttles to idle and determine spin direction. A correct and timely spin analysis is essential so that the pilot can expedite the proper recovery procedures and minimize altitude loss.

Each aircraft has specific spin recovery procedures. When the flight controls have been neutralized and the direction of the spin has been determined, anti-spin flight control inputs must be implemented. These procedures include the application of full rudder opposite to the direction of the spin. A pilot can minimize confusion in this regard by stepping on the rudder pedal that is opposite to the direction of the turn needle. If the aircraft is spinning to the left, step on the right rudder and if the aircraft is spinning to the right, step on the left rudder. The use of the rudder is important because the tail is the only control surface that is not stalled. In a spin, the rudder is still flying and will respond to control inputs.

Additional anti-spin corrections may be required based on the type of aircraft that is being flown. For example, spin recovery procedures for some aircraft require a pilot to displace the ailerons into the direction of the spin. In other types of aircraft the stick must be pushed forward of the neutral position.

In either case once the spin has broken, the pilot must quickly center the rudder pedals to avoid inducing a spin in the opposite direction. Anti-spin controls will quickly become pro-spin inputs after the initial rotation has stopped. If a spin reverses direction due to improper recovery procedures, the aircraft enters what is called a progressive spin. In a progressive spin, the aircraft rapidly reverses direction and causes extreme disorientation along with excessive altitude loss. It is critical for a pilot to remain focused on the cockpit gages during a spin and not succumb to the temptation of relying on external visual cues.

When the rotation of the aircraft has ceased, the rudder pedals must be quickly centered. The next step is to determine if the aircraft is flying again. The AOA gage and the airspeed indicator are used to determine if the aircraft is still stalled. Even after the rotation has ceased, the aircraft might still be stalled. A primary indicator that the aircraft is no longer in a spin is the Angle of Attack gage. When the needle breaks free from its pegged position, the stall has broken.

The last step in spin recovery is to return the aircraft to a level attitude. After an aircraft has ceased spinning and has broken free from stall, it can be flown. The pilot must ensure that the aircraft has reached its maneuvering airspeed before rolling the aircraft toward the nearest horizon. A steady pull on the stick is initiated to return the plane to a level attitude. The amount of pull that a pilot can be use to bring the nose of the aircraft back to the horizon is limited by the angle of attack and the presence of any buffet. If excessive backstick is used during spin recovery, the aircraft may stall again.

A pilot can benefit immensely by flying acrobatic maneuvers. The acrobatic experience gives a pilot the ability to develop a better feel for the airplane and attain a higher level of confidence. Acrobatic flight is a perfect activity for those who relish swift acceleration, rapid climbs and high "g" forces associated with maneuvering flight.

CHAPTER VII - FLYING OPPORTUNITIES

Military Aviation

Military aviation provides young men and women with an exciting opportunity to fly high performance aircraft from a multitude of locations around the world. A lengthy commitment is required in terms of time and effort. Training is extensive and thorough. Candidates who sign up for flight training programs are expected to serve a minimum of eight years on active duty, after receiving their wings. As we will see, many roads lead to aviation flight training.

Each branch of the military, (including the National Guard and the Coast Guard) has a flight program designed to instruct the novice aviator. Assignment to these programs can be accomplished by attending one of the military service academies, participating in a college ROTC program, or applying for a Direct Commission. In order to qualify, the candidate must successfully pass an evaluation that is designed to measure their qualifications for a flight training program. Most of the services require a college degree as a prerequisite for consideration.

Once a candidate is selected, a sequence of events begins that leads them from program acceptance to a winging ceremony. Flight candidates begin their adventure by attending service specific basic training courses. These courses can consist of several schools that vary in duration from three to nine months. Following the successful completion of these basic courses, the student is assigned to flight school for aviation instruction. Before strapping into an aircraft, the student is assigned to ground school courses where detailed information is provided about aviation related subjects such as airborne navigation, aircraft systems, aerodynamics, meteorology, aviation physiology and water survival. In addition, the student must complete a series of physical fitness tests and successfully pass a thorough aviation physical examination.

When ground school is complete the flight student is assigned to primary flight training. Now it is time to begin flying an aircraft. All aspects of flight training are graded, to include: flight briefs, preflight, individual flight maneuvers and the flight debriefs. After primary flight training is complete each student is selected for a specific "pipeline." The student is assigned to one of three aviation communities. These communities are helicopters, jets and propeller driven aircraft.

The selection process is based on class standing and service requirements. Community specific training is conducted at follow on duty stations. Intermediate flight training is the next step in the process. Intermediate flight training is designed to help a student gain a familiarity with the type of aircraft that they will be flying in the future. The Intermediate phase of flight training focuses on flight familiarization, instrument training, formation skills, and basic mission profiles. At the completion of intermediate flight training a flight student is transferred to advanced flight training. Advanced flight training places a greater emphasis on mission planning and the tactical employment of an aircraft.

Different communities have a unique focus regarding mission specific training. For example, training in the jet community encompasses low level navigation flight training, air combat maneuvering, ordnance delivery and Carrier Qualification for Navy and Marine Corps pilots. In the helicopter community, training is focused on long range navigation, hoist operations, external cargo lifts and tactical formation flying. In the propeller community, the emphasis is on radio instrument navigation, VFR flight and low level navigation. Regardless of community, a students final evaluation stresses aircraft systems knowledge, emergency procedures and performance limitations. Following the completion of advanced flight training, a flight student receives their well earned flight wings.

Pilots are not the only individuals who are trained to fly. Aircrew training is also conducted at military bases around the country. Aircrew personnel are trained to fly in support roles onboard multicrew aircraft. Flight Officers, Weapons Systems Officers and Crew Chiefs all contribute to the accomplishment of the mission. These individuals do not physically fly the aircraft but manage a sophisticated array of onboard computer systems or handle passengers and cargo that are carried on the aircraft. Newly designated aircrew are sent to their operational squadrons for follow on training. They join up with pilots and begin flying as a team.

When a pilot completes advanced flight training, they are selected to fly a specific type of aircraft. For example, a Navy pilot in the jet pipeline could be selected to fly an F-18. Class standing and the needs of the service are the basis for this selection process.

Newly designated aviators are assigned to training squadrons where they are taught how to fly the aircraft they have been selected to fly. Syllabus training is mission oriented with emphasis on the flying that they will be doing in the tactical squadron. Advanced aviation skills are mastered during this phase. Instructional flights include low level ordnance delivery, night carrier qualification, night vision goggle training and advance air combat maneuvering.

When a pilot completes the tactical training syllabus they are transferred to an operational squadron for duty. In their squadron, pilots are taught by more experienced pilots in the unit. These veteran flight instructors possess extensive experience and are tasked with the responsibility of sharing special skills with each newly assigned officer. Operational training varies by community. Some of the more common training flights include low light level navigation, ordnance delivery missions, special weapons delivery, long range patrols, air combat maneuvering, special mission operations, rappelling, parachute operations, fast rope insertions, emergency extractions and simulated recoveries of downed aircrew. Pilots normally remain in their first squadron for three to four years before rotating to a follow on assignment.

Commercial Flight Schools

Many airports have Fixed Base Operators (FBOs) that support the refueling and maintenance of aircraft. In addition to these services, FBOs often operate certified flight schools that provide flight instruction for the adventurous at heart. A variety of ratings can be obtained at these facilities. The first rating of interest is the single engine land rating. This VFR rating allows a pilot to fly in the touch and go pattern and venture out into the local flying area. A cross country flight is also included in the syllabus to familiarize the pilot with operations at other airfields. Prior to any flight instruction, a ground school course must be taken. The course covers essential aviation related subjects and is designed to familiarize a fledgling pilot with the terminology associated with aviation.

Flight training is culminated by a solo flight. During the solo, the student is allowed to fly an aircraft unassisted in the landing pattern. The traditional "shirt cutting" serves as a rite of passage after the student completes their solo flight.

After obtaining a single engine rating the pilot may elect to pursue advanced ratings. The next logical step is to seek an instrument rating that certifies a pilot for flight in IFR flight conditions. Additional ratings include multi-engine land and seaplane ratings. The graduate level of commercial aviation includes the Flight Engineer and Air Transport Pilot ratings. Age and flight hour restrictions must be met before an ATP rating can be issued. Pilots interested in becoming flight instructors can procure a Certified Flight Instructor (CFI) rating. All of these ratings require an appropriate ground school and an inflight evaluation.

Budding pilots who are interested in flying should contact the nearest aviation facility for more information on how to begin a career in aviation. Local flight schools provide the necessary aircraft, fuel and flight instructors based on an hourly rate.

Individuals who are interested in flying commercially must build the appropriate amount of flight hours before seeking employment with an air carrier. Those who have their eyes set on aviation as a career can gain valuable experience by working for a commuter airline. This is a useful way to build time and learn about commercial flying. Commercial aviation hiring is cyclical and opportunities are often based on the economy. Significant time as an Aircraft Commander, flight ratings and extensive flight experience are all factors that increase the chances for an interview with a major carrier.

CHAPTER VIII - MILITARY TACTICAL FLYING

Night Vision Goggles

Many aircraft are equipped with the capability to turn night into day. Several military and civilian aircraft have a variety of systems that are designed to help the crew see in the dark. Helmet mounted devices such as Night Vision Goggles (NVG's), are a pilots best friend when flying at night. NVG's resemble binoculars that are suspended from a pilot's helmet. They are held in place by a unique mounting mechanism that positions two cylindrical devices directly in front of their eyes.

The NVG system amplifies all available ambient light that is provided from external sources such as the moon and the stars. The NVG ocular tubes are designed to capture and intensify any image that is being viewed. Other sources of ambient light include surface lighting and an infrared light that can be mounted to an aircraft and used to observe the ground below. NVG's are required in order to see an infrared light source since infrared light is invisible to the naked eye.

Objects being viewed with NVG's are all cast in a greenish hue. The picture quality varies based the type of NVG's that are used, the ambient light that is available and the weather conditions. The state of the atmosphere significantly affects the ability to acquire a clear and well defined image. Images clarity is also based on how well the NVG's have been focused during preflight. Excess ambient light is also a hindrance to an NVG system. The bright lights of a city will cause the NVG image to "bloom" and "whiteout." The image can be temporarily lost in the brightness but it will return when the user looks away from the bright lights.

NVG's are not a replacement for day vision. Under low light level conditions there is no moon. The NVG image can become grainy and lose acuity. Technological advances are improving the quality of night vision devices. Some of the more current NVG models have a higher definition and perform better under low light level conditions.

Night Vision Goggles provide a relatively limited field of view. The average pilot can only see a forty degree area when both eyes are focused on an object. In order for a pilot to see the horizon, a continuous scan is necessary. The pilot must consciously move their head back and forth. A good scan is essential in order to avoid obstacles such as towers trees and buildings. Since visual acuity is reduced when flying on NVG's it is imperative that a pilot perform a thorough map study prior to take off.

All known obstacles must be clearly marked on the map and the location of any power lines must be highlighted. Power lines are extremely difficult to see when flying on NVG's. The proper detection technique is to look for the support stanchions and fly directly over the top of these metal posts. Power lines are often strung across the wide expanse of a deep canyon. Orange cylindrical devices are attached to these power lines at the cables lowest point in order to make them more visible. Despite these efforts, aircraft are lost to wire strikes during day and night operations. Disorientation and reduced visibility caused by fog, low clouds or blowing sand are several factors that can contribute to an accident.

Another device a pilot can use to see in the dark is a Forward Looking Infrared Radar, or FLIR. A FLIR analyzes temperature differences between objects and displays their heat signature in color on a television screen located in the cockpit. A FLIR camera can be mounted to the nose of the aircraft or on a wing station. The FLIR is operated by the use of a toggle switch or a hand held control box, depending on the aircraft. The FLIR controller is used to position, rotate and focus the FLIR. A FLIR is very sensitive and the focus knob must be continuously adjusted in order to maintain proper clarity. A polarity selector switch gives the pilot the option of choosing either black or white to determine what color will be used to display the hotter temperatures. A FLIR is also capable of zooming to a high magnification setting in order to focus in on a specific area and observe it in greater detail.

The FLIR includes a heading indicator that constantly displays the magnetic direction the FLIR is pointed. Situational awareness is important while operating a FLIR system. The FLIR can be rotated to either side of the aircraft to look at images. Pilots who rely on the FLIR system for night navigation must be alert to the ever-present danger of viewing something that is not located directly off the nose of the aircraft. A pilot could erroneously assume that there are no obstacles in front of the aircraft when in fact, there really are. The quality of a FLIR picture is based on ambient conditions and the operator's ability.

A third way that a pilot can see in the dark is by illuminating an object with a bright light. Many aircraft are equipped with a compact, high candle power light mounted to the airframe. One such light is called a Night Sun. With the flip of a switch, the Night Sun can project a brilliant light that is capable of illuminating a large area on the ground. The bright white light of the Night Sun can be focused into a narrow beam or expanded to shine over a wide area. The ability to successfully use artificial light is based on the amount of moisture in the air. Any attempt to use a Night Sun under foggy conditions is useless. The water vapor suspended in the air will reflect light back toward the pilot, creating a large white halo around the aircraft.

Search lights are frequently used during rescue operations to look for lost personnel. A Night Sun is adjusted by using an electrical motor that rotates the light in the desired direction. Search lights are easily mounted on the cross tube of a helicopter.

Formation Flying

Military and civilian pilots often fly in formation during maneuvers and flight demonstrations. Formation flight serves many purposes. One basic purpose is to facilitate the movement of multiple aircraft from point A to point B. Formation flight also provides protection during combat. Attacks by enemy aircraft are more difficult when flown against a large, well defended formation. Formation flying requires thorough planning and a detailed briefing. During preparations for a formation flight, all participants in the formation should be present for the brief. The conduct of the flight must be clearly understood before the formation takes off. A formation leader is responsible for the safety of the flight and must ensure that all aircrew clearly understand what will occur during the flight.

Formation flight is employed by military aviators to gain a tactical advantage over an adversary. Strength in numbers is essential for the success of a mission. As we have seen, enemy aircraft have a more difficult time attacking large flights. Formation flights are used to maintain flight integrity and flight discipline. These flights can be compared to a convoy of ships at sea.

Defensive weapon systems are installed on aircraft flying during combat operations. Flights flown into enemy territory should have at a minimum a flight lead and a wingman for tactical integrity. The additional set of eyes is helpful for detecting enemy aircraft and to help locate specific targets on the ground. An added benefit of flying in formation is the ability to assist in the recovery of a downed aircrew. Fighter coverage, bombing missions, combat rescue and tactical troop lifts are all flown into an objective area using multi-aircraft formations.

The successful execution of a formation flight is defined by a pilot's ability to remain in a fixed position relative to other aircraft in the flight. Proper position is maintained by the use of precise flight control inputs. An alert formation pilot is responsive to the slightest movement of another aircraft in formation.

There are four basic positions that are used during formation flight. The flight leader is responsible for assigning these positions to each member of the flight.

The four formation positions are parade, cruise, tactical cruise and combat spread. The position of each aircraft in any formation flight is determined by three factors: bearing, distance and elevation. Bearing is the angle that is measured from lead's "six o'clock" position to the location of the wingman. The nose to tail distance is measured in feet.

Step-down is the third factor that is used to determine position. Step-down is measured in feet. It is the distance that each aircraft must remain below the aircraft in front of them. Step-down provides every aircraft in the flight with the necessary separation. It serves as an important safety buffer so that each aircraft can avoid one another while maneuvering. Two aircraft should never be at the same altitude in a formation flying.

Parade position is the closest and least maneuverable of all the formation positions. Aircraft flying in the parade position use bearing, distance and step-down to maintain the flight. The proper bearing line for the parade position is forty-five degrees. The nose to tail distance is ten feet and the step-down for parade is eight feet. Refer to Figure (16) for a diagram of the various formation positions.

Helicopter formation flights must use step up instead of step-down to maintain vertical separation between aircraft. The hazards associated with whirling rotor blades are avoided by placing a wingman's rotor blades above and well clear of the helicopter in front of them.

Aircraft flying in parade position must remain on the side assigned by the flight leader. The formation leader is the one who signals the wingman when it is time to cross over to the other side. Control inputs and power adjustments in parade position must be deliberate. Due to the close proximity to each other any erratic flying cannot be tolerated. Parade is used when the formation is entering or departing an airfield. It is also flown at an airshow, flight demonstrations and during military fly-by's. Parade may also be flown out of necessity. During periods of poor flight visibility a flight leader often brings a wingman in close so that they can keep each other in sight.

The second formation position is called the cruise position. In cruise, each aircraft flies a bit deeper on the forty-five degree bearing line. Nose to tail separation between aircraft is increased to thirty feet. While in cruise, pilots are free to maneuver on an arc extending from the 45 degree bearing on the left to the 45 degree bearing on the right.

The cruise position is maintained by varying angle of bank. Radius of turn is employed to increase or decrease the distance between the lead aircraft. Throttle movements are minimized in order to conserve fuel. When the lead aircraft is maneuvering, each aircraft in the flight must also maneuver and vary their angle of bank to stay in position. When the maneuvering sequence is complete, each pilot returns to their proper position on the 45 degree bearing line.

The third formation position is called tactical cruise. Tactical cruise is utilized when the emphasis is placed on flight maneuverability and flexibility. In the tactical cruise position, the nose to tail distance between each aircraft is increased up to one thousand feet. The pilot can now fly on an even wider arc around the flight leader. The arc extends from an abeam position on the right of lead to an abeam position on the left of lead. The area represents a semicircle of maneuvering airspace. Tactical cruise minimizes the possibility of an enemy aircraft successfully shooting down two aircraft on single pass. A direct hit is less likely when multiple aircraft are maneuvering at different altitudes.

The fourth formation position is called "Combat Spread." Combat spread is used when all eyes must be focused ahead of the flight out toward a known or suspected enemy threat. In combat spread, wingmen are located abeam the flight lead and are expected to maintain that position with one thousand feet of horizontal separation.

During a formation flight, it is the flight leader's responsibility to assign a tactical formation that is best suited for the situation. The most basic element of a formation is the section. A section is comprised of two aircraft. The second aircraft in the flight is referred to as the wingman or the "dash two". A section is capable of flying in parade, cruise, tactical cruise and combat spread positions. For the most part however, a section is usually flown in echelon, on the 45 degree bearing line. The wingman is located on either the right or left side of lead. Refer to Figure (17) for a diagram of formations.

Another formation that can be flown in section is column. Column formation consists of two or more aircraft positioned at the six o'clock from lead aircraft with at least 1000 feet of separation. Column formation is employed when the section is established on final approach for landing.

A "division" is a large formation comprised of two sections. A division can be flown in echelon, fingertip, wedge, diamond, and column formations. The echelon formation is used to bring a flight into the airfield for the "break".

Fingertip is a formation that is commonly used by a division in order to proceed from point A to point B. The fingertip formation consists of two sections. Both sections are flown in echelon. The second section is positioned on a 45 degree bearing on one side while lead's wingman is positioned on the other side. A space is provided between the two sections so that lead's wingman can maneuver on either side of the flight.

The diamond and the wedge are additional formations that are used by a flight leader to control a division. They are less maneuverable because of the fixed position of each aircraft in the flight. These formations are normally flown in the parade or cruise position. The diamond and the wedge are employed at airshows, flight demonstrations and official ceremonies. As the name implies, a diamond formation resembles a diamond in the sky. An aircraft is positioned at each point of the diamond. The wedge resembles a letter V since it is comprised of three aircraft, with the V oriented in the direction of flight. The fourth type of formation flown by a division is the column.

The Break

The "break" is a flight maneuver that is utilized by a formation returning to a ship or an airfield. Also referred to as the "overhead", the "break" is an effective way for aircraft to detach from the flight and enter the landing pattern. The formation leader prepares a flight for the break by maneuvering the formation to the "initial". The "initial" is another term for a point over the ground located approximately five miles from the approach end of the runway. After crossing the initial the formation leader moves the flight into echelon position.

Aircraft in the flight are positioned on the side that is opposite to the direction of the break. Breaks to the left are commenced from right echelon while breaks to the right are accomplished from left echelon. The break altitude is determined by course rules for the landing airfield. Breaks are normally flown at elevations varying from 600 to 1500 feet above the ground. When the flight is aligned with the landing runway in echelon formation, the formation leader contacts the tower and requests clearance for the "break." The controller clears the flight to break over a specific point on the runway. In some cases, the flight may be told to continue "upwind". The delay may be necessary in order to sequence the flight behind other aircraft in the landing pattern.

Before initiating a break, the flight leader visually checks to ensure that the area is clear in the direction of the break. When it is time to break, the wingman signals the flight by kissing "bunched" fingertips with his lips. He then move his arm toward the flight and opens his fingers. After signaling for the break lead rolls his aircraft into a high angle of bank turn and pulls back on the stick. The break is normally performed at 6 g's.

During the break, the speed brakes are deployed and the throttles are reduced to flight idle. Altitude in the break is maintained by varying angle of bank. If the airplane begins to climb, the pilot increases angle of bank in order to dissipate energy. As the aircraft returns to break altitude the angle of bank must be decreased.

A break is executed for one hundred and eighty degrees of heading change. When the aircraft is rolled wings level it is now established on the "downwind" portion of the landing pattern. Three seconds after lead breaks, the next aircraft in the flight breaks and follows lead. The remaining aircraft in the flight break at the appropriate interval.

The Landing Pattern

The break is used to decelerate the aircraft down to its proper approach airspeed and to provide the pilot with sufficient time to configure the aircraft for landing. After rolling out of the break the pilot must continue to slow the aircraft down to its landing gear extension speed. The landing gear extension speed is an airspeed where the landing gear can be safely deployed. Wing flaps are lowered immediately after the landing gear is lowered.

On the downwind leg the pilot must complete the landing checklist and call the tower for a landing clearance. The tower controller is responsible for observing the position of each aircraft in the landing pattern. Following their radio call, the pilot will receive one of three possible clearances. The first type of clearance is an authorization to land. In this case the pilot is permitted to continue with the remainder of the approach and land.

The second type of clearance is a landing clearance that is issued when there are two or more aircraft in the landing pattern. The pilot is informed by the tower, "You are number two on the approach". In this case the pilot must report the other aircraft in sight before a landing clearance can be issued.

The third call a pilot may receive from the tower is a "waveoff" call. A waveoff may be initiated for a variety of reasons. For example, an insufficient landing interval may exist between two aircraft, or there may be an obstruction on the runway such as a vehicle or another aircraft. A pilot may elect to initiate a waveoff if excessive maneuvering is required to properly align the aircraft with the runway. In each case, the waveoff must be executed in a timely manner. Full power is selected, the speed brakes are retracted and the aircraft is flown up and away from the runway. Waveoffs are mandatory anytime they are directed by the tower or whenever an unsafe situation exists.

The landing pattern is designed to handle aircraft taking off, practicing "touch and goes", and executing full stop landings. There are two types of landing patterns used by pilots. These patterns are called the "box" pattern and the "carrier" pattern. The "box" pattern is a pattern that is flown by civilian pilots, Air Force pilots and Army pilots. The "Carrier" pattern is flown by Navy, Marine Corps, and Coast Guard aviators.

The "box" pattern resembles an elongated rectangle when viewed from above. Refer to Figure (18) for a diagram of the Box and the Carrier patterns. The "box" pattern consists of a downwind leg, a "base" leg, an upwind leg and a crosswind turn. On the downwind leg a pilot receives a landing clearance and continues to fly beyond the intended landing area. At a designated point, (about 45 degrees past the abeam position), the aircraft is turned for ninety degrees, onto the "base leg". The base leg is perpendicular to the runway. As the aircraft approaches the extended centerline of the runway a turn is commenced for another ninety degrees of heading change. The aircraft is now aligned with the runway for the final approach.

The "Carrier" pattern is used during shore based and shipboard operations. The "Carrier" pattern prepares a pilot for landing on an aircraft carrier. Unlike the box pattern, the carrier pattern is oval in shape. A pilot can enter the carrier pattern from the break, the downwind or on a base leg. Downwind procedures out of the break are identical to the box pattern until reaching the "abeam" position. Passing the abeam position however, the pilot immediately commences an arcing, descending turn toward the landing runway. The aircraft is turned for one hundred and eighty degrees of heading change and is rolled wings level on runway centerline. The goal of the Box and the Carrier patterns is to establish the aircraft on final approach with the proper glide path, approach speed and rate of descent for landing.

The control tower designates which runway will be used as the active landing runway. Wind direction is the primary consideration when assigning the "duty" runway. As previously discussed, an aircraft performs better aerodynamically if it takes off and lands into the wind. During takeoff, a headwind reduces the distance that an aircraft must travel before becoming airborne. While landing, a headwind helps to minimize the distance that is required in order to stop the aircraft. Some airfields are relatively small and may have only one runway available for takeoff and landing. In this case, there are only two possible departure and recovery options available. A strong wind blowing perpendicular to the runway can make landings more difficult for a pilot.

There are two types of crosswind conditions in a landing pattern. The first crosswind condition is the "overshooting" crosswind and the second condition is the "undershooting" crosswind.

The term "overshooting" is a good description of what occurs when a pilot fails to compensate for the detrimental effects of the wind.

During a turn to final with an "overshooting" crosswind an aircraft will be pushed rapidly toward the runway. If angle of bank is not increased the aircraft will be pushed through the final approach course and will "overshoot" the runway. In some cases this overshoot may be significant and a fairly dramatic correction must be made to fly the aircraft back toward the runway. A "major play" for the runway in close however typically results in another "overshoot", thereby driving the aircraft to the other side of the final approach course. When this scenario occurs the pilot should waveoff the landing and "Take it Around" for another landing.

The proper correction for an "overshooting" crosswind is to establish a "crab" into the wind on the downwind leg. In the Carrier pattern a greater angle of bank is used in the turn to final. The steeper turn counters the lateral effects of the wind. On final approach, a "crab" into the wind must be utilized so that the proper ground track is maintained to touchdown.

When flying the "box" pattern, the proper correction for an overshooting crosswind involves a rapid transition from the base leg to the final approach course. During the initial turn to the base leg, the aircraft is pushed by a tailwind component. Its groundspeed will increase significantly. The aircraft moves rapidly toward the final approach course. An expeditious turn must be initiated in order to prevent overshooting the runway.

The second type of crosswind condition in the landing pattern is called an "undershooting" crosswind. An undershooting crosswind blows perpendicular to the runway as well. In this case however, the wind is coming from the other direction. An "undershooting" crosswind actually holds an aircraft away from the runway. To compensate for an undershooting condition on downwind, a crab must be initiated. In the carrier pattern, a shallower turn off of the abeam position is used to counter the effects of the wind.

If the "box" pattern is being flown with an undershooting crosswind, a pilot will remain on the base leg for a longer period of time, to compensate for the headwind component. Failure to correct for an "undershooting" crosswind will cause the aircraft to roll out "inside" the runway centerline. Like any crosswind condition, the pilot must "crab" into the wind, prevent lateral drift and maintain proper track over the ground. Refer to Figure (19) for a diagram of an undershooting and an overshooting crosswind.

CHAPTER IX -- WATCH THE WEATHER

Aviation Weather

It is important for a pilot to understand the effects of weather on aviation. Prior to each flight, a thorough study of enroute and destination conditions is essential. A weather forecast should be obtained for the route of flight and final destination two hours either side of the scheduled arrival time. This information is essential for preflight planning in order to determine the safest and most expeditious route of flight. The pilot must also determine if an alternate airfield is required since weather changes constantly and creates can significantly affect the outcome of a flight. During the preflight planning sequence, a pilot must be able to read and understand the weather forecasts provided by the National Weather Service.

For example, it is important to know what type of weather is generated during the passage of different frontal boundaries. Weather associated with these fronts often present a unique set of problems that a pilot must be prepared for. The movement and overall influence of a frontal system on the departure, enroute and terminal phases of flight are a key concern. Weather must be continuously monitored and updated while airborne. If the route of flight must be modified due to weather, care must be taken to understand what effects the newly assigned route will have on total fuel consumption, time enroute and arrival procedures. A pilot must maintain a constant vigilance and an eye on the weather since the safety of the crew and the passengers are at stake.

Wind

Information about the current and forecast wind is essential for flight planning and the flight itself. There are several methods that can be used to determine the direction of the wind. Pilot weather briefings provide a pilot with current and forecast winds. The wind is an important factor during the departure, enroute and terminal phases of flight. The most important consideration is the effect of the wind on time enroute and fuel consumption. Wind is reported in degrees magnetic and expressed in terms of the direction that it is coming from. Wind intensity is reported in nautical miles per hour. If gusty conditions exist, the strength of the gusts are reported along with the wind information.

The second way to obtain wind direction and intensity is through the use of the Automated Terminal Information Service, or ATIS. When approaching an airfield the pilot can listen to the continuous loop transmission that is broadcast over a discreet radio frequency. An ATIS broadcast is identified by letters of the alphabet.

A pilot should monitor ATIS on the ground prior to taxi and in the air. In both cases, the pilot should notify the controller that they have received the current ATIS. For example, if ATIS information "E" is current, the pilot will acknowledge receipt during the call for taxi. "Lazy Acres tower, RQ123, taxi for takeoff, with information Echo." By doing so, the controller does not have to repeat all of the weather information to the pilot. ATIS is an important service in high density traffic areas. Clear and concise communications are necessary since there are a large number of calls transmitted on an approach control frequency. By dialing up ATIS the pilot helps reduce this verbal congestion.

The third way to obtain wind information is to request it from the control tower. For example winds may be report to a pilot as follows. "Winds are two two zero (220) degrees at 10 knots, gusts to twenty five." Based on this information, a pilot knows that the wind is blowing from the southwest to the northeast at ten knots with a temporary condition where the wind is gusting up to twenty five knots. If the wind is shifting significantly, it will be reported as "variable." The extent of the shift may be reported as well. For example, "Winds are light and variable from one zero zero (100) to one eight zero (180) degrees." Wind less than five knots is generally reported as calm.

Several devices on an airfield are provided to help determine wind direction. These devices include a wind sock, a tetrahedron, a flag, the leaves on a tree and smoke from a fire as it floats up into the air.

A windsock is a tapered nylon tube that is usually bright orange in color. It is designed with a wide throat that narrows to a small opening at the end. In order to keep the windsock open, it is sewn around a large metal ring located at the top of a long pole. The pole can swivel freely for three hundred and sixty degrees of rotation.

Wind intensity is indicated by the fullness of the windsock. A completely extended windsock indicates that winds are in excess of twelve knots. A half filled sock represents eight to ten knot of wind and one third full indicates approximately five knots of wind. A windsock can be found near the control tower and close to the approach end of a runway. The windsock serves as a quick reference for a pilot just prior to takeoff. At night the windsock is illuminated so it can be seen in the dark.

Another device designed to display wind direction is a tetrahedron. The tetrahedron is a large wooden structure that faithfully points into the wind. It is often centrally located on an airfield and it resembles an elongated pyramid. The tetrahedron swivels freely about and its long, narrow end is designed to point into the wind. Like the windsock a tetrahedron is illuminated at night. One disadvantage to a tetrahedron is the fact that it does not depict wind intensity, only its direction. A tetrahedron however is very sensitive and responsive to the slightest change in wind direction.

Smoke from a smokestack or a chimney provides a pilot with an excellent visual indicator of the wind's direction and intensity. The movement of a smoke column toward the horizon reveals what direction the wind is coming from. Like the windsock, the degree of displacement indicates the strength of the breeze. On a calm day, the smoke will rise in a vertical column. When a strong wind is present the smoke may only rise a short distance before it is pushed over by the fast moving air. Other indicators of wind direction include the movement of tree tops and flags blowing in the breeze.

Wind direction and intensity can also be determined while airborne. For example, a pilot can look at a body of water from above and discern the direction of the wind. The surface of the water is always much calmer near the upwind shore. Bushes, trees and buildings tend to shield the water from the strong effects of the wind. Calmer waters along this shoreline are a valuable indicator of wind direction. As the wind moves toward the center of the lake, it descends down onto the surface creating turbulence and waves. In contrast, the leeward shore has the strongest breeze since there is little resistance to slow it down. White cap and large waves are good indicators of both wind intensity and wind direction.

When viewed from above, wind direction can be detected by observing distinctive streaks that are displayed on the water. These markings serve as a weather vane and clearly reveal the direction of the wind. Gusty winds are evidenced by dark, intense swirls as they race quickly across the water's unsettled surface.

Moving higher into the atmosphere, the direction and intensity of the wind can vary significantly. Surface winds are affected by the contour of the earth. They sun's radiant energy and the movement of weather systems also affect the strength and the direction of the wind. Winds at altitude are unobstructed by buildings, trees and mountains and tend to be much stronger in intensity. For example, winds at twenty-five thousand feet may be blowing from the south at fifty knots while surface winds may be coming from the northwest at ten knots.

The jet stream is a powerful and narrow band of wind that originates in the north and flows predominantly from west to east. This concentrated stream of air can be compared to a powerful river of energy moving across the sky. The jet stream is situated in a portion of the atmosphere called the troposphere. The troposphere is located five miles above the surface of the earth. Winds in the jet stream can travel at speeds in excess of one hundred and fifty miles per hour. In the United States, the jet stream descends out of Canada and sweeps across the country, affecting surface temperatures and the weather we experience daily. During the winter, the jet stream penetrates much deeper into the southern regions of the country. Waves of cold arctic air push down from the north, bringing with them bitter temperatures and wintry weather.

Throughout the winter months, the jet stream flows south in a crescent shape advance. Cold weather and freezing conditions are propelled on an easterly course as the jet stream drifts across the nation. In summer months however, the jet stream remains north and tends to flatten out. A pilot can benefit from the jet stream by knowing where these strong air currents are located. The momentum of the jet stream can slingshot an aircraft across the country. The increased ground speed will significantly reduce fuel consumption and total time enroute.

For example, if the jet stream is blowing from west to east at eighty knots an aircraft flying to the east will benefit from the additional eighty knots of wind. In addition, the groundspeed of the aircraft will be increased up to eighty knots compared to a no wind day. On the other hand when a pilot flies on a westerly course, the task at hand is to minimize the detrimental effects of the jet stream. With a headwind, the aircraft's progress over the ground will be significantly slower. Therefore, the pilot should select an enroute altitude where the wind is less intense. After takeoff, groundspeed checks can be conducted to determine the strength of the wind and its effect on groundspeed. An altitude change may be the best way to obtain lighter headwinds.

The importance of thorough preflight planning is essential as a way to anticipate the effects of wind. A pilot should contact the weather service and evaluate what the current winds are at various altitudes. Forecast winds should be obtained since they are an important part of determining what enroute altitude will be filed on the flight plan.

During the flight, a pilot maintains the fuel log which is used to determine the effects of the wind on fuel consumption and the total time enroute. Forecast winds may not develop as predicted and the intensity of the headwind may be less than expected. If stronger winds develop, the expected time of arrival (ETA) at the filed destination will be delayed. The pilot may elect to fly at another altitude or may opt to add power and increase groundspeed. When power is added, fuel flow will increase along with total fuel consumption.

A pilot can use several visual cues to determine when an aircraft has passed into a region of strong winds. During the initial climb to altitude, the air near the earth's surface may be hazy and stagnant. As the aircraft gains altitude the pilot can see a transition point where the air begins to clear and visibility improves significantly. Rising above this layer of haze there is usually a noticeable change in wind direction and intensity.

Another indication that an aircraft has entered a high wind region is when a pilot observes clouds tops that are tapered and pulled downwind. Large cumulonimbus thunderclouds often build to heights in excess of forty thousand feet. As they grow, the churning tops of these towering giants are thrust higher and higher into the atmosphere. The classic anvil shape of a cumulonimbus cloud is formed when the upper portion of the cloud intrudes into the fast moving jet stream. Refer to Figure (20) for a diagram of cloud formations associated with a warm and cold front.

The Effects of Wind on Groundspeed

A ground speed check is a valuable tool for pilots to determine how fast an airplane is moving over the ground. There are several ways to measure ground speed. One method is to mark the position of the aircraft on the map and then track its movement for a specified period of time. When the timing is complete the pilot must plot the aircraft's new position on the map and then measure the distance between the two points. Groundspeed is computed by dividing the time of flight into sixty and multiplying that number by the distance the airplane flew.

For example, if an aircraft flew thirty miles in ten minutes, the number ten minutes is divided into sixty minutes to get six. The number six is then multiplied by the distance flown (thirty miles). As a result the ground speed of the aircraft is one hundred and eighty miles per hour.

Another quick way to measure groundspeed is to use miles per minute. For example if an aircraft covers three miles in one minute, it is flying at a speed of three miles per minute. (3 miles per minute x 60 minutes = 180 MPH).

To simplify the task, many aircraft have navigation equipment installed in the cockpit that provides mileage information for a pilot. Navigational aids and computers can measure how far an aircraft is away from the airport or a NAVAID station. DME or Distance Measuring Equipment presents a continuously updated readout of the current mileage from the station. Groundspeed checks can be conducted utilizing DME instead of the less accurate map measurement technique.

For example, a pilot notes the time and the current DME reading. In this case we will use 30 miles. As the aircraft proceeds away from the station the DME indicator will increase. When a designated period of time has expired, the pilot notes the new DME reading. In our example, the aircraft flew for ten minutes and covered a distance of 30 miles. 60 minutes divided by ten minutes equals six and six times 30 miles equals a groundspeed of 180 miles per hour.

It is important for a pilot to be able to determine the strength of a headwind or tailwind component while airborne. The airspeed indicator in the cockpit does not reveal how fast an airplane is traveling over the ground.

Dew Point

Pilots must be alert for a temperature condition commonly referred to as "the spread." Despite the sound, "the spread" is not a type of margarine nor is it a 500 acre ranch in Texas. The spread is the temperature difference between the outside air temperature and the dew point. The temperature/dew point spread is particularly important to a pilot since it is an indication of potential moisture in the air. Visible moisture often takes the form of fog, frost or mist.

Moisture is present in the atmosphere in varying amounts. It is important to understand that warm air is able to hold more moisture than cold air. For example, when the warm air of the daytime is cooled at night, it is unable to retain the same amount of moisture. As it cools the air becomes saturated and water droplets appear as fog or as dew on the ground.

As you can see, a pilot must keep a watchful eye on the temperature, dew point spread since visible moisture in the air can be a serious impediment to navigation. If a thick blanket of fog settles unexpectedly on an airfield, a VFR landing becomes a potentially dangerous undertaking. As a rule of thumb, if the temperature/dew point "spread" is less than four degrees, conditions are optimum for the formation of fog.

On a twilight drive through the countryside, fog can be seen settling into low lying areas where the air is much cooler. Factors contributing to the formation of fog include calm winds, clear skies and high moisture content in the air. Stable atmospheric conditions are a prerequisite for fog. A moderate wind will disperse any moisture and keep fog from developing. The sudden onset of fog is very dangerous for anyone trying to navigate at night. Fog is a milky obstruction that seriously impedes forward visibility.

When foggy conditions are anticipated, a pilot should file an IFR flight plan and avoid the unsafe practice of "Scud Running." Scud running is a term that is used to describe a method of flying where an aircraft is located between the ground and a low ceiling. The hazards associated with scud running are considerable when you realize that there is very little maneuvering room for the aircraft. These marginal distances are not sufficient for safe flight. In the case of low ceilings, it is wise to file an instrument flight plan and proceed to a destination on an IFR clearance. By doing so the aircraft can be flow at a higher altitude, clear of any obstacles. A pilot who chooses to fly under marginal VFR conditions must also be prepared to divert to an alternate airfield. If the destination field goes below landing minimums the pilot must have a plan. A "socked in" airfield is of little value to a pilot who cannot navigate due to low clouds and poor visibility.

Freezing Level

Knowing the location of the freezing level in the atmosphere is very important to a pilot. The freezing level is an altitude above the ground where the outside air temperature is equal to thirty-two degrees Fahrenheit. The freezing level is particularly important when visible moisture is present in the atmosphere. If the outside air temperature is within four degrees of freezing and visible moisture is present, there is a high probability that ice may form on engine intakes and wing surfaces. Moisture freezes instantaneously as it strikes the super-cooled surface of a metal airplane. When ice accumulates on an aircraft it can damage or adversely affect many of the critical flight components. For this reason, knowing the location of the freezing level is very important.

When visible moisture is present near the freezing level, a pilot should plan to transition quickly through this region. The potential for ice accumulation is reduced when the pilot minimizes the time that is spent there. A pilot should avoid accepting holding clearances in clouds close to this region. Icing conditions are usually limited to a narrow band in the atmosphere. Above this area visible moisture is already frozen and is not a threat to plane's aerodynamic performance. At altitudes below the freezing level, visible moisture is not cold enough to form ice.

In some cases a temperature inversion may exist in the atmosphere. A temperature inversion is a condition where a layer of warm air is located above cooler air. When visible moisture is present, a temperature inversion can be both deceiving and dangerous. As an airplane descends through a region of moist warm air, water will collect on the fuselage. If the aircraft continues its descent into the colder air below the moisture on the wings will freeze rapidly and may form a thick layer of ice on the aircraft.

Hail

Hail can be extremely damaging to an aircraft's nose cone and the leading edges of its wings. Hail is frozen precipitation that must be given a wide berth. In order for hail to form, there must be the vertical movement of moisture within a mature thunderstorm. During the developmental phase of a thunderstorm, powerful air currents travel up and down within these large cells. Updrafts can carry liquid moisture into the freezing temperatures above. When this occurs, water droplets are transformed into ice crystals. Over time, these frozen ice particles float back down toward earth until they are caught up again in another updraft and lifted back into the stormy heights. Large hail is formed when this process occurs over and over again. These icy voyagers take multiple trips up and down within the storm cloud. A new layer of ice is added each time as hail climbs through the visible moisture and into the freezing level.

With the passage of time the elevator ride must come to a decisive end. Hail becomes heavier than what the air currents can support. The ice is thrust downward toward the earth or it is carried upward and tossed out the top of the cloud. Hail is very damaging and extremely dangerous to aircraft. Flying in the path of large hail is a recipe for disaster. Smooth round balls of ice striking a wing traveling over 300 miles per hour will create many ball peen size dents on any exposed surface. Pilots are trained to be watchful of hazardous weather and to give these dangerous conditions a wide berth.

Weather Radar

Most large commercial aircraft are equipped with weather radar. Weather radar provides a pilot with up to the minute information concerning weather conditions that exist in front of the aircraft. Weather radar eliminates much of the guess work and minimizes the chances of exposing passengers to hazardous flight conditions. Imbedded thunderstorms are particularly dangerous since these large storms are hidden among the clouds. Without radar, an unsuspecting pilot could fly into clouds and inadvertently encounter a thunderstorm. Flying blind is a dangerous proposition. Convective conditions in unstable air results in significant vertical movement. The turbulence associated with these storms is a real threat. With radar the regions of convective activity are visibly displayed on the screen. Colors are used to depict the intensity levels of the storm.

Wind Shear and Microbursts

A wind shear and a microburst are natural phenomenon that occurs under special meteorological conditions. Wind shear is a radical change in the direction and the speed of the wind. It can have a dramatic effect on an aircraft in flight.

For example, a valuable headwind can quickly become a dangerous tailwind during an aircraft's descent for landing. The unexpected loss of wind can result in a loss of lift. A beneficial headwind may quickly become an unwelcome tailwind. The aircraft will have to fly faster at touchdown and a longer stopping distance will be required. Landings with a tailwind component will increase braking requirements in order to decelerate the aircraft to a taxi.

Of greater concern when dealing with wind shear is the sudden loss of the lift generating wind. The rapid onset of a wind shear can place an aircraft on the fence aerodynamically. Weather that contributes to a wind shear condition includes thunderstorms, squall lines and frontal passage. All large passenger aircraft are now equipped with wind shear alert warning systems. If an aircraft experiences a rapid loss of altitude or airspeed, a loud audio warning is sounded in the cockpit. A computer generated voice loudly announces "Wind Shear, Wind Sheer." In response to the warning, the pilot must immediately react by increasing the throttles to maximum power while raising the nose of the aircraft to its limits of stall. A high nose attitude helps minimize any additional loss in altitude.

A Microburst is another type of weather phenomenon that is of grave concern to a pilot. Microbursts are extremely strong columns of air that descend out of mature thunderstorms. The downward rush of air begins when energy in a storm cloud dissipates and gravity draws the cooler air toward the earth. This powerful surge of air pours downward like water rushing from an open faucet. As the air strikes the ground it curls outward like a steamroller in a circular wave.

A pilot's concern with a microburst is twofold. As the flowing column of air surges downward it can strike the top of the aircraft, causing an immediate loss of altitude. A more insidious danger occurs when a microburst reaches the ground. The headwind that is created emanates outward in every direction. When a low flying aircraft encounters a microburst, flight conditions can change very rapidly. Strong headwinds are initially encountered. These headwinds help generate lift and a higher indicated airspeed. The aircraft may actually climb due to the lift.

In response to this condition, a pilot's normal response is to reduce power and attempt to maintain the assigned altitude. If the aircraft is established on an approach the pilot will attempt to maintain a specified rate of descent.

Reducing power in response to a microburst is the wrong answer. As the aircraft passes through a temporary headwind condition it transitions into the center of the microburst. Under a newly introduced, low power state the aircraft proceeds out the back side of the microburst into a powerful tailwind. A dramatic loss of indicated airspeed and lift is experienced. The powerful headwind quickly becomes a very strong tailwind that degrades performance and demands an immediate response. Refer to figure (21) for a depiction of the effects of a microburst on an aircraft.

In the case of a microburst, the solution is to increase throttles to maximum power and raise the nose of the aircraft to the limits of stall. The object is to minimize altitude loss and fly out of the tailwind condition. This is particularly important when the aircraft is precipitously close to the ground. The best way to avoid flying into a wind shear or a microburst is to stay alert and be attentive to these adverse weather conditions. Pilots who experience a wind shear or a microburst should immediately report the occurrence to the control tower along with the amount of airspeed and altitude that was lost.

Runway Icing

A serious threat to aviation is the formation of ice on both the runways and the aerodynamic surfaces of an aircraft. In each case, the aircraft's performance is degraded. Ice on a runway significantly increases the stopping distance that is necessary for the airplane. An aircraft's performance is adversely affected by ice, much like a car is when it slips and slides on an icy highway. In both cases the weight of the vehicle is carried on a set of tires. Normal braking action is significantly reduced or rendered ineffective by an icy surface. Braking distance on glaze ice will increase dramatically and the directional control of the aircraft is more difficult. A pilot must be aware of any icing conditions before attempting to land. Icy runways are reported on ATIS and by the tower. Pilots are alerted to the danger so that they can take the appropriate precautions prior to landing.

Arrested landings

As we have previously discussed, many tactical jet aircraft have a unique way of dealing with a wet or an icy runway. In a case where a runway is wet or icy, the pilot has the option of lowering a tail hook and performing an arrested landing. The arresting gear is located at the approach end of a runway. It is comprised of a thick, braided wire. During the arrested landing the wire is snatched up off of the runway by the curled portion of the tail hook. The pilot literally flies the aircraft and the tail hook to a point on the runway. As the aircraft lands, the tail hook is dragged into the "wire". Hydraulic pressure is used to hold the tail hook down and to minimize any tendency for it to bounce over the wire. As the tail hook engages the arresting cable, it pulls the thick wire down the runway. The aircraft decelerates to a very abrupt stop.

The arresting gear is a valuable piece of equipment. If a pilot executes a normal landing and encounters unexpected slippery conditions, a "go around" must be initiated. Power is added to the engines and the speed brakes are immediately retracted. Once safely airborne, the pilot can reenter the landing pattern and set up for an arrested landing.

In some cases however, adverse conditions may be encountered after the aircraft has traveled too far down the runway and a safe go around cannot be executed. In this situation, the pilot must engage the long field arresting gear. The long field gear may be the pilot's last ray of hope for keeping an aircraft on the runway. The long field arresting gear is located in the last 1000 feet of the runway. In many cases it is bi-directional, which means that it can be engaged from either direction.

Many runways have long field gear installed. In addition they also have overrun gear installed. Overrun gear is designed to stop an aircraft after it has departed the runway. The overrun is located in the grassy overrun area, just beyond the departure end of a runway. In lieu of ejecting, a pilot may elect to stay with the aircraft and engage the overrun gear with the tail hook. The tail hook is used to catch one of the large heavy chain links that is extended across the width of the overrun. These large links in a very large chain serve as heavy arresting devices. When the tail hook engages one of these bulky chain links, it pulls a folded segment from both sides rapidly decelerating the aircraft.

In contrast, a large commercial aircraft uses a different system to decelerate an airplane on the runway. Thrust reversers are mounted to the back of each jet engine. The thrust reverser is designed to slow an aircraft down by blocking the flow of exhaust gas as the aircraft rolls down the runway. Large clamshell doors swing open, redirecting the flow of hot gasses forward and reducing the ground roll. Heavy braking requirements are minimized due to the forces of the thrust reverser system. On a slippery runway, care must be taken to ensure that power is evenly applied to each reverser.

In a perfect world, the safest way to land an aircraft is on a runway where the ice and snow has been properly cleared. In many cases this is not possible. After touchdown, a pilot must quickly assess the braking action of the airplane. It is essential for a pilot to keep the aircraft on runway centerline. When either of these requirements can not be met, the pilot should immediately initiate a "go around."

Aircraft Icing

When ice forms on the surface of an aircraft it alters the physical shape of the wing. As a result, the aerodynamic performance of the wing is adversely affected. Air flowing over the control surfaces is modified by the presence of ice. It is imperative for an aircraft to be free of ice or snow prior to takeoff. The wing and tail sections are critical aerodynamic surfaces. Disturbed airflow over the wing will lead to stall at higher airspeeds and lower angles of attack. Ice that forms on the surface of a wing functions like a turbulence generator. It disturbs the flow of air across the top of the wing. The results are a dramatic reduction in lift, which significantly degrades overall performance and efficiency. Under these circumstances, a higher airspeed must be maintained when a pilot icing is detected in flight.

Ice removal involves the application of a deicing fluid that contains an ethylene glycol base. Critical aerodynamic surfaces are sprayed to remove any existing ice and prevent ice from forming prior to takeoff. Deicing solutions quickly melt through any snow or ice that has accumulated on the surface of the aircraft. After deicing is complete, the aircraft must takeoff soon or it will have to be deiced again.

Ice can form on an aircraft's surface in a variety of ways. Rime ice is a softer ice that possesses a milky appearance. It develops when the metal of an aircraft is repeatedly exposed to moisture. During the freezing process, air is caught between the layers, creating a lumpy and opaque appearance. When an aircraft is flying in and out of clouds at the freezing level, it is more likely to encounter rime ice.

Clear ice is another type of ice that can form on an aircraft. Clear ice develops when super-cooled water strikes the freezing metal surface of the wing. In this case, the moisture instantly adheres to the wing's leading edges and creates a clear transparent glaze.

Frost is the third type of ice that forms on aircraft during cold winter nights. In order for frost to form however, the airplane must be sitting still. Frost is created when water condenses out of the atmosphere and settles onto a wing's surface. The pilot must pay closed attention during the aircraft preflight. The presence of ice or frost will adversely affect the aerodynamic performance of a wing.

Most large commercial aircraft are equipped with systems designed to prevent ice from forming on critical aerodynamic surfaces. In many cases, these aircraft are also configured with systems that are designed to remove ice after it has formed. Anti-ice systems utilize bleed air that is drawn from the compressor section of an engine. Hot air is directed to the leading edges of the wings and the engine intakes. The high pressure air is vented through small holes located in the surface of these critical areas. Hot air is used to prevent ice from forming. It raises the temperature of the surrounding metal surfaces.

Engine intakes accumulate ice more readily due to a concentrated flow of air passing through narrow intakes. The venturi effect causes the flow of air to accelerate and creates extremely low temperatures. The cooling provides an environment that is very favorable for ice formation. Left unattended, large ice deposits can accumulate on these air intakes. As the ice forms it obstructs the flow of air into the engine and performance problems can develop. Higher engine temperatures are a symptom of obstructed intakes.

Deicing systems are designed to remove ice after it has already formed. An example of a deicing system that is used on aircraft are rubber deicing boots. Deicing boots are installed on a wings leading edge during the manufacturing process. When ice accumulates on a wing, the system is activated. Compressed air is routed from the engine to the rubber boots. They quickly inflate and shed any ice that has formed on a wing's leading edge. The deicing boots rapidly deflate and return to their normal shape.

Deicing systems are capable of being used on repeated occasions. Any time that additional icing occurs, the system can be engaged. Care must be taken to use the deicing system judiciously. If the boots are deployed before the ice is completely frozen, this soft layer of ice may flex and not break free from the wing. In this case the ice will bow out and create a "domed" layer of ice. The deicing system will unfortunately be rendered ineffective when this situation occurs. As a result, ice will continue to accumulate on the wing until a descent is made into warmer air.

Relative Humidity

Relative humidity is a measure of the moisture content in the air compared with the amount of moisture that the air is capable of holding. Warm air can hold more moisture than cold air. The moisture content in the air is measured in terms of 100 percent saturation. For example, hot desert air is capable of holding a considerable amount of water vapor. In reality however it usually has a low relative humidity of only 10 percent. On the other hand, a tropical rain forest with the same temperature may have humidity levels averaging over ninety percent. When air is completely saturated, moisture is released in the form of dew, mist or rain.

A colder climate has similar characteristics. Cold air with a relative humidity of ninety percent however will contain considerably less water vapor than the same volume of air on a warm day.

Relative humidity measurements are important to a pilot since moist air is not as aerodynamically efficient as dry air. Water molecules suspended in the air are less dense and produce less lift than the dry dense air of a cold winter day. Therefore, aerodynamic performance is adversely affected by humidity. As we have seen, a combination of heat, humidity and high elevation is a concern for an aviator. An aircraft's performance is most seriously affected when taking off from a high altitude airport with intensely hot temperatures and high humidity. The combination of these three conditions creates the worst scenario for aerodynamic performance.

For example, an aircraft taking off from an airport in Denver, Colorado (the "Mile High City") during a rain shower on a hot summer day will require an extended takeoff roll in order to reach Vr and become airborne. The aircraft will also experience a reduced rate of climb due to these adverse conditions. Before flight the pilot must take a close look at the length of the runway, the airfield elevation, the outside air temperature, the strength of the wind and the aircraft's takeoff weight.

Pilots of large commercial aircraft utilize runway performance charts in order to compute takeoff power settings, takeoff refusal speeds and takeoff rotation speeds. These charts are designed for each major runway on the airfield. They are also used to ensure that the aircraft can climb safely and avoid any obstacles that located in the departure corridor. Tall buildings, mountain peaks and radio towers are all potential threats to a pilot.

On rare occasions, an emergency may occur during takeoff that requires an immediate landing. The pilot must return expeditiously to the departure airfield. Before the emergency landing can be initiated however, a variety of things must be accomplished. One important consideration is the requirement to dump fuel. In order to prevent overstressing an aircraft due to a high landing weight, fuel must be dumped. Dumping fuel is a quick and effective way to achieve this goal. A longer runway may also be necessary for landing in order to ensure that there is sufficient distance for rollout after touchdown.

In contrast, airfields located at sea level with dry, cold weather are optimum locations for efficient aerodynamic performance during takeoff and landing. Unfortunately, all airports are not located at low altitudes in cool dry climates. A pilot must be able to takeoff and land with confidence at any major airport in the world. Safe landings must be possible at high altitude airfields with humid tropical conditions. Weight reduction may be requited when extreme weather conditions exist. The pilot may have to plan an additional refueling stop enroute in order to lighten the load for takeoff. Another option is to send personal effects on a later flight when the temperature has cooled.

Frontal Systems

Frontal systems are a defined by the merging of two air masses with significantly different temperatures. In terms of understanding how temperature plays a role in frontal systems, it is important to know that the atmosphere behaves much like water. When swimming in a lake you may have noticed that the colder water tends to settle closer to the bottom. The warmer water that is heated by the sun floats closer to the surface.

The air that is associated with a cold front behaves in a similar manner. Heavier cold air settles close to the earth's surface and displaces warm air upward into the atmosphere as it moves over the ground.

A front is defined by the temperature of an overtaking airmass. These temperatures are measured against the temperature of the existing air mass. For example, during the month of January a frigid arctic air mass flows south and delivers a blast of cold air to the country's midsection. The temperature of the air on both side of the front is very cold, but the overtaking air mass is significantly colder. Therefore it is defined as a cold front.

Cold Fronts

As a cold front passes, the cool dense air travels along the earth's surface of the earth and functions like an aerodynamic wedge. The existing warm air is bulldozed and displaced skyward. A vertical movement of the warmer air creates an unstable atmospheric condition. The clashing of these distinct air masses creates strong winds and violent storms.

Gusty winds that precede the advance of a cold front are known as "Squall Lines." A squall line results from the tumultuous mixture of the warm and cold air at the leading edge of the cold front. The swirling breezes of a squall line announce the impending arrival of a powerful storm. Large storm clouds travel behind the squall line. Due to their rapid rate of movement, cold fronts often arrive unexpectedly. They do not stay long however because of their swift groundspeed. As a cold front passes it leaves clearing skies and cooler temperatures in its wake.

Cold fronts tend to propagate more destructive weather than warm fronts because of the energy associated with squall lines and the rapid vertical movement of air. The damaging effects of a cold front can be experienced on the ground or in the air. Severe turbulence, hail, tornadoes and wind shear are potentially dangerous byproducts of a fast moving cold front.

The following descriptive word picture demonstrates how the powerful movement of a cold front can quickly alter the weather on a sunny summer afternoon.

"The flickering sun shone brightly through the outstretched branches of a tree lined street. Afternoon shadows began their measured trek across the concrete's sun bleached surface. Imperceptibly a light swirling breeze stirred and danced lightly down the wide expanse of the boulevard. A transparent cloud of dust trailed in flighty pursuit. The outstretched leaves of a towering oak tree rustled noisily overhead.

Slowly the wind strengthened and began pushing resolutely through the swaying treetops. Surging gusts parted the canopy and dove downward toward the pavement below. A vertical column of air impacted the ground and sent a rush of cool freshness throughout the neighborhood. The wind strengthened. Surging currents of air pressed closer to the earth. The approaching storm was heralded by the hollow rumble of thunder murmuring imposingly in the distance.

Afternoon shadows faded quickly and the sky darkened under the ominous advance of towering storm clouds. The growl of thunder grew louder, hammering relentlessly against the sides of windswept homes.

Cold, ladle size drops of rain began to fall, pelting warm dry concrete in a pepper-stained array. The rain grew in intensity, catching unsuspecting bystanders in a flurry of wind and water. The storm unleashed a torrent of rain while tree branches flailed angrily, thrashing wildly against the wind.

Misty plumes of steam rose lazily above the water soaked pavement. The storm intensified as lightning flashed brilliantly through a churning wall of clouds. A deafening roar of thunder exploded overhead, releasing an oppressive barrage of marble size hail. The clamoring ice ricocheted wildly from neighborhood rooftops, in staccato like fashion."

The scene is familiar to all whom have experienced the strength and power of a cold front rushing hastily toward them on a warm summer day. In extreme cases, these powerful weather systems can create destructive tornadoes and gale force winds.

Warm Fronts

A warm front is the movement of warm air that overtakes an existing cold air mass. A warm front is more sublime in nature and tends to roll up on the back of the colder air. Weather associated with a warm front is more stable and is characterized by steady rain and drizzle that falls over an extended period of time. The initial indications of a warm front are high cirrus clouds. Gradually ceilings lower and visibility worsens. The bad weather associated with a warm front creeps down to lower altitudes. The low ceilings and poor visibility are located well behind the storms leading edge.

The image that a slow moving warm front paints is a more benign picture. "The roundness of the moon shone brightly in the early autumn morning. Roads and rooftops of the coastal community were bathed in a milky white glow. A translucent halo encircled the mottled surface of the moon signaling an impending change in the weather. Dawns first light painted the eastern horizon in a fiery red glow. The musky smell of approaching rain drifted inland on the shoulders of a light sea breeze.

As the day progressed, ceilings dropped and visibility worsened. A misty shroud settled over the lowlands while a thick blanket of fog spread inland immersing the sky in a sea of opaque. Distant objects began to lose their definition as a light mist settled softly into the treetops. Tiny water droplets form and drip from leaf to leaf on their wayward descent to the marshy ground below."

Stationary Fronts

A stationary front is formed when two adjacent pressure systems stagnate. The overtaking air mass stalls and little movement occur between the two thermal layers. Due to the lack of movement, the weather associated with a stationary front can persist for a long period of time. Little energy is available to drive either air mass in a direction. Warm moist air settles close to the earth causing lengthy periods of fog, drizzle and overcast skies. Low ceilings and poor horizontal visibility are the primary characteristics of a stationary front.

Clouds

Clouds can be observed in a variety of sizes and shapes. The cloud formations that are present along the route of flight will effect where a pilot can safely fly his aircraft. Particular attention must be paid to forecast weather during mission planning and the preflight phases of flight. After takeoff, weather updates should be obtained during the enroute portion of the flight.

Clouds are classified by their shape, moisture content and distance above the earth. Cumulus clouds for example are large billowy white clouds that float lazily above the ground on a clear summer day. These same cumulus clouds can also be observed at higher altitudes. In the case of high altitude cumulous clouds, they are prefaced by the term "alto." Therefore, high altitude cumulous clouds are referred to as altocumulus clouds. Low altitude clouds that spread out and blanket the sky are called "stratus" clouds. Stratus clouds found at higher altitudes are called altostratus clouds. Clouds that produce rain are prefaced by the word "nimbo". The term nimbo means rain. A nimbostratus cloud is a rain producing stratus cloud. The following is a description of the many of the more common cloud formations and the effects that they have on aviation.

Cirrus Clouds

Cirrus clouds are wispy plumes of white located in the upper levels of the troposphere. Cirrus clouds contain frozen ice particles that have been crystallized under extremely cold temperatures. These clouds have a thin transparent appearance due to the small size of the ice particles that are scattered across a wide area. The presence of feathery cirrus clouds indicates the potential for rain in the next forty-eight hours. The long swirling cirrus clouds that fill the sky are called "Mares Tails." Cirrus clouds normally do not have an adverse effect on a flying aircraft since the moisture that is suspend in these clouds is already frozen. The ice particles in a cirrus cloud are small and do not adhere to the surface of an aircraft.

Stratus Clouds

Stratus clouds are associated with warm fronts. They are more stable and tend to blanket the sky from horizon to horizon. The thickness of the cloud layer varies significantly. Stratus clouds are created when a warm front overtakes a cooler air mass. High altitude stratus clouds are an initial indicator of an approaching warm front. Over the course of a day or so, these clouds will descend, dropping closer and closer to the ground. Flying conditions will transition from VFR flight to IFR as stratus clouds approach. These clouds frequently descend low enough to come in contact with the ground in the form of fog.

Conclusion

Weather is an important part of aviation. A pilot must be very familiar with the effects of weather. It is essential for a pilot to keep a wary, well trained eye on enroute weather conditions and the weather at the final destination. An old adage about severe weather and mechanical problems is summarized in a time tested piece of advice. "Remember, that it is always easier to be on the ground and wish you were in the air than to be in the air and wish that you were on the ground."

CHAPTER X - ROTARY WING FLIGHT

Helicopters, A Historical Perspective

Despite their ungainly appearance, the helicopter is a versatile flying machine capable of landing in very remote and inhospitable areas. The helicopter requires minimal space during its vertical descent into a landing zone. It is truly a welcome sight to anyone who has been lost or injured in a remote location. Helicopters were originally developed to transport men and equipment from one area to another. Early generation helicopters were rudimentary in design and significantly underpowered. Pilots were required to constantly fly these unstable machines by manually controlling the throttles in order to maintain proper engine and rotor RPM. Whenever a demand or a load was placed on the engine, additional fuel had to be added by increasing the throttles. In contrast when the pilot descended the throttle had to be reduced in order to keep the engine and rotor system from an overspeed condition. Less demand on the engines required a corresponding reduction in fuel flow.

Despite these early limitations, helicopters evolved and were successfully employed by the military during the Korean and Vietnam conflicts. The helicopter underwent extensive development during this period of time. Modifications and improvements were made based on the trial by fire scenarios experienced during combat. These improvements were an integral part of the modern day advances associated with helicopter technology.

Helicopters are a valuable addition to the battlefield during a conflict. The helicopter provides a commander with the unique capability to expeditiously insert personnel and equipment into a combat zone. Helicopters are also extremely useful for moving supplies and equipment. Offensive operations are enhanced by the element of surprise and the ability to quickly mass troops into a designated area.

Helicopters also provide a foot soldier on the ground with a measure of confidence and security. If the unfortunate situation occurs where a soldier is wounded in combat, the casualty knows that they will be quickly evacuate from the front lines to an aid station in the rear.

Search and Rescue teams with qualified medical Corpsmen onboard provide prompt treatment for wounded soldiers and downed airmen. Helicopters are also designed to operate from ships at sea. Many ship-to-shore missions included combat resupply, vertical assault, and external cargo lift. During the Vietnam War, several unique and versatile helicopters were introduced. Transport helicopters were built to move heavy cargo, troops and bulky equipment. Smaller utility helicopters were designed for tactical insertions, combat search and rescue missions, parachute operations and reconnaissance missions. The helicopter proved to be a noble workhorse during this period.

How Helicopters Fly

A helicopter is an amazing sight to see as it hovers and maneuvers in forward flight. Helicopters are comprised of many moving parts that work together in unison. The fact that helicopters can fly is a testament to precise and meticulous aeronautical engineering. To understand how a helicopter creates lift and is able to fly, several aerodynamic principles must be discussed. The overriding requirement is for sufficient lift to be generated in order to raise the weight of a large aircraft vertically off of the ground.

Helicopters manufacture lift by employing a main rotor system. The engines in a helicopter are designed to provide sufficient power for flight. The engines drive a gearbox that is connected to a transmission through a common drive shaft. The transmission converts the driveshaft's power into a vertical rotation, turning the mast and the attached main rotor blades.

In addition to the requirement to generate vertical lift, helicopters must also be able to compensate for another powerful force that is a byproduct of lift. The force is called "torque". Torque is created when the main rotor system is turning. In flight the fuselage of a helicopter is designed to hang suspended beneath the main rotor blades. As the rotor system turns it creates torque. Torque is an opposing force that attempts to turn the fuselage of a helicopter in the opposite direction of blade rotation. Higher pitch angle on the rotor blades results in increased transmission torque. If torque is left unopposed, it will cause the fuselage of a helicopter to spin uncontrollably. Engineers who design helicopters must take torque into account and integrate a system that counteracts these adverse effects.

There are three different anti-torque designs used on modern day helicopters. The first system involves the use of a tail rotor. A tail rotor is powered by a drive shaft that is connected directly to the transmission. Bearings hold the drive shaft in place and a reduction system is used to decrease the rotational speed of the shaft to a more manageable level.

The tail rotor is designed to spin vertically instead of horizontally. The lift that is created by the tail rotor is directed sideways. Thrust on the tail rotor is increased or decreased by varying the pitch angle of the tail rotor blades. Rudder pedals in the cockpit are physically connected to the tail rotor through a series of mechanical linkages. The pedals are used to control the movement of the tail rotor blades. The torque effect on helicopters with main rotor systems rotating counterclockwise will force the fuselage to spin to the right. The torque effect on a helicopter with main rotor systems turning clockwise will spin the fuselage to the left.

A tail rotor system is used to maintain the proper heading during forward flight. It is also used to align the nose of the aircraft in a hover. In a hover the application of left rudder increases the pitch angle on the tail rotor blades. The tail rotor blades take a bigger "bite" out of the air and the tail moves to the right. In response, the nose of the aircraft swings to the left in the desired direction of turn.

Conversely a turn to the right in a hover is initiated by adding right rudder. Right pedal decreases the pitch angle of the tail rotor blades so that the torque generated by the main rotor system is used to rotate the nose of the aircraft to the right.

The second method of dealing with torque in a helicopter is the integration of two main rotor systems. Torque effect is negated when two rotor systems spin in opposite directions. Several designs are employed on helicopters that use counter-rotating systems. The first design incorporates two rotor systems that are mounted on the same mast. Each system rotates in the opposite direction. Another method is to install separate transmissions on both ends of the helicopter. A common drive shaft connects the two transmissions. These two transmissions are synchronized to prevent the overlapping of rotor blades as they turn.

A third way to counteract torque on a helicopter is to duct high pressure air from the engine directly to the tail section of the helicopter. Air is drawn from the compressor section and routed to nozzles that are designed to pivot. Tail movement is controlled by modifying the direction and intensity of engine bleed air as it is released from the nozzles. The variable thrust nozzles guide the movement of the tail during hover and forward flight.

As you can see, there are many creative ways to deal with the unseen, yet ever-present effects of torque on the fuselage of a helicopter.

Helicopter Flight Controls

The flight controls of a helicopter consist of three basic components. These components are designed to direct the movement of the aircraft through a three dimensional world of space. The collective lever is used to increase or decrease the pitch angle of the main rotor blades. The collective lever is mechanically attached to the main rotor system. As the collective is raised, pitch on the main rotor blades is increased. In response, the rotor system takes a larger "bite" out of the air and causes the helicopter to climb.

The rate of climb is based on the amount of pull on the collective lever and is directly related to the pitch angle on the main rotor blades. In a hover the collective lever is raised until enough lift is created to raise the aircraft vertically off the ground.

The main rotor system of a helicopter is designed to rotate at 100 percent RPM during hover and forward flight. In a hover however, the engines must work harder to maintain that 100 percent rotor RPM. An automatic fuel control senses the demands on the engines and meters more fuel in the combustion section. The additional fuel causes the engines to work harder. The rotor RPM however remains constant.

During a hover the fuel flow is noticeably higher. The main rotor system must generate all of the lift in order for the helicopter to fly. It is advantageous for a pilot to hover into the wind. The flow of air across the rotor system helps to augment lift production.

The "cyclic" directs the movement of the helicopter fore and aft, left and right. A cyclic stick resembles the control stick found in military fixed wing aircraft. A cyclic is mechanically connected to the control tubes located within the fuselage of the helicopter. These control tubes are designed to relay flight control inputs directly to the moveable control surfaces on a helicopter.

A very important control mechanism that is mounted to the transmission is called the stationary swashplate. The stationary swashplate supports a complimentary device called the rotating swashplate. The rotating swashplate is mounted on top of the stationary swashplate and it spins on bearings that are positioned between the two parts. Control tubes run from the rotating swashplate up to a rotor hub located on top of the mast. These control tubes are connected to the main rotor blades to control their movement.

When the cyclic stick is moved, the stationary swashplate tilts and moves in the desired direction of turn. The rotating swashplate moves in tandem with the stationary swashplate. Control tubes lead from the swashplate up to the top of the mast. They are used to adjust the pitch angle of the main rotor blades.

Now lets put this confusing picture together. It is very difficult to see all these moving parts work together given the high rate of rotation that the main rotor system experiences. It is more beneficial to look at a specific maneuver and relate the control changes to the maneuver. For example, during the transition from a hover to forward flight, the cyclic is moved forward. Power is added by increasing the collective. and the swashplates tilt in the desired direction. The rotor blades dip forward and the aircraft accelerates. The same is true for sideward and rearward flight.

The third flight control system in helicopters is an anti-torque device referred to as the rudder pedals. Rudder pedals control the movement of the tail rotor in forward flight and in a hover. Refer to Figure (22) for a depiction of these various flight controls. It is the combined movement of all three systems that enables a pilot to fly a helicopter and maneuver gracefully through the air.

Hovering Flight

One of the more difficult tasks associated with flying a helicopter is the act of hovering. The art of hovering can only be mastered after a significant amount of practice. Practice improves a pilot's experience level and minimizes the amount of conscious attention that is required in order to hover. In other words, practice refines ability. A pilot must learn how to anticipate the control inputs that are necessary to smoothly hover a helicopter. Over time, a pilot develops a feel for hovering and avoids the temptation to over control the aircraft.

The following is a brief description of what a pilot must do to successfully hover a helicopter. Hovering begins by raising the collective lever until the aircraft feels "light on the skids." From this point, the collective is raised steadily until the helicopter lifts free from the ground and climbs vertically into the air. After the helicopter is established in a hover, the pilot must quickly scan the horizon to evaluate the overall stability and effectiveness of the control inputs. The primary method that must be used to detect drift is a scan that is out toward the horizon and down toward the ground. As the eyes are focused toward the horizon the pilot must integrate several frequent glances down at the ground to detect any apparent signs of drift."

Any time that the collective is raised, left rudder pedal inputs must be anticipated to counteract torque. Left pedal inputs are required for helicopters with main rotor systems that rotate counterclockwise.

When the aircraft breaks free of the ground, any drift will be apparent. A common mistake that a fledgling pilot makes during their first attempt to hover is the tendency to snatch the helicopter off the ground. In this case the helicopter will rocket rapidly skyward. The collective lever should be smoothly raised until the helicopter lifts free from the ground and is established in a stable, five foot hover. A quick disciplined scan is essential for detecting drift and maintaining proper nose alignment.

Learning how to hover a helicopter is very difficult. The challenges associated with this task are similar to what it takes to master the art of wind surfing or learning how to juggle. With practice and the passage of time, a pilot's flying skills can be perfected.

Flight Characteristics

A helicopter is able to hover and fly due to the airflow that is created by the main rotor blades. Lift generating air is drawn down from above the rotor blades and pulled through the rotor system. Air molecules are propelled powerfully downward toward the ground while in a hover. The helicopter's "rotor wash" strikes the earth and rebounds back into the air. The upward flow of air is re-circulated back through the whirling rotor blades.

When a helicopter climbs and transitions to forward flight it benefits aerodynamically from relative wind as it flows across the rotor system. When the helicopter is established in forward flight, the collective pitch setting can be reduced. The power demands on the engine are not as great due to more efficient aerodynamic flow.

The transition from a hover to forward flight requires timely coordination in order to successfully complete this maneuver. A fledgling pilot's first attempt at forward flight can be a rather colorful experience. Problems typically encountered during this phase include the failure to maintain proper heading, the tendency to climb rapidly and the inattentive reluctance to maintain little or no forward airspeed.

After a helicopter pilot has mastered the transition from stable hover to forward flight, the next challenge is to reverse the process and decelerate from forward flight into a smooth, stable five foot hover. The initial tendency for a new pilot is to decelerate much too swiftly and end up hovering short of the intended landing area. Or the pilot may carry excess energy on final approach and overshoot the intended point of landing. Practice and experience are two essential elements that are needed for a pilot to gain a true "feel" for the aircraft.

Autorotative Landings

An autorotative landing is an emergency maneuver that is conducted in response to the loss of power in a helicopter. Unlike jet aircraft, helicopter crews do not wear parachutes. The helicopter pilot cannot eject if mechanical problems occur. The solution to this unique dilemma is the autorotation. Total loss of power in a helicopter is a rare occurrence. However, if there is a power loss, the pilot is faced with the requirement to land. Gliding distances are based on the aerodynamic design of the helicopter. The Rate of descent during an autorotation is affected by the pitch setting of the main rotor blades. An autorotation may be executed for reasons that include an engine failure, a transmission drive shaft failure or the complete loss of tail rotor authority.

During an autorotation, airflow through the main rotor system is reversed. When the loss of power occurs, the collective lever must be lowered quickly in order to preserve inertia and maintain the proper RPM on the main rotor blades. As the helicopter transitions to an autorotative descent, the air begins to flow from beneath the rotor system.

The best example of an autorotation that can be found in nature when a maple seed breaks free from its lofty perch and floats lightly to the ground below. The wings attached to the seed pod cause it to spin. The rotation of the pod creates lift and slows its rate off descent. On a windy day a falling seed can drift very far from a tree in search of fertile ground.

During an autorotation, the rotor system continues to turn. The phenomenon is much like the blades of a fan in an open window. The sill mounted fan spins steadily in the face of a stiff breeze.

When a helicopter is established in an autorotation, the RPM of the main rotor blades must be controlled by the pilot. RPM is adjusted by raising or lowering the collective lever. If the main rotor blades are spinning too fast, the pilot simply increases the pitch angle on the blades with the collective lever. The rotor blades take a bigger bite out of the air, increasing drag and slowing the rotor system down. As blade rotation returns to the optimum speed, the collective must be lowered slightly in order to prevent the RPM from decaying below that speed.

An RPM gage is installed inside the cockpit of a helicopter. It provides the pilot with the ability to monitor main rotor speed. Experienced pilots also use the sound that the main rotor system makes as it spins to assess rate of rotation. A high RPM state has a distinct sound that can be heard by the pilot and the crew. The whir of the blades is a useful cue for the pilot and serves as a reminder to crosscheck the RPM gage. The subtle audio hint suggests to the pilot that it may be time to increase the collective.

Another essential task that a pilot is faced with during an autorotation is the need to locate a suitable landing area. During the initial stages of an autorotation, the helicopter must be turned immediately toward the selected landing zone. A quick response helps to minimize altitude loss and increase the probability of reaching the site. The elevation above ground is a key factor for determining how far a helicopter can glide in an autorotation. Low altitude autorotation provides little time for maneuvering. The pilot can usually only make shallow turns prior to landing.

Another important consideration during an autorotation is the direction of the wind. It is beneficial for the pilot to align a helicopter into the wind during the final landing phase. Wind flowing over the main rotor system provides a pilot with additional lift that can be used to turn the rotor system. A strong headwind also helps to minimize the helicopter's forward airspeed during the landing. As the helicopter gets close to the ground, the pilot initiates a "flare". The flare helps reduce forward airspeed and slow the rate of descent. During the flare the nose is raised in order to preserve inertia in the main rotor system. A flare is maintained until the helicopter approaches the ground.

Just prior to landing, the pilot levels the aircraft. As the helicopter settles to the ground, the pilot must raise the collective lever. By doing so, the pitch angle on the main rotor blades is increased and the rate of descent is dramatically reduced.

Rotor inertia must be carefully preserved throughout the maneuver so that there is sufficient energy at the bottom to ensure a safe landing. The odds of performing a successful autorotation are based on several factors that include the type of terrain below the aircraft, the weather conditions, a pilot's reaction to the loss of power and the height of the helicopter above the ground.

Hovering Autorotations

The need to execute an autorotation may not always occur during forward flight or at altitude. In some cases a pilot must react quickly to an engine failure while hovering. If power is lost during a hover, the aircraft is leveled and the landing is cushioned with a steady pull on the collective.

Practical Uses for Helicopters

The helicopter is a versatile aircraft that is useful for accomplishing a variety of tasks. The ability to hover over the ground is one of the many things that makes a helicopter so unique. During a high hover, passengers are afforded an unobstructed view of the earth below. The helicopter can fly at slow airspeeds for extended periods of time at altitude. The helicopter is an excellent platform for viewing activities such as parades, rush hour traffic or sporting events.

Hovering is a high power, high demand flight condition that increases fuel consumption significantly and reduces the stability of the aircraft. Whenever possible, a pilot should attempt to hover into the wind. The airflow across the rotor system generates additional lift that helps to stabilize the aircraft and reduce the workload in the cockpit. In contrast, hovering with a tailwind decreases stability, requires additional power and dictates a more concerted effort to maintain a constant position over the ground.

A helicopter is a valuable tool during search and rescue operations. Snow skiers, mountain climbers and hikers often take on more than they can handle when their adventurous spirit leads them deep into the wilderness. Activities in the great outdoors can lead to unforeseen injuries. These injuries may result in immobility, exposure to the elements, and possible unconsciousness. Poor preparation, early nightfall, or a fast moving storm may lead to extreme situations where a stranded individual requires the services of a helicopter. In fact, a helicopter may be the only viable recovery option in these cases.

Rescue helicopters are configured with medical equipment and supplies. The equipment is essential so that paramedics, nurses and doctors onboard the aircraft can treat a patient while enroute to a medical hospital or trauma center. These state of the art life support systems may be the difference between life and death. The time savings that a helicopter provides is another crucial factor in the race to save a life.

On many search and rescue helicopters a rescue hoist is mounted to the fuselage. A functional rescue hoist is an integral part of a successful search and rescue operation. The hoist can be operated by the flying pilot or by a designated crewman in the cabin. The Crew Chief is positioned in the back of the helicopter and is responsible for assisting passengers and the pilot during a flight. The Crew Chief communicates with the pilot when conducting hoist operations on an intercom system. Valuable information is provided regarding an aircraft's position in relation to obstacles. It is the crew chief's role to verbally describe all aspects of the hoist operation. The crew chief presents word pictures that describe rate of movement of the hoist, the helicopters position over the ground and the physical location of the victim. It is very important for a pilot to hold a stable hover when hoisting. The crew chief provides the assistance to make the mission a success.

Hoist Operations

Hoisting requires a skilled hand. A steady hover must be maintained over one spot, in what usually are less than ideal weather conditions. A high number of mishaps frequently occur in mountainous regions and on the open seas. Due to the strong gusty winds and inclement weather typically associated with these types of rescues, the task of hovering is even more challenging. Hoist operations are valuable in providing timely assistance for victims in distress. Once the mishap location is known the aircraft can proceed directly to the site and begin the recovery effort. In some cases, the victims may have a radio and can provide the aircraft with their general location. SOS broadcasts are transmitted over a designated emergency frequency that all pilots monitor during flight.

Hoisting is a unique and valuable capability that provides a pilot with the ability to conducted a rescue in rugged and inhospitable terrain. Hoisting is perfectly suited for a situation where the helicopter cannot land safely and perform a conventional pickup. Instead, the pilot hovers above the rescue area and lowers the hoist cable to the ground. Many times medical personnel are sent down the hoist cable to the ground in order to assess the situation and assist in the rescue. Specific types of rescue equipment can be used to facilitate the pickup. Victims can be retrieved by the use of a horseshoe shaped device called a "horse collar". The horse collar is attached to the end of the hoist cable and wrapped around the back of the victim, forming a loop. A large retaining hook at the end of the collar is used to connect the free end of the horse collar to the base of the hoist cable.

When the victim is safely attached to the hoist cable, the tension is brought out of the cable very slowly. As the slack is removed the horse collar slides up under the victims arms. The victim is then lifted off of the ground and raised up to the helicopter. Hoist operations can be conducted to the water as well. It is not uncommon for sailing crews to be stranded on a floundering ship in rough seas. In many cases, they have already abandoned ship and are left floating aimlessly in a life raft. In this situation, the horse collar is lowered to the water and the victim swims to the pick-up point. Care must be taken so that the pilot does not to get too close to any rafts or flotation devices. A raft can be lifted out of the water and pulled up into the rotor system.

The hoist is a perfect tool to facilitate the rescue of distressed personnel under extreme situations. If a victim is debilitated however and a back injury is suspected, a litter must be used to pull the patient up into the helicopter. A liter is a stretcher without legs. It is used to raise someone who must remain in the prone position. The injured patient is placed on the litter and is lifted up to the helicopter as a way to minimize any excess pressure on their back.

Hoisting has extensive commercial applications as well. The lumber industry uses helicopters equipped with hoists to lift equipment into and out of remote sites. Helicopters are also used to lift lumber in remote areas to consolidation points. The helicopter is a versatile and valuable tool designed for a variety of applications.

Medical Evacuation

The true value of a helicopter is demonstrated when it is involved in a life saving endeavor. The capability to respond quickly and access remote locations is what makes a helicopter so unique. After takeoff a helicopter can proceed directly to an accident site, saving valuable time. Ground rescue vehicles must travel by roads and may become caught in heavy traffic. They may also be faced with a long drive to the rescue site. Helicopters are fast and are not subject to roadblocks or detours. One limitation that helicopters do have is the weather. Low ceilings, reduced visibility and thunderstorm activity can create a potentially dangerous situation for the aircrew. A pilot may have to divert to an alternate location for the pickup due to the weather. On certain occasions a pilot may not be able to fly and a rescue must be initiated by ground crew personnel.

In most cases however, weather is not a factor for a pilot. Rescue helicopters are able to proceed to an accident scene. Individuals who are injured in serious automobile accidents can benefit significantly from the responsiveness of a "Life Flight" helicopter. During a medical emergency, time is of the essence. The ability to deliver sophisticated medical equipment to the scene of an accident and provide immediate emergency care is very valuable. Paramedics are an essential part of the team. They are crucial for life saving rescues.

Military Helicopters

The greatest employer of helicopter assets in the world is the United States military. All branches of the armed forces including the Air National Guard and the Coast Guard fly helicopters. The military employs helicopters tactically, to support operations on the ground and at sea. Transport helicopters are used to move large numbers of troops. Escort helicopters are deployed to protect transport helicopters while flying in combat missions. Smaller utility helicopters are used for special missions and for Special Forces operations.

Special Missions

Special Missions flights involve the tactical insertion and extraction mission of personnel and equipment behind enemy lines. Many times Special Missions are conducted from helicopters due to their ability to hover and remain hidden. A low level ingress to the objective area is used by a pilot to mask the noise of the rotor blades and remain unseen. A variety of techniques can be used to successfully insert and extract Special Forces teams into designated areas. The helicopter provides a delivery method that is quick, agile and unobtrusive. The following chapter summarizes the various methods that are used to accomplish this mission.

CHAPTER XI - UNCONVENTIONAL FLIGHT

Parachute Operations - An Overview

Parachuting is an exciting and breathtaking activity. The first step in jumping involves ground school training and classes with certified instructors. The jumper must be able to respond quickly and deal with any unusual situations that may occur.

A large number of people are taught how to parachute while in the military. The course of instruction is conducted at a Jump School that is sponsored by the U. S. Army. The course involves ground school training and parachute jumps from transport aircraft and helicopters.

Parachute operations are planned well in advance. A scheduled jump must be listed on a flight NOTAM or Notice to Airmen. NOTAMs are published so that non-participating aircraft are aware that parachuting activities are being held in the local area. Jump sites are denoted on a VFR Sectional chart with the symbol of a deployed parachute. Before releasing any jumpers, the pilot must announce on a designated radio frequency that the jump zone is going "Hot". The duration of the jump is also included in the announcement.

There are a wide variety of parachutes that can be used by jumpers. These chutes differ drastically in terms of maneuverability, rate of descent and design. For example, a conventional military parachute is not very maneuverable and has a relatively high rate of descent. Chutes used during competitive parachuting events are relatively small, compact and very maneuverable. A jumper can control their rate of descent with these types of chutes. The landing phase is important since these chutes can be flared just prior to touchdown.

Military Parachute Operations

Military parachute operations are conducted during daylight and darkness. Night jumps are used during conflicts to minimize a parachutist's exposure to the enemy and to employ an element of surprise. A night jump is more challenging due to the loss of visual depth perception along with the danger of unseen obstacles and rough terrain in the landing area.

Parachute operations during peacetime are conducted over a large open area called a Drop Zone or a "DZ". A drop zone is a smooth flat field void of any trees, structures or obstacles. On the ground in the drop zone there are wind measuring devices, a radioman and a signal panel which is used to mark the designated landing area. The radioman serves as a safety observer and the one who authorizes the release of jumpers from the aircraft.

Before conducting the drops in a peacetime environment, the aircraft is flown over the intended landing area for a "streamer pass." During the streamer pass a long, thin piece of fabric is dropped from an aircraft. The streamer is a used to determine how the winds at altitude will affect a jumper during their descent to the drop zone below. The pilot can plan their approach to the jump zone based on the results of the streamer pass. The aircraft is properly positioned for the jump. If there is a significant wind, the aircraft must be offset well upwind from the intended point of landing. When the jumper leaves the aircraft they deploy their parachute. The wind pushes the jumpers back toward the landing zone.

Parachute operations are conducted from a variety of altitudes. In addition, several opening techniques are utilized. Jump altitudes during a normal practice jump are conducted at fifteen hundred feet above the ground. The use of a "static line" is common. A static line is a cord attached to a physical hard point on the aircraft. The other end of the static line is tied to the ripcord of a jumpers parachute. Immediately after leaving the aircraft, the static line pulls the ripcord and automatically deploys the jumper's primary chute.

A parachutist can use several additional jump techniques to arrive safely in a drop zone. One method is the High Altitude, Low Opening jump (HALO). A HALO jump is employed as a way to reduce the possibility of being detected by personnel on the ground. Each parachutist leaves the aircraft and free falls rapidly until approaching one thousand feet AGL. At this low altitude, the chute is finally opened. HALO drops are often initiated from as high as sixteen thousand feet above ground. The jumper descends at a high rate of speed and waits until they are in close proximity to the ground.

In contrast to a HALO jump, a HAHO jump or High Altitude, High Opening is another jump technique that can be used to reach a landing zone safely. In this case, the jumper leaves the aircraft at a high altitude. The release point is a location that is well displaced from the intended point of landing. Early chute opening allows a jumper to use wind to "fly" toward the drop zone. The jumper can cover a significant distance over the ground before touchdown.

Parachuting from a helicopter is conducted at relatively slow forward airspeeds. Parachutists jumping from helicopters usually exit from a side door or ramps located at the back of the aircraft. Helicopters are able to land expeditiously at remote drop zones and pick up personnel for follow-on jumps. Transport aircraft dispense jumpers out the back via a lowered ramp. These aircraft must return to a designated airfield in order to load additional jumpers. The speed in delivery using a helicopter is often overshadowed by the volume of jumpers that a large fixed wing aircraft can provide for an operation.

Military FAST Rope Insertions

The FAST Rope system is a relatively new method of tactically inserting troops into a designated zone. The FAST Rope system is an insertion system designed primarily for use in helicopters. A FAST Rope consists of a gantry that is mounted internally. The gantry consists of a vertical pole that runs from the floor of the helicopter to the ceiling of the cabin. An arm is attached to the gantry pole that is swiveled out the cargo door and into the slipstream. When fully deployed, the gantry arm is extended beyond the edge of the cabin floor. As the helicopter transitions to a high hover over an insertion point, a thick FAST Rope attached to the gantry is dropped to the ground below. The insertion team members simply slide down the thick rope in rapid succession. The FAST Rope system is similar to what happens during a three alarm fire at a firehouse. As the alarm sounds, firemen slide down the brass fire pole to their fire engines below.

FAST Rope insertions are suited for locations where a helicopter cannot land. Places such as oil rigs, small clearings and fortified compounds are good examples of FAST rope insertion sites. On final approach to the drop zone, the FAST Rope is dropped as the helicopter transitions to a stable hover. Insertion teams consisting of four to five people can leave the aircraft and reach the ground in less than fifteen seconds. When the last man is safely on the ground, the FAST Rope is released from the gantry and dropped to the landing zone below. The helicopter is free to transition to forward flight and egress the area. FAST Rope insertions are a swift and efficient way to deliver personnel into a zone in a minimal amount of time. The FAST Rope system helps to reduce an aircraft's exposure to enemy fire. The technique also minimizes the possibility of detection by ground personnel.

Rappelling

Rappelling is another way to tactically insert personnel. It is similar to a FAST Rope insertion. In the case of rappelling however, thinner ropes are attached to hard points inside the cabin. When the helicopter transitions to a hover the rappelling ropes are deployed and the team members are free to slide down the ropes. Unlike FAST Rope operations, rappelling team members are physically connected to the rope. Rappelling ropes are fed through a series of rings that are integrated into the harness. Each rappeller controls the rate of descent by employing a braking technique with the rope. Friction is applied by pulling up the rope up against metal rings. After reaching the ground, each rappeller must disconnect their rope from the harness. Rappelling is an effective insertion method that has been used for many years. It is a reliable and proven technique and serves as a sound alternative to FAST Rope.

Water Insertions

Frequently a tactical insertion may be required into the water. Another way to expeditiously dispense personnel from a helicopter is by conducting a Water Insertion. Water Insertions are performed along coastal areas, lakes, streams, rivers and ponds. During a water insertion, the helicopter pilot ingresses to the drop point at very low altitude. The flight profile conforms to the terrain and is used to minimize exposure. Low altitude flying also helps to muffle and disburse the sound of the rotor blades.

Swimmers onboard the helicopter wear wet suits, fins, a snorkel and a mask. As the helicopter approaches the insertion point, the pilot descends to a low hover and taxies over the surface of the water at an altitude of five to ten feet. During helocasting operations it is important to maintain a forward airspeed of less than ten knots.

Upon reaching the insertion point, each team member releases their safety belt and jumps into the water. Water insertions are used by Navy Seal Team members and Marine Corps Reconnaissance units to conduct beach studies, support riverine operations and facilitate intelligence gathering missions. The goal of a water insertion is to place the team at their designated location without compromising the position of the helicopter or the team.

Extraction Methods

After the team members have completed their assigned mission, they must proceed to a pre-briefed location for an extraction by helicopter. In many cases, the extraction zone may not be large enough or suitable enough for a helicopter to land. In anticipation of this dilemma, a variety of extraction methods have been developed to bring team members out of a tight situation. A hoist can be used to lift personnel up into the helicopter. Hoist operations have their limits however. Repeated cycles on the hoist are necessary in order to lift each team member onto the aircraft. The goal of a tactical extraction is to ensure there is minimal exposure to enemy observation during the mission. A hoist operation subjects the aircraft and the aircrew to lengthy periods of time in a hover.

The elevation of the helicopter above the ground is another limitation. High hover altitudes require longer times for the hoist to be lowered and raised. This can add substantial delay to a recovery. A pilot may have to maintain a very high hover above the ground due to obstacles such as trees or a tower near the pickup zone.

In some cases a pilot may be able to descend low enough into the zone so that a portion of the aircraft can be landed. A wheel or a skid can be placed on the ground while the pilot continues to fly the aircraft in a level hover. Special Operations team members can climb onto the helicopter by pulling themselves up through an open entrance. When the terrain is unsuitable for landing, the pilot may elect to hover slightly above the lowest obstacle in the landing zone and pull each team member onboard the low flying machine.

Another extraction method is conducted by installing a device called a Jacob's ladder. A Jacob's ladder is a long rope ladder with wooden rungs that can be dropped from the back or the side of a helicopter. Team members climb the ladder, rung by rung and pull themselves into the hovering helicopter. A few disadvantages associated with the Jacob's ladder is excessive exposure time and the inability to quickly extract heavy gear and equipment. All portable gear must be secured to an individual's body during the climb and large cumbersome items must be tied to a rope or hoisted up separately. As each team member climbs the ladder, the surplus gear is pulled up into the helicopter.

SPIE Extractions

Under certain conditions, team members may have a requirement to be extracted expeditiously from a pick up zone. The SPIE rig rope is designed to meet this requirement. SPIE stands for Special Insertion and Extraction. The SPIE rig is a long rope that is attached to the bottom of the helicopter. The rope is carried in the main cabin area of the helicopter while flying to a designated extraction area. As the helicopter transitions to a hover over the pickup point, a crewman drops the SPIE rig out of the helicopter and onto the ground below. Participating team member must wear a device called a SPIE body harness. A SPIE harness is used to connect each individual to the SPIE rope. The SPIE harness is similar to the one worn during rappelling operations.

When the helicopter is established in a hover over the pick-up zone, the team members connect their harness to a metal fitting that is woven into the fiber of the SPIE rope. The connection is made with several metal "gated D rings". The gated portion allows the team member to quickly connect to the SPIE rope.

A "thumbs up" by each team member indicates that all are ready for the extraction. In response to the signal, the pilot commences a slow vertical climb to altitude. Sufficient separation must be established between the team member on the bottom of the rope and the ground below. Before the pilot can transition to forward flight, the Crew Chief must verify that the appropriate clearance exists. The aircraft is then flown to the nearest suitable landing area with men suspended beneath the helicopter at the end of a rope.

When the SPIE aircraft is established over the intended landing point the team is slowly lowered to the ground. Their rate of descent is adjusted based on verbal instructions from the Crew Chief. As a team member's feet hit the ground they walk away from the helicopter carrying their portion of the SPIE rope with them. The SPIE rope can be quickly loaded onto the helicopter for another expeditious pickup. SPIE extractions are a quick and efficient way to lift personnel from a place where a helicopter is unable to land. The SPIE extraction also minimizes exposure time when low altitude flight techniques are utilized into an out of the pickup zone.

A SPIE Rig can be modified for an extraction from the water. Life jackets or small floats are attached to the rope at various points along the bottom. The flotation devices keep the SPIE Rope afloat on the surface and more accessible. When a SPIE rig is dropped into the water, each team member swims to the rope and connects their harness to the rig. The flotation devices save valuable time since team members do not have to pull a heavy line out of the deep water. After the team gives the pilot a thumbs up each member rolls over on their back. Initially they are pulled through the water before rising into the air.

The versatility of the helicopter is demonstrated in the unique supporting role that it can play during special mission operations. Low altitude delivery methods that a helicopter is capable of providing are critical for the safe insertion and extraction of military personnel into and out of a designated area.

Armed Escort

The role of an attack helicopter is to protect transport aircraft during the ingress, landing and egress phase of an operation. When a transport helicopter proceeds toward a landing zone, the escort aircraft fly at the edge of the formation protecting the front, side and rear of the flight. Attack aircraft are also used to defend friendly ground troops and personnel from attack. They can also be employed offensively against enemy targets in front of friendly lines.

Several highly sophisticated escort helicopters have been manufactured in recent years. The Cobra and Apache aircraft are two of the more commonly known escort helicopters that are actively deployed by the United States military. Attack helicopters are configured with internally mounted guns, rocket pods, flares, illumination rounds, anti-tank missiles, and anti-aircraft missiles. The role of the attack helicopter during offensive operations is to assist the ground unit commander with the destruction of armored vehicles, tanks and personnel carriers on the battlefield.

Attack helicopters are also very maneuverable. They are designed to fly fast and accelerate rapidly. When escorting a flight of transport aircraft into a landing zone the attack helicopters must dash ahead to conduct a thorough reconnaissance of the objective area. Their primary role is to suppress any enemy fires and to direct the transports into the landing zone.

The main rotor system of an attack helicopter is very large. These rotor blades carve powerfully through the atmosphere and pull massive amounts of air through a broad expanse of whirling metal. Due to the wide span of its rotor blades, an attack helicopter can accelerate rapidly and generate the necessary dash speed to accomplish the mission. The narrow fuselage of an attack helicopter is designed to provide an aerodynamic advantage and minimize parasite drag. The agility of the attack helicopter is derived from a low drag state and a surplus of power. The narrow fuselage of an attack helicopter is an effective way to reduce the radar signature of the aircraft and minimize its exposure as a target.

Critical components on an attack helicopter are well armored. In the event of small arms fire, the rotor system and fuselage are designed to absorb the impact of the rounds and to keep functioning. A critical protective measure is the use of low level flight techniques. The swift passage of a helicopter just above the treetops significantly reduces the time that an enemy can use a weapon system to acquire, track and engage the helicopter.

Advanced Technology

Improvements on helicopter design and efficiency have resulted in the capacity for increased airspeed, greater maneuverability and better efficiency. The use of composite materials in both helicopters and fixed wing aircraft has resulted in significant weight savings. A new concept is also being introduced into aviation. The performance of a helicopter and the speed of an airplane are being combined to create a new kind of flying. The Bell/Boeing V-22 design is a hybrid of both types of aircraft. At first glance in flight, the aircraft appears to be a fixed wing airplane. The large propeller blades and unusual angle of the wing reveal an aircraft that is decidedly unique. Two engines located at each wing tip transition from forward flight to a hover as the entire wing rotates to the vertical position.

These two large propeller systems become oversized rotor blades in a hover. During takeoff, the aircraft can become airborne by hovering vertically or by executing a rolling takeoff down a runway. The V-22's propellers are canted slightly forward during a rolling takeoff. As the aircraft begins to lift off the runway, the wings are slowly rotated forward until assuming the role of a conventional propeller driven aircraft. The elongated blades bite cleanly into the air providing a smooth, vibration free ride.

There are many military and civilian applications for the V-22 aircraft. The V-22 can be used as a commuter aircraft landing in sites located close to business centers in urban areas. The speed of the V-22 is a valuable asset as well. Airspeeds unheard of in a helicopter are commonplace with the V-22. Since the V-22 can be flown at speeds in excess of two hundred and fifty knots it is a very useful when a significant amount of ground must be covered. The success of the V-22 is based on innovation and a creative design.

CHAPTER XII CONCLUSION

What the Future Holds

In conclusion, aviation is alive and well. Present day aviation is undergoing a period of phenomenal growth and opportunity. Many exciting discoveries and experiences are in store for those who seek the adventure and the challenge of flight. In a world of high speed travel and constant innovation, the realm of space will bring continents closer together as aircraft are launched from runways and flown into a shallow orbit. Flung half way around the world, these hypersonic aircraft will descend and land in record time on the opposite side of the earth.

As part of this growth, many talented men and women are needed. The goal of this book has been to spur your interest in aviation and provide you with an overview of flying in general. Your life will surely be affected by aviation, whether you are a passenger on a commercial airplane or at the flight controls as the pilot. Several challenges await those who fly. A great adventure awaits you, so enjoy the ride.

FIGURES

1 - Aerodynamic Components

2 - Flight Control Surfaces

3 - Stall Characteristics

4 - Flight Plan

5 - Fuel Plan

6 - Airfield Diagram

7 - VFR Navigation

8 - RMI Indicator

9 - RMI Navigation

10 - Crosswind and Ground Track

11 - IFR Charts

12 - IFR Approach Plate

13 - ILS Approach Indicator

14 - Holding Pattern

15 - Aerobatic Maneuvers

16 - Formation Positions

17 - Types of Formations

18 - Landing Patterns

19 - Crosswind effects on Landing

20 - Cloud Formations

21 - Microburst Effects

22 - Helicopter Flight Controls

MANUSCRIPT OVERVIEW:

DESCRIPTION

The Mystery of Flight provides the reader with a clear and concise understanding of aviation. The book portrays the excitement and wonder of flight through the use of descriptive paragraphs. These excerpts convey to the reader a sense of what it is like to fly various types of aircraft. The theme of the book focuses on how man is capable of flight. In addition, the book describes many of the specific skills and techniques that are necessary in order to fly safely. The Mystery of Flight is designed to stir a reader's interest in aviation and provide them with a better understanding of a very challenging profession.

MANUSCRIPT DETAILS

The Mystery of Flight is a complete book that is 52,000 words in length. The page count is 145 pages including the Table of Contents and the Index.

SPECIAL EDITORIAL FEATURES

An experienced aviator with over 5,500 hours of flight experience wrote the Mystery of Flight. The author has flown a variety of aircraft to include military, multiengine jets, twin engine helicopters and commercial jet aircraft.

The Mystery of Flight provides the reader with a "seat of the pants," experience. Feel what it is like to strap on a military jet aircraft and take off. Roll down the runway and race skyward at the controls of a powerful fighter aircraft. It is a ride the reader won't forget.

Learn how a large commercial aircraft can lift free from the persistent tug of earth's gravity and rise gracefully into the air on outstretched wings.

Learn what it takes to prepare an aircraft for flight and understand what steps are necessary for a pilot to takeoff and successfully navigate to a far away destination.

Read about the mechanics of rotary wing flight and the aerodynamic principles that encompass helicopter flying. Understand how a pilot controls both direction and altitude in a hover.

ORDERING INFORMATION

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