16-1

EMERGENCY SITUATIONS

This chapter contains information on dealing with

non-normal and emergency situations that may occur in

flight. The key to successful management of an

emergency situation, and/or preventing a non-normal

situation from progressing into a true emergency, is

a thorough familiarity with, and adherence to, the

procedures developed by the airplane manufacturer and

contained in the FAA-approved Airplane Flight Manual

and/or Pilot’s Operating Handbook (AFM/POH). The

following guidelines are generic and are not meant to

replace the airplane manufacturer’s recommended

procedures. Rather, they are meant to enhance the

pilot’s general knowledge in the area of non-normal and

emergency operations. If any of the guidance in this

chapter conflicts in any way with the manufacturer’s

recommended procedures for a particular make and

model airplane, the manufacturer’s recommended

procedures take precedence.

EMERGENCY LANDINGS

This section contains information on emergency landing techniques in small fixed-wing airplanes. The

guidelines that are presented apply to the more adverse

terrain conditions for which no practical training is

possible. The objective is to instill in the pilot the

knowledge that almost any terrain can be considered

“suitable” for a survivable crash landing if the pilot

knows how to use the airplane structure for self-protection

and the protection of passengers.

TYPES OF EMERGENCY LANDINGS

The different types of emergency landings are defined

as follows.

• Forced landing. An immediate landing, on or off

an airport, necessitated by the inability to continue further flight. A typical example of which is

an airplane forced down by engine failure.

• Precautionary landing. A premeditated landing,

on or off an airport, when further flight is possible but inadvisable. Examples of conditions that

may call for a precautionary landing include

deteriorating weather, being lost, fuel shortage,

and gradually developing engine trouble.

• Ditching. A forced or precautionary landing on

water. 

A precautionary landing, generally, is less hazardous

than a forced landing because the pilot has more time

for terrain selection and the planning of the approach.

In addition, the pilot can use power to compensate for

errors in judgment or technique. The pilot should be

aware that too many situations calling for a precautionary landing are allowed to develop into immediate

forced landings, when the pilot uses wishful thinking

instead of reason, especially when dealing with a

self-inflicted predicament. The non-instrument rated

pilot trapped by weather, or the pilot facing imminent

fuel exhaustion who does not give any thought to the

feasibility of a precautionary landing accepts an

extremely hazardous alternative.

PSYCHOLOGICAL HAZARDS

There are several factors that may interfere with a

pilot’s ability to act promptly and properly when faced

with an emergency.

• Reluctance to accept the emergency situation.

A pilot who allows the mind to become paralyzed

at the thought that the airplane will be on the

ground, in a very short time, regardless of the

pilot’s actions or hopes, is severely handicapped

in the handling of the emergency. An unconscious

desire to delay the dreaded moment may lead to

such errors as: failure to lower the nose to maintain flying speed, delay in the selection of the

most suitable landing area within reach, and

indecision in general. Desperate attempts to

correct whatever went wrong, at the expense of

airplane control, fall into the same category.

• Desire to save the airplane. The pilot who has

been conditioned during training to expect to find

a relatively safe landing area, whenever the flight

instructor closed the throttle for a simulated

forced landing, may ignore all basic rules of

airmanship to avoid a touchdown in terrain where

airplane damage is unavoidable. Typical consequences are: making a 180° turn back to the

runway when available altitude is insufficient;

stretching the glide without regard for minimum

control speed in order to reach a more appealing

field; accepting an approach and touchdown

situation that leaves no margin for error. The

desire to save the airplane, regardless of the risks

involved, may be influenced by two other factors:

the pilot’s financial stake in the airplane and the

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certainty that an undamaged airplane implies no

bodily harm. There are times, however, when a

pilot should be more interested in sacrificing the

airplane so that the occupants can safely walk

away from it.

• Undue concern about getting hurt. Fear is a

vital part of the self-preservation mechanism.

However, when fear leads to panic, we invite that

which we want most to avoid. The survival

records favor pilots who maintain their composure and know how to apply the general concepts

and procedures that have been developed through

the years. The success of an emergency landing is

as much a matter of the mind as of skills. 

BASIC SAFETY CONCEPTS

GENERAL

A pilot who is faced with an emergency landing in terrain that makes extensive airplane damage inevitable

should keep in mind that the avoidance of crash

injuries is largely a matter of: (1) keeping vital

structure (cockpit/cabin area) relatively intact by using

dispensable structure (such as wings, landing gear, and

fuselage bottom) to absorb the violence of the stopping

process before it affects the occupants, (2) avoiding

forceful bodily contact with interior structure.

The advantage of sacrificing dispensable structure is

demonstrated daily on the highways. A head-on car

impact against a tree at 20 miles per hour (m.p.h.) is

less hazardous for a properly restrained driver than a

similar impact against the driver’s door. Accident

experience shows that the extent of crushable structure

between the occupants and the principal point of

impact on the airplane has a direct bearing on the

severity of the transmitted crash forces and, therefore,

on survivability.

Avoiding forcible contact with interior structure is a

matter of seat and body security. Unless the occupant

decelerates at the same rate as the surrounding

structure, no benefit will be realized from its relative

intactness. The occupant will be brought to a stop violently in the form of a secondary collision.

Dispensable airplane structure is not the only available

energy absorbing medium in an emergency situation.

Vegetation, trees, and even manmade structures may

be used for this purpose. Cultivated fields with dense

crops, such as mature corn and grain, are almost as

effective in bringing an airplane to a stop with

repairable damage as an emergency arresting device

on a runway. [Figure 16-1] Brush and small trees

provide considerable cushioning and braking effect

without destroying the airplane. When dealing with

natural and manmade obstacles with greater strength

than the dispensable airplane structure, the pilot must

plan the touchdown in such a manner that only nonessential structure is “used up” in the principal

slowing down process.

The overall severity of a deceleration process is

governed by speed (groundspeed) and stopping

distance. The most critical of these is speed; doubling

the groundspeed means quadrupling the total destructive energy, and vice versa. Even a small change in

groundspeed at touchdown—be it as a result of wind

or pilot technique—will affect the outcome of a

controlled crash. It is important that the actual

touchdown during an emergency landing be made at

the lowest possible controllable airspeed, using all

available aerodynamic devices.

Most pilots will instinctively—and correctly—look

for the largest available flat and open field for an emergency landing. Actually, very little stopping distance

is required if the speed can be dissipated uniformly;

that is, if the deceleration forces can be spread evenly

over the available distance. This concept is designed

into the arresting gear of aircraft carriers that provides

a nearly constant stopping force from the moment of

hookup.

The typical light airplane is designed to provide

protection in crash landings that expose the occupants

to nine times the acceleration of gravity (9 G) in a

forward direction. Assuming a uniform 9 G deceleration, at 50 m.p.h. the required stopping distance is

about 9.4 feet. While at 100 m.p.h. the stopping distance is about 37.6 feet—about four times as great.

[Figure 16-2] Although these figures are based on an

ideal deceleration process, it is interesting to note what

can be accomplished in an effectively used short stopping distance. Understanding the need for a firm

but uniform deceleration process in very poor terrain

enables the pilot to select touchdown conditions that

will spread the breakup of dispensable structure over a

short distance, thereby reducing the peak deceleration

of the cockpit/cabin area.

Figure 16-1. Using vegetation to absorb energy.

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ATTITUDE AND SINK RATE CONTROL

The most critical and often the most inexcusable error

that can be made in the planning and execution of an

emergency landing, even in ideal terrain, is the loss of

initiative over the airplane’s attitude and sink rate at

touchdown. When the touchdown is made on flat, open

terrain, an excessive nose-low pitch attitude brings the

risk of “sticking” the nose in the ground. Steep bank

angles just before touchdown should also be avoided,

as they increase the stalling speed and the likelihood of

a wingtip strike.

Since the airplane’s vertical component of velocity will

be immediately reduced to zero upon ground contact, it

must be kept well under control. A flat touchdown at a

high sink rate (well in excess of 500 feet per minute

(f.p.m.)) on a hard surface can be injurious without

destroying the cockpit/cabin structure, especially during

gear up landings in low-wing airplanes. A rigid bottom

construction of these airplanes may preclude adequate

cushioning by structural deformation. Similar impact

conditions may cause structural collapse of the overhead

structure in high-wing airplanes. On soft terrain, an

excessive sink rate may cause digging in of the lower

nose structure and severe forward deceleration. 

TERRAIN SELECTION

A pilot’s choice of emergency landing sites is governed

by:

• The route selected during preflight planning.

• The height above the ground when the emergency

occurs.

• Excess airspeed (excess airspeed can be converted into distance and/or altitude).

The only time the pilot has a very limited choice is during the low and slow portion of the takeoff. However,

even under these conditions, the ability to change the

impact heading only a few degrees may ensure a

survivable crash.

If beyond gliding distance of a suitable open area, the

pilot should judge the available terrain for its energy

absorbing capability. If the emergency starts at a

considerable height above the ground, the pilot should

be more concerned about first selecting the desired

general area than a specific spot. Terrain appearances

from altitude can be very misleading and considerable

altitude may be lost before the best spot can be

pinpointed. For this reason, the pilot should not

hesitate to discard the original plan for one that is obviously better. However, as a general rule, the pilot

should not change his or her mind more than once; a

well-executed crash landing in poor terrain can be less

hazardous than an uncontrolled touchdown on an

established field.

AIRPLANE CONFIGURATION

Since flaps improve maneuverability at slow speed,

and lower the stalling speed, their use during final

approach is recommended when time and circumstances permit. However, the associated increase in

drag and decrease in gliding distance call for caution in

the timing and the extent of their application;

premature use of flap, and dissipation of altitude,

may jeopardize an otherwise sound plan. 

A hard and fast rule concerning the position of a

retractable landing gear at touchdown cannot be given.

In rugged terrain and trees, or during impacts at high

sink rate, an extended gear would definitely have a

protective effect on the cockpit/cabin area. However,

this advantage has to be weighed against the possible

side effects of a collapsing gear, such as a ruptured fuel

tank. As always, the manufacturer’s recommendations

as outlined in the AFM/POH should be followed.

When a normal touchdown is assured, and ample stopping distance is available, a gear up landing on level, but

soft terrain, or across a plowed field, may result in less

airplane damage than a gear down landing. [Figure 16-3]

9g Deceleration

37.6 ft.

50 m.p.h. 100 m.p.h.

9.4 ft.

Figure 16-2. Stopping distance vs. groundspeed.

Figure 16-3. Intentional gear up landing.

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Deactivation of the airplane’s electrical system before

touchdown reduces the likelihood of a post-crash fire.

However, the battery master switch should not be

turned off until the pilot no longer has any need for

electrical power to operate vital airplane systems.

Positive airplane control during the final part of the

approach has priority over all other considerations,

including airplane configuration and cockpit checks.

The pilot should attempt to exploit the power available

from an irregularly running engine; however, it is generally better to switch the engine and fuel off just

before touchdown. This not only ensures the pilot’s

initiative over the situation, but a cooled down engine

reduces the fire hazard considerably. 

APPROACH

When the pilot has time to maneuver, the planning of

the approach should be governed by three factors.

• Wind direction and velocity.

• Dimensions and slope of the chosen field.

• Obstacles in the final approach path.

These three factors are seldom compatible. When compromises have to be made, the pilot should aim for a

wind/obstacle/terrain combination that permits a final

approach with some margin for error in judgment or

technique. A pilot who overestimates the gliding range

may be tempted to stretch the glide across obstacles in

the approach path. For this reason, it is sometimes

better to plan the approach over an unobstructed area,

regardless of wind direction. Experience shows that a

collision with obstacles at the end of a ground roll, or

slide, is much less hazardous than striking an obstacle

at flying speed before the touchdown point is reached.

TERRAIN TYPES

Since an emergency landing on suitable terrain resembles a situation in which the pilot should be familiar

through training, only the more unusual situation will

be discussed.

CONFINED AREAS

The natural preference to set the airplane down on the

ground should not lead to the selection of an open spot

between trees or obstacles where the ground cannot be

reached without making a steep descent.

Once the intended touchdown point is reached, and the

remaining open and unobstructed space is very limited, it may be better to force the airplane down on the

ground than to delay touchdown until it stalls (settles).

An airplane decelerates faster after it is on the ground

than while airborne. Thought may also be given to the

desirability of ground-looping or retracting the landing

gear in certain conditions.

A river or creek can be an inviting alternative in otherwise rugged terrain. The pilot should ensure that the

water or creek bed can be reached without snagging

the wings. The same concept applies to road landings

with one additional reason for caution; manmade

obstacles on either side of a road may not be visible

until the final portion of the approach.

When planning the approach across a road, it should

be remembered that most highways, and even rural

dirt roads, are paralleled by power or telephone lines.

Only a sharp lookout for the supporting structures, or

poles, may provide timely warning.

TREES (FOREST)

Although a tree landing is not an attractive prospect,

the following general guidelines will help to make the

experience survivable.

• Use the normal landing configuration (full flaps,

gear down).

• Keep the groundspeed low by heading into the

wind.

• Make contact at minimum indicated airspeed, but

not below stall speed, and “hang” the airplane in

the tree branches in a nose-high landing attitude.

Involving the underside of the fuselage and both

wings in the initial tree contact provides a more

even and positive cushioning effect, while preventing penetration of the windshield. [Figure

16-4]

• Avoid direct contact of the fuselage with heavy

tree trunks.

• Low, closely spaced trees with wide, dense

crowns (branches) close to the ground are much

better than tall trees with thin tops; the latter

allow too much free fall height. (A free fall from

75 feet results in an impact speed of about 40

knots, or about 4,000 f.p.m.)

• Ideally, initial tree contact should be symmetrical; that is, both wings should meet equal

resistance in the tree branches. This distribution

of the load helps to maintain proper airplane

attitude. It may also preclude the loss of one

wing, which invariably leads to a more rapid and

less predictable descent to the ground.

• If heavy tree trunk contact is unavoidable once

the airplane is on the ground, it is best to involve

both wings simultaneously by directing the airplane between two properly spaced trees. Do not

attempt this maneuver, however, while still

airborne.

WATER (DITCHING) AND SNOW

A well-executed water landing normally involves less

deceleration violence than a poor tree landing or a

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touchdown on extremely rough terrain. Also an

airplane that is ditched at minimum speed and in a normal landing attitude will not immediately sink upon

touchdown. Intact wings and fuel tanks (especially

when empty) provide floatation for at least several

minutes even if the cockpit may be just below the

water line in a high-wing airplane.

Loss of depth perception may occur when landing on a

wide expanse of smooth water, with the risk of flying

into the water or stalling in from excessive altitude. To

avoid this hazard, the airplane should be “dragged in”

when possible. Use no more than intermediate flaps on

low-wing airplanes. The water resistance of fully

extended flaps may result in asymmetrical flap failure

and slowing of the airplane. Keep a retractable gear up

unless the AFM/POH advises otherwise.

A landing in snow should be executed like a ditching,

in the same configuration and with the same regard for

loss of depth perception (white out) in reduced visibility and on wide open terrain. 

ENGINE FAILURE AFTER TAKEOFF

(SINGLE-ENGINE)

The altitude available is, in many ways, the controlling

factor in the successful accomplishment of an emergency landing. If an actual engine failure should occur

immediately after takeoff and before a safe maneuvering

altitude is attained, it is usually inadvisable to attempt

to turn back to the field from where the takeoff was

made. Instead, it is safer to immediately establish the

proper glide attitude, and select a field directly ahead

or slightly to either side of the takeoff path.

The decision to continue straight ahead is often

difficult to make unless the problems involved in

attempting to turn back are seriously considered. In the

first place, the takeoff was in all probability made into

the wind. To get back to the takeoff field, a downwind

turn must be made. This increases the groundspeed and

rushes the pilot even more in the performance of

procedures and in planning the landing approach.

Secondly, the airplane will be losing considerable

altitude during the turn and might still be in a bank

when the ground is contacted, resulting in the airplane

cartwheeling (which would be a catastrophe for the

occupants, as well as the airplane). After turning downwind, the apparent increase in groundspeed could

mislead the pilot into attempting to prematurely slow

down the airplane and cause it to stall. On the other

hand, continuing straight ahead or making a slight turn

allows the pilot more time to establish a safe landing

attitude, and the landing can be made as slowly as

possible, but more importantly, the airplane can be

landed while under control.

Concerning the subject of turning back to the runway

following an engine failure on takeoff, the pilot should

determine the minimum altitude an attempt of such a

maneuver should be made in a particular airplane.

Experimentation at a safe altitude should give the pilot

an approximation of height lost in a descending 180°

turn at idle power. By adding a safety factor of about

25 percent, the pilot should arrive at a practical decision height. The ability to make a 180° turn does not

necessarily mean that the departure runway can be

reached in a power-off glide; this depends on the wind,

the distance traveled during the climb, the height

reached, and the glide distance of the airplane without

power. The pilot should also remember that a turn back

to the departure runway may in fact require more than

a 180° change in direction.

Consider the following example of an airplane which

has taken off and climbed to an altitude of 300 feet

AGL when the engine fails. [Figure 16-5 on next

page]. After a typical 4 second reaction time, the pilot

elects to turn back to the runway. Using a standard rate

(3° change in direction per second) turn, it will take 1

minute to turn 180°. At a glide speed of 65 knots, the

radius of the turn is 2,100 feet, so at the completion of

the turn, the airplane will be 4,200 feet to one side of

the runway. The pilot must turn another 45° to head the

airplane toward the runway. By this time the total

change in direction is 225° equating to 75 seconds plus

the 4 second reaction time. If the airplane in a poweroff glide descends at approximately 1,000 f.p.m., it

Figure 16-4.Tree landing.

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will have descended 1,316, feet placing it 1,016 feet

below the runway.

EMERGENCY DESCENTS

An emergency descent is a maneuver for descending

as rapidly as possible to a lower altitude or to the

ground for an emergency landing. [Figure 16-6] The

need for this maneuver may result from an uncontrollable fire, a sudden loss of cabin pressurization, or any

other situation demanding an immediate and rapid

descent. The objective is to descend the airplane as

soon and as rapidly as possible, within the structural

limitations of the airplane. Simulated emergency

descents should be made in a turn to check for other air

traffic below and to look around for a possible

emergency landing area. A radio call announcing

descent intentions may be appropriate to alert other

aircraft in the area. When initiating the descent, a bank

of approximately 30 to 45° should be established to

maintain positive load factors (“G” forces) on the

airplane.

Emergency descent training should be performed as

recommended by the manufacturer, including the configuration and airspeeds. Except when prohibited by

the manufacturer, the power should be reduced to idle,

and the propeller control (if equipped) should be

placed in the low pitch (or high revolutions per minute

(r.p.m.)) position. This will allow the propeller to act

as an aerodynamic brake to help prevent an excessive

airspeed buildup during the descent. The landing gear

and flaps should be extended as recommended by the

manufacturer. This will provide maximum drag so that

the descent can be made as rapidly as possible, without excessive airspeed. The pilot should not allow the

airplane’s airspeed to pass the never-exceed speed

(VNE), the maximum landing gear extended speed

(VLE), or the maximum flap extended speed (VFE), as

applicable. In the case of an engine fire, a high

airspeed descent could blow out the fire. However, the

weakening of the airplane structure is a major concern

and descent at low airspeed would place less stress on

the airplane. If the descent is conducted in turbulent

conditions, the pilot must also comply with the design

maneuvering speed (VA) limitations. The descent

should be made at the maximum allowable airspeed

consistent with the procedure used. This will provide

increased drag and therefore the loss of altitude as

quickly as possible. The recovery from an emergency

descent should be initiated at a high enough altitude to

ensure a safe recovery back to level flight or a

precautionary landing.

When the descent is established and stabilized during

training and practice, the descent should be terminated.

Figure 16-5. Turning back to the runway after engine failure.

4,480 Ft.

180°

225°

300 Ft. AGL

1,016 Ft.

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In airplanes with piston engines, prolonged practice of

emergency descents should be avoided to prevent

excessive cooling of the engine cylinders.

IN-FLIGHT FIRE

A fire in flight demands immediate and decisive action.

The pilot therefore must be familiar with the procedures

outlined to meet this emergency contained in the

AFM/POH for the particular airplane. For the purposes

of this handbook, in-flight fires are classified as: inflight engine fires, electrical fires, and cabin fires.

ENGINE FIRE

An in-flight engine compartment fire is usually caused

by a failure that allows a flammable substance such as

fuel, oil or hydraulic fluid to come in contact with a hot

surface. This may be caused by a mechanical failure of

the engine itself, an engine-driven accessory, a

defective induction or exhaust system, or a broken

line. Engine compartment fires may also result from

maintenance errors, such as improperly installed/fastened lines and/or fittings resulting in leaks.

Engine compartment fires can be indicated by smoke

and/or flames coming from the engine cowling area.

They can also be indicated by discoloration, bubbling,

and/or melting of the engine cowling skin in cases

where flames and/or smoke is not visible to the pilot.

By the time a pilot becomes aware of an in-flight

engine compartment fire, it usually is well developed.

Unless the airplane manufacturer directs otherwise in

the AFM/POH, the first step on discovering a fire

should be to shut off the fuel supply to the engine by

placing the mixture control in the idle cut off position

and the fuel selector shutoff valve to the OFF position.

The ignition switch should be left ON in order to use

up the fuel that remains in the fuel lines and components between the fuel selector/shutoff valve and

the engine. This procedure may starve the engine

compartment of fuel and cause the fire to die naturally.

If the flames are snuffed out, no attempt should be

made to restart the engine.

If the engine compartment fire is oil-fed, as evidenced

by thick black smoke, as opposed to a fuel-fed fire

which produces bright orange flames, the pilot should

consider stopping the propeller rotation by feathering

or other means, such as (with constant-speed propellers) placing the pitch control lever to the minimum

r.p.m. position and raising the nose to reduce airspeed

until the propeller stops rotating. This procedure will

stop an engine-driven oil (or hydraulic) pump from

continuing to pump the flammable fluid which is

feeding the fire.

Some light airplane emergency checklists direct the

pilot to shut off the electrical master switch. However,

the pilot should consider that unless the fire is electrical

in nature, or a crash landing is imminent, deactivating

the electrical system prevents the use of panel radios

for transmitting distress messages and will also cause

air traffic control (ATC) to lose transponder returns.

Pilots of powerless single-engine airplanes are left

with no choice but to make a forced landing. Pilots of

twin-engine airplanes may elect to continue the flight

to the nearest airport. However, consideration must be

given to the possibility that a wing could be seriously

impaired and lead to structural failure. Even a brief but

intense fire could cause dangerous structural damage.

In some cases, the fire could continue to burn under

the wing (or engine cowling in the case of a singleengine airplane) out of view of the pilot. Engine

compartment fires which appear to have been

extinguished have been known to rekindle with

changes in airflow pattern and airspeed.

The pilot must be familiar with the airplane’s emergency descent procedures. The pilot must bear in mind

that: 

• The airplane may be severely structurally damaged to the point that its ability to remain under

control could be lost at any moment.

• The airplane may still be on fire and susceptible

to explosion.

• The airplane is expendable and the only thing that

matters is the safety of those on board.

ELECTRICAL FIRES

The initial indication of an electrical fire is usually the

distinct odor of burning insulation. Once an electrical

fire is detected, the pilot should attempt to identify the

faulty circuit by checking circuit breakers, instruments,

avionics, and lights. If the faulty circuit cannot be readily detected and isolated, and flight conditions permit,

the battery master switch and alternator/generator

switches should be turned off to remove the possible

source of the fire. However, any materials which have

been ignited may continue to burn.

Figure 16-6. Emergency descent.

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If electrical power is absolutely essential for the flight,

an attempt may be made to identify and isolate the

faulty circuit by:

1. Turning the electrical master switch OFF.

2. Turning all individual electrical switches OFF.

3. Turning the master switch back ON.

4. Selecting electrical switches that were ON before

the fire indication one at a time, permitting a short

time lapse after each switch is turned on to check

for signs of odor, smoke, or sparks.

This procedure, however, has the effect of recreating

the original problem. The most prudent course of

action is to land as soon as possible.

CABIN FIRE

Cabin fires generally result from one of three sources:

(1) careless smoking on the part of the pilot and/or

passengers; (2) electrical system malfunctions; (3)

heating system malfunctions. A fire in the cabin presents the pilot with two immediate demands: attacking

the fire, and getting the airplane safely on the ground

as quickly as possible. A fire or smoke in the cabin

should be controlled by identifying and shutting down

the faulty system. In many cases, smoke may be

removed from the cabin by opening the cabin air vents.

This should be done only after the fire extinguisher (if

available) is used. Then the cabin air control can be

opened to purge the cabin of both smoke and fumes. If

smoke increases in intensity when the cabin air vents

are opened, they should be immediately closed. This

indicates a possible fire in the heating system, nose

compartment baggage area (if so equipped), or that the

increase in airflow is feeding the fire.

On pressurized airplanes, the pressurization air system

will remove smoke from the cabin; however, if the

smoke is intense, it may be necessary to either depressurize at altitude, if oxygen is available for all

occupants, or execute an emergency descent.

In unpressurized single-engine and light twin-engine

airplanes, the pilot can attempt to expel the smoke

from the cabin by opening the foul weather windows.

These windows should be closed immediately if the

fire becomes more intense. If the smoke is severe, the

passengers and crew should use oxygen masks if available, and the pilot should initiate an immediate

descent. The pilot should also be aware that on some

airplanes, lowering the landing gear and/or wing flaps

can aggravate a cabin smoke problem. 

FLIGHT CONTROL

MALFUNCTION/FAILURE

TOTAL FLAP FAILURE

The inability to extend the wing flaps will necessitate

a no-flap approach and landing. In light airplanes a noflap approach and landing is not particularly difficult

or dangerous. However, there are certain factors which

must be considered in the execution of this maneuver. 

A no-flap landing requires substantially more runway

than normal. The increase in required landing distance

could be as much as 50 percent.

When flying in the traffic pattern with the wing flaps

retracted, the airplane must be flown in a relatively

nose-high attitude to maintain altitude, as compared to

flight with flaps extended. Losing altitude can be more

of a problem without the benefit of the drag normally

provided by flaps. A wider, longer traffic pattern may

be required in order to avoid the necessity of diving to

lose altitude and consequently building up excessive

airspeed.

On final approach, a nose-high attitude can make it

difficult to see the runway. This situation, if not anticipated, can result in serious errors in judgment of

height and distance. Approaching the runway in a

relatively nose-high attitude can also cause the

perception that the airplane is close to a stall. This may

cause the pilot to lower the nose abruptly and risk

touching down on the nosewheel.

With the flaps retracted and the power reduced for

landing, the airplane is slightly less stable in the pitch

and roll axes. Without flaps, the airplane will tend to

float considerably during roundout. The pilot should

avoid the temptation to force the airplane onto the runway at an excessively high speed. Neither should the

pilot flare excessively, because without flaps this

might cause the tail to strike the runway.

ASYMMETRIC (SPLIT) FLAP

An asymmetric “split” flap situation is one in which

one flap deploys or retracts while the other remains in

position. The problem is indicated by a pronounced

roll toward the wing with the least flap deflection

when wing flaps are extended/retracted. 

The roll encountered in a split flap situation is countered with opposite aileron. The yaw caused by the

additional drag created by the extended flap will

require substantial opposite rudder, resulting in a

cross-control condition. Almost full aileron may be

required to maintain a wings-level attitude, especially

at the reduced airspeed necessary for approach and

landing. The pilot therefore should not attempt to land

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16-9

with a crosswind from the side of the deployed flap,

because the additional roll control required to counteract the crosswind may not be available.

The pilot must be aware of the difference in stall

speeds between one wing and the other in a split flap

situation. The wing with the retracted flap will stall

considerably earlier than the wing with the deployed

flap. This type of asymmetrical stall will result in an

uncontrollable roll in the direction of the stalled (clean)

wing. If altitude permits, a spin will result.

The approach to landing with a split flap condition

should be flown at a higher than normal airspeed. The

pilot should not risk an asymmetric stall and subsequent loss of control by flaring excessively. Rather, the

airplane should be flown onto the runway so that the

touchdown occurs at an airspeed consistent with a safe

margin above flaps-up stall speed. 

LOSS OF ELEVATOR CONTROL

In many airplanes, the elevator is controlled by two

cables: a “down” cable and an “up” cable. Normally,

a break or disconnect in only one of these cables will

not result in a total loss of elevator control. In most

airplanes, a failed cable results in a partial loss of

pitch control. In the failure of the “up” elevator cable

(the “down” elevator being intact and functional) the

control yoke will move aft easily but produce no

response. Forward yoke movement, however, beyond

the neutral position produces a nosedown attitude.

Conversely, a failure of the “down” elevator cable,

forward movement of the control yoke produces no

effect. The pilot will, however, have partial control of

pitch attitude with aft movement.

When experiencing a loss of up-elevator control, the

pilot can retain pitch control by:

• Applying considerable nose-up trim.

• Pushing the control yoke forward to attain and

maintain desired attitude.

• Increasing forward pressure to lower the nose and

relaxing forward pressure to raise the nose.

• Releasing forward pressure to flare for landing.

When experiencing a loss of down-elevator control,

the pilot can retain pitch control by:

• Applying considerable nosedown trim.

• Pulling the control yoke aft to attain and maintain

attitude.

• Releasing back pressure to lower the nose and

increasing back pressure to raise the nose.

• Increasing back pressure to flare for landing.

Trim mechanisms can be useful in the event of an

in-flight primary control failure. For example, if the

linkage between the cockpit and the elevator fails in

flight, leaving the elevator free to weathervane in the

wind, the trim tab can be used to raise or lower the

elevator, within limits. The trim tabs are not as effective as normal linkage control in conditions such as

low airspeed, but they do have some positive effect—

usually enough to bring about a safe landing.

If an elevator becomes jammed, resulting in a total loss

of elevator control movement, various combinations of

power and flap extension offer a limited amount of

pitch control. A successful landing under these conditions, however, is problematical.

LANDING GEAR MALFUNCTION

Once the pilot has confirmed that the landing gear has

in fact malfunctioned, and that one or more gear legs

refuses to respond to the conventional or alternate

methods of gear extension contained in the AFM/POH,

there are several methods that may be useful in

attempting to force the gear down. One method is to

dive the airplane (in smooth air only) to VNE speed (red

line on the airspeed indicator) and (within the limits of

safety) execute a rapid pull up. In normal category

airplanes, this procedure will create a 3.8 G load on the

structure, in effect making the landing gear weigh 3.8

times normal. In some cases, this may force the landing gear into the down and locked position. This

procedure requires a fine control touch and good feel

for the airplane. The pilot must avoid exceeding the

design stress limits of the airplane while attempting to

lower the landing gear. The pilot must also avoid an

accelerated stall and possible loss of control while

attention is directed to solving the landing gear

problem.

Another method that has proven useful in some cases

is to induce rapid yawing. After stabilizing at or

slightly less than maneuvering speed (VA), the pilot

should alternately and aggressively apply rudder in one

direction and then the other in rapid sequence. The

resulting yawing action may cause the landing gear to

fall into place.

If all efforts to extend the landing gear have failed, and

a gear up landing is inevitable, the pilot should select

an airport with crash and rescue facilities. The pilot

should not hesitate to request that emergency equipment be standing by.

When selecting a landing surface, the pilot should consider that a smooth, hard-surface runway usually

causes less damage than rough, unimproved grass

strips. A hard surface does, however, create sparks that

can ignite fuel. If the airport is so equipped, the pilot

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can request that the runway surface be foamed. The

pilot should consider burning off excess fuel. This will

reduce landing speed and fire potential.

If the landing gear malfunction is limited to one main

landing gear leg, the pilot should consume as much

fuel from that side of the airplane as practicable,

thereby reducing the weight of the wing on that side.

The reduced weight makes it possible to delay the

unsupported wing from contacting the surface during

the landing roll until the last possible moment.

Reduced impact speeds result in less damage.

If only one landing gear leg fails to extend, the pilot

has the option of landing on the available gear legs, or

landing with all the gear legs retracted. Landing on

only one main gear usually causes the airplane to veer

strongly in the direction of the faulty gear leg after

touchdown. If the landing runway is narrow, and/or

ditches and obstacles line the runway edge, maximum

directional control after touchdown is a necessity. In

this situation, a landing with all three gear retracted

may be the safest course of action.

If the pilot elects to land with one main gear retracted

(and the other main gear and nose gear down and

locked), the landing should be made in a nose-high

attitude with the wings level. As airspeed decays, the

pilot should apply whatever aileron control is necessary to keep the unsupported wing airborne as long as

possible. [Figure 16-7] Once the wing contacts the

surface, the pilot can anticipate a strong yaw in that

direction. The pilot must be prepared to use full

opposite rudder and aggressive braking to maintain

some degree of directional control.

When landing with a retracted nosewheel (and the

main gear extended and locked) the pilot should hold

the nose off the ground until almost full up-elevator

has been applied. [Figure 16-8] The pilot should then

release back pressure in such a manner that the nose

settles slowly to the surface. Applying and holding full

up-elevator will result in the nose abruptly dropping to

the surface as airspeed decays, possibly resulting in

burrowing and/or additional damage. Brake pressure

should not be applied during the landing roll unless

absolutely necessary to avoid a collision with obstacles.

If the landing must be made with only the nose gear

extended, the initial contact should be made on the aft

fuselage structure with a nose-high attitude. This

procedure will help prevent porpoising and/or wheelbarrowing. The pilot should then allow the nosewheel

to gradually touch down, using nosewheel steering as

necessary for directional control.

SYSTEMS MALFUNCTIONS

ELECTRICAL SYSTEM

The loss of electrical power can deprive the pilot of

numerous critical systems, and therefore should not

be taken lightly even in day/VFR conditions. Most

in-flight failures of the electrical system are located

in the generator or alternator. Once the generator or

alternator system goes off line, the electrical source

in a typical light airplane is a battery. If a warning

light or ammeter indicates the probability of an alternator or generator failure in an airplane with only one

generating system, however, the pilot may have very

little time available from the battery.

The rating of the airplane battery provides a clue to how

long it may last. With batteries, the higher the amperage

load, the less the usable total amperage. Thus a 25-amp

hour battery could produce 5 amps per hour for 5 hours,

but if the load were increased to 10 amps, it might last

only 2 hours. A 40-amp load might discharge the battery

fully in about 10 or 15 minutes. Much depends on the

battery condition at the time of the system failure. If the

battery has been in service for a few years, its power may

be reduced substantially because of internal resistance.

Or if the system failure was not detected immediately,

much of the stored energy may have already been used. It

is essential, therefore, that the pilot immediately shed

non-essential loads when the generating source fails.

[Figure 16-9] The pilot should then plan to land at the

nearest suitable airport.

What constitutes an “emergency” load following a

generating system failure cannot be predetermined,

because the actual circumstances will always be

somewhat different—for example, whether the flight

is VFR or IFR, conducted in day or at night, in clouds

or in the clear. Distance to nearest suitable airport can

also be a factor.

Figure 16-7. Landing with one main gear retracted.

Figure 16-8. Landing with nosewheel retracted.

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16-11

The pilot should remember that the electrically powered

(or electrically selected) landing gear and flaps will not

function properly on the power left in a partially

depleted battery. Landing gear and flap motors use up

power at rates much greater than most other types of

electrical equipment. The result of selecting these

motors on a partially depleted battery may well result in

an immediate total loss of electrical power.

If the pilot should experience a complete in-flight loss

of electrical power, the following steps should be

taken:

• Shed all but the most necessary electricallydriven equipment.

• Understand that any loss of electrical power is

critical in a small airplane—notify ATC of the situation immediately. Request radar vectors for a

landing at the nearest suitable airport.

• If landing gear or flaps are electrically controlled

or operated, plan the arrival well ahead of time.

Expect to make a no-flap landing, and anticipate

a manual landing gear extension.

PITOT-STATIC SYSTEM

The source of the pressure for operating the airspeed

indicator, the vertical speed indicator, and the altimeter

is the pitot-static system. The major components of the

pitot-static system are the impact pressure chamber

and lines, and the static pressure chamber and lines,

each of which are subject to total or partial blockage

by ice, dirt, and/or other foreign matter. Blockage of

the pitot-static system will adversely affect instrument

operation. [Figure 16-10 on next page]

Partial static system blockage is insidious in that it

may go unrecognized until a critical phase of flight.

During takeoff, climb, and level-off at cruise altitude

the altimeter, airspeed indicator, and vertical speed

indicator may operate normally. No indication of

malfunction may be present until the airplane begins

a descent.

If the static reference system is severely restricted, but

not entirely blocked, as the airplane descends, the

static reference pressure at the instruments begins to

lag behind the actual outside air pressure. While

descending, the altimeter may indicate that the airplane

is higher than actual because the obstruction slows the

airflow from the static port to the altimeter. The

vertical speed indicator confirms the altimeter’s information regarding rate of change, because the reference

pressure is not changing at the same rate as the outside

air pressure. The airspeed indicator, unable to tell

whether it is experiencing more airspeed pitot pressure

or less static reference pressure, indicates a higher

airspeed than actual. To the pilot, the instruments

indicate that the airplane is too high, too fast, and

descending at a rate much less than desired.

If the pilot levels off and then begins a climb, the

altitude indication may still lag. The vertical speed

indicator will indicate that the airplane is not climbing

as fast as actual. The indicated airspeed, however, may

begin to decrease at an alarming rate. The least amount

of pitch-up attitude may cause the airspeed needle to

indicate dangerously near stall speed.

Managing a static system malfunction requires that the

pilot know and understand the airplane’s pitot-static

system. If a system malfunction is suspected, the pilot

should confirm it by opening the alternate static

source. This should be done while the airplane is

climbing or descending. If the instrument needles

move significantly when this is done, a static pressure

problem exists and the alternate source should be used

during the remainder of the flight. 

ABNORMAL ENGINE INSTRUMENT

INDICATIONS

The AFM/POH for the specific airplane contains information that should be followed in the event of any

A. Continuous Load

Pitot Heating (Operating)

Wingtip Lights

Heater Igniter

**Navigation Receivers

**Communications Receivers

Fuel Indicator

Instrument Lights (overhead)

Engine Indicator

Compass Light

Landing Gear Indicator

Flap Indicator

B. Intermittent Load

Starter

Landing Lights

Heater Blower Motor

Flap Motor

Landing Gear Motor

Cigarette Lighter

Transceiver (keyed)

Fuel Boost Pump

Cowl Flap Motor

Stall Warning Horn

** Amperage for radios varies with equipment. In general, 

the more recent the model, the less amperage required.

NOTE: Panel and indicator lights usually draw less than 

one amp.

1

4

1

1-4

1-2

1

2

1

1

1

1

1

2

1

1

1

1

1

1

1

1

3.30

3.00

1-20

1-2 each

1-2 each

0.40

0.60

0.30

0.20

0.17

0.17

100.00

17.80

14.00

13.00

10.00

7.50

5-7

2.00

1.00

1.50

Electrical Loads for

Light Single

Number

of Units

Total

Amperes

Figure 16-9. Electrical load for light single.

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16-12

abnormal engine instrument indications. The table on

the next page offers generic information on some of

the more commonly experienced in-flight abnormal

engine instrument indications, their possible causes,

and corrective actions. [Table 1]

DOOR OPENING IN FLIGHT

In most instances, the occurrence of an inadvertent

door opening is not of great concern to the safety of a

flight, but rather, the pilot’s reaction at the moment the

incident happens. A door opening in flight may be

accompanied by a sudden loud noise, sustained noise

level and possible vibration or buffeting. If a pilot

allows himself or herself to become distracted to the

point where attention is focused on the open door

rather than maintaining control of the airplane, loss of

control may result, even though disruption of airflow

by the door is minimal. 

In the event of an inadvertent door opening in flight or

on takeoff, the pilot should adhere to the following.

• Concentrate on flying the airplane. Particularly in

light single- and twin-engine airplanes; a cabin

door that opens in flight seldom if ever compromises the airplane’s ability to fly. There may be

some handling effects such as roll and/or yaw, but

in most instances these can be easily overcome.

• If the door opens after lift-off, do not rush to land.

Climb to normal traffic pattern altitude, fly a normal traffic pattern, and make a normal landing.

• Do not release the seat belt and shoulder harness

in an attempt to reach the door. Leave the door

alone. Land as soon as practicable, and close the

door once safely on the ground.

• Remember that most doors will not stay wide

open. They will usually bang open, then settle

partly closed. A slip towards the door may cause

it to open wider; a slip away from the door may

push it closed.

• Do not panic. Try to ignore the unfamiliar noise

and vibration. Also, do not rush. Attempting to

get the airplane on the ground as quickly as possible may result in steep turns at low altitude.

• Complete all items on the landing checklist.

• Remember that accidents are almost never

caused by an open door. Rather, an open door

accident is caused by the pilot’s distraction or

failure to maintain control of the airplane.

INADVERTENT VFR FLIGHT INTO IMC

GENERAL

It is beyond the scope of this handbook to incorporate a course of training in basic attitude instrument

flying. This information is contained in FAA-H8083-15, Instrument Flying Handbook. Certain

pilot certificates and/or associated ratings require

training in instrument flying and a demonstration of

specific instrument flying tasks on the practical test.

Effect of Blocked

Pitot/Static

Sources on Airspeed,

Altimeter and

Vertical Speed Indications

Pitot Source Blocked

One Static

Source Blocked

Both Static

Sources Blocked

Both Static and

Pitot Sources Blocked

Increases with altitude

gain; decreases

with altitude loss.

Decreases with altitude

gain; increases

with altitude loss.

Unaffected Unaffected

Does not change

with actual gain or

loss of altitude.

Does not change

with actual variations

in vertical speed.

Inaccurate while sideslipping; very sensitive in turbulence.

All indications remain constant, regardless of actual changes

in airspeed, altitude and vertical speed.

Indicated Airspeed Indicated Altitude Indicated

Vertical Speed

Figure 16-10. Effects of blocked pitot-static sources.

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16-13

Pilots and flight instructors should refer to FAA-H8083-15 for guidance in the performance of these

tasks, and to the appropriate practical test standards

for information on the standards to which these

required tasks must be performed for the particular

certificate level and/or rating. The pilot should

remember, however, that unless these tasks are practiced on a continuing and regular basis, skill erosion

begins almost immediately. In a very short time, the

pilot’s assumed level of confidence will be much

higher than the performance he or she will actually

be able to demonstrate should the need arise.

Accident statistics show that the pilot who has not

been trained in attitude instrument flying, or one

whose instrument skills have eroded, will lose control of the airplane in about 10 minutes once forced

to rely solely on instrument reference. The purpose

of this section is to provide guidance on practical

emergency measures to maintain airplane control for

a limited period of time in the event a VFR pilot

encounters IMC conditions. The main goal is not

precision instrument flying; rather, it is to help the

VFR pilot keep the airplane under adequate control

until suitable visual references are regained.

MALFUNCTION PROBABLE CAUSE CORRECTIVE ACTION

Loss of r.p.m. during cruise flight

(non-altitude engines)

Carburetor or induction icing or air filter

clogging

Apply carburetor heat. If dirty filter is

suspected and non-filtered air is available,

switch selector to unfiltered position.

Loss of manifold pressure during cruise

flight

Same as above Same as above.

Turbocharger failure Possible exhaust leak. Shut down engine

or use lowest practicable power setting.

Land as soon as possible.

Gain of manifold pressure during cruise 

flight

Throttle has opened, propeller control has

decreased r.p.m., or improper method of

power reduction

Readjust throttle and tighten friction lock.

Reduce manifold pressure prior to

reducing r.p.m.

High oil temperature Oil congealed in cooler Reduce power. Land. Preheat engine.

Inadequate engine cooling Reduce power. Increase airspeed.

Detonation or preignition Observe cylinder head temperatures for

high reading. Reduce manifold pressure.

Enrich mixture.

Forth coming internal engine faiure Land as soon as possible or feather

propeller and stop engine.

Land as soon as possible or feather

propeller and stop engine.

Defective thermostatic oil cooler control Land as soon as possible. Consult

maintenance personnel.

Low oil temperature Engine not warmed up to operating

temperature

Warm engine in prescribed manner.

High oil pressure Cold oil Same as above.

Same as above.

Same as above.

Same as above.

Same as above.

Same as above.

Possible internal plugging Reduce power. Land as soon as possible.

Low oil pressure Broken pressure relief valve

Insufficient oil

Burned out bearings

Fluctuating oil pressure Low oil supply, loose oil lines, defective

pressure relief valve

Improper cowl flap adjustment Adjust cowl flaps.

Adjust cowl flaps.

Insufficient airspeed for cooling Increase airspeed.

Improper mixture adjustment Adjust mixture.

Detonation or preignition Reduce power, enrich mixture, increase

cooling airflow.

Low cylinder head temperature

High cylinder head temperature

Excessive cowl flap opening

Excessively rich mixture Adjust mixture control.

Exteneded glides without clearing engine Clear engine long enough to keep

temperatures at minimum range.

Ammeter indicating discharge Alternator or generator failure Shed unnecessary electrical load. Land

as soon as practicable.

Load meter indicating zero Same as above

Surging r.p.m. and overspeeding Defective propeller

Defective propeller governor

Adjust propeller r.p.m.

Defective engine Consult maintenance.

Consult maintenance personnel.

Consult maintenance.

Adjust propeller control. Attempt to

restore normal operation.

Defective tachometer

Improper mixture setting Readjust mixture for smooth operation.

Adjust mixture for smooth operation.

Loss of airspeed in cruise flight with

manifold pressure and r.p.m. constant

Possible loss of one or more cylinders Land as soon as possible.

Rough running engine Improper mixture control setting

Defective ignition or valves

Detonation or preignition Reduce power, enrich mixture, open cowl

flaps to reduce cylinder head temp. Land

as soon as practicable.

Induction air leak Reduce power. Consult maintenance.

Plugged fuel nozzle (Fuel injection)

Excessive fuel pressure or fuel flow Lean mixture control.

Loss of fuel pressure Engine driven pump failure Turn on boost tanks.

No fuel Switch tanks, turn on fuel.

Table 1.

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16-14

The first steps necessary for surviving an encounter

with instrument meteorological conditions (IMC) by a

VFR pilot are:

• Recognition and acceptance of the seriousness of

the situation and the need for immediate remedial

action.

• Maintaining control of the airplane.

• Obtaining the appropriate assistance in getting the

airplane safely on the ground.

RECOGNITION

A VFR pilot is in IMC conditions anytime he or she is

unable to maintain airplane attitude control by reference

to the natural horizon, regardless of the circumstances

or the prevailing weather conditions. Additionally, the

VFR pilot is, in effect, in IMC anytime he or she is inadvertently, or intentionally for an indeterminate period of

time, unable to navigate or establish geographical

position by visual reference to landmarks on the

surface. These situations must be accepted by the pilot

involved as a genuine emergency, requiring appropriate

action.

The pilot must understand that unless he or she is

trained, qualified, and current in the control of an airplane solely by reference to flight instruments, he or she

will be unable to do so for any length of time. Many

hours of VFR flying using the attitude indicator as a

reference for airplane control may lull a pilot into a false

sense of security based on an overestimation of his or

her personal ability to control the airplane solely by

instrument reference. In VFR conditions, even though

the pilot thinks he or she is controlling the airplane by

instrument reference, the pilot also receives an overview

of the natural horizon and may subconsciously rely on it

more than the cockpit attitude indicator. If the natural

horizon were to suddenly disappear, the untrained

instrument pilot would be subject to vertigo, spatial

disorientation, and inevitable control loss.

MAINTAINING AIRPLANE CONTROL

Once the pilot recognizes and accepts the situation, he

or she must understand that the only way to control the

airplane safely is by using and trusting the flight instruments. Attempts to control the airplane partially by

reference to flight instruments while searching outside

the cockpit for visual confirmation of the information

provided by those instruments will result in inadequate

airplane control. This may be followed by spatial

disorientation and complete control loss.

The most important point to be stressed is that the pilot

must not panic. The task at hand may seem overwhelming, and the situation may be compounded by

extreme apprehension. The pilot therefore must make

a conscious effort to relax.

The pilot must understand the most important concern—in fact the only concern at this point—is to keep

the wings level. An uncontrolled turn or bank usually

leads to difficulty in achieving the objectives of any

desired flight condition. The pilot will find that good

bank control has the effect of making pitch control

much easier.

The pilot should remember that a person cannot feel

control pressures with a tight grip on the controls.

Relaxing and learning to “control with the eyes and

the brain” instead of only the muscles, usually takes

considerable conscious effort.

The pilot must believe what the flight instruments

show about the airplane’s attitude regardless of what

the natural senses tell. The vestibular sense (motion

sensing by the inner ear) can and will confuse the pilot.

Because of inertia, the sensory areas of the inner ear

cannot detect slight changes in airplane attitude, nor

can they accurately sense attitude changes which occur

at a uniform rate over a period of time. On the other

hand, false sensations are often generated, leading the

pilot to believe the attitude of the airplane has changed

when, in fact, it has not. These false sensations result

in the pilot experiencing spatial disorientation.

ATTITUDE CONTROL

An airplane is, by design, an inherently stable platform

and, except in turbulent air, will maintain approximately straight-and-level flight if properly trimmed

and left alone. It is designed to maintain a state of

equilibrium in pitch, roll, and yaw. The pilot must be

aware, however, that a change about one axis will

affect the stability of the others. The typical light

airplane exhibits a good deal of stability in the yaw

axis, slightly less in the pitch axis, and even lesser still

in the roll axis. The key to emergency airplane attitude

control, therefore, is to:

• Trim the airplane with the elevator trim so that it

will maintain hands-off level flight at cruise airspeed.

• Resist the tendency to over control the airplane.

Fly the attitude indicator with fingertip control.

No attitude changes should be made unless the

flight instruments indicate a definite need for a

change.

• Make all attitude changes smooth and small, yet

with positive pressure. Remember that a small

change as indicated on the horizon bar corresponds to a proportionately much larger change

in actual airplane attitude. 

• Make use of any available aid in attitude control

such as autopilot or wing leveler.

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16-15

The primary instrument for attitude control is the attitude indicator. [Figure 16-11] Once the airplane is

trimmed so that it will maintain hands-off level flight

at cruise airspeed, that airspeed need not vary until the

airplane must be slowed for landing. All turns, climbs

and descents can and should be made at this airspeed.

Straight flight is maintained by keeping the wings level

using “fingertip pressure” on the control wheel. Any

pitch attitude change should be made by using no more

than one bar width up or down.

TURNS

Turns are perhaps the most potentially dangerous

maneuver for the untrained instrument pilot for two

reasons. 

• The normal tendency of the pilot to over control,

leading to steep banks and the possibility of a

“graveyard spiral.” 

• The inability of the pilot to cope with the instability resulting from the turn.

When a turn must be made, the pilot must anticipate

and cope with the relative instability of the roll axis.

The smallest practical bank angle should be used—in

any case no more than 10° bank angle. [Figure 16-12]

A shallow bank will take very little vertical lift from

the wings resulting in little if any deviation in altitude.

It may be helpful to turn a few degrees and then return

to level flight, if a large change in heading must be

made. Repeat the process until the desired heading is

reached. This process may relieve the progressive

overbanking that often results from prolonged turns.

CLIMBS

If a climb is necessary, the pilot should raise the

miniature airplane on the attitude indicator no more

than one bar width and apply power. [Figure 16-13]

The pilot should not attempt to attain a specific climb

speed but accept whatever speed results. The objective is to deviate as little as possible from level flight

attitude in order to disturb the airplane’s equilibrium

as little as possible. If the airplane is properly

trimmed, it will assume a nose-up attitude on its own

commensurate with the amount of power applied.

Torque and P-factor will cause the airplane to have a

Figure 16-11. Attitude indicator.

Figure 16-12. Level turn.

Figure 16-13. Level climb.

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tendency to bank and turn to the left. This must be

anticipated and compensated for. If the initial power

application results in an inadequate rate of climb,

power should be increased in increments of 100 r.p.m.

or 1 inch of manifold pressure until the desired rate of

climb is attained. Maximum available power is

seldom necessary. The more power used the more the

airplane will want to bank and turn to the left.

Resuming level flight is accomplished by first

decreasing pitch attitude to level on the attitude

indicator using slow but deliberate pressure, allowing

airspeed to increase to near cruise value, and then

decreasing power.

DESCENTS

Descents are very much the opposite of the climb

procedure if the airplane is properly trimmed for

hands-off straight-and-level flight. In this configuration, the airplane requires a certain amount of thrust to

maintain altitude. The pitch attitude is controlling the

airspeed. The engine power, therefore, (translated into

thrust by the propeller) is maintaining the selected

altitude. Following a power reduction, however slight,

there will be an almost imperceptible decrease in

airspeed. However, even a slight change in speed

results in less down load on the tail, whereupon the

designed nose heaviness of the airplane causes it to

pitch down just enough to maintain the airspeed for

which it was trimmed. The airplane will then descend

at a rate directly proportionate to the amount of thrust

that has been removed. Power reductions should be

made in increments of 100 r.p.m. or 1 inch of manifold

pressure and the resulting rate of descent should never

exceed 500 f.p.m. The wings should be held level on

the attitude indicator, and the pitch attitude should not

exceed one bar width below level. [Figure 16-14]

COMBINED MANEUVERS

Combined maneuvers, such as climbing or descending

turns should be avoided if at all possible by an

untrained instrument pilot already under the stress of

an emergency situation. Combining maneuvers will

only compound the problems encountered in individual

maneuvers and increase the risk of control loss.

Remember that the objective is to maintain airplane

control by deviating as little as possible from straightand-level flight attitude and thereby maintaining as

much of the airplane’s natural equilibrium as possible.

When being assisted by air traffic controllers from the

ground, the pilot may detect a sense of urgency as he

or she is being directed to change heading and/or altitude. This sense of urgency reflects a normal concern

for safety on the part of the controller. But the pilot

must not let this prompt him or her to attempt a maneuver

that could result in loss of control.

TRANSITION TO VISUAL FLIGHT

One of the most difficult tasks a trained and qualified

instrument pilot must contend with is the transition

from instrument to visual flight prior to landing. For

the untrained instrument pilot, these difficulties are

magnified.

The difficulties center around acclimatization and

orientation. On an instrument approach the trained

instrument pilot must prepare in advance for the

transition to visual flight. The pilot must have a

mental picture of what he or she expects to see once

the transition to visual flight is made and quickly

acclimatize to the new environment. Geographical

orientation must also begin before the transition as the

pilot must visualize where the airplane will be in relation to the airport/runway when the transition occurs

so that the approach and landing may be completed by

visual reference to the ground.

In an ideal situation the transition to visual flight is

made with ample time, at a sufficient altitude above

terrain, and to visibility conditions sufficient to

accommodate acclimatization and geographical

orientation. This, however, is not always the case. The

untrained instrument pilot may find the visibility still

limited, the terrain completely unfamiliar, and altitude

above terrain such that a “normal” airport traffic

pattern and landing approach is not possible.

Additionally, the pilot will most likely be under

considerable self-induced psychological pressure to

Figure 16-14. Level descent.

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16-17

get the airplane on the ground. The pilot must take this

into account and, if possible, allow time to become

acclimatized and geographically oriented before

attempting an approach and landing, even if it means

flying straight and level for a time or circling the

airport. This is especially true at night.

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Ch 16.qxd 5/7/04 10:30 AM Page 16-18
100-HOUR INSPECTION—

An inspection, identical in scope to an

annual inspection. Must be conducted

every 100 hours of flight on aircraft of

under 12,500 pounds that are used

for hire.

ABSOLUTE ALTITUDE—

The vertical distance of an airplane

above the terrain, or above ground

level (AGL).

ABSOLUTE CEILING—

The altitude at which a climb is no

longer possible.

ACCELERATE-GO DISTANCE—

The distance required to accelerate to

V1 with all engines at takeoff power,

experience an engine failure at V1 and

continue the takeoff on the remaining

engine(s). The runway required

includes the distance required to

climb to 35 feet by which time V2

speed must be attained.

ACCELERATE-STOP

DISTANCE—The distance required

to accelerate to V1 with all engines at

takeoff power, experience an engine

failure at V1, and abort the takeoff and

bring the airplane to a stop using braking action only (use of thrust reversing is not considered).

ACCELERATION—Force involved

in overcoming inertia, and which may

be defined as a change in velocity per

unit of time.

ACCESSORIES—Components that

are used with an engine, but are not a

part of the engine itself. Units such as

magnetos, carburetors, generators,

and fuel pumps are commonly

installed engine accessories.

ADJUSTABLE STABILIZER—

A stabilizer that can be adjusted in

flight to trim the airplane, thereby

even a trim tab, which provides

aerodynamic force when it interacts

with a moving stream of air.

AIRMANSHIP SKILLS—The skills

of coordination, timing, control touch,

and speed sense in addition to the

motor skills required to fly an aircraft.

AIRMANSHIP—

A sound acquaintance with the

principles of flight, the ability to

operate an airplane with competence

and precision both on the ground and

in the air, and the exercise of sound

judgment that results in optimal

operational safety and efficiency. 

AIRPLANE FLIGHT MANUAL

(AFM)—A document developed by

the airplane manufacturer and

approved by the Federal Aviation

Administration (FAA). It is specific to

a particular make and model airplane

by serial number and it contains

operating procedures and limitations.

AIRPLANE OWNER/

INFORMATION MANUAL—A

document developed by the airplane

manufacturer containing general

information about the make and

model of an airplane. The airplane

owner’s manual is not FAA-approved

and is not specific to a particular serial

numbered airplane. This manual is not

kept current, and therefore cannot be

substituted for the AFM/POH.

AIRPORT/FACILITY

DIRECTORY—

A publication designed primarily as a

pilot’s operational manual containing

all airports, seaplane bases, and

heliports open to the public including

communications data, navigational

facilities, and certain special notices

and procedures. This publication is

issued in seven volumes according to

geographical area.

allowing the airplane to fly hands-off

at any given airspeed.

ADVERSE YAW—A condition of

flight in which the nose of an airplane

tends to yaw toward the outside of the

turn. This is caused by the higher

induced drag on the outside wing,

which is also producing more lift.

Induced drag is a by-product of the lift

associated with the outside wing.

AERODYNAMIC CEILING—

The point (altitude) at which, as the

indicated airspeed decreases with altitude, it progressively merges with the

low speed buffet boundary where prestall buffet occurs for the airplane at a

load factor of 1.0 G. 

AERODYNAMICS—The science of

the action of air on an object, and with

the motion of air on other gases.

Aerodynamics deals with the

production of lift by the aircraft, the

relative wind, and the atmosphere.

AILERONS—Primary flight control

surfaces mounted on the trailing edge

of an airplane wing, near the tip.

Ailerons control roll about the longitudinal axis.

AIR START—The act or instance of

starting an aircraft’s engine while in

flight, especially a jet engine after

flameout.

AIRCRAFT LOGBOOKS—

Journals containing a record of total

operating time, repairs, alterations or

inspections performed, and all

Airworthiness Directive (AD) notes

complied with. A maintenance

logbook should be kept for the

airframe, each engine, and each

propeller.

AIRFOIL—An airfoil is any surface,

such as a wing, propeller, rudder, or

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AIRWORTHINESS—A condition

in which the aircraft conforms to its

type certificated design including

supplemental type certificates, and

field approved alterations. The

aircraft must also be in a condition for

safe flight as determined by annual,

100 hour, preflight and any other

required inspections.

AIRWORTHINESS

CERTIFICATE—

A certificate issued by the FAA to all

aircraft that have been proven to meet

the minimum standards set down by

the Code of Federal Regulations.

AIRWORTHINESS 

DIRECTIVE—A regulatory notice

sent out by the FAA to the registered

owner of an aircraft informing the

owner of a condition that prevents the

aircraft from continuing to meet

its conditions for airworthiness.

Airworthiness Directives (AD notes)

must be complied with within the

required time limit, and the fact of

compliance, the date of compliance,

and the method of compliance must be

recorded in the aircraft’s maintenance

records.

ALPHA MODE OF

OPERATION—The operation of a

turboprop engine that includes all of

the flight operations, from takeoff to

landing. Alpha operation is typically

between 95 percent to 100 percent of

the engine operating speed.

ALTERNATE AIR—A device

which opens, either automatically

or manually, to allow induction airflow to continue should the primary

induction air opening become

blocked.

ALTERNATE STATIC SOURCE—

A manual port that when opened

allows the pitot static instruments to

sense static pressure from an alternate

location should the primary static port

become blocked.

ALTERNATOR/GENERATOR—A

device that uses engine power to generate electrical power.

ALTIMETER—A flight instrument

that indicates altitude by sensing

pressure changes. 

pitch, which is the up and down

movement of the airplane’s nose. 

ATTITUDE— The position of an

aircraft as determined by the

relationship of its axes and a reference, usually the earth’s horizon.

AUTOKINESIS—This is caused by

staring at a single point of light

against a dark background for more

than a few seconds. After a few

moments, the light appears to move

on its own.

AUTOPILOT—An automatic flight

control system which keeps an aircraft

in level flight or on a set course.

Automatic pilots can be directed by

the pilot, or they may be coupled to a

radio navigation signal.

AXES OF AN AIRCRAFT—Three

imaginary lines that pass through an

aircraft’s center of gravity. The axes

can be considered as imaginary axles

around which the aircraft turns. The

three axes pass through the center of

gravity at 90° angles to each other.

The axis from nose to tail is the

longitudinal axis, the axis that passes

from wingtip to wingtip is the lateral

axis, and the axis that passes vertically

through the center of gravity is the

vertical axis.

AXIAL FLOW COMPRESSOR—

A type of compressor used in a turbine

engine in which the airflow through

the compressor is essentially linear.

An axial-flow compressor is made up

of several stages of alternate rotors

and stators. The compressor ratio is

determined by the decrease in area of

the succeeding stages.

BACK SIDE OF THE POWER

CURVE— Flight regime in which

flight at a higher airspeed requires a

lower power setting and a lower

airspeed requires a higher power

setting in order to maintain altitude.

BALKED LANDING—

A go-around.

BALLAST—Removable or permanently installed weight in an aircraft

ALTITUDE (AGL)—The actual

height above ground level (AGL) at

which the aircraft is flying.

ALTITUDE (MSL)—The actual

height above mean sea level (MSL) at

which the aircraft is flying.

ALTITUDE CHAMBER—A device

that simulates high altitude conditions

by reducing the interior pressure. The

occupants will suffer from the same

physiological conditions as flight at

high altitude in an unpressurized

aircraft. 

ALTITUDE ENGINE—

A reciprocating aircraft engine having

a rated takeoff power that is

producible from sea level to an

established higher altitude.

ANGLE OF ATTACK—The acute

angle between the chord line of the

airfoil and the direction of the relative

wind.

ANGLE OF INCIDENCE—

The angle formed by the chord line of

the wing and a line parallel to the

longitudinal axis of the airplane.

ANNUAL INSPECTION—

A complete inspection of an aircraft

and engine, required by the Code

of Federal Regulations, to be

accomplished every 12 calendar

months on all certificated aircraft.

Only an A&P technician holding an

Inspection Authorization can conduct

an annual inspection.

ANTI-ICING—The prevention of

the formation of ice on a surface. Ice

may be prevented by using heat or by

covering the surface with a chemical

that prevents water from reaching the

surface. Anti-icing should not be confused with deicing, which is the

removal of ice after it has formed on

the surface.

ATTITUDE INDICATOR—

An instrument which uses an artificial

horizon and miniature airplane to

depict the position of the airplane in

relation to the true horizon. The

attitude indicator senses roll as well as

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used to bring the center of gravity into

the allowable range.

BALLOON—The result of a too

aggressive flare during landing

causing the aircraft to climb.

BASIC EMPTY WEIGHT

(GAMA)—Basic empty weight

includes the standard empty weight

plus optional and special equipment

that has been installed. 

BEST ANGLE OF CLIMB (VX)—

The speed at which the aircraft will

produce the most gain in altitude in a

given distance.

BEST GLIDE—The airspeed in

which the aircraft glides the furthest

for the least altitude lost when in

non-powered flight.

BEST RATE OF CLIMB (VY)—

The speed at which the aircraft will

produce the most gain in altitude in

the least amount of time.

BLADE FACE—The flat portion of a

propeller blade, resembling the

bottom portion of an airfoil.

BLEED AIR—Compressed air

tapped from the compressor stages of

a turbine engine by use of ducts and

tubing. Bleed air can be used for

deice, anti-ice, cabin pressurization,

heating, and cooling systems.

BLEED VALVE—In a turbine

engine, a flapper valve, a popoff

valve, or a bleed band designed to

bleed off a portion of the compressor

air to the atmosphere. Used to

maintain blade angle of attack and

provide stall-free engine acceleration

and deceleration.

BOOST PUMP—An electrically

driven fuel pump, usually of the

centrifugal type, located in one of the

fuel tanks. It is used to provide fuel to

the engine for starting and providing

fuel pressure in the event of failure of

the engine driven pump. It also

pressurizes the fuel lines to prevent

vapor lock.

CAMBERED—The camber of an

airfoil is the characteristic curve of its

upper and lower surfaces. The upper

camber is more pronounced, while the

lower camber is comparatively flat.

This causes the velocity of the airflow

immediately above the wing to be

much higher than that below the wing.

CARBURETOR ICE— Ice that

forms inside the carburetor due to the

temperature drop caused by the

vaporization of the fuel. Induction

system icing is an operational hazard

because it can cut off the flow of the

fuel/air charge or vary the fuel/air

ratio.

CARBURETOR—1. Pressure: A

hydromechanical device employing a

closed feed system from the fuel

pump to the discharge nozzle. It

meters fuel through fixed jets

according to the mass airflow through

the throttle body and discharges it

under a positive pressure. Pressure

carburetors are distinctly different

from float-type carburetors, as they do

not incorporate a vented float

chamber or suction pickup from a

discharge nozzle located in the venturi

tube. 2. Float-type: Consists

essentially of a main air passage

through which the engine draws its

supply of air, a mechanism to control

the quantity of fuel discharged in

relation to the flow of air, and a means

of regulating the quantity of fuel/air

mixture delivered to the engine

cylinders.

CASCADE REVERSER—A thrust

reverser normally found on turbofan

engines in which a blocker door and a

series of cascade vanes are used to

redirect exhaust gases in a forward

direction.

CENTER OF GRAVITY (CG)—

The point at which an airplane would

balance if it were possible to suspend

it at that point. It is the mass center of

the airplane, or the theoretical point at

which the entire weight of the airplane

is assumed to be concentrated. It may

be expressed in inches from the reference datum, or in percent of mean

aerodynamic chord (MAC). The location depends on the distribution of

weight in the airplane.

BUFFETING—The beating of an

aerodynamic structure or surface by

unsteady flow, gusts, etc.; the irregular shaking or oscillation of a vehicle

component owing to turbulent air or

separated flow.

BUS BAR—An electrical power

distribution point to which several

circuits may be connected. It is often a

solid metal strip having a number of

terminals installed on it. 

BUS TIE—A switch that connects

two or more bus bars. It is usually

used when one generator fails and

power is lost to its bus. By closing the

switch, the operating generator

powers both busses. 

BYPASS AIR—The part of a

turbofan’s induction air that bypasses

the engine core.

BYPASS RATIO—The ratio of the

mass airflow in pounds per second

through the fan section of a turbofan

engine to the mass airflow that passes

through the gas generator portion of

the engine. Or, the ratio between fan

mass airflow (lb/sec.) and core engine

mass airflow (lb/sec.).

CABIN PRESSURIZATION—A

condition where pressurized air is

forced into the cabin simulating

pressure conditions at a much lower

altitude and increasing the aircraft

occupants comfort.

CALIBRATED AIRSPEED

(CAS)—Indicated airspeed corrected

for installation error and instrument

error. Although manufacturers attempt

to keep airspeed errors to a minimum,

it is not possible to eliminate all errors

throughout the airspeed operating

range. At certain airspeeds and with

certain flap settings, the installation

and instrument errors may total

several knots. This error is generally

greatest at low airspeeds. In the

cruising and higher airspeed ranges,

indicated airspeed and calibrated

airspeed are approximately the same.

Refer to the airspeed calibration chart

to correct for possible airspeed errors.

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CENTER-OF-GRAVITY

LIMITS—The specified forward and

aft points within which the CG must

be located during flight. These limits

are indicated on pertinent airplane

specifications.

CENTER-OF-GRAVITY

RANGE—The distance between the

forward and aft CG limits indicated on

pertinent airplane specifications.

CENTRIFUGAL

FLOW COMPRESSOR—

An impeller-shaped device that receives

air at its center and slings air outward at

high velocity into a diffuser for increased

pressure. Also referred to as a radial outflow compressor.

CHORD LINE—An imaginary

straight line drawn through an airfoil

from the leading edge to the trailing

edge.

CIRCUIT BREAKER—

A circuit-protecting device that opens

the circuit in case of excess current

flow. A circuit breakers differs from a

fuse in that it can be reset without

having to be replaced.

CLEAR AIR TURBULENCE—

Turbulence not associated with any

visible moisture.

CLIMB GRADIENT—The ratio

between distance traveled and altitude

gained.

COCKPIT RESOURCE

MANAGEMENT—Techniques

designed to reduce pilot errors and

manage errors that do occur utilizing

cockpit human resources. The

assumption is that errors are going to

happen in a complex system with

error-prone humans.

COEFFICIENT OF LIFT—See

LIFT COEFFICIENT.

COFFIN CORNER—The flight

regime where any increase in airspeed

will induce high speed mach buffet

and any decrease in airspeed will

induce low speed mach buffet.

CONDITION LEVER—In a turbine

engine, a powerplant control that controls the flow of fuel to the engine.

The condition lever sets the desired

engine r.p.m. within a narrow range

between that appropriate for ground

and flight operations.

CONFIGURATION—This is a

general term, which normally refers to

the position of the landing gear

and flaps.

CONSTANT SPEED

PROPELLER— A controllablepitch propeller whose pitch is

automatically varied in flight by a

governor to maintain a constant r.p.m.

in spite of varying air loads.

CONTROL TOUCH—The ability to

sense the action of the airplane and its

probable actions in the immediate

future, with regard to attitude and

speed variations, by sensing and

evaluation of varying pressures and

resistance of the control surfaces

transmitted through the cockpit flight

controls.

CONTROLLABILITY—A measure

of the response of an aircraft relative

to the pilot’s flight control inputs.

CONTROLLABLE PITCH

PROPELLER—A propeller in which

the blade angle can be changed during

flight by a control in the cockpit.

CONVENTIONAL LANDING

GEAR—Landing gear employing a

third rear-mounted wheel. These

airplanes are also sometimes referred

to as tailwheel airplanes.

COORDINATED FLIGHT—

Application of all appropriate flight

and power controls to prevent slipping

or skidding in any flight condition.

COORDINATION—The ability to

use the hands and feet together

subconsciously and in the proper

relationship to produce desired results

in the airplane.

CORE AIRFLOW—Air drawn into

the engine for the gas generator.

COMBUSTION CHAMBER— The

section of the engine into which fuel

is injected and burned.

COMMON TRAFFIC

ADVISORY FREQUENCY—The

common frequency used by airport

traffic to announce position reports in

the vicinity of the airport.

COMPLEX AIRCRAFT—

An aircraft with retractable landing

gear, flaps, and a controllable-pitch

propeller, or is turbine powered.

COMPRESSION RATIO—1. In a

reciprocating engine, the ratio of the

volume of an engine cylinder with the

piston at the bottom center to the

volume with the piston at top center.

2. In a turbine engine, the ratio of the

pressure of the air at the discharge to

the pressure of air at the inlet.

COMPRESSOR BLEED AIR—

See BLEED AIR.

COMPRESSOR BLEED

VALVES—See BLEED VALVE.

COMPRESSOR SECTION— The

section of a turbine engine that

increases the pressure and density of

the air flowing through the engine.

COMPRESSOR STALL—In gas

turbine engines, a condition in an

axial-flow compressor in which one

or more stages of rotor blades fail to

pass air smoothly to the succeeding

stages. A stall condition is caused by a

pressure ratio that is incompatible

with the engine r.p.m. Compressor

stall will be indicated by a rise in

exhaust temperature or r.p.m.

fluctuation, and if allowed to

continue, may result in flameout and

physical damage to the engine. 

COMPRESSOR SURGE—A severe

compressor stall across the entire

compressor that can result in severe

damage if not quickly corrected. This

condition occurs with a complete

stoppage of airflow or a reversal of

airflow. 

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COWL FLAPS—Devices arranged

around certain air-cooled engine

cowlings which may be opened or

closed to regulate the flow of air

around the engine.

CRAB—A flight condition in which

the nose of the airplane is pointed into

the wind a sufficient amount to counteract a crosswind and maintain a

desired track over the ground.

CRAZING—Small fractures in

aircraft windshields and windows

caused from being exposed to the

ultraviolet rays of the sun and

temperature extremes.

CRITICAL ALTITUDE—

The maximum altitude under standard

atmospheric conditions at which a

turbocharged engine can produce its

rated horsepower.

CRITICAL ANGLE 

OF ATTACK—The angle of attack at

which a wing stalls regardless of

airspeed, flight attitude, or weight.

CRITICAL ENGINE—The engine

whose failure has the most adverse

effect on directional control.

CROSS CONTROLLED—

A condition where aileron deflection

is in the opposite direction of rudder

deflection.

CROSSFEED—A system that allows

either engine on a twin-engine

airplane to draw fuel from any fuel

tank.

CROSSWIND COMPONENT—

The wind component, measured in

knots, at 90° to the longitudinal axis

of the runway.

CURRENT LIMITER—A device

that limits the generator output to a

level within that rated by the

generator manufacturer.

DATUM (REFERENCE

DATUM)—An imaginary vertical

plane or line from which all

measurements of moment arm are

taken. The datum is established by the

manufacturer. Once the datum has

been selected, all moment arms and

parasite drag to compensate for the

additional induced drag caused by the

down aileron. This balancing of the

drag forces helps minimize adverse

yaw.

DIFFUSION—Reducing the velocity

of air causing the pressure to increase.

DIRECTIONAL STABILITY—

Stability about the vertical axis of an

aircraft, whereby an aircraft tends to

return, on its own, to flight aligned

with the relative wind when disturbed

from that equilibrium state. The

vertical tail is the primary contributor

to directional stability, causing an

airplane in flight to align with the

relative wind.

DITCHING—Emergency landing in

water.

DOWNWASH—

Air deflected perpendicular to the

motion of the airfoil.

DRAG—An aerodynamic force on a

body acting parallel and opposite to

the relative wind. The resistance of

the atmosphere to the relative motion

of an aircraft. Drag opposes thrust and

limits the speed of the airplane.

DRAG CURVE—

A visual representation of the amount

of drag of an aircraft at various

airspeeds.

DRIFT ANGLE—Angle between

heading and track.

DUCTED-FAN ENGINE—

An engine-propeller combination that

has the propeller enclosed in a radial

shroud. Enclosing the propeller

improves the efficiency of the

propeller.

DUTCH ROLL—A combination of

rolling and yawing oscillations that

normally occurs when the dihedral

effects of an aircraft are more

powerful than the directional stability.

Usually dynamically stable but

objectionable in an airplane because

of the oscillatory nature.

the location of CG range are measured

from this point.

DECOMPRESSION SICKNESS—

A condition where the low pressure at

high altitudes allows bubbles of

nitrogen to form in the blood and

joints causing severe pain. Also

known as the bends.

DEICER BOOTS—Inflatable rubber

boots attached to the leading edge of

an airfoil. They can be sequentially

inflated and deflated to break away ice

that has formed over their surface.

DEICING—Removing ice after it

has formed.

DELAMINATION—The separation

of layers.

DENSITY ALTITUDE—

This altitude is pressure altitude corrected for variations from standard

temperature. When conditions are

standard, pressure altitude and density

altitude are the same. If the temperature is above standard, the density altitude is higher than pressure altitude. If

the temperature is below standard, the

density altitude is lower than pressure

altitude. This is an important altitude

because it is directly related to the

airplane’s performance.

DESIGNATED PILOT

EXAMINER (DPE)—An individual

designated by the FAA to administer

practical tests to pilot applicants.

DETONATION—

The sudden release of heat energy

from fuel in an aircraft engine caused

by the fuel-air mixture reaching its

critical pressure and temperature.

Detonation occurs as a violent

explosion rather than a smooth

burning process.

DEWPOINT—The temperature at

which air can hold no more water.

DIFFERENTIAL AILERONS—

Control surface rigged such that the

aileron moving up moves a greater

distance than the aileron moving

down. The up aileron produces extra

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DYNAMIC HYDROPLANING—A

condition that exists when landing on

a surface with standing water deeper

than the tread depth of the tires. When

the brakes are applied, there is a

possibility that the brake will lock up

and the tire will ride on the surface of

the water, much like a water ski.

When the tires are hydroplaning,

directional control and braking action

are virtually impossible. An effective

anti-skid system can minimize the

effects of hydroplaning.

DYNAMIC STABILITY—

The property of an aircraft that causes

it, when disturbed from straight-andlevel flight, to develop forces or

moments that restore the original

condition of straight and level.

ELECTRICAL BUS—

See BUS BAR.

ELECTROHYDRAULIC—

Hydraulic control which is electrically

actuated.

ELEVATOR—

The horizontal, movable primary

control surface in the tail section, or

empennage, of an airplane. The

elevator is hinged to the trailing edge

of the fixed horizontal stabilizer.

EMERGENCY LOCATOR

TRANSMITTER—A small, selfcontained radio transmitter that will

automatically, upon the impact of a

crash, transmit an emergency signal

on 121.5, 243.0, or 406.0 MHz.

EMPENNAGE—The section of the

airplane that consists of the vertical

stabilizer, the horizontal stabilizer,

and the associated control surfaces.

ENGINE PRESSURE RATIO

(EPR)—The ratio of turbine

discharge pressure divided by

compressor inlet pressure that is used

as an indication of the amount of

thrust being developed by a turbine

engine.

ENVIRONMENTAL SYSTEMS—

In an aircraft, the systems, including

the supplemental oxygen systems, air

conditioning systems, heaters, and

FIXED SHAFT TURBOPROP

ENGINE—A turboprop engine

where the gas producer spool is

directly connected to the output shaft.

FIXED-PITCH PROPELLERS—

Propellers with fixed blade angles.

Fixed-pitch propellers are designed as

climb propellers, cruise propellers, or

standard propellers.

FLAPS—Hinged portion of the

trailing edge between the ailerons and

fuselage. In some aircraft, ailerons

and flaps are interconnected to

produce full-span “flaperons.” In

either case, flaps change the lift and

drag on the wing.

FLAT PITCH—

A propeller configuration when the

blade chord is aligned with the direction of rotation.

FLICKER VERTIGO—

A disorientating condition caused

from flickering light off the blades of

the propeller.

FLIGHT DIRECTOR—An automatic flight control system in which

the commands needed to fly the airplane are electronically computed and

displayed on a flight instrument. The

commands are followed by the human

pilot with manual control inputs or, in

the case of an autopilot system, sent to

servos that move the flight controls. 

FLIGHT IDLE—Engine speed,

usually in the 70-80 percent range, for

minimum flight thrust.

FLOATING—A condition when

landing where the airplane does not

settle to the runway due to excessive

airspeed.

FORCE (F)—The energy applied to

an object that attempts to cause the

object to change its direction, speed,

or motion. In aerodynamics, it is

expressed as F, T (thrust), L (lift), W

(weight), or D (drag), usually in

pounds.

FORM DRAG—The part of parasite

drag on a body resulting from the

pressurization systems, which make it

possible for an occupant to function at

high altitude.

EQUILIBRIUM—A condition that

exists within a body when the sum of

the moments of all of the forces acting

on the body is equal to zero. In

aerodynamics, equilibrium is when all

opposing forces acting on an aircraft

are balanced (steady, unaccelerated

flight conditions).

EQUIVALENT SHAFT

HORSEPOWER (ESHP)—

A measurement of the total horsepower of a turboprop engine, including that provided by jet thrust. 

EXHAUST GAS TEMPERATURE

(EGT)—The temperature of the

exhaust gases as they leave the

cylinders of a reciprocating engine or

the turbine section of a turbine engine.

EXHAUST MANIFOLD—The part

of the engine that collects exhaust

gases leaving the cylinders.

EXHAUST—The rear opening of a

turbine engine exhaust duct. The

nozzle acts as an orifice, the size of

which determines the density and

velocity of the gases as they emerge

from the engine.

FALSE HORIZON—An optical

illusion where the pilot confuses a row

of lights along a road or other straight

line as the horizon.

FALSE START—

See HUNG START.

FEATHERING PROPELLER

(FEATHERED)—A controllable

pitch propeller with a pitch range

sufficient to allow the blades to be

turned parallel to the line of flight to

reduce drag and prevent further

damage to an engine that has been

shut down after a malfunction.

FIXATION—

A psychological condition where the

pilot fixes attention on a single source

of information and ignores all

other sources.

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integrated effect of the static pressure

acting normal to its surface resolved

in the drag direction.

FORWARD SLIP—A slip in which

the airplane’s direction of motion continues the same as before the slip was

begun. In a forward slip, the airplane’s

longitudinal axis is at an angle to its

flightpath. 

FREE POWER TURBINE

ENGINE—A turboprop engine

where the gas producer spool is on a

separate shaft from the output shaft.

The free power turbine spins

independently of the gas producer and

drives the output shaft.

FRICTION DRAG—The part of

parasitic drag on a body resulting

from viscous shearing stresses over its

wetted surface.

FRISE-TYPE AILERON—Aileron

having the nose portion projecting

ahead of the hinge line. When the

trailing edge of the aileron moves up,

the nose projects below the wing’s

lower surface and produces some

parasite drag, decreasing the amount

of adverse yaw.

FUEL CONTROL UNIT—

The fuel-metering device used on a

turbine engine that meters the proper

quantity of fuel to be fed into the

burners of the engine. It integrates the

parameters of inlet air temperature,

compressor speed, compressor

discharge pressure, and exhaust gas

temperature with the position of the

cockpit power control lever.

FUEL EFFICIENCY—Defined as

the amount of fuel used to produce a

specific thrust or horsepower divided

by the total potential power contained

in the same amount of fuel.

FUEL HEATERS—A radiator-like

device which has fuel passing through

the core. A heat exchange occurs to

keep the fuel temperature above the

freezing point of water so that

entrained water does not form ice

crystals, which could block fuel flow.

FUEL INJECTION—

A fuel metering system used on some

aircraft reciprocating engines in

GO-AROUND—

Terminating a landing approach.

GOVERNING RANGE—The range

of pitch a propeller governor can

control during flight.

GOVERNOR—A control which

limits the maximum rotational speed

of a device.

GROSS WEIGHT—

The total weight of a fully loaded

aircraft including the fuel, oil, crew,

passengers, and cargo.

GROUND ADJUSTABLE TRIM

TAB—A metal trim tab on a control

surface that is not adjustable in flight.

Bent in one direction or another while

on the ground to apply trim forces to

the control surface.

GROUND EFFECT—A condition

of improved performance encountered when an airplane is operating

very close to the ground. When an

airplane’s wing is under the influence

of ground effect, there is a reduction

in upwash, downwash, and wingtip

vortices. As a result of the reduced

wingtip vortices, induced drag is

reduced. 

GROUND IDLE—Gas turbine

engine speed usually 60-70 percent of

the maximum r.p.m. range, used as a

minimum thrust setting for ground

operations.

GROUND LOOP—A sharp, uncontrolled change of direction of an

airplane on the ground.

GROUND POWER UNIT (GPU)—

A type of small gas turbine whose

purpose is to provide electrical power,

and/or air pressure for starting aircraft

engines. A ground unit is connected to

the aircraft when needed. Similar to

an aircraft-installed auxiliary power

unit.

GROUNDSPEED (GS)—The actual

speed of the airplane over the ground.

It is true airspeed adjusted for

wind. Groundspeed decreases with a

headwind, and increases with

a tailwind.

which a constant flow of fuel is fed to

injection nozzles in the heads of all

cylinders just outside of the intake

valve. It differs from sequential fuel

injection in which a timed charge of

high-pressure fuel is sprayed directly

into the combustion chamber of the

cylinder.

FUEL LOAD—The expendable part

of the load of the airplane. It includes

only usable fuel, not fuel required to

fill the lines or that which remains

trapped in the tank sumps.

FUEL TANK SUMP—A sampling

port in the lowest part of the fuel tank

that the pilot can utilize to check for

contaminants in the fuel.

FUSELAGE—The section of the

airplane that consists of the cabin

and/or cockpit, containing seats for

the occupants and the controls for the

airplane.

GAS GENERATOR—The basic

power producing portion of a gas

turbine engine and excluding such

sections as the inlet duct, the

fan section, free power turbines,

and tailpipe. Each manufacturer

designates what is included as the gas

generator, but generally consists of

the compressor, diffuser, combustor,

and turbine.

GAS TURBINE ENGINE—A form

of heat engine in which burning fuel

adds energy to compressed air and

accelerates the air through the

remainder of the engine. Some of the

energy is extracted to turn the air

compressor, and the remainder

accelerates the air to produce thrust.

Some of this energy can be converted

into torque to drive a propeller or a

system of rotors for a helicopter.

GLIDE RATIO—The ratio between

distance traveled and altitude lost

during non-powered flight.

GLIDEPATH—The path of an

aircraft relative to the ground while

approaching a landing.

GLOBAL POSITION SYSTEM

(GPS)—A satellite-based radio positioning, navigation, and time-transfer

system.

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GROUND TRACK—The aircraft’s

path over the ground when in flight. 

GUST PENETRATION SPEED—

The speed that gives the greatest

margin between the high and low

mach speed buffets.

GYROSCOPIC PRECESSION—

An inherent quality of rotating bodies,

which causes an applied force to be

manifested 90o in the direction of

rotation from the point where the

force is applied.

HAND PROPPING—Starting an

engine by rotating the propeller by

hand.

HEADING—The direction in which

the nose of the aircraft is pointing

during flight.

HEADING BUG—A marker on the

heading indicator that can be rotated

to a specific heading for reference

purposes, or to command an autopilot

to fly that heading.

HEADING INDICATOR—

An instrument which senses airplane

movement and displays heading based

on a 360o azimuth, with the final zero

omitted. The heading indicator, also

called a directional gyro, is fundamentally a mechanical instrument

designed to facilitate the use of the

magnetic compass. The heading indicator is not affected by the forces that

make the magnetic compass difficult

to interpret.

HEADWIND COMPONENT—The

component of atmospheric winds that

acts opposite to the aircraft’s flightpath.

HIGH PERFORMANCE

AIRCRAFT—An aircraft with an

engine of more than 200 horsepower.

HORIZON—The line of sight

boundary between the earth and the

sky.

HORSEPOWER—

The term, originated by inventor

James Watt, means the amount of

work a horse could do in one second.

engine. Some igniters resemble spark

plugs, while others, called glow plugs,

have a coil of resistance wire that

glows red hot when electrical current

flows through the coil.

IMPACT ICE—Ice that forms on the

wings and control surfaces or on the

carburetor heat valve, the walls of the

air scoop, or the carburetor units

during flight. Impact ice collecting on

the metering elements of the

carburetor may upset fuel metering or

stop carburetor fuel flow.

INCLINOMETER—An instrument

consisting of a curved glass tube,

housing a glass ball, and damped with

a fluid similar to kerosene. It may be

used to indicate inclination, as a level,

or, as used in the turn indicators, to

show the relationship between gravity

and centrifugal force in a turn.

INDICATED AIRSPEED (IAS)—

The direct instrument reading

obtained from the airspeed indicator,

uncorrected for variations in atmospheric density, installation error, or

instrument error. Manufacturers use

this airspeed as the basis for determining airplane performance. Takeoff,

landing, and stall speeds listed in the

AFM or POH are indicated airspeeds

and do not normally vary with altitude

or temperature.

INDICATED ALTITUDE—

The altitude read directly from the

altimeter (uncorrected) when it is set

to the current altimeter setting.

INDUCED DRAG—That part of

total drag which is created by the

production of lift. Induced drag

increases with a decrease in airspeed.

INDUCTION MANIFOLD—The

part of the engine that distributes

intake air to the cylinders.

INERTIA—The opposition which a

body offers to a change of motion.

INITIAL CLIMB—This stage of the

climb begins when the airplane leaves

the ground, and a pitch attitude has

One horsepower equals 550

foot-pounds per second, or 33,000

foot-pounds per minute.

HOT START—In gas turbine

engines, a start which occurs with

normal engine rotation, but exhaust

temperature exceeds prescribed

limits. This is usually caused by an

excessively rich mixture in the

combustor. The fuel to the engine

must be terminated immediately to

prevent engine damage.

HUNG START—In gas turbine

engines, a condition of normal light

off but with r.p.m. remaining at some

low value rather than increasing to the

normal idle r.p.m. This is often the

result of insufficient power to the

engine from the starter. In the event of

a hung start, the engine should be shut

down.

HYDRAULICS—The branch of

science that deals with the

transmission of power by incompressible fluids under pressure.

HYDROPLANING—A condition

that exists when landing on a surface

with standing water deeper than the

tread depth of the tires. When the

brakes are applied, there is a

possibility that the brake will lock up

and the tire will ride on the surface of

the water, much like a water ski.

When the tires are hydroplaning,

directional control and braking action

are virtually impossible. An effective

anti-skid system can minimize the

effects of hydroplaning.

HYPOXIA—A lack of sufficient

oxygen reaching the body tissues.

IFR (INSTRUMENT FLIGHT

RULES)—Rules that govern the

procedure for conducting flight in

weather conditions below VFR

weather minimums. The term “IFR”

also is used to define weather

conditions and the type of flight plan

under which an aircraft is operating.

IGNITER PLUGS—The electrical

device used to provide the spark for

starting combustion in a turbine

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been established to climb away from

the takeoff area.

INTEGRAL FUEL TANK—

A portion of the aircraft structure,

usually a wing, which is sealed off and

used as a fuel tank. When a wing is

used as an integral fuel tank, it is

called a “wet wing.”

INTERCOOLER—A device used to

reduce the temperature of the

compressed air before it enters the

fuel metering device. The resulting

cooler air has a higher density, which

permits the engine to be operated with

a higher power setting.

INTERNAL COMBUSTION 

ENGINES—An engine that produces

power as a result of expanding hot

gases from the combustion of fuel and

air within the engine itself. A steam

engine where coal is burned to heat up

water inside the engine is an example

of an external combustion engine. 

INTERSTAGE TURBINE

TEMPERATURE (ITT)—The temperature of the gases between the high

pressure and low pressure turbines.

INVERTER—An electrical device

that changes DC to AC power. 

ISA (INTERNATIONAL

STANDARD ATMOSPHERE)—

Standard atmospheric conditions

consisting of a temperature of 59°F

(15°C), and a barometric pressure of

29.92 in. Hg. (1013.2 mb) at sea level.

ISA values can be calculated for

various altitudes using a standard

lapse rate of approximately 2°C per

1,000 feet.

JET POWERED AIRPLANE—An

aircraft powered by a turbojet or

turbofan engine.

KINESTHESIA—The sensing of

movements by feel.

LATERAL AXIS—An imaginary

line passing through the center of

gravity of an airplane and extending

across the airplane from wingtip

to wingtip.

the coefficient of drag for any given

angle of attack.

LIFT-OFF—The act of becoming

airborne as a result of the wings

lifting the airplane off the ground, or

the pilot rotating the nose up,

increasing the angle of attack to start a

climb. 

LIMIT LOAD FACTOR—Amount

of stress, or load factor, that an aircraft

can withstand before structural

damage or failure occurs.

LOAD FACTOR—The ratio of the

load supported by the airplane’s wings

to the actual weight of the aircraft and

its contents. Also referred to as

G-loading.

LONGITUDINAL AXIS—

An imaginary line through an aircraft

from nose to tail, passing through its

center of gravity. The longitudinal

axis is also called the roll axis of the

aircraft. Movement of the ailerons

rotates an airplane about its

longitudinal axis.

LONGITUDINAL STABILITY

(PITCHING)—Stability about the

lateral axis. A desirable characteristic

of an airplane whereby it tends to

return to its trimmed angle of attack

after displacement.

MACH—Speed relative to the speed

of sound. Mach 1 is the speed of

sound.

MACH BUFFET—

Airflow separation behind a

shock-wave pressure barrier caused

by airflow over flight surfaces

exceeding the speed of sound.

MACH COMPENSATING

DEVICE—A device to alert the pilot

of inadvertent excursions beyond its

certified maximum operating speed.

MACH CRITICAL—The MACH

speed at which some portion of the

airflow over the wing first equals

MACH 1.0. This is also the speed at

which a shock wave first appears on

the airplane. 

LATERAL STABILITY

(ROLLING)—The stability about the

longitudinal axis of an aircraft.

Rolling stability or the ability of an

airplane to return to level flight due to

a disturbance that causes one of the

wings to drop.

LEAD-ACID BATTERY—

A commonly used secondary cell

having lead as its negative plate and

lead peroxide as its positive plate.

Sulfuric acid and water serve as the

electrolyte.

LEADING EDGE DEVICES—

High lift devices which are found on

the leading edge of the airfoil. The

most common types are fixed slots,

movable slats, and leading edge flaps.

LEADING EDGE—The part of an

airfoil that meets the airflow first.

LEADING EDGE FLAP—

A portion of the leading edge of an

airplane wing that folds downward to

increase the camber, lift, and drag of

the wing. The leading-edge flaps are

extended for takeoffs and landings to

increase the amount of aerodynamic

lift that is produced at any given

airspeed.

LICENSED EMPTY WEIGHT—

The empty weight that consists of the

airframe, engine(s), unusable fuel,

and undrainable oil plus standard and

optional equipment as specified in the

equipment list. Some manufacturers

used this term prior to GAMA

standardization.

LIFT—One of the four main forces

acting on an aircraft. On a fixed-wing

aircraft, an upward force created by

the effect of airflow as it passes over

and under the wing.

LIFT COEFFICIENT— A coefficient representing the lift of a given

airfoil. Lift coefficient is obtained by

dividing the lift by the free-stream

dynamic pressure and the representative area under consideration. 

LIFT/DRAG RATIO—

The efficiency of an airfoil section. It

is the ratio of the coefficient of lift to

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MACH TUCK—A condition that can

occur when operating a swept-wing

airplane in the transonic speed range.

A shock wave could form in the root

portion of the wing and cause the

air behind it to separate. This

shock-induced separation causes the

center of pressure to move aft. This,

combined with the increasing amount

of nose down force at higher speeds to

maintain left flight, causes the nose to

“tuck.” If not corrected, the airplane

could enter a steep, sometimes

unrecoverable dive. 

MAGNETIC COMPASS—A device

for determining direction measured

from magnetic north.

MAIN GEAR—The wheels of an

aircraft’s landing gear that supports

the major part of the aircraft’s weight.

MANEUVERABILITY—Ability of

an aircraft to change directions along

a flightpath and withstand the stresses

imposed upon it.

MANEUVERING SPEED (VA) —

The maximum speed where full,

abrupt control movement can be used

without overstressing the airframe.

MANIFOLD PRESSURE (MP)—

The absolute pressure of the fuel/air

mixture within the intake manifold,

usually indicated in inches of

mercury. 

MAXIMUM ALLOWABLE

TAKEOFF POWER—The maximum power an engine is allowed to

develop for a limited period of time;

usually about one minute.

MAXIMUM LANDING

WEIGHT—The greatest weight that

an airplane normally is allowed to

have at landing.

MAXIMUM RAMP WEIGHT—

The total weight of a loaded aircraft,

including all fuel. It is greater than the

takeoff weight due to the fuel that will

be burned during the taxi and runup

operations. Ramp weight may also be

referred to as taxi weight.

allows air to continue flowing over the

top of the wing and delays airflow

separation.

MUSHING—A flight condition

caused by slow speed where the

control surfaces are marginally

effective. 

N1, N2, N3—Spool speed expressed in

percent rpm. N1 on a turboprop is the

gas producer speed. N1 on a turbofan

or turbojet engine is the fan speed or

low pressure spool speed. N2 is the

high pressure spool speed on engine

with 2 spools and medium pressure

spool on engines with 3 spools with

N3 being the high pressure spool.

NACELLE—

A streamlined enclosure on an aircraft

in which an engine is mounted.

On multiengine propeller-driven

airplanes, the nacelle is normally

mounted on the leading edge of the

wing.

NEGATIVE STATIC 

STABILITY—The initial tendency

of an aircraft to continue away from

the original state of equilibrium after

being disturbed.

NEGATIVE TORQUE SENSING

(NTS)— A system in a turboprop

engine that prevents the engine from

being driven by the propeller. The

NTS increases the blade angle when

the propellers try to drive the engine. 

NEUTRAL STATIC

STABILITY—The initial tendency

of an aircraft to remain in a new

condition after its equilibrium has

been disturbed.

NICKEL-CADMIUM BATTERY

(NICAD)— A battery made up of

alkaline secondary cells. The positive

plates are nickel hydroxide, the

negative plates are cadmium

hydroxide, and potassium hydroxide

is used as the electrolyte.

NORMAL CATEGORY—

An airplane that has a seating

configuration, excluding pilot seats,

MAXIMUM TAKEOFF

WEIGHT—The maximum allowable

weight for takeoff.

MAXIMUM WEIGHT—

The maximum authorized weight of

the aircraft and all of its equipment as

specified in the Type Certificate Data

Sheets (TCDS) for the aircraft.

MAXIMUM ZERO FUEL

WEIGHT (GAMA)—The maximum

weight, exclusive of usable fuel.

MINIMUM CONTROLLABLE

AIRSPEED—An airspeed at which

any further increase in angle of attack,

increase in load factor, or reduction in

power, would result in an immediate

stall.

MINIMUM DRAG SPEED

(L/DMAX)—The point on the total

drag curve where the lift-to-drag ratio

is the greatest. At this speed, total drag

is minimized.

MIXTURE—The ratio of fuel to air

entering the engine’s cylinders.

MMO—Maximum operating speed

expressed in terms of a decimal of

mach speed.

MOMENT ARM—The distance

from a datum to the applied force.

MOMENT INDEX (OR INDEX)—

A moment divided by a constant such

as 100, 1,000, or 10,000. The purpose

of using a moment index is to simplify

weight and balance computations of

airplanes where heavy items and long

arms result in large, unmanageable

numbers.

MOMENT—The product of the

weight of an item multiplied by its

arm. Moments are expressed in

pound-inches (lb-in). Total moment is

the weight of the airplane multiplied

by the distance between the datum and

the CG.

MOVABLE SLAT—A movable

auxiliary airfoil on the leading edge of

a wing. It is closed in normal flight but

extends at high angles of attack. This

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of nine or less, a maximum

certificated takeoff weight of 12,500

pounds or less, and intended for

nonacrobatic operation.

NORMALIZING

(TURBONORMALIZING)—

A turbocharger that maintains sea

level pressure in the induction manifold at altitude.

OCTANE—The rating system of

aviation gasoline with regard to its

antidetonating qualities.

OVERBOOST—A condition in

which a reciprocating engine has

exceeded the maximum manifold

pressure allowed by the manufacturer.

Can cause damage to engine

components.

OVERSPEED—A condition in

which an engine has produced more

r.p.m. than the manufacturer

recommends, or a condition in which

the actual engine speed is higher than

the desired engine speed as set on the

propeller control. 

OVERTEMP—A condition in which

a device has reached a temperature

above that approved by the

manufacturer or any exhaust

temperature that exceeds the

maximum allowable for a given operating condition or time limit. Can

cause internal damage to an engine.

OVERTORQUE—A condition in

which an engine has produced more

torque (power) than the manufacturer

recommends, or a condition in a

turboprop or turboshaft engine where

the engine power has exceeded the

maximum allowable for a given

operating condition or time limit. Can

cause internal damage to an engine.

PARASITE DRAG—That part of

total drag created by the design or

shape of airplane parts. Parasite drag

increases with an increase in airspeed.

PAYLOAD (GAMA)—The weight

of occupants, cargo, and baggage.

P-FACTOR—A tendency for an

aircraft to yaw to the left due to the

for scheduling fuel flow to the

combustion chambers of a turbine

engine.

POWER—Implies work rate or units

of work per unit of time, and as such,

it is a function of the speed at which

the force is developed. The term

“power required” is generally

associated with reciprocating engines.

POWERPLANT—

A complete engine and propeller

combination with accessories.

PRACTICAL SLIP LIMIT—The

maximum slip an aircraft is capable of

performing due to rudder travel limits.

PRECESSION—The tilting or

turning of a gyro in response to

deflective forces causing slow drifting

and erroneous indications in

gyroscopic instruments.

PREIGNITION—Ignition occurring

in the cylinder before the time of

normal ignition. Preignition is often

caused by a local hot spot in the

combustion chamber igniting the

fuel/air mixture.

PRESSURE ALTITUDE—

The altitude indicated when the

altimeter setting window (barometric

scale) is adjusted to 29.92. This is the

altitude above the standard datum

plane, which is a theoretical plane

where air pressure (corrected to 15oC)

equals 29.92 in. Hg. Pressure altitude

is used to compute density altitude,

true altitude, true airspeed, and other

performance data.

PROFILE DRAG—The total of the

skin friction drag and form drag for a

two-dimensional airfoil section.

PROPELLER BLADE ANGLE—

The angle between the propeller chord

and the propeller plane of rotation.

PROPELLER LEVER—

The control on a free power turbine

turboprop that controls propeller

speed and the selection for propeller

feathering.

PROPELLER SLIPSTREAM—

The volume of air accelerated behind

a propeller producing thrust.

descending propeller blade on the

right producing more thrust than the

ascending blade on the left. This

occurs when the aircraft’s

longitudinal axis is in a climbing

attitude in relation to the relative

wind. The P-factor would be to the

right if the aircraft had a counterclockwise rotating propeller.

PILOT’S OPERATING

HANDBOOK (POH)—A document

developed by the airplane

manufacturer and contains the FAAapproved Airplane Flight Manual

(AFM) information.

PISTON ENGINE—A reciprocating

engine.

PITCH—The rotation of an airplane

about its lateral axis, or on a propeller,

the blade angle as measured from

plane of rotation. 

PIVOTAL ALTITUDE—A specific

altitude at which, when an airplane

turns at a given groundspeed, a projecting of the sighting reference line

to a selected point on the ground will

appear to pivot on that point.

PNEUMATIC SYSTEMS—

The power system in an aircraft used

for operating such items as landing

gear, brakes, and wing flaps with

compressed air as the operating fluid.

PORPOISING—

Oscillating around the lateral axis of

the aircraft during landing.

POSITION LIGHTS—Lights on an

aircraft consisting of a red light on the

left wing, a green light on the right

wing, and a white light on the tail.

CFRs require that these lights be

displayed in flight from sunset to

sunrise.

POSITIVE STATIC STABILITY—

The initial tendency to return to a state

of equilibrium when disturbed from

that state.

POWER DISTRIBUTION BUS—

See BUS BAR.

POWER LEVER—The cockpit

lever connected to the fuel control unit

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PROPELLER

SYNCHRONIZATION—

A condition in which all of

the propellers have their pitch

automatically adjusted to maintain a

constant r.p.m. among all of the

engines of a multiengine aircraft.

PROPELLER—A device for

propelling an aircraft that, when

rotated, produces by its action on

the air, a thrust approximately

perpendicular to its plane of rotation.

It includes the control components

normally supplied by its

manufacturer.

RAMP WEIGHT—The total weight

of the aircraft while on the ramp. It

differs from takeoff weight by the

weight of the fuel that will be

consumed in taxiing to the point of

takeoff.

RATE OF TURN—The rate in

degrees/second of a turn.

RECIPROCATING ENGINE—An

engine that converts the heat energy

from burning fuel into the

reciprocating movement of the pistons. This movement is converted into

a rotary motion by the connecting rods

and crankshaft.

REDUCTION GEAR—The gear

arrangement in an aircraft engine that

allows the engine to turn at a faster

speed than the propeller.

REGION OF REVERSE

COMMAND—Flight regime in

which flight at a higher airspeed

requires a lower power setting and a

lower airspeed requires a higher

power setting in order to maintain

altitude.

REGISTRATION

CERTIFICATE—A State and Federal certificate that documents

aircraft ownership.

RELATIVE WIND—The direction

of the airflow with respect to the wing.

If a wing moves forward horizontally,

the relative wind moves backward

horizontally. Relative wind is parallel

to and opposite the flightpath of

the airplane.

alignment guidance during takeoff

and landings. The centerline consists

of a line of uniformly spaced stripes

and gaps.

RUNWAY EDGE LIGHTS—

Runway edge lights are used to

outline the edges of runways during

periods of darkness or restricted

visibility conditions. These light

systems are classified according to the

intensity or brightness they are

capable of producing: they are the

High Intensity Runway Lights

(HIRL), Medium Intensity Runway

Lights (MIRL), and the Low Intensity

Runway Lights (LIRL). The HIRL

and MIRL systems have variable

intensity controls, whereas the LIRLs

normally have one intensity setting.

RUNWAY END IDENTIFIER

LIGHTS (REIL)—One component

of the runway lighting system. These

lights are installed at many airfields

to provide rapid and positive

identification of the approach end of a

particular runway.

RUNWAY INCURSION—

Any occurrence at an airport

involving an aircraft, vehicle, person,

or object on the ground that creates a

collision hazard or results in loss of

separation with an aircraft taking off,

intending to takeoff, landing, or

intending to land. 

RUNWAY THRESHOLD

MARKINGS—Runway threshold

markings come in two configurations. They either consist of eight

longitudinal stripes of uniform

dimensions disposed symmetrically

about the runway centerline, or the

number of stripes is related to the

runway width. A threshold marking

helps identify the beginning of the

runway that is available for landing.

In some instances, the landing

threshold may be displaced.

SAFETY (SQUAT) SWITCH—An

electrical switch mounted on one of

the landing gear struts. It is used to

sense when the weight of the aircraft

is on the wheels.

SCAN—A procedure used by the

pilot to visually identify all resources

of information in flight.

REVERSE THRUST—A condition

where jet thrust is directed forward

during landing to increase the rate of

deceleration.

REVERSING PROPELLER—

A propeller system with a pitch

change mechanism that includes full

reversing capability. When the pilot

moves the throttle controls to reverse,

the blade angle changes to a pitch

angle and produces a reverse thrust,

which slows the airplane down during

a landing.

ROLL—The motion of the aircraft

about the longitudinal axis. It is

controlled by the ailerons.

ROUNDOUT (FLARE)—

A pitch-up during landing approach to

reduce rate of descent and forward

speed prior to touchdown.

RUDDER—The movable primary

control surface mounted on the

trailing edge of the vertical fin of an

airplane. Movement of the rudder

rotates the airplane about its vertical

axis.

RUDDERVATOR—A pair of control

surfaces on the tail of an aircraft

arranged in the form of a V. These

surfaces, when moved together by the

control wheel, serve as elevators, and

when moved differentially by the

rudder pedals, serve as a rudder.

RUNWAY CENTERLINE

LIGHTS—Runway centerline lights

are installed on some precision

approach runways to facilitate landing

under adverse visibility conditions.

They are located along the runway

centerline and are spaced at 50-foot

intervals. When viewed from the

landing threshold, the runway

centerline lights are white until the

last 3,000 feet of the runway. The

white lights begin to alternate with red

for the next 2,000 feet, and for the last

1,000 feet of the runway, all centerline

lights are red.

RUNWAY CENTERLINE

MARKINGS—

The runway centerline identifies the

center of the runway and provides

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SEA LEVEL—A reference height

used to determine standard

atmospheric conditions and altitude

measurements.

SEGMENTED CIRCLE—A visual

ground based structure to provide

traffic pattern information.

SERVICE CEILING—

The maximum density altitude where

the best rate-of-climb airspeed will

produce a 100 feet-per-minute climb

at maximum weight while in a clean

configuration with maximum continuous power.

SERVO TAB—An auxiliary control

mounted on a primary control surface,

which automatically moves in the

direction opposite the primary control

to provide an aerodynamic assist in

the movement of the control.

SHAFT HORSE POWER (SHP)—

Turboshaft engines are rated in shaft

horsepower and calculated by use of

a dynamometer device. Shaft

horsepower is exhaust thrust

converted to a rotating shaft.

SHOCK WAVES—A compression

wave formed when a body moves

through the air at a speed greater than

the speed of sound.

SIDESLIP—A slip in which the

airplane’s longitudinal axis remains

parallel to the original flightpath, but the

airplane no longer flies straight ahead.

Instead, the horizontal component of

wing lift forces the airplane to move

sideways toward the low wing. 

SINGLE ENGINE ABSOLUTE

CEILING—The altitude that a twinengine airplane can no longer climb

with one engine inoperative.

SINGLE ENGINE SERVICE

CEILING—The altitude that a twinengine airplane can no longer climb at

a rate greater then 50 f.p.m. with one

engine inoperative.

SKID—A condition where the tail of

the airplane follows a path outside the

path of the nose during a turn.

SPLIT SHAFT

TURBINE ENGINE—See FREE

POWER TURBINE ENGINE.

SPOILERS—High-drag devices that

can be raised into the air flowing over

an airfoil, reducing lift and increasing

drag. Spoilers are used for roll control

on some aircraft. Deploying spoilers

on both wings at the same time allows

the aircraft to descend without gaining speed. Spoilers are also used to

shorten the ground roll after landing.

SPOOL—A shaft in a turbine engine

which drives one or more

compressors with the power derived

from one or more turbines.

STABILATOR—A single-piece horizontal tail surface on an airplane that

pivots around a central hinge point. A

stabilator serves the purposes of both

the horizontal stabilizer and

the elevator.

STABILITY—The inherent quality

of an airplane to correct for conditions

that may disturb its equilibrium, and

to return or to continue on the original

flightpath. It is primarily an airplane

design characteristic.

STABILIZED APPROACH—A

landing approach in which the pilot

establishes and maintains a constant

angle glidepath towards a predetermined point on the landing runway. It

is based on the pilot’s judgment of

certain visual cues, and depends on

the maintenance of a constant final

descent airspeed and configuration. 

STALL—A rapid decrease in lift

caused by the separation of airflow

from the wing’s surface brought on by

exceeding the critical angle of attack.

A stall can occur at any pitch attitude

or airspeed.

STALL STRIPS—A spoiler attached

to the inboard leading edge of some

wings to cause the center section of

the wing to stall before the tips. This

assures lateral control throughout the

stall.

SLIP—An intentional maneuver to

decrease airspeed or increase rate of

descent, and to compensate for a

crosswind on landing. A slip can also

be unintentional when the pilot fails

to maintain the aircraft in coordinated

flight. 

SPECIFIC FUEL

CONSUMPTION—

Number of pounds of fuel consumed

in 1 hour to produce 1 HP.

SPEED—The distance traveled in a

given time.

SPEED BRAKES—A control

system that extends from the airplane

structure into the airstream to

produce drag and slow the airplane.

SPEED INSTABILITY—

A condition in the region of reverse

command where a disturbance that

causes the airspeed to decrease causes

total drag to increase, which in turn,

causes the airspeed to decrease

further. 

SPEED SENSE—The ability to

sense instantly and react to any

reasonable variation of airspeed.

SPIN—An aggravated stall that

results in what is termed an “autorotation” wherein the airplane follows a

downward corkscrew path. As the airplane rotates around the vertical axis,

the rising wing is less stalled than the

descending wing creating a rolling,

yawing, and pitching motion. 

SPIRAL INSTABILITY—

A condition that exists when the static

directional stability of the airplane is

very strong as compared to the effect

of its dihedral in maintaining lateral

equilibrium.

SPIRALING SLIPSTREAM—The

slipstream of a propeller-driven

airplane rotates around the airplane.

This slipstream strikes the left side of

the vertical fin, causing the airplane to

yaw slightly. Vertical stabilizer offset

is sometimes used by aircraft designers to counteract this tendency.

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STANDARD ATMOSPHERE—

At sea level, the standard atmosphere

consists of a barometric pressure of

29.92 inches of mercury (in. Hg.) or

1013.2 millibars, and a temperature of

15°C (59°F). Pressure and temperature normally decrease as altitude

increases. The standard lapse rate in

the lower atmosphere for each 1,000

feet of altitude is approximately 1 in.

Hg. and 2°C (3.5°F). For example, the

standard pressure and temperature at

3,000 feet mean sea level (MSL) is

26.92 in. Hg. (29.92 - 3) and 9°C

(15°C - 6°C).

STANDARD DAY—

See STANDARD ATMOSPHERE.

STANDARD EMPTY WEIGHT

(GAMA)—This weight consists of

the airframe, engines, and all items of

operating equipment that have fixed

locations and are permanently

installed in the airplane; including

fixed ballast, hydraulic fluid, unusable

fuel, and full engine oil.

STANDARD WEIGHTS—These

have been established for numerous

items involved in weight and balance

computations. These weights should

not be used if actual weights are

available.

STANDARD-RATE TURN—A turn

at the rate of 3o per second which

enables the airplane to complete a

360o turn in 2 minutes.

STARTER/GENERATOR—

A combined unit used on turbine

engines. The device acts as a starter

for rotating the engine, and after

running, internal circuits are shifted to

convert the device into a generator. 

STATIC STABILITY—The initial

tendency an aircraft displays when

disturbed from a state of equilibrium.

STATION—A location in the

airplane that is identified by a number

designating its distance in inches from

the datum. The datum is, therefore,

identified as station zero. An item

located at station +50 would have an

arm of 50 inches.

TAXIWAY LIGHTS—

Omnidirectional lights that outline the

edges of the taxiway and are blue in

color. 

TAXIWAY TURNOFF LIGHTS—

Flush lights which emit a steady green

color.

TETRAHEDRON—

A large, triangular-shaped, kite-like

object installed near the runway.

Tetrahedrons are mounted on a pivot

and are free to swing with the wind to

show the pilot the direction of the

wind as an aid in takeoffs and

landings.

THROTTLE—The valve in a

carburetor or fuel control unit that

determines the amount of fuel-air

mixture that is fed to the engine.

THRUST LINE—An imaginary line

passing through the center of the

propeller hub, perpendicular to the

plane of the propeller rotation.

THRUST REVERSERS—Devices

which redirect the flow of jet exhaust

to reverse the direction of thrust.

THRUST—The force which imparts

a change in the velocity of a mass.

This force is measured in pounds but

has no element of time or rate. The

term, thrust required, is generally

associated with jet engines. A forward

force which propels the airplane

through the air.

TIMING—The application of

muscular coordination at the proper

instant to make flight, and all

maneuvers incident thereto, a constant

smooth process.

TIRE CORD—Woven metal wire

laminated into the tire to provide extra

strength. A tire showing any cord

must be replaced prior to any further

flight.

TORQUE METER—An indicator

used on some large reciprocating

engines or on turboprop engines to

indicate the amount of torque the

engine is producing.

STICK PULLER—A device that

applies aft pressure on the control

column when the airplane is approaching the maximum operating speed.

STICK PUSHER—A device that

applies an abrupt and large forward

force on the control column when the

airplane is nearing an angle of attack

where a stall could occur. 

STICK SHAKER—An artificial

stall warning device that vibrates the

control column.

STRESS RISERS—

A scratch, groove, rivet hole, forging

defect or other structural discontinuity

that causes a concentration of stress.

SUBSONIC—Speed below the speed

of sound.

SUPERCHARGER—An engine- or

exhaust-driven air compressor used to

provide additional pressure to the

induction air so the engine can

produce additional power.

SUPERSONIC—Speed above the

speed of sound.

SUPPLEMENTAL TYPE

CERTIFICATE (STC)—

A certificate authorizing an alteration

to an airframe, engine, or component

that has been granted an Approved

Type Certificate.

SWEPT WING—A wing planform

in which the tips of the wing are

farther back than the wing root.

TAILWHEEL AIRCRAFT—

SEE CONVENTIONAL LANDING

GEAR.

TAKEOFF ROLL

(GROUND ROLL)—The total

distance required for an aircraft to

become airborne.

TARGET REVERSER—A thrust

reverser in a jet engine in which

clamshell doors swivel from the

stowed position at the engine tailpipe

to block all of the outflow and redirect

some component of the thrust

forward.

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G-15

TORQUE SENSOR—

See TORQUE METER.

TORQUE—1. A resistance to turning

or twisting. 2. Forces that produce a

twisting or rotating motion. 3. In an

airplane, the tendency of the aircraft

to turn (roll) in the opposite direction

of rotation of the engine and propeller. 

TOTAL DRAG—The sum of the

parasite and induced drag.

TOUCHDOWN ZONE LIGHTS—

Two rows of transverse light bars

disposed symmetrically about the

runway centerline in the runway

touchdown zone.

TRACK—The actual path made over

the ground in flight.

TRAILING EDGE—The portion of

the airfoil where the airflow over the

upper surface rejoins the lower

surface airflow.

TRANSITION LINER—

The portion of the combustor that

directs the gases into the turbine

plenum.

TRANSONIC—At the speed of

sound.

TRANSPONDER—The airborne

portion of the secondary surveillance

radar system. The transponder emits a

reply when queried by a radar facility.

TRICYCLE GEAR—Landing gear

employing a third wheel located on

the nose of the aircraft.

TRIM TAB—A small auxiliary

hinged portion of a movable control

surface that can be adjusted during

flight to a position resulting in a

balance of control forces.

TRIPLE SPOOL ENGINE—

Usually a turbofan engine design

where the fan is the N1 compressor,

followed by the N2 intermediate

compressor, and the N3 high pressure

compressor, all of which rotate on

separate shafts at different speeds. 

TURBINE SECTION—The section

of the engine that converts high

pressure high temperature gas into

rotational energy.

TURBOCHARGER—

An air compressor driven by exhaust

gases, which increases the pressure of

the air going into the engine through

the carburetor or fuel injection

system.

TURBOFAN ENGINE—A turbojet

engine in which additional propulsive

thrust is gained by extending a portion

of the compressor or turbine blades

outside the inner engine case. The

extended blades propel bypass air

along the engine axis but between the

inner and outer casing. The air is not

combusted but does provide additional thrust. 

TURBOJET ENGINE—A jet

engine incorporating a turbine-driven

air compressor to take in and compress air for the combustion of fuel,

the gases of combustion being used

both to rotate the turbine and create a

thrust producing jet. 

TURBOPROP ENGINE—A turbine

engine that drives a propeller through

a reduction gearing arrangement.

Most of the energy in the exhaust

gases is converted into torque, rather

than its acceleration being used to

propel the aircraft.

TURBULENCE—An occurrence in

which a flow of fluid is unsteady.

TURN COORDINATOR—A rate

gyro that senses both roll and yaw due

to the gimbal being canted. Has

largely replaced the turn-and-slip

indicator in modern aircraft.

TURN-AND-SLIP INDICATOR—

A flight instrument consisting of a rate

gyro to indicate the rate of yaw and a

curved glass inclinometer to indicate

the relationship between gravity and

centrifugal force. The turn-and-slip

indicator indicates the relationship

between angle of bank and rate of

yaw. Also called a turn-and-bank

indicator.

TROPOPAUSE—The boundary

layer between the troposphere and the

mesosphere which acts as a lid to

confine most of the water vapor, and

the associated weather, to the

troposphere.

TROPOSPHERE—The layer of the

atmosphere extending from the

surface to a height of 20,000 to 60,000

feet depending on latitude.

TRUE AIRSPEED (TAS)—

Calibrated airspeed corrected for altitude and nonstandard temperature.

Because air density decreases with an

increase in altitude, an airplane has to

be flown faster at higher altitudes to

cause the same pressure difference

between pitot impact pressure and

static pressure. Therefore, for a given

calibrated airspeed, true airspeed

increases as altitude increases; or for a

given true airspeed, calibrated airspeed decreases as altitude increases.

TRUE ALTITUDE—The vertical

distance of the airplane above sea

level—the actual altitude. It is often

expressed as feet above mean sea

level (MSL). Airport, terrain, and

obstacle elevations on aeronautical

charts are true altitudes.

T-TAIL—An aircraft with the

horizontal stabilizer mounted on the

top of the vertical stabilizer, forming

a T.

TURBINE BLADES—The portion

of the turbine assembly that absorbs

the energy of the expanding gases and

converts it into rotational energy.

TURBINE OUTLET

TEMPERATURE (TOT)—

The temperature of the gases as they

exit the turbine section.

TURBINE PLENUM—The portion

of the combustor where the gases are

collected to be evenly distributed to

the turbine blades.

TURBINE ROTORS—The portion

of the turbine assembly that mounts to

the shaft and holds the turbine blades

in place.

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G-16

TURNING ERROR—One of the

errors inherent in a magnetic compass

caused by the dip compensating

weight. It shows up only on turns to or

from northerly headings in the

Northern Hemisphere and southerly

headings in the Southern Hemisphere.

Turning error causes the compass to

lead turns to the north or south and lag

turns away from the north or south.

ULTIMATE LOAD FACTOR—

In stress analysis, the load that causes

physical breakdown in an aircraft or

aircraft component during a strength

test, or the load that according to

computations, should cause such a

breakdown.

UNFEATHERING

ACCUMULATOR—Tanks that hold

oil under pressure which can be used

to unfeather a propeller.

UNICOM—

A nongovernment air/ground radio

communication station which may

provide airport information at public

use airports where there is no tower or

FSS.

UNUSABLE FUEL—Fuel that

cannot be consumed by the engine.

This fuel is considered part of the

empty weight of the aircraft.

USEFUL LOAD—The weight of the

pilot, copilot, passengers, baggage,

usable fuel, and drainable oil. It is the

basic empty weight subtracted from

the maximum allowable gross weight.

This term applies to general aviation

aircraft only.

UTILITY CATEGORY—

An airplane that has a seating

configuration, excluding pilot seats,

of nine or less, a maximum

certificated takeoff weight of 12,500

pounds or less, and intended for

limited acrobatic operation.

V-BARS—The flight director

displays on the attitude indicator that

provide control guidance to the pilot.

V-SPEEDS—Designated speeds for a

specific flight condition.

VFE—The maximum speed with the

flaps extended. The upper limit of the

white arc.

VFO—The maximum speed that the

flaps can be extended or retracted.

VFR TERMINAL AREA

CHARTS (1:250,000)—

Depict Class B airspace which

provides for the control or

segregation of all the aircraft within

the Class B airspace. The chart depicts

topographic information and

aeronautical information which

includes visual and radio aids

to navigation, airports, controlled

airspace, restricted areas, obstructions, and related data.

V-G DIAGRAM—A chart that

relates velocity to load factor. It is

valid only for a specific weight,

configuration, and altitude and shows

the maximum amount of positive or

negative lift the airplane is capable of

generating at a given speed. Also

shows the safe load factor limits and

the load factor that the aircraft can

sustain at various speeds.

VISUAL APPROACH SLOPE

INDICATOR (VASI)—

The most common visual glidepath

system in use. The VASI provides

obstruction clearance within 10° of

the extended runway centerline, and

to 4 nautical miles (NM) from the

runway threshold.

VISUAL FLIGHT

RULES (VFR)—

Code of Federal Regulations that govern the procedures for conducting

flight under visual conditions.

VLE—Landing gear extended speed.

The maximum speed at which an

airplane can be safely flown with the

landing gear extended.

VLOF—Lift-off speed. The speed at

which the aircraft departs the runway

during takeoff.

VLO—Landing gear operating speed.

The maximum speed for extending or

retracting the landing gear if using an

airplane equipped with retractable

landing gear.

VAPOR LOCK—A condition in

which air enters the fuel system and it

may be difficult, or impossible, to

restart the engine. Vapor lock may

occur as a result of running a fuel tank

completely dry, allowing air to enter

the fuel system. On fuel-injected

engines, the fuel may become so hot it

vaporizes in the fuel line, not allowing

fuel to reach the cylinders.

VA—The design maneuvering speed.

This is the “rough air” speed and the

maximum speed for abrupt

maneuvers. If during flight, rough air

or severe turbulence is encountered,

reduce the airspeed to maneuvering

speed or less to minimize stress on the

airplane structure. It is important to

consider weight when referencing this

speed. For example, VA may be 100

knots when an airplane is heavily

loaded, but only 90 knots when the

load is light.

VECTOR—A force vector is a

graphic representation of a force and

shows both the magnitude and

direction of the force.

VELOCITY—The speed or rate of

movement in a certain direction.

VERTICAL AXIS—An imaginary

line passing vertically through the

center of gravity of an aircraft. The

vertical axis is called the z-axis or the

yaw axis.

VERTICAL CARD COMPASS—

A magnetic compass that consists of

an azimuth on a vertical card,

resembling a heading indicator with a

fixed miniature airplane to accurately

present the heading of the aircraft.

The design uses eddy current

damping to minimize lead and lag

during turns.

VERTICAL

SPEED INDICATOR (VSI)—

An instrument that uses static pressure

to display a rate of climb or descent in

feet per minute. The VSI can also

sometimes be called a vertical

velocity indicator (VVI).

VERTICAL STABILITY—Stability

about an aircraft’s vertical axis. Also

called yawing or directional stability.

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G-17

VMC—Minimum control airspeed.

This is the minimum flight speed at

which a twin-engine airplane can be

satisfactorily controlled when an

engine suddenly becomes inoperative

and the remaining engine is at takeoff

power.

VMD—Minimum drag speed.

VMO—Maximum operating speed

expressed in knots.

VNE—Never-exceed speed. Operating

above this speed is prohibited since it

may result in damage or structural

failure. The red line on the airspeed

indicator.

VNO—Maximum structural cruising

speed. Do not exceed this speed

except in smooth air. The upper limit

of the green arc.

VP—Minimum dynamic hydroplaning speed. The minimum speed

required to start dynamic

hydroplaning.

VR—Rotation speed. The speed that

the pilot begins rotating the aircraft

prior to lift-off.

VS0—Stalling speed or the minimum

steady flight speed in the landing configuration. In small airplanes, this is

the power-off stall speed at the maximum landing weight in the landing

configuration (gear and flaps down).

The lower limit of the white arc.

VS1—Stalling speed or the minimum

steady flight speed obtained in a

specified configuration. For most

airplanes, this is the power-off stall

speed at the maximum takeoff weight

in the clean configuration (gear up, if

retractable, and flaps up). The lower

limit of the green arc.

VSSE—Safe, intentional one-engine

inoperative speed. The minimum

speed to intentionally render the

critical engine inoperative.

V-TAIL—A design which utilizes

two slanted tail surfaces to perform

equal to the mass of the body times

the local value of gravitational

acceleration. One of the four main

forces acting on an aircraft.

Equivalent to the actual weight of the

aircraft. It acts downward through the

aircraft’s center of gravity toward the

center of the Earth. Weight opposes

lift.

WEIGHT AND BALANCE—The

aircraft is said to be in weight and

balance when the gross weight of the

aircraft is under the max gross weight,

and the center of gravity is within

limits and will remain in limits for the

duration of the flight.

WHEELBARROWING—

A condition caused when forward

yoke or stick pressure during takeoff

or landing causes the aircraft to ride

on the nosewheel alone.

WIND CORRECTION ANGLE—

Correction applied to the course to

establish a heading so that track will

coincide with course.

WIND

DIRECTION INDICATORS—

Indicators that include a wind sock,

wind tee, or tetrahedron. Visual

reference will determine wind

direction and runway in use.

WIND SHEAR—A sudden, drastic

shift in windspeed, direction, or both

that may occur in the horizontal or

vertical plane.

WINDMILLING—When the air

moving through a propeller creates

the rotational energy.

WINDSOCK—A truncated cloth

cone open at both ends and mounted

on a freewheeling pivot that indicates

the direction from which the wind is

blowing.

WING—Airfoil attached to each side

of the fuselage and are the main

lifting surfaces that support the

airplane in flight.

the same functions as the surfaces of a

conventional elevator and rudder

configuration. The fixed surfaces act

as both horizontal and vertical

stabilizers.

VX—Best angle-of-climb speed. The

airspeed at which an airplane gains the

greatest amount of altitude in a given

distance. It is used during a short-field

takeoff to clear an obstacle.

VXSE—Best angle of climb speed with

one engine inoperative. The airspeed

at which an airplane gains the greatest

amount of altitude in a given distance

in a light, twin-engine airplane

following an engine failure.

VY—Best rate-of-climb speed. This

airspeed provides the most altitude

gain in a given period of time.

VYSE—Best rate-of-climb speed with

one engine inoperative. This airspeed

provides the most altitude gain in a

given period of time in a light, twinengine airplane following an engine

failure.

WAKE TURBULENCE—Wingtip

vortices that are created when an

airplane generates lift. When an

airplane generates lift, air spills over

the wingtips from the high pressure

areas below the wings to the low

pressure areas above them. This flow

causes rapidly rotating whirlpools of

air called wingtip vortices or wake

turbulence.

WASTE GATE—A controllable

valve in the tailpipe of an aircraft

reciprocating engine equipped with a

turbocharger. The valve is controlled

to vary the amount of exhaust gases

forced through the turbocharger

turbine.

WEATHERVANE—The tendency of

the aircraft to turn into the relative

wind. 

WEIGHT—A measure of the

heaviness of an object. The force by

which a body is attracted toward the

center of the Earth (or another

celestial body) by gravity. Weight is

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G-18

WING AREA—The total surface of

the wing (square feet), which includes

control surfaces and may include

wing area covered by the fuselage

(main body of the airplane), and

engine nacelles.

WING SPAN—

The maximum distance from wingtip

to wingtip.

WINGTIP VORTICES—

The rapidly rotating air that spills over

an airplane’s wings during flight. The

intensity of the turbulence depends on

the airplane’s weight, speed, and

configuration. It is also referred to as

ZERO FUEL WEIGHT—

The weight of the aircraft to include

all useful load except fuel.

ZERO SIDESLIP—A maneuver in a

twin-engine airplane with one engine

inoperative that involves a small

amount of bank and slightly

uncoordinated flight to align the

fuselage with the direction of travel

and minimize drag.

ZERO THRUST

(SIMULATED FEATHER)—

An engine configuration with a low

power setting that simulates a

propeller feathered condition. 

wake turbulence. Vortices from heavy

aircraft may be extremely hazardous

to small aircraft.

WING TWIST—A design feature

incorporated into some wings to

improve aileron control effectiveness

at high angles of attack during an

approach to a stall.

YAW—Rotation about the vertical

axis of an aircraft.

YAW STRING—A string on the nose

or windshield of an aircraft in view of

the pilot that indicates any slipping or

skidding of the aircraft.

Glossary.qxd 5/7/04 10:46 AM Page G-18
I-1

180° POWER-OFF APPROACH 8-23

360° POWER-OFF APPROACH 8-24

90° POWER-OFF APPROACH 8-21

A

ABSOLUTE CEILING 12-8

ACCELERATED STALL 4-9

ACCELERATE-GO DISTANCE 12-8

ACCELERATE-STOP DISTANCE 12-8

ACCURACY APPROACH 8-21

180° power-off 8-23

360° power-off 8-24

90° power-off 8-21

ADVERSE YAW 3-8

AFTER LANDING 2-11

crosswind tailwheel 13-5

roll 8-7

tailwheel 13-4

AIMING POINT 8-8

AIRCRAFT LOGBOOKS 2-1

AIRFOIL TYPES 11-1

AIRMANSHIP 1-1

skills 1-1

AIRPLANE EQUIPMENT, Night 10-3

AIRPLANE FEEL 3-2

AIRPLANE LIGHTING, Night 10-3

AIRPORT LIGHTING 10-4

AIRPORT TRAFFIC PATTERN 7-1

base leg 7-3

crosswind leg 7-4

departure leg 7-4

downwind leg 7-3

entry leg 7-3

final approach leg 7-3

upwind leg 7-3

AIRWORTHINESS DIRECTIVES 2-1

ALTERNATOR/GENERATOR 12-7

ALTITUDE TURBOCHARGING 11-7

ANTI-ICING 12-7

APPROACH AND LANDING 8-1

after-landing roll 8-7

base leg 8-1

crosswind 8-15

emergency 8-25

estimating height and movement 8-4

faulty 8-27

final approach 8-2

go-around 8-11

multiengine 12-14

night 10-6

normal 8-1

roundout (flare) 8-5

short-field 8-17

soft-field 8-19

stabilized approach 8-7

touchdown 8-6

turbulent air 8-17

use of flaps 8-3

ATTITUDE FLYING 3-2

AUTOPILOT 12-6

AXIAL FLOW 14-5

B

BACK SIDE OF THE POWER CURVE 8-19

BALLOONING 8-3, 8-30

BANK ATTITUDE 3-2

BASE LEG 7-3, 8-1

BEFORE TAKEOFF CHECK 2-11

BEST ANGLE OF CLIMB (VX) 3-13, 12-1

one engine inoperative (VXSE) 12-1

BEST GLIDE SPEED 3-16

BEST RATE OF CLIMB 3-13, 12-1

one engine inoperative (VYSE) 12-1

BETA RANGE 14-7

BLACK HOLE APPROACH 10-2

BOUNCING 8-30

BUS BAR 14-8

BUS TIE 14-9

BYPASS AIR 15-2

BYPASS RATIO 15-2

C

CASCADE REVERSER 15-14

CENTRIFUGAL COMPRESSOR

STAGE 14-5

CHANDELLE 9-4

CHECKLISTS, Use of, 1-6

CIRCUIT BREAKER 14-9

CLEAR OF RUNWAY 2-11

CLIMB GRADIENT 12-8

Index.qxd 5/7/04 10:52 AM Page I-1
I-2

CLIMBS 3-13

maximum performance 5-8

night 10-5

COCKPIT MANAGEMENT 2-7

COLLISION AVOIDANCE 1-4

COMBUSTION CHAMBER 14-1

COMBUSTION HEATER 12-6

COMPLEX AIRPLANE 11-1

COMPRESSION RATIO 15-1

COMPRESSOR 14-1

CONDITION LEVER 14-4

CONES 10-1

CONFINED AREA 16-4

CONSTANT-SPEED PROPELLER 11-4

blade angle control 11-5

governing range 11-5

operation 11-5

CONTROLLABLE-PITCH PROPELLER 11-3

CONVENTIONAL GEAR AIRPLANE 13-1

CORE AIRFLOW 15-2

CRAZING 2-2

CRITICAL ALTITUDE 11-7

CRITICAL MACH 15-7

CROSS-CONTROL STALL 4-10

CROSSWIND APPROACH

AND LANDING 8-13

CROSSWIND COMPONENT 5-6

CROSSWIND LEG 7-4

CROSSWIND TAKEOFF 5-5

CURRENT LIMITER 14-9

D

DEICING 12-7

DEPARTURE LEG 7-4

DESCENTS 3-15

minimum safe airspeed 3-16

partial power 3-16

DITCHING 16-1

DOWNWASH 8-3

DOWNWIND LEG 7-3

DRAG DEVICES 15-13

DRIFT 6-2

DUCTED FAN 15-2

E

EGT 11-8

EIGHTS ACROSS A ROAD 6-11

EIGHTS ALONG A ROAD 6-9

EIGHTS AROUND PYLONS 6-11

EIGHTS-ON-PYLONS 6-12

ELEMENTARY EIGHTS 6-9

ELEVATOR TRIM STALL 4-11

ELT 2-1

EMERGENCIES

abnormal instrument indications 16-11

door open in flight 16-12

electrical system 16-10

engine failure 16-5

fires 16-7

flap failure 16-8

landing gear malfunction 16-9

loss of elevator control 16-9

night 10-8

pitot-static system 16-11

VFR flight into IMC 16-12

EMERGENCY APPROACH

AND LANDING 8-25

EMERGENCY DESCENTS 16-6

EMERGENCY GEAR

EXTENSION SYSTEM 11-10

EMERGENCY LANDINGS 16-1

airplane configuration 16-3

psychological hazards 16-1

safety concepts 16-2

terrain selection 16-3

terrain types 16-4

EMERGENCY LOCATOR

TRANSMITTER 2-1

ENGINE FAILURE AFTER TAKEOFF 16-5

ENGINE FAILURE, MULTIENGINE

approach and landing 12-22

during flight 12-21

flight principles 12-23

takeoff 12-18

ENGINE SHUTDOWN 2-12

ENGINE STARTING 2-7

ENTRY LEG 7-3

EXHAUST GAS TEMPERATURE 11-8

EXHAUST MANIFOLD 11-7

EXHAUST SECTION 14-1

F

FALSE START 14-10

FAULTY APPROACHES 8-27

ballooning 8-30

floating 8-29

high final 8-27

high roundout 8-28

low final 8-27

slow final 8-28

FEATHERING 12-3

FEDERAL AVIATION ADMINISTRATION (FAA) 1-1

FEEL OF THE AIRPLANE 3-2

FINAL APPROACH 8-2

FINAL APPROACH LEG 7-3

FIRES

cabin 16-8

electrical 16-7

engine 16-7

Index.qxd 5/7/04 10:52 AM Page I-2
I-3

FIXED SHAFT ENGINE 14-3

FLAP EXTENSION SPEED (VFE) 12-15

FLAPS 11-1

effectiveness 11-2

function 11-1

operational procedures 11-2

use of 8-3

FLARE 8-5

FLIGHT CONTROLS 3-1

FLIGHT DIRECTOR 12-6

FLIGHT IDLE 14-7

FLIGHT INSTRUCTOR, ROLE OF 1-3

FLIGHT SAFETY 1-4

FLIGHT STANDARDS DISTRICT

OFFICE (FSDO) 1-2

FLIGHT TRAINING SCHOOLS 1-3

FLOATING 8-29

FORCED LANDING 16-1

FORWARD SLIP 8-10

FOUR FUNDAMENTALS 3-1

FREE TURBINE ENGINE 14-5

FUEL CONTROL UNIT 14-6

FUEL CONTROLLER 14-1

FUEL CROSSFEED 12-5

FUEL HEATER 15-3

G

GAS GENERATOR 15-2

GAS TURBINE ENGINE 14-1

GLIDE 3-16

GLIDE RATIO 3-16

GO-AROUND (REJECTED LANDING) 8-11, 12-17

GOVERNING RANGE 11-5

GROUND BOOSTING 11-7

GROUND EFFECT 5-7, 8-13

GROUND INSPECTION 2-1

GROUND LOOP 8-33, 13-6

GROUND OPERATIONS 2-7

GROUND REFERENCE MANEUVERS 6-1

drift and ground track control 6-2

eights across a road 6-11

eights along a road 6-9

eights around pylons 6-11

eights-on-pylons (pylon eights) 6-12

rectangular course 6-4

s-turns across a road 6-6

turns around a point 6-7

GROUND ROLL 5-1

GROUND TRACK CONTROL 6-2

GROUNDSPEED 6-3

HAND PROPPING 2-8

HAND SIGNALS 2-7

HIGH PERFORMANCE AIRPLANE 11-1

HOT START 14-10

HUNG START 14-10

HYDROPLANING 8-34

I

ILLUSIONS 10-2

INITIAL CLIMB 5-1

INTAKE MANIFOLD 11-7

INTEGRATED FLIGHT INSTRUCTION 3-3

INTENTIONAL SPIN 4-15

INVERTER 14-8

JET AIRPLANE 15-1

approach and landing 15-19

low speed flight 15-10

pilot sensations 15-15

rotation and lift-off 15-18

stalls 15-10

takeoff and climb 15-16

touchdown and rollout 15-24

J

JET ENGINE 15-1

efficiency 15-5

fuel heater 15-3

ignition 15-3

operating 15-2

K

KINESTHESIA 3-2

L

L/DMAX 3-16

LANDING GEAR

controls 11-10

electrical 11-9

electrohydraulic 11-9

emergency extension 11-10

hydraulic 11-9

malfunction 16-9

operational procedures 11-12

position indicators 11-10

retractable 11-9 

safety devices 11-10

tailwheel 13-1

LATERAL AXIS 3-2

LAZY EIGHT 9-6

LEVEL FLIGHT 3-4

LIFT-OFF 5-1

LIFT-OFF SPEED (VLOF) 12-1

Index.qxd 5/7/04 10:52 AM Page I-3
I-4

LONGITUDINAL AXIS 3-2

LOSS OF DIRECTIONAL

CONTROL DEMONSTRATION 12-27

M

MACH 15-7

MACH BUFFET BOUNDARIES 15-8

MACH TUCK 15-7

MANEUVERING SPEED 9-1

MAXIMUM OPERATING SPEED 15-6

MAXIMUM PERFORMANCE

CLIMB 5-8

MAXIMUM SAFE

CROSSWIND VELOCITIES 8-16

MINIMUM CONTROL SPEED (VMC) 12-2

MINIMUM CONTROLLABLE

AIRSPEED 4-1

MINIMUM DRAG SPEED 4-2

MULTIENGINE AIRPLANE 12-1

approach and landing 12-14

crosswind approach and landing 12-16

engine failure during flight 12-21

engine failure on takeoff 12-18

fuel crossfeed 12-5

go-around 12-17

ground operation 12-12

level off and cruise 12-14

one engine inoperative approach and 

landing 12-22

propeller 12-3

propeller synchronization 12-5

rejected takeoff 12-18

short-field operations 12-16

slow flight 12-25

stalls 12-25 

takeoff and climb 12-12

weight and balance 12-10

MUSHING 3-2

N

NIGHT OPERATIONS

airplane equipment 10-3

airplane lighting 10-3

airport and navigation lighting aids 10-4

approach and landing 10-6

emergencies 10-8

illusions 10-2

orientation and navigation 10-6

pilot equipment 10-3

preparation and preflight 10-4

start, taxi, and runup 10-5

takeoff and climb 10-5

NIGHT VISION 10-1

NOISE ABATEMENT 5-11

NORMAL TAKEOFF 5-2

NOSE BAGGAGE COMPARTMENT 12-7

O

ONE-ENGINE-INOPERATIVE SPEED (VSSE) 12-1

OVERBANKING TENDENCY 3-9

OVERBOOST CONDITION 11-9

OVERSPEED 15-8

P

PARALLAX ERROR 3-11

PARKING 2-11

PILOT EQUIPMENT, Night 10-3

PILOT EXAMINER, Role of 1-2

PITCH AND POWER 3-19

PITCH ATTITUDE 3-2

PIVOTAL ALTITUDE 6-14

PORPOISING 8-31

POSITION LIGHTS 10-3

POSITIVE TRANSFER OF CONTROLS 1-6

POSTFLIGHT 2-12

POWER CURVE 8-19

POWER LEVER 14-4

PRACTICAL SLIP LIMIT 8-11

PRACTICAL TEST STANDARDS (PTS) 1-4

PRECAUTIONARY LANDING 16-1

PREFLIGHT INSPECTION 2-2

PRESSURE CONTROLLER 11-7

PROPELLER 11-3, 12-3

PROPELLER BLADE ANGLE 11-4

control 11-5

PROPELLER CONTROL 11-4

PROPELLER SYNCHRONIZATION 12-5

PSYCHOLOGICAL HAZARDS 16-1

PYLON EIGHTS 6-12

R

RADIUS OF TURN 3-10

RECTANGULAR COURSE 6-4

REGION OF REVERSE COMMAND 8-19

REJECTED LANDING 8-11

REJECTED TAKEOFF 5-11, 12-18

RETRACTABLE LANDING GEAR 11-9

approach and landing 11-13

controls 11-10

electrical 11-9

electrohydraulic 11-9

emergency extension 11-10

hydraulic 11-9

Index.qxd 5/7/04 10:52 AM Page I-4
I-5

operational procedures 11-12

position indicators 11-10

safety devices 11-10

takeoff and climb 11-13

transition training 11-14

REVERSE THRUST 14-7

RODS 10-1

ROTATING BEACON 10-4

ROTATION 5-1

ROTATION SPEED (VR) 12-1

ROUGH-FIELD TAKEOFF 5-10

ROUNDOUT 8-5

ballooning 8-3

floating 8-29

high 8-28

late or rapid 8-29

RUNWAY INCURSION 1-5

RUNWAY LIGHTS 10-4

S

SAFETY CONCEPTS 16-2

SECONDARY STALL 4-9

SECURING 2-12

SEGMENTED CIRCLE 7-3

SERVICE CEILING 12-8

SERVICING 2-12

SHORT-FIELD

approach and landing 8-17

tailwheel 13-3

takeoff 5-8

SIDESLIP 5-6, 8-10

SINK RATE 16-3

SKID 3-8

SLIP 3-8, 8-10

SLOW FLIGHT 4-1, 12-25

SOFT FIELD

approach and landing 8-19

tailwheel 13-4

takeoff 5-10

SPEED BRAKE 15-13

SPEED INSTABILITY 4-2

SPIN AWARENESS 12-26

SPINS 4-12

developed phase 4-14

entry phase 4-13

incipient phase 4-13

intentional 4-15

procedures 4-13

recovery phase 4-14

weight and balance requirements 4-16

SPLIT SHAFT ENGINE 14-5

SPOILERS 15-13

SQUAT SWITCH 11-10

STABILIZED APPROACH 8-7, 15-21

STALL AWARENESS 1-6

STALLS 4-3

accelerated 4-9

characteristics 4-6

cross-control 4-10

elevator trim 4-11

imminent 4-6

jet airplane 15-10

multiengine 12-25

power-off 4-7

power-on 4-8

recognition 4-3

recovery 4-4

secondary 4-9

use of ailerons/rudders 4-5

STEEP SPIRAL 9-3

STEEP TURNS 9-1

STRAIGHT FLIGHT 3-5

STRAIGHT-AND-LEVEL FLIGHT 3-4

S-TURNS ACROSS A ROAD 6-6

T

TAILWHEEL AIRPLANES 13-1

crosswind landing 13-5

crosswind takeoff 13-3

short-field landing 13-6

short-field takeoff 13-3

soft-field landing 13-6

soft-field takeoff 13-4

takeoff 13-3

takeoff roll 13-2

taxiing 13-1

touchdown 13-4

wheel landing 13-6

TAKEOFF

crosswind 5-5

ground effect 5-7

multiengine 12-2

night 10-5

normal 5-2

rejected 5-11

roll 5-1

short field 5-8

soft/rough field 5-10

tailwheel 13-3

tailwheel crosswind 13-3

tailwheel short-field 13-3

tailwheel soft-field 13-4

TARGET REVERSER 15-14

TAXIING 2-9

tailwheel 13-1

THRUST LEVER 15-4

THRUST REVERSERS 15-14

TOUCHDOWN 8-6

bounce 8-30

crab 8-32

drift 8-32

Index.qxd 5/7/04 10:52 AM Page I-5
I-6

ground loop 8-33

hard landing 8-32

porpoise 8-31

tailwheel 13-4

wheelbarrowing 8-32

wing rise 8-33

TRACK 6-2

TRAFFIC PATTERN INDICATOR 7-3

TRANSITION TRAINING

complex airplane 11-14

high performance airplane 11-14

jet powered airplanes 15-1

multiengine airplane 12-31

tailwheel airplanes 13-1

turbopropeller powered airplanes 14-12

TRANSONIC FLOW 15-7

TRIM CONTROL 3-6

TURBINE INLET TEMPERATURE 11-8

TURBINE SECTION 14-1

TURBOCHARGER 11-7

failure 11-9

heat management 11-8

operating characteristics 11-8

TURBOFAN ENGINE 15-2

TURBOPROP AIRPLANE 14-1

electrical system 14-8

operational considerations 14-10

TURBOPROP ENGINES 14-2

TURBULENT AIR APPROACH

AND LANDING 8-17

TURNS 3-7

climbing 3-15

coordinated 3-9

gliding 3-18

level 3-7

medium 3-7

shallow 3-7

steep 3-8

TURNS AROUND A POINT 6-7

U

UPWIND LEG 7-3

V

VFR FLIGHT INTO

IMC CONDITIONS 16-12

VISUAL GROUND INSPECTION 2-1

V-SPEEDS 12-1, 15-16, 15-19

W 

WASTE GATE 11-7

WEATHERVANE 5-5

WEIGHT AND BALANCE 12-10

WHEEL LANDING 13-6

WHEELBARROWING 5-9, 8-17, 8-32

WINDSOCK 7-3

WINGTIP WASHOUT 4-5

Y

YAW 3-2

YAW DAMPER 12-6

Index.qxd 5/7/04 10:52 AM Page I-6