NIGHT VISION

Generally, most pilots are poorly informed about night

vision. Human eyes never function as effectively at

night as the eyes of animals with nocturnal habits, but

if humans learn how to use their eyes correctly and

know their limitations, night vision can be improved

significantly. There are several reasons for training to

use the eyes correctly.

One reason is the mind and eyes act as a team for a person to see well; both team members must be used

effectively. The construction of the eyes is such that to

see at night they are used differently than during the

day. Therefore, it is important to understand the eye’s

construction and how the eye is affected by darkness.

Innumerable light-sensitive nerves, called “cones” and

“rods,” are located at the back of the eye or retina, a

layer upon which all images are focused. These nerves

connect to the cells of the optic nerve, which transmits

messages directly to the brain. The cones are located in

the center of the retina, and the rods are concentrated

in a ring around the cones. [Figure 10-1]

The function of the cones is to detect color, details, and

faraway objects. The rods function when something is

seen out of the corner of the eye or peripheral vision.

They detect objects, particularly those that are moving,

but do not give detail or color—only shades of gray.

Both the cones and the rods are used for vision during

daylight.

Although there is not a clear-cut division of function,

the rods make night vision possible. The rods and

cones function in daylight and in moonlight, but in the

absence of normal light, the process of night vision is

placed almost entirely on the rods.

The fact that the rods are distributed in a band around

the cones and do not lie directly behind the pupils

makes off-center viewing (looking to one side of an

object) important during night flight. During daylight,

an object can be seen best by looking directly at it, but

at night a scanning procedure to permit off-center

viewing of the object is more effective. Therefore, the

pilot should consciously practice this scanning procedure to improve night vision.

The eye’s adaptation to darkness is another important

aspect of night vision. When a dark room is entered, it

is difficult to see anything until the eyes become

adjusted to the darkness. Most everyone has experienced this after entering a darkened movie theater. In

this process, the pupils of the eyes first enlarge to

receive as much of the available light as possible. After

approximately 5 to 10 minutes, the cones become

adjusted to the dim light and the eyes become 100

Cones for:

• Color

• Detail

• Day

Rods for:

• Gray

• Peripheral

• Day & Night

Area of Best

Day Vision

Area of Best

Night Vision

Area of Best

Night Vision

Figure 10-1. Rods and cones.

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times more sensitive to the light than they were before

the dark room was entered. Much more time, about 30

minutes, is needed for the rods to become adjusted to

darkness, but when they do adjust, they are about

100,000 times more sensitive to light than they were in

the lighted area. After the adaptation process is complete, much more can be seen, especially if the eyes are

used correctly.

After the eyes have adapted to the dark, the entire

process is reversed when entering a lighted room. The

eyes are first dazzled by the brightness, but become

completely adjusted in a very few seconds, thereby losing their adaptation to the dark. Now, if the dark room

is reentered, the eyes again go through the long process

of adapting to the darkness.

The pilot before and during night flight must consider

the adaptation process of the eyes. First, the eyes

should be allowed to adapt to the low level of light

and then they should be kept adapted. After the eyes

have become adapted to the darkness, the pilot should

avoid exposing them to any bright white light that

will cause temporary blindness and could result in

serious consequences.

Temporary blindness, caused by an unusually bright

light, may result in illusions or after images until the

eyes recover from the brightness. The brain creates

these illusions reported by the eyes. This results in

misjudging or incorrectly identifying objects, such as

mistaking slanted clouds for the horizon or populated

areas for a landing field. Vertigo is experienced as a

feeling of dizziness and imbalance that can create or

increase illusions. The illusions seem very real and

pilots at every level of experience and skill can be

affected. Recognizing that the brain and eyes can play

tricks in this manner is the best protection for flying at

night.

Good eyesight depends upon physical condition.

Fatigue, colds, vitamin deficiency, alcohol, stimulants,

smoking, or medication can seriously impair vision.

Keeping these facts in mind and taking adequate precautions should safeguard night vision.

In addition to the principles previously discussed, the

following items will aid in increasing night vision

effectiveness.

• Adapt the eyes to darkness prior to flight and

keep them adapted. About 30 minutes is needed

to adjust the eyes to maximum efficiency after

exposure to a bright light.

• If oxygen is available, use it during night flying.

Keep in mind that a significant deterioration in

night vision can occur at cabin altitudes as low as

5,000 feet.

• Close one eye when exposed to bright light to

help avoid the blinding effect.

• Do not wear sunglasses after sunset.

• Move the eyes more slowly than in daylight.

• Blink the eyes if they become blurred.

• Concentrate on seeing objects.

• Force the eyes to view off center.

• Maintain good physical condition.

• Avoid smoking, drinking, and using drugs that

may be harmful.

NIGHT ILLUSIONS

In addition to night vision limitations, pilots should be

aware that night illusions could cause confusion and

concerns during night flying. The following discussion covers some of the common situations that cause

illusions associated with night flying.

On a clear night, distant stationary lights can be mistaken for stars or other aircraft. Even the northern

lights can confuse a pilot and indicate a false horizon.

Certain geometrical patterns of ground lights, such as

a freeway, runway, approach, or even lights on a moving train can cause confusion. Dark nights tend to

eliminate reference to a visual horizon. As a result,

pilots need to rely less on outside references at night

and more on flight and navigation instruments.

Visual autokinesis can occur when a pilot stares at a

single light source for several seconds on a dark night.

The result is that the light will appear to be moving.

The autokinesis effect will not occur if the pilot

expands the visual field. It is a good procedure not to

become fixed on one source of light.

Distractions and problems can result from a flickering

light in the cockpit, anticollision light, strobe lights,

or other aircraft lights and can cause flicker vertigo. If

continuous, the possible physical reactions can be

nausea, dizziness, grogginess, unconsciousness,

headaches, or confusion. The pilot should try to eliminate any light source causing blinking or flickering

problems in the cockpit.

A black-hole approach occurs when the landing is

made from over water or non-lighted terrain where the

runway lights are the only source of light. Without

peripheral visual cues to help, pilots will have trouble

orientating themselves relative to Earth. The runway

can seem out of position (downsloping or upsloping)

and in the worse case, results in landing short of the

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runway. If an electronic glide slope or visual approach

slope indicator (VASI) is available, it should be used.

If navigation aids (NAVAIDs) are unavailable, careful

attention should be given to using the flight instruments to assist in maintaining orientation and a normal

approach. If at any time the pilot is unsure of his or her

position or attitude, a go-around should be executed.

Bright runway and approach lighting systems, especially where few lights illuminate the surrounding

terrain, may create the illusion of less distance to the

runway. In this situation, the tendency is to fly a

higher approach. Also, when flying over terrain with

only a few lights, it will make the runway recede or

appear farther away. With this situation, the tendency

is common to fly a lower-than-normal approach. If

the runway has a city in the distance on higher terrain, the tendency will be to fly a lower-than-normal

approach. A good review of the airfield layout and

boundaries before initiating any approach will help

the pilot maintain a safe approach angle.

Illusions created by runway lights result in a variety of

problems. Bright lights or bold colors advance the runway, making it appear closer.

Night landings are further complicated by the difficulty

of judging distance and the possibility of confusing

approach and runway lights. For example, when a double row of approach lights joins the boundary lights of

the runway, there can be confusion where the approach

lights terminate and runway lights begin. Under certain

conditions, approach lights can make the aircraft seem

higher in a turn to final, than when its wings are level.

PILOT EQUIPMENT

Before beginning a night flight, carefully consider

personal equipment that should be readily available

during the flight. At least one reliable flashlight is

recommended as standard equipment on all night

flights. Remember to place a spare set of batteries in

the flight kit. A D-cell size flashlight with a bulb

switching mechanism that can be used to select white

or red light is preferable. The white light is used while

performing the preflight visual inspection of the airplane,

and the red light is used when performing cockpit operations. Since the red light is nonglaring, it will not impair

night vision. Some pilots prefer two flashlights, one

with a white light for preflight, and the other a penlight type with a red light. The latter can be suspended

by a string from around the neck to ensure the light is

always readily available. One word of caution; if a red

light is used for reading an aeronautical chart, the red

features of the chart will not show up.

Aeronautical charts are essential for night cross-country flight and, if the intended course is near the edge of

the chart, the adjacent chart should also be available.

The lights of cities and towns can be seen at surprising

distances at night, and if this adjacent chart is not available to identify those landmarks, confusion could

result. Regardless of the equipment used, organization

of the cockpit eases the burden on the pilot and

enhances safety.

AIRPLANE EQUIPMENT 

AND LIGHTING

Title 14 of the Code of Federal Regulations (14 CFR)

part 91 specifies the basic minimum airplane equipment required for night flight. This equipment includes

only basic instruments, lights, electrical energy source,

and spare fuses.

The standard instruments required for instrument

flight under 14 CFR part 91 are a valuable asset for

aircraft control at night. An anticollision light system,

including a flashing or rotating beacon and position

lights, is required airplane equipment. Airplane position lights are arranged similar to those of boats and

ships. A red light is positioned on the left wingtip, a

green light on the right wingtip, and a white light on

the tail. [Figure 10-2]

Figure 10-2. Position lights.

This arrangement provides a means by which pilots

can determine the general direction of movement of

other airplanes in flight. If both a red and green light of

another aircraft were observed, the airplane would be

flying toward the pilot, and could be on a collision

course.

Landing lights are not only useful for taxi, takeoffs,

and landings, but also provide a means by which airplanes can be seen at night by other pilots. The Federal

Aviation Administration (FAA) has initiated a voluntary pilot safety program called “Operation Lights

ON.” The “lights on” idea is to enhance the “see and

be seen” concept of averting collisions both in the air

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and on the ground, and to reduce the potential for bird

strikes. Pilots are encouraged to turn on their landing

lights when operating within 10 miles of an airport.

This is for both day and night, or in conditions of

reduced visibility. This should also be done in areas

where flocks of birds may be expected.

Although turning on aircraft lights supports the see and

be seen concept, pilots should not become complacent

about keeping a sharp lookout for other aircraft. Most

aircraft lights blend in with the stars or the lights of the

cities at night and go unnoticed unless a conscious

effort is made to distinguish them from other lights.

AIRPORT AND NAVIGATION 

LIGHTING AIDS

The lighting systems used for airports, runways,

obstructions, and other visual aids at night are other

important aspects of night flying.

Lighted airports located away from congested areas

can be identified readily at night by the lights outlining

the runways. Airports located near or within large

cities are often difficult to identify in the maze of

lights. It is important not to only know the exact location of an airport relative to the city, but also to be able

to identify these airports by the characteristics of their

lighting pattern.

Aeronautical lights are designed and installed in a variety of colors and configurations, each having its own

purpose. Although some lights are used only during

low ceiling and visibility conditions, this discussion

includes only the lights that are fundamental to visual

flight rules (VFR) night operation.

It is recommended that prior to a night flight, and

particularly a cross-country night flight, the pilot check

the availability and status of lighting systems at the

destination airport. This information can be found on

aeronautical charts and in the Airport/Facility

Directory. The status of each facility can be determined by reviewing pertinent Notices to Airmen

(NOTAMs).

A rotating beacon is used to indicate the location of

most airports. The beacon rotates at a constant speed,

thus producing what appears to be a series of light

flashes at regular intervals. These flashes may be one

or two different colors that are used to identify various

types of landing areas. For example:

• Lighted civilian land airports—alternating white

and green.

• Lighted civilian water airports—alternating

white and yellow.

• Lighted military airports—alternating white and

green, but are differentiated from civil airports

by dual peaked (two quick) white flashes, then

green.

Beacons producing red flashes indicate obstructions or

areas considered hazardous to aerial navigation.

Steady burning red lights are used to mark obstructions on or near airports and sometimes to supplement

flashing lights on en route obstructions. High intensity

flashing white lights are used to mark some supporting

structures of overhead transmission lines that stretch

across rivers, chasms, and gorges. These high intensity

lights are also used to identify tall structures, such as

chimneys and towers.

As a result of the technological advancements in

aviation, runway lighting systems have become

quite sophisticated to accommodate takeoffs and

landings in various weather conditions. However,

the pilot whose flying is limited to VFR only needs

to be concerned with the following basic lighting of

runways and taxiways.

The basic runway lighting system consists of two

straight parallel lines of runway-edge lights defining the lateral limits of the runway. These lights are

aviation white, although aviation yellow may be

substituted for a distance of 2,000 feet from the far

end of the runway to indicate a caution zone. At

some airports, the intensity of the runway-edge

lights can be adjusted to satisfy the individual needs

of the pilot. The length limits of the runway are

defined by straight lines of lights across the runway

ends. At some airports, the runway threshold lights

are aviation green, and the runway end lights are

aviation red.

At many airports, the taxiways are also lighted. A taxiway-edge lighting system consists of blue lights that

outline the usable limits of taxi paths.

PREPARATION AND PREFLIGHT

Night flying requires that pilots be aware of, and operate within, their abilities and limitations. Although

careful planning of any flight is essential, night flying

demands more attention to the details of preflight

preparation and planning.

Preparation for a night flight should include a thorough

review of the available weather reports and forecasts

with particular attention given to temperature/dewpoint

spread. A narrow temperature/dewpoint spread may

indicate the possibility of ground fog. Emphasis

should also be placed on wind direction and speed,

since its effect on the airplane cannot be as easily

detected at night as during the day.

On night cross-country flights, appropriate aeronautical charts should be selected, including the

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appropriate adjacent charts. Course lines should be

drawn in black to be more distinguishable.

Prominently lighted checkpoints along the prepared

course should be noted. Rotating beacons at airports,

lighted obstructions, lights of cities or towns, and

lights from major highway traffic all provide excellent

visual checkpoints. The use of radio navigation aids

and communication facilities add significantly to the

safety and efficiency of night flying.

All personal equipment should be checked prior to

flight to ensure proper functioning. It is very disconcerting to find, at the time of need, that a flashlight, for

example, does not work.

All airplane lights should be turned ON momentarily

and checked for operation. Position lights can be

checked for loose connections by tapping the light fixture. If the lights blink while being tapped, further

investigation to determine the cause should be made

prior to flight.

The parking ramp should be examined prior to entering the airplane. During the day, it is quite easy to see

stepladders, chuckholes, wheel chocks, and other

obstructions, but at night it is more difficult. A check

of the area can prevent taxiing mishaps.

STARTING,TAXIING, AND RUNUP

After the pilot is seated in the cockpit and prior to starting the engine, all items and materials to be used on the

flight should be arranged in such a manner that they

will be readily available and convenient to use.

Extra caution should be taken at night to assure the

propeller area is clear. Turning the rotating beacon ON,

or flashing the airplane position lights will serve to

alert persons nearby to remain clear of the propeller.

To avoid excessive drain of electrical current from the

battery, it is recommended that unnecessary electrical

equipment be turned OFF until after the engine has

been started.

After starting and before taxiing, the taxi or landing

light should be turned ON. Continuous use of the landing light with r.p.m. power settings normally used for

taxiing may place an excessive drain on the airplane’s

electrical system. Also, overheating of the landing light

could become a problem because of inadequate airflow

to carry the heat away. Landing lights should be used

as necessary while taxiing. When using landing lights,

consideration should be given to not blinding other

pilots. Taxi slowly, particularly in congested areas. If

taxi lines are painted on the ramp or taxiway, these

lines should be followed to ensure a proper path along

the route.

The before takeoff and runup should be performed

using the checklist. During the day, forward movement

of the airplane can be detected easily. At night, the

airplane could creep forward without being noticed

unless the pilot is alert for this possibility. Hold or

lock the brakes during the runup and be alert for any

forward movement.

TAKEOFF AND CLIMB

Night flying is very different from day flying and

demands more attention of the pilot. The most noticeable difference is the limited availability of outside

visual references. Therefore, flight instruments should

be used to a greater degree in controlling the airplane.

This is particularly true on night takeoffs and climbs.

The cockpit lights should be adjusted to a minimum

brightness that will allow the pilot to read the instruments and switches and yet not hinder the pilot’s outside vision. This will also eliminate light reflections on

the windshield and windows.

After ensuring that the final approach and runway are

clear of other air traffic, or when cleared for takeoff by

the tower, the landing lights and taxi lights should be

turned ON and the airplane lined up with the centerline

of the runway. If the runway does not have centerline

lighting, use the painted centerline and the runwayedge lights. After the airplane is aligned, the heading

indicator should be noted or set to correspond to the

known runway direction. To begin the takeoff, the

brakes should be released and the throttle smoothly

advanced to maximum allowable power. As the airplane accelerates, it should be kept moving straight

ahead between and parallel to the runway-edge lights.

The procedure for night takeoffs is the same as for normal daytime takeoffs except that many of the runway

visual cues are not available. Therefore, the flight

instruments should be checked frequently during the

takeoff to ensure the proper pitch attitude, heading, and

airspeed are being attained. As the airspeed reaches the

normal lift-off speed, the pitch attitude should be

adjusted to that which will establish a normal climb.

This should be accomplished by referring to both outside visual references, such as lights, and to the flight

instruments. [Figure 10-3]

Figure 10-3. Establish a positive climb.

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10-6

After becoming airborne, the darkness of night often

makes it difficult to note whether the airplane is getting closer to or farther from the surface. To ensure the

airplane continues in a positive climb, be sure a climb

is indicated on the attitude indicator, vertical speed

indicator (VSI), and altimeter. It is also important to

ensure the airspeed is at best climb speed.

Necessary pitch and bank adjustments should be made

by referencing the attitude and heading indicators. It is

recommended that turns not be made until reaching a

safe maneuvering altitude.

Although the use of the landing lights provides help

during the takeoff, they become ineffective after the

airplane has climbed to an altitude where the light

beam no longer extends to the surface. The light can

cause distortion when it is reflected by haze, smoke, or

fog that might exist in the climb. Therefore, when the

landing light is used for the takeoff, it may be turned

off after the climb is well established provided other

traffic in the area does not require its use for collision

avoidance.

ORIENTATION AND NAVIGATION

Generally, at night it is difficult to see clouds and

restrictions to visibility, particularly on dark nights or

under overcast. The pilot flying under VFR must exercise caution to avoid flying into clouds or a layer of

fog. Usually, the first indication of flying into restricted

visibility conditions is the gradual disappearance of

lights on the ground. If the lights begin to take on an

appearance of being surrounded by a halo or glow, the

pilot should use caution in attempting further flight in

that same direction. Such a halo or glow around lights

on the ground is indicative of ground fog. Remember

that if a descent must be made through fog, smoke, or

haze in order to land, the horizontal visibility is considerably less when looking through the restriction than it

is when looking straight down through it from above.

Under no circumstances should a VFR night-flight be

made during poor or marginal weather conditions

unless both the pilot and aircraft are certificated and

equipped for flight under instrument flight rules (IFR).

The pilot should practice and acquire competency in

straight-and-level flight, climbs and descents, level

turns, climbing and descending turns, and steep turns.

Recovery from unusual attitudes should also be practiced, but only on dual flights with a flight instructor.

The pilot should also practice these maneuvers with all

the cockpit lights turned OFF. This blackout training is

necessary if the pilot experiences an electrical or

instrument light failure. Training should also include

using the navigation equipment and local NAVAIDs.

In spite of fewer references or checkpoints, night crosscountry flights do not present particular problems if

preplanning is adequate, and the pilot continues to

monitor position, time estimates, and fuel consumed.

NAVAIDs, if available, should be used to assist in

monitoring en route progress.

Crossing large bodies of water at night in singleengine airplanes could be potentially hazardous, not

only from the standpoint of landing (ditching) in the

water, but also because with little or no lighting the

horizon blends with the water, in which case, depth

perception and orientation become difficult. During

poor visibility conditions over water, the horizon will

become obscure, and may result in a loss of orientation. Even on clear nights, the stars may be reflected

on the water surface, which could appear as a continuous array of lights, thus making the horizon difficult

to identify.

Lighted runways, buildings, or other objects may

cause illusions to the pilot when seen from different

altitudes. At an altitude of 2,000 feet, a group of lights

on an object may be seen individually, while at 5,000

feet or higher, the same lights could appear to be one

solid light mass. These illusions may become quite

acute with altitude changes and if not overcome could

present problems in respect to approaches to lighted

runways.

APPROACHES AND LANDINGS

When approaching the airport to enter the traffic pattern and land, it is important that the runway lights

and other airport lighting be identified as early as

possible. If the airport layout is unfamiliar to the

pilot, sighting of the runway may be difficult until

very close-in due to the maze of lights observed in

the area. [Figure 10-4] The pilot should fly toward

the rotating beacon until the lights outlining the runway are distinguishable. To fly a traffic pattern of

proper size and direction, the runway threshold and

runway-edge lights must be positively identified.

Once the airport lights are seen, these lights should

be kept in sight throughout the approach.

Figure 10-4. Use light patterns for orientation.

Ch 10.qxd 7/13/04 11:10 AM Page 10-6
Distance may be deceptive

at night due to limited

lighting conditions. A lack

of intervening references

on the ground and the

inability of the pilot to compare the size and location of

different ground objects

cause this. This also applies

to the estimation of altitude

and speed. Consequently,

more dependence must be

placed on flight instruments,

particularly the altimeter and

the airspeed indicator.

When entering the traffic

pattern, allow for plenty of

time to complete the

before landing checklist. If

the heading indicator contains a heading bug, setting it

to the runway heading will be an excellent reference

for the pattern legs.

Every effort should be made to maintain the recommended airspeeds and execute the approach and

landing in the same manner as during the day. A low,

shallow approach is definitely inappropriate during

a night operation. The altimeter and VSI should be

constantly cross-checked against the airplane’s position

along the base leg and final approach. A visual

approach slope indicator (VASI) is an indispensable aid

in establishing and maintaining a proper glidepath.

[Figure 10-5]

After turning onto the final approach and aligning the

airplane midway between the two rows of runway-edge

lights, the pilot should note and correct for any wind

drift. Throughout the final approach, pitch and power

should be used to maintain a stabilized approach. Flaps

should be used the same as in a normal approach.

Usually, halfway through the final approach, the landing light should be turned on. Earlier use of the landing

light may be necessary because of “Operation Lights

ON” or for local traffic considerations. The landing

light is sometimes ineffective since the light beam will

usually not reach the ground from higher altitudes. The

light may even be reflected back into the pilot’s eyes

by any existing haze, smoke, or fog. This disadvantage

is overshadowed by the safety considerations provided

by using the “Operation Lights ON” procedure around

other traffic.

The roundout and touchdown should be made in the

same manner as in day landings. At night, the judgment of height, speed, and sink rate is impaired by the

scarcity of observable objects in the landing area. The

inexperienced pilot may have a tendency to round out

too high until attaining familiarity with the proper

height for the correct roundout. To aid in determining

the proper roundout point, continue a constant

approach descent until the landing lights reflect on the

runway and tire marks on the runway can be seen

clearly. At this point the roundout should be started

smoothly and the throttle gradually reduced to idle

as the airplane is touching down. [Figure 10-6]

During landings without the use of landing lights, the

roundout may be started when the runway lights at the

If both light bars are white,

you are too high. 

If you see red over red, you 

are below the glidepath.

Above Glidepath Below Glidepath On Glidepath

If the far bar is red and the 

near bar is white, you are on 

the glidepath. The memory 

aid "red over white, you're all 

right," is helpful in recalling 

the correct sequence of lights.

Figure 10-5. VASI.

Figure 10-6. Roundout when tire marks are visible.

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10-8

far end of the runway first appear to be rising higher

than the nose of the airplane. This demands a smooth

and very timely roundout, and requires that the pilot

feel for the runway surface using power and pitch

changes, as necessary, for the airplane to settle slowly

to the runway. Blackout landings should always be

included in night pilot training as an emergency

procedure.

NIGHT EMERGENCIES

Perhaps the pilot’s greatest concern about flying a singleengine airplane at night is the possibility of a complete

engine failure and the subsequent emergency landing.

This is a legitimate concern, even though continuing

flight into adverse weather and poor pilot judgment

account for most serious accidents.

If the engine fails at night, several important procedures

and considerations to keep in mind are:

• Maintain positive control of the airplane and

establish the best glide configuration and airspeed.

Turn the airplane towards an airport or away from

congested areas.

• Check to determine the cause of the engine

malfunction, such as the position of fuel selectors, magneto switch, or primer. If possible, the

cause of the malfunction should be corrected

immediately and the engine restarted.

• Announce the emergency situation to Air Traffic

Control (ATC) or UNICOM. If already in radio

contact with a facility, do not change frequencies, unless instructed to change.

• If the condition of the nearby terrain is known,

turn towards an unlighted portion of the area.

Plan an emergency approach to an unlighted

portion.

• Consider an emergency landing area close to

public access if possible. This may facilitate

rescue or help, if needed.

• Maintain orientation with the wind to avoid a

downwind landing.

• Complete the before landing checklist, and

check the landing lights for operation at altitude

and turn ON in sufficient time to illuminate the

terrain or obstacles along the flightpath. The

landing should be completed in the normal landing attitude at the slowest possible airspeed. If

the landing lights are unusable and outside visual

references are not available, the airplane should

be held in level-landing attitude until the ground

is contacted.

• After landing, turn off all switches and evacuate

the airplane as quickly as possible.

Ch 10.qxd 7/13/04 11:10 AM Page 10-8
11-1

HIGH PERFORMANCE AND COMPLEX

AIRPLANES

Transition to a complex airplane, or a high performance

airplane, can be demanding for most pilots without previous experience. Increased performance and increased

complexity both require additional planning, judgment,

and piloting skills. Transition to these types of

airplanes, therefore, should be accomplished in a

systematic manner through a structured course of

training administered by a qualified flight instructor.

A complex airplane is defined as an airplane equipped

with a retractable landing gear, wing flaps, and a

controllable-pitch propeller. For a seaplane to be

considered complex, it is required to have wing flaps and

a controllable-pitch propeller. A high performance

airplane is defined as an airplane with an engine of more

than 200 horsepower.

WING FLAPS

Airplanes can be designed to fly fast or slow. High

speed requires thin, moderately cambered airfoils with

a small wing area, whereas the high lift needed for low

speeds is obtained with thicker highly cambered

airfoils with a larger wing area. [Figure 11-1] Many

attempts have been made to compromise this

conflicting requirement of high cruise and slow

landing speeds.

Since an airfoil cannot have two different cambers at

the same time, one of two things must be done. Either

the airfoil can be a compromise, or a cruise airfoil can

be combined with a device for increasing the camber of

the airfoil for low-speed flight. One method for varying

an airfoil’s camber is the addition of trailing edge flaps.

Engineers call these devices a high-lift system.

FUNCTION OF FLAPS

Flaps work primarily by changing the camber of the

airfoil since deflection adds aft camber. Flap deflection

does not increase the critical (stall) angle of attack, and

in some cases flap deflection actually decreases the

critical angle of attack. 

Deflection of trailing edge control surfaces, such as the

aileron, alters both lift and drag. With aileron

deflection, there is asymmetrical lift (rolling moment)

and drag (adverse yaw). Wing flaps differ in that

deflection acts symmetrically on the airplane. There is

no roll or yaw effect, and pitch changes depend on the

airplane design.

Straight

Elliptical

Tapered

Sweptback

Delta

Figure 11-1. Airfoil types.

Ch 11.qxd 5/7/04 8:50 AM Page 11-1
11-2

Pitch behavior depends on flap type, wing position,

and horizontal tail location. The increased camber

from flap deflection produces lift primarily on the rear

portion of the wing. This produces a nosedown

pitching moment; however, the change in tail load

from the downwash deflected by the flaps over the

horizontal tail has a significant influence on the

pitching moment. Consequently, pitch behavior

depends on the design features of the particular airplane.

Flap deflection of up to 15° primarily produces lift

with minimal drag. The tendency to balloon up with

initial flap deflection is because of lift increase, but the

nosedown pitching moment tends to offset the balloon.

Deflection beyond 15° produces a large increase in

drag. Drag from flap deflection is parasite drag, and

as such is proportional to the square of the speed. Also,

deflection beyond 15° produces a significant noseup

pitching moment in most high-wing airplanes because

the resulting downwash increases the airflow over the

horizontal tail.

FLAP EFFECTIVENESS

Flap effectiveness depends on a number of factors, but

the most noticeable are size and type. For the purpose

of this chapter, trailing edge flaps are classified as four

basic types: plain (hinge), split, slotted, and Fowler.

[Figure 11-2]

The plain or hinge flap is a hinged section of the wing.

The structure and function are comparable to the other

control surfaces—ailerons, rudder, and elevator. The

split flap is more complex. It is the lower or underside

portion of the wing; deflection of the flap leaves the

trailing edge of the wing undisturbed. It is, however,

more effective than the hinge flap because of greater

lift and less pitching moment, but there is more drag.

Split flaps are more useful for landing, but the partially

deflected hinge flaps have the advantage in takeoff.

The split flap has significant drag at small deflections,

whereas the hinge flap does not because airflow

remains “attached” to the flap.

The slotted flap has a gap between the wing and the

leading edge of the flap. The slot allows high

pressure airflow on the wing undersurface to energize

the lower pressure over the top, thereby delaying flow

separation. The slotted flap has greater lift than the

hinge flap but less than the split flap; but, because of

a higher lift-drag ratio, it gives better takeoff and

climb performance. Small deflections of the slotted

flap give a higher drag than the hinge flap but less

than the split. This allows the slotted flap to be used

for takeoff.

The Fowler flap deflects down and aft to increase the

wing area. This flap can be multi-slotted making it the

most complex of the trailing edge systems. This

system does, however, give the maximum lift

coefficient. Drag characteristics at small deflections

are much like the slotted flap. Because of structural

complexity and difficulty in sealing the slots, Fowler

flaps are most commonly used on larger airplanes.

OPERATIONAL PROCEDURES

It would be impossible to discuss all the many airplane

design and flap combinations. This emphasizes the

importance of the FAA-approved Airplane Flight

Manual and/or Pilot’s Operating Handbook

(AFM/POH) for a given airplane. However, while

some AFM/POHs are specific as to operational use of

flaps, many are lacking. Hence, flap operation makes

pilot judgment of critical importance. In addition, flap

operation is used for landings and takeoffs, during

which the airplane is in close proximity to the ground

where the margin for error is small.

Since the recommendations given in the AFM/POH are

based on the airplane and the flap design combination,

Plain Flap

Split Flap

Slotted Flap

Fowler Flap

Figure 11-2. Four basic types of flaps.

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11-3

the pilot must relate the manufacturer’s recommendation to aerodynamic effects of flaps. This requires that

the pilot have a basic background knowledge of flap

aerodynamics and geometry. With this information, the

pilot must make a decision as to the degree of flap

deflection and time of deflection based on runway and

approach conditions relative to the wind conditions.

The time of flap extension and degree of deflection are

related. Large flap deflections at one single point in the

landing pattern produce large lift changes that require

significant pitch and power changes in order to

maintain airspeed and glide slope. Incremental

deflection of flaps on downwind, base, and final

approach allow smaller adjustment of pitch and power

compared to extension of full flaps all at one time. This

procedure facilitates a more stabilized approach.

A soft- or short-field landing requires minimal speed at

touchdown. The flap deflection that results in minimal

groundspeed, therefore, should be used. If obstacle

clearance is a factor, the flap deflection that results in

the steepest angle of approach should be used. It

should be noted, however, that the flap setting that

gives the minimal speed at touchdown does not

necessarily give the steepest angle of approach;

however, maximum flap extension gives the steepest

angle of approach and minimum speed at touchdown.

Maximum flap extension, particularly beyond 30 to

35°, results in a large amount of drag. This requires

higher power settings than used with partial flaps.

Because of the steep approach angle combined with

power to offset drag, the flare with full flaps becomes

critical. The drag produces a high sink rate that must

be controlled with power, yet failure to reduce power

at a rate so that the power is idle at touchdown allows

the airplane to float down the runway. A reduction in

power too early results in a hard landing.

Crosswind component is another factor to be

considered in the degree of flap extension. The

deflected flap presents a surface area for the wind to

act on. In a crosswind, the “flapped” wing on the

upwind side is more affected than the downwind

wing. This is, however, eliminated to a slight extent

in the crabbed approach since the airplane is more

nearly aligned with the wind. When using a wing low

approach, however, the lowered wing partially

blankets the upwind flap, but the dihedral of the wing

combined with the flap and wind make lateral control

more difficult. Lateral control becomes more difficult

as flap extension reaches maximum and the

crosswind becomes perpendicular to the runway.

Crosswind effects on the “flapped” wing become more

pronounced as the airplane comes closer to the ground.

The wing, flap, and ground form a “container” that is

filled with air by the crosswind. With the wind striking

the deflected flap and fuselage side and with the flap

located behind the main gear, the upwind wing will

tend to rise and the airplane will tend to turn into the

wind. Proper control position, therefore, is essential

for maintaining runway alignment. Also, it may

be necessary to retract the flaps upon positive

ground contact.

The go-around is another factor to consider when

making a decision about degree of flap deflection

and about where in the landing pattern to extend

flaps. Because of the nosedown pitching moment

produced with flap extension, trim is used to offset

this pitching moment. Application of full power in

the go-around increases the airflow over the

“flapped” wing. This produces additional lift

causing the nose to pitch up. The pitch-up tendency

does not diminish completely with flap retraction

because of the trim setting. Expedient retraction of

flaps is desirable to eliminate drag, thereby allowing

rapid increase in airspeed; however, flap retraction

also decreases lift so that the airplane sinks rapidly.

The degree of flap deflection combined with design

configuration of the horizontal tail relative to the

wing requires that the pilot carefully monitor pitch

and airspeed, carefully control flap retraction to

minimize altitude loss, and properly use the rudder

for coordination. Considering these factors, the pilot

should extend the same degree of deflection at the

same point in the landing pattern. This requires that a

consistent traffic pattern be used. Therefore, the pilot

can have a preplanned go-around sequence based on

the airplane’s position in the landing pattern.

There is no single formula to determine the degree of

flap deflection to be used on landing, because a

landing involves variables that are dependent on each

other. The AFM/POH for the particular airplane will

contain the manufacturer’s recommendations for

some landing situations. On the other hand,

AFM/POH information on flap usage for takeoff is

more precise. The manufacturer’s requirements are

based on the climb performance produced by a given

flap design. Under no circumstances should a flap

setting given in the AFM/POH be exceeded

for takeoff.

CONTROLLABLE-PITCH PROPELLER

Fixed-pitch propellers are designed for best efficiency

at one speed of rotation and forward speed. This type

of propeller will provide suitable performance in

a narrow range of airspeeds; however, efficiency

would suffer considerably outside this range. To

provide high propeller efficiency through a wide

range of operation, the propeller blade angle

must be controllable. The most convenient

Ch 11.qxd 5/7/04 8:50 AM Page 11-3
11-4

way of controlling the propeller blade angle is by

means of a constant-speed governing system. 

CONSTANT-SPEED PROPELLER

The constant-speed propeller keeps the blade angle

adjusted for maximum efficiency for most conditions

of flight. When an engine is running at constant

speed, the torque (power) exerted by the engine at the

propeller shaft must equal the opposing load provided

by the resistance of the air. The r.p.m. is controlled by

regulating the torque absorbed by the propeller—in

other words by increasing or decreasing the

resistance offered by the air to the propeller. In the

case of a fixed-pitch propeller, the torque absorbed

by the propeller is a function of speed, or r.p.m. If the

power output of the engine is changed, the engine will

accelerate or decelerate until an r.p.m. is reached at

which the power delivered is equal to the power

absorbed. In the case of a constant-speed propeller,

the power absorbed is independent of the r.p.m., for

by varying the pitch of the blades, the air resistance

and hence the torque or load, can be changed without

reference to propeller speed. This is accomplished

with a constant-speed propeller by means of a

governor. The governor, in most cases, is geared to

the engine crankshaft and thus is sensitive to changes

in engine r.p.m.

The pilot controls the engine r.p.m. indirectly by means

of a propeller control in the cockpit, which is

connected to the governor. For maximum takeoff

power, the propeller control is moved all the way

forward to the low pitch/high r.p.m. position, and the

throttle is moved forward to the maximum allowable

manifold pressure position. To reduce power for climb

or cruise, manifold pressure is reduced to the desired

value with the throttle, and the engine r.p.m. is reduced

by moving the propeller control back toward the high

pitch/low r.p.m. position until the desired r.p.m. is

observed on the tachometer. Pulling back on the

propeller control causes the propeller blades to move

to a higher angle. Increasing the propeller blade angle

(of attack) results in an increase in the resistance of the

air. This puts a load on the engine so it slows down. In

other words, the resistance of the air at the higher blade

angle is greater than the torque, or power, delivered to

the propeller by the engine, so it slows down to a point

where the two forces are in balance. 

When an airplane is nosed up into a climb from level

flight, the engine will tend to slow down. Since the

governor is sensitive to small changes in engine r.p.m.,

it will decrease the blade angle just enough to keep the

engine speed from falling off. If the airplane is nosed

down into a dive, the governor will increase the blade

angle enough to prevent the engine from overspeeding.

This allows the engine to maintain a constant r.p.m.,

and thus maintain the power output. Changes in

airspeed and power can be obtained by changing

r.p.m. at a constant manifold pressure; by changing

the manifold pressure at a constant r.p.m.; or by

changing both r.p.m. and manifold pressure. Thus

the constant-speed propeller makes it possible to

obtain an infinite number of power settings. 

TAKEOFF, CLIMB, AND CRUISE

During takeoff, when the forward motion of the

airplane is at low speeds and when maximum power

and thrust are required, the constant-speed propeller

sets up a low propeller blade angle (pitch). The low

blade angle keeps the angle of attack, with respect to

the relative wind, small and efficient at the low speed.

[Figure 11-3]

At the same time, it allows the propeller to “slice it

thin” and handle a smaller mass of air per revolution.

This light load allows the engine to turn at maximum

r.p.m. and develop maximum power. Although the

mass of air per revolution is small, the number of

revolutions per minute is high. Thrust is maximum at

the beginning of the takeoff and then decreases as the

airplane gains speed and the airplane drag increases.

Due to the high slipstream velocity during takeoff,

the effective lift of the wing behind the propeller(s)

is increased.

As the airspeed increases after lift-off, the load on the

engine is lightened because of the small blade angle.

The governor senses this and increases the blade angle

slightly. Again, the higher blade angle, with the higher

speeds, keeps the angle of attack with respect to the

relative wind small and efficient. 

Angle of 

 Attack

Chord

Line

Plane of

Propeller

Rotation 

Angle of 

Attack

Chord Line

(Blade Face)

STATIONARY FORWARD MOTION

Plane of 

Propeller

Rotation 

Forward 

Airspeed

Relative

Wind

Relative

Wind

Figure 11-3. Propeller blade angle.

Ch 11.qxd 5/7/04 8:50 AM Page 11-4
11-5

For climb after takeoff, the power output of the engine

is reduced to climb power by decreasing the manifold

pressure and lowering r.p.m. by increasing the blade

angle. At the higher (climb) airspeed and the higher

blade angle, the propeller is handling a greater mass of

air per second at a lower slipstream velocity. This

reduction in power is offset by the increase in propeller

efficiency. The angle of attack is again kept small by

the increase in the blade angle with an increase

in airspeed. 

At cruising altitude, when the airplane is in level flight,

less power is required to produce a higher airspeed

than is used in climb. Consequently, engine power is

again reduced by lowering the manifold pressure and

increasing the blade angle (to decrease r.p.m.). The

higher airspeed and higher blade angle enable the

propeller to handle a still greater mass of air per

second at still smaller slipstream velocity. At normal

cruising speeds, propeller efficiency is at, or near

maximum efficiency. Due to the increase in blade

angle and airspeed, the angle of attack is still small

and efficient.

BLADE ANGLE CONTROL

Once the pilot selects the r.p.m. settings for the

propeller, the propeller governor automatically adjusts

the blade angle to maintain the selected r.p.m. It does

this by using oil pressure. Generally, the oil pressure

used for pitch change comes directly from the engine

lubricating system. When a governor is employed,

engine oil is used and the oil pressure is usually

boosted by a pump, which is integrated with the

governor. The higher pressure provides a quicker blade

angle change. The r.p.m. at which the propeller is to

operate is adjusted in the governor head. The pilot

changes this setting by changing the position of the

governor rack through the cockpit propeller control.

On some constant-speed propellers, changes in pitch

are obtained by the use of an inherent centrifugal

twisting moment of the blades that tends to flatten the

blades toward low pitch, and oil pressure applied to a

hydraulic piston connected to the propeller blades

which moves them toward high pitch. Another type of

constant-speed propeller uses counterweights attached

to the blade shanks in the hub. Governor oil pressure

and the blade twisting moment move the blades toward

the low pitch position, and centrifugal force acting on

the counterweights moves them (and the blades)

toward the high pitch position. In the first case above,

governor oil pressure moves the blades towards high

pitch, and in the second case, governor oil pressure and

the blade twisting moment move the blades toward low

pitch. A loss of governor oil pressure, therefore, will

affect each differently. 

GOVERNING RANGE

The blade angle range for constant-speed propellers

varies from about 11 1/2 to 40°. The higher the speed

of the airplane, the greater the blade angle range.

[Figure 11-4]

The range of possible blade angles is termed the

propeller’s governing range. The governing range is

defined by the limits of the propeller blade’s travel

between high and low blade angle pitch stops. As long

as the propeller blade angle is within the governing

range and not against either pitch stop, a constant

engine r.p.m. will be maintained. However, once the

propeller blade reaches its pitch-stop limit, the engine

r.p.m. will increase or decrease with changes in

airspeed and propeller load similar to a fixed-pitch

propeller. For example, once a specific r.p.m. is

selected, if the airspeed decreases enough, the

propeller blades will reduce pitch, in an attempt to

maintain the selected r.p.m., until they contact their

low pitch stops. From that point, any further

reduction in airspeed will cause the engine r.p.m.

to decrease. Conversely, if the airspeed increases,

the propeller blade angle will increase until the

high pitch stop is reached. The engine r.p.m. will

then begin to increase.

CONSTANT-SPEED

PROPELLER OPERATION

The engine is started with the propeller control in the

low pitch/high r.p.m. position. This position reduces

the load or drag of the propeller and the result is easier

starting and warm-up of the engine. During warm-up,

the propeller blade changing mechanism should be

operated slowly and smoothly through a full cycle.

This is done by moving the propeller control (with the

Fixed Gear

Retractable

Turbo Retractable

Turbine Retractable

Transport Retractable

Aircraft Type Design Speed

(m.p.h.)

Blade Angle

Range

Pitch

Low High

160

180

225/240

250/300

325

111/

2°

15°

20°

30°

40°

101/

2°

11°

14°

10°

10/15°

22°

26°

34°

40°

50/55°

Figure 11-4. Blade angle range (values are approximate).

Ch 11.qxd 5/7/04 8:50 AM Page 11-5
11-6

manifold pressure set to produce about 1,600 r.p.m.)

to the high pitch/low r.p.m. position, allowing the

r.p.m. to stabilize, and then moving the propeller

control back to the low pitch takeoff position. This

should be done for two reasons: to determine

whether the system is operating correctly, and to

circulate fresh warm oil through the propeller

governor system. It should be remembered that the

oil has been trapped in the propeller cylinder since

the last time the engine was shut down. There is a

certain amount of leakage from the propeller

cylinder, and the oil tends to congeal, especially if

the outside air temperature is low. Consequently, if

the propeller isn’t exercised before takeoff, there is

a possibility that the engine may overspeed

on takeoff. 

An airplane equipped with a constant-speed propeller

has better takeoff performance than a similarly powered

airplane equipped with a fixed-pitch propeller. This is

because with a constant-speed propeller, an airplane can

develop its maximum rated horsepower (red line on the

tachometer) while motionless. An airplane with a fixedpitch propeller, on the other hand, must accelerate down

the runway to increase airspeed and aerodynamically

unload the propeller so that r.p.m. and horsepower can

steadily build up to their maximum. With a constantspeed propeller, the tachometer reading should come up

to within 40 r.p.m. of the red line as soon as full power is

applied, and should remain there for the entire takeoff.

Excessive manifold pressure raises the cylinder

compression pressure, resulting in high stresses within

the engine. Excessive pressure also produces high

engine temperatures. A combination of high manifold

pressure and low r.p.m. can induce damaging

detonation. In order to avoid these situations, the

following sequence should be followed when making

power changes.

• When increasing power, increase the r.p.m. first,

and then the manifold pressure.

• When decreasing power, decrease the manifold

pressure first, and then decrease the r.p.m.

It is a fallacy that (in non-turbocharged engines) the

manifold pressure in inches of mercury (inches Hg)

should never exceed r.p.m. in hundreds for cruise

power settings. The cruise power charts in the

AFM/POH should be consulted when selecting cruise

power settings. Whatever the combinations of r.p.m.

and manifold pressure listed in these charts—they have

been flight tested and approved by the airframe and

powerplant engineers for the respective airframe and

engine manufacturer. Therefore, if there are power

settings such as 2,100 r.p.m. and 24 inches manifold

pressure in the power chart, they are approved for use.

With a constant-speed propeller, a power descent can

be made without overspeeding the engine. The system

compensates for the increased airspeed of the descent

by increasing the propeller blade angles. If the descent

is too rapid, or is being made from a high altitude, the

maximum blade angle limit of the blades is not

sufficient to hold the r.p.m. constant. When this

occurs, the r.p.m. is responsive to any change

in throttle setting.

Some pilots consider it advisable to set the propeller

control for maximum r.p.m. during the approach to

have full horsepower available in case of emergency.

If the governor is set for this higher r.p.m. early in the

approach when the blades have not yet reached their

minimum angle stops, the r.p.m. may increase to

unsafe limits. However, if the propeller control is not

readjusted for the takeoff r.p.m. until the approach is

almost completed, the blades will be against, or very

near their minimum angle stops and there will be little

if any change in r.p.m. In case of emergency, both

throttle and propeller controls should be moved to

takeoff positions.

Many pilots prefer to feel the airplane respond

immediately when they give short bursts of the

throttle during approach. By making the approach

under a little power and having the propeller control

set at or near cruising r.p.m., this result can

be obtained.

Although the governor responds quickly to any change

in throttle setting, a sudden and large increase in the

throttle setting will cause a momentary overspeeding

of the engine until the blades become adjusted to

absorb the increased power. If an emergency

demanding full power should arise during approach,

the sudden advancing of the throttle will cause

momentary overspeeding of the engine beyond the

r.p.m. for which the governor is adjusted. This

temporary increase in engine speed acts as an

emergency power reserve.

Some important points to remember concerning

constant-speed propeller operation are:

• The red line on the tachometer not only indicates

maximum allowable r.p.m.; it also indicates

the r.p.m. required to obtain the engine’s

rated horsepower.

• A momentary propeller overspeed may occur

when the throttle is advanced rapidly for takeoff.

This is usually not serious if the rated r.p.m. is

not exceeded by 10 percent for more than

3 seconds.

• The green arc on the tachometer indicates the

normal operating range. When developing

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11-7

power in this range, the engine drives the propeller. Below the green arc, however, it is usually

the windmilling propeller that powers the

engine. Prolonged operation below the green arc

can be detrimental to the engine.

• On takeoffs from low elevation airports, the

manifold pressure in inches of mercury may

exceed the r.p.m. This is normal in most cases.

The pilot should consult the AFM/POH

for limitations.

• All power changes should be made smoothly

and slowly to avoid overboosting and/or

overspeeding.

TURBOCHARGING

The turbocharged engine allows the pilot to maintain

sufficient cruise power at high altitudes where there is

less drag, which means faster true airspeeds and

increased range with fuel economy. At the same time,

the powerplant has flexibility and can be flown at a low

altitude without the increased fuel consumption of a

turbine engine. When attached to the standard

powerplant, the turbocharger does not take any

horsepower from the powerplant to operate; it is

relatively simple mechanically, and some models can

pressurize the cabin as well.

The turbocharger is an exhaust-driven device, which

raises the pressure and density of the induction air

delivered to the engine. It consists of two separate

components: a compressor and a turbine connected by

a common shaft. The compressor supplies pressurized

air to the engine for high altitude operation. The

compressor and its housing are between the ambient

air intake and the induction air manifold. The turbine

and its housing are part of the exhaust system and

utilize the flow of exhaust gases to drive the

compressor. [Figure 11-5]

The turbine has the capability of producing manifold

pressure in excess of the maximum allowable for the

particular engine. In order not to exceed the maximum

allowable manifold pressure, a bypass or waste gate is

used so that some of the exhaust will be diverted

overboard before it passes through the turbine.

The position of the waste gate regulates the output of

the turbine and therefore, the compressed air available

to the engine. When the waste gate is closed, all of the

exhaust gases pass through and drive the turbine. As

the waste gate opens, some of the exhaust gases are

routed around the turbine, through the exhaust bypass

and overboard through the exhaust pipe.

The waste gate actuator is a spring-loaded piston,

operated by engine oil pressure. The actuator, which

adjusts the waste gate position, is connected to the

waste gate by a mechanical linkage.

The control center of the turbocharger system is

the pressure controller. This device simplifies

turbocharging to one control: the throttle. Once the

pilot has set the desired manifold pressure, virtually no

throttle adjustment is required with changes in altitude.

The controller senses compressor discharge

requirements for various altitudes and controls the oil

pressure to the waste gate actuator which adjusts the

waste gate accordingly. Thus the turbocharger

maintains only the manifold pressure called for by the

throttle setting. 

GROUND BOOSTING VS. ALTITUDE

TURBOCHARGING

Altitude turbocharging (sometimes called “normalizing”) is accomplished by using a turbocharger that

will maintain maximum allowable sea level manifold

pressure (normally 29 – 30 inches Hg) up to a certain

altitude. This altitude is specified by the airplane

manufacturer and is referred to as the airplane’s

critical altitude. Above the critical altitude,

EXHAUST GAS

DISCHARGE

WASTE GATE

This controls the amount of exhaust through the turbine. 

Waste gate position is actuated by engine oil pressure.

TURBOCHARGER

The turbocharger incorporates a 

turbine, which is driven by exhaust 

gases, and a compressor that 

pressurizes the incoming air.

THROTTLE BODY

This regulates airflow 

to the engine.

INTAKE MANIFOLD

Pressurized air from the 

turbocharger is supplied to 

the cylinders.

EXHAUST MANIFOLD

Exhaust gas is ducted through 

the exhaust manifold and is 

used to turn the turbine which 

drives the compressor.

AIR INTAKE

Intake air is ducted to 

the turbocharger where 

it is compressed.

Figure 11-5.Turbocharging system.

Ch 11.qxd 5/7/04 8:50 AM Page 11-7
11-8

the manifold pressure decreases as additional altitude

is gained. Ground boosting, on the other hand, is an

application of turbocharging where more than the

standard 29 inches of manifold pressure is used in

flight. In various airplanes using ground boosting,

takeoff manifold pressures may go as high as 45

inches of mercury.

Although a sea level power setting and maximum

r.p.m. can be maintained up to the critical altitude,

this does not mean that the engine is developing sea

level power. Engine power is not determined just by

manifold pressure and r.p.m. Induction air

temperature is also a factor. Turbocharged induction

air is heated by compression. This temperature rise

decreases induction air density which causes a

power loss. Maintaining the equivalent horsepower

output will require a somewhat higher manifold

pressure at a given altitude than if the induction air

were not compressed by turbocharging. If, on the

other hand, the system incorporates an automatic

density controller which, instead of maintaining a

constant manifold pressure, automatically positions

the waste gate so as to maintain constant air density

to the engine, a near constant horsepower output

will result.

OPERATING CHARACTERISTICS

First and foremost, all movements of the power

controls on turbocharged engines should be slow and

gentle. Aggressive and/or abrupt throttle movements

increase the possibility of overboosting. The pilot

should carefully monitor engine indications when

making power changes.

When the waste gate is open, the turbocharged engine

will react the same as a normally aspirated engine

when the r.p.m. is varied. That is, when the r.p.m. is

increased, the manifold pressure will decrease slightly.

When the engine r.p.m. is decreased, the manifold

pressure will increase slightly. However, when the

waste gate is closed, manifold pressure variation with

engine r.p.m. is just the opposite of the normally

aspirated engine. An increase in engine r.p.m. will

result in an increase in manifold pressure, and a

decrease in engine r.p.m. will result in a decrease in

manifold pressure. 

Above the critical altitude, where the waste gate

is closed, any change in airspeed will result in a

corresponding change in manifold pressure. This is

true because the increase in ram air pressure with an

increase in airspeed is magnified by the compressor

resulting in an increase in manifold pressure. The

increase in manifold pressure creates a higher mass

flow through the engine, causing higher turbine speeds

and thus further increasing manifold pressure.

When running at high altitudes, aviation gasoline may

tend to vaporize prior to reaching the cylinder. If this

occurs in the portion of the fuel system between the

fuel tank and the engine-driven fuel pump, an

auxiliary positive pressure pump may be needed in the

tank. Since engine-driven pumps pull fuel, they are

easily vapor locked. A boost pump provides positive

pressure—pushes the fuel—reducing the tendency to

vaporize.

HEAT MANAGEMENT

Turbocharged engines must be thoughtfully and

carefully operated, with continuous monitoring of

pressures and temperatures. There are two temperatures that are especially important—turbine inlet

temperature (TIT) or in some installations exhaust gas

temperature (EGT), and cylinder head temperature.

TIT or EGT limits are set to protect the elements in the

hot section of the turbocharger, while cylinder head

temperature limits protect the engine’s internal parts.

Due to the heat of compression of the induction air, a

turbocharged engine runs at higher operating

temperatures than a non-turbocharged engine. Because

turbocharged engines operate at high altitudes, their

environment is less efficient for cooling. At altitude

the air is less dense and therefore, cools less

efficiently. Also, the less dense air causes the

compressor to work harder. Compressor turbine

speeds can reach 80,000 – 100,000 r.p.m., adding

to the overall engine operating temperatures.

Turbocharged engines are also operated at higher

power settings a greater portion of the time. 

High heat is detrimental to piston engine operation. Its

cumulative effects can lead to piston, ring, and

cylinder head failure, and place thermal stress on other

operating components. Excessive cylinder head

temperature can lead to detonation, which in turn can

cause catastrophic engine failure. Turbocharged

engines are especially heat sensitive. The key to

turbocharger operation, therefore, is effective heat

management.

The pilot monitors the condition of a turbocharged

engine with manifold pressure gauge, tachometer,

exhaust gas temperature/turbine inlet temperature

gauge, and cylinder head temperature. The pilot

manages the “heat system” with the throttle, propeller

r.p.m., mixture, and cowl flaps. At any given cruise

power, the mixture is the most influential control over

the exhaust gas/turbine inlet temperature. The throttle

regulates total fuel flow, but the mixture governs the

fuel to air ratio. The mixture, therefore, controls

temperature.

Exceeding temperature limits in an after takeoff climb

is usually not a problem since a full rich mixture cools

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11-9

with excess fuel. At cruise, however, the pilot normally

reduces power to 75 percent or less and simultaneously

adjusts the mixture. Under cruise conditions,

temperature limits should be monitored most closely

because it’s there that the temperatures are most likely

to reach the maximum, even though the engine is

producing less power. Overheating in an enroute

climb, however, may require fully open cowl flaps and

a higher airspeed.

Since turbocharged engines operate hotter at altitude

than do normally aspirated engines, they are more

prone to damage from cooling stress. Gradual

reductions in power, and careful monitoring of

temperatures are essential in the descent phase. The

pilot may find it helpful to lower the landing gear to

give the engine something to work against while power

is reduced and provide time for a slow cool down. It

may also be necessary to lean the mixture slightly to

eliminate roughness at the lower power settings.

TURBOCHARGER FAILURE

Because of the high temperatures and pressures

produced in the turbine exhaust systems, any

malfunction of the turbocharger must be treated with

extreme caution. In all cases of turbocharger operation,

the manufacturer’s recommended procedures should

be followed. This is especially so in the case of

turbocharger malfunction. However, in those instances

where the manufacturer’s procedures do not

adequately describe the actions to be taken in the event

of a turbocharger failure, the following procedures

should be used.

OVERBOOST CONDITION

If an excessive rise in manifold pressure occurs during

normal advancement of the throttle (possibly owing to

faulty operation of the waste gate):

• Immediately retard the throttle smoothly to limit

the manifold pressure below the maximum for

the r.p.m. and mixture setting.

• Operate the engine in such a manner as to avoid a

further overboost condition.

LOW MANIFOLD PRESSURE

Although this condition may be caused by a minor

fault, it is quite possible that a serious exhaust leak has

occurred creating a potentially hazardous situation:

• Shut down the engine in accordance with the

recommended engine failure procedures, unless

a greater emergency exists that warrants continued engine operation.

• If continuing to operate the engine, use the lowest power setting demanded by the situation and

land as soon as practicable.

It is very important to ensure that corrective

maintenance is undertaken following any

turbocharger malfunction.

RETRACTABLE LANDING GEAR

The primary benefits of being able to retract the

landing gear are increased climb performance and

higher cruise airspeeds due to the resulting decrease in

drag. Retractable landing gear systems may be

operated either hydraulically or electrically, or may

employ a combination of the two systems. Warning

indicators are provided in the cockpit to show the pilot

when the wheels are down and locked and when they

are up and locked or if they are in intermediate

positions. Systems for emergency operation are also

provided. The complexity of the retractable landing

gear system requires that specific operating procedures

be adhered to and that certain operating limitations not

be exceeded.

LANDING GEAR SYSTEMS

An electrical landing gear retraction system utilizes an

electrically driven motor for gear operation. The

system is basically an electrically driven jack for

raising and lowering the gear. When a switch in the

cockpit is moved to the UP position, the electric motor

operates. Through a system of shafts, gears, adapters,

an actuator screw, and a torque tube, a force is

transmitted to the drag strut linkages. Thus, the gear

retracts and locks. Struts are also activated that open

and close the gear doors. If the switch is moved to the

DOWN position, the motor reverses and the gear

moves down and locks. Once activated the gear motor

will continue to operate until an up or down limit

switch on the motor’s gearbox is tripped.

A hydraulic landing gear retraction system utilizes

pressurized hydraulic fluid to actuate linkages to raise

and lower the gear. When a switch in the cockpit is

moved to the UP position, hydraulic fluid is directed

into the gear up line. The fluid flows through

sequenced valves and downlocks to the gear

actuating cylinders. A similar process occurs during

gear extension. The pump which pressurizes the fluid

in the system can be either engine driven or

electrically powered. If an electrically powered pump

is used to pressurize the fluid, the system is referred

to as an electrohydraulic system. The system also

incorporates a hydraulic reservoir to contain excess

fluid, and to provide a means of determining system

fluid level.

Regardless of its power source, the hydraulic pump is

designed to operate within a specific range. When a

sensor detects excessive pressure, a relief valve within

the pump opens, and hydraulic pressure is routed back

to the reservoir. Another type of relief valve prevents

excessive pressure that may result from thermal expansion. Hydraulic pressure is also regulated by limit

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11-10

switches. Each gear has two limit switches—one

dedicated to extension and one dedicated to retraction.

These switches de-energize the hydraulic pump after

the landing gear has completed its gear cycle. In the

event of limit switch failure, a backup pressure relief

valve activates to relieve excess system pressure.

CONTROLS AND POSITION INDICATORS

Landing gear position is controlled by a switch in the

cockpit. In most airplanes, the gear switch is shaped

like a wheel in order to facilitate positive identification

and to differentiate it from other cockpit controls.

[Figure 11-6]

Landing gear position indicators vary with different

make and model airplanes. The most common types of

landing gear position indicators utilize a group of

lights. One type consists of a group of three green

lights, which illuminate when the landing gear is down

and locked. [Figure 11-6] Another type consists of one

green light to indicate when the landing gear is down

and an amber light to indicate when the gear is up. Still

other systems incorporate a red or amber light to

indicate when the gear is in transit or unsafe for

landing. [Figure 11-7] The lights are usually of the

“press to test” type, and the bulbs are interchangeable.

[Figure 11-6]

Other types of landing gear position indicators consist

of tab-type indicators with markings “UP” to indicate

the gear is up and locked, a display of red and white

diagonal stripes to show when the gear is unlocked, or

a silhouette of each gear to indicate when it locks in

the DOWN position.

LANDING GEAR SAFETY DEVICES

Most airplanes with a retractable landing gear have a

gear warning horn that will sound when the airplane is

configured for landing and the landing gear is not

down and locked. Normally, the horn is linked to the

throttle or flap position, and/or the airspeed indicator

so that when the airplane is below a certain airspeed,

configuration, or power setting with the gear retracted,

the warning horn will sound.

Accidental retraction of a landing gear may be

prevented by such devices as mechanical downlocks,

safety switches, and ground locks. Mechanical

downlocks are built-in components of a gear retraction

system and are operated automatically by the gear

retraction system. To prevent accidental operation of

the downlocks, and inadvertent landing gear retraction

while the airplane is on the ground, electrically

operated safety switches are installed.

A landing gear safety switch, sometimes referred to as

a squat switch, is usually mounted in a bracket on one

of the main gear shock struts. [Figure 11-8] When the

strut is compressed by the weight of the airplane, the

switch opens the electrical circuit to the motor or

mechanism that powers retraction. In this way, if the

landing gear switch in the cockpit is placed in the

RETRACT position when weight is on the gear, the

gear will remain extended, and the warning horn may

sound as an alert to the unsafe condition. Once the

weight is off the gear, however, such as on takeoff, the

safety switch will release and the gear will retract.

Many airplanes are equipped with additional safety

devices to prevent collapse of the gear when the

airplane is on the ground. These devices are called

ground locks. One common type is a pin installed in

aligned holes drilled in two or more units of the

landing gear support structure. Another type is a

spring-loaded clip designed to fit around and hold two

or more units of the support structure together. All

types of ground locks usually have red streamers

permanently attached to them to readily indicate

whether or not they are installed.

EMERGENCY GEAR EXTENSION SYSTEMS

The emergency extension system lowers the landing

gear if the main power system fails. Some airplanes

Figure 11-6. Typical landing gear switches and position

indicators.

Figure 11-7. Typical landing gear switches and position

indicators.

Ch 11.qxd 5/7/04 8:50 AM Page 11-10
11-11

have an emergency release handle in the cockpit,

which is connected through a mechanical linkage to

the gear uplocks. When the handle is operated, it

releases the uplocks and allows the gears to free fall, or

extend under their own weight. [Figure 11-9]

Safety Switch

Landing Gear

Selector Valve

Lock Release

Solenoid

Lock-Pin

28V DC

Bus Bar

Figure 11-8. Landing gear safety switch.

Hand Pump Compressed Gas

Hand Crank

Figure 11-9.Typical emergency gear extension systems.

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11-12

should then turn on the battery master switch and

ensure that the landing gear position indicators show

that the gear is down and locked. 

External inspection of the landing gear should

consist of checking individual system components.

[Figure 11-10] The landing gear, wheel well, and

adjacent areas should be clean and free of mud and

debris. Dirty switches and valves may cause false

safe light indications or interrupt the extension cycle

before the landing gear is completely down and

locked. The wheel wells should be clear of any

obstructions, as foreign objects may damage the gear

or interfere with its operation. Bent gear doors may

Figure 11-10. Retractable landing gear inspection

checkpoints.

On other airplanes, release of the uplock is

accomplished using compressed gas, which is directed

to uplock release cylinders.

In some airplanes, design configurations make

emergency extension of the landing gear by gravity

and air loads alone impossible or impractical. In these

airplanes, provisions are included for forceful gear

extension in an emergency. Some installations are

designed so that either hydraulic fluid or compressed

gas provides the necessary pressure, while others use a

manual system such as a hand crank for emergency

gear extension. [Figure 11-9] Hydraulic pressure for

emergency operation of the landing gear may be

provided by an auxiliary hand pump, an accumulator,

or an electrically powered hydraulic pump depending

on the design of the airplane.

OPERATIONAL PROCEDURES

PREFLIGHT

Because of their complexity, retractable landing gears

demand a close inspection prior to every flight. The

inspection should begin inside the cockpit. The pilot

should first make certain that the landing gear selector

switch is in the GEAR DOWN position. The pilot

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11-13

be an indication of possible problems with normal

gear operation.

Shock struts should be properly inflated and the

pistons clean. Main gear and nose gear uplock and

downlock mechanisms should be checked for general

condition. Power sources and retracting mechanisms

should be checked for general condition, obvious

defects, and security of attachment. Hydraulic lines

should be checked for signs of chafing, and leakage

at attach points. Warning system micro switches

(squat switches) should be checked for cleanliness

and security of attachment. Actuating cylinders,

sprockets, universals, drive gears, linkages and any

other accessible components should be checked for

condition and obvious defects. The airplane structure

to which the landing gear is attached should be

checked for distortion, cracks, and general condition.

All bolts and rivets should be intact and secure.

TAKEOFF AND CLIMB

Normally, the landing gear should be retracted after

lift-off when the airplane has reached an altitude

where, in the event of an engine failure or other

emergency requiring an aborted takeoff, the airplane

could no longer be landed on the runway. This procedure, however, may not apply to all situations. Landing

gear retraction should be preplanned, taking into

account the length of the runway, climb gradient,

obstacle clearance requirements, the characteristics of

the terrain beyond the departure end of the runway, and

the climb characteristics of the particular airplane. For

example, in some situations it may be preferable, in the

event of an engine failure, to make an off airport forced

landing with the gear extended in order to take

advantage of the energy absorbing qualities of terrain

(see Chapter 16). In which case, a delay in retracting

the landing gear after takeoff from a short runway may

be warranted. In other situations, obstacles in the climb

path may warrant a timely gear retraction after takeoff.

Also, in some airplanes the initial climb pitch attitude

is such that any view of the runway remaining is

blocked, making an assessment of the feasibility of

touching down on the remaining runway difficult.

Premature landing gear retraction should be avoided.

The landing gear should not be retracted until a

positive rate of climb is indicated on the flight

instruments. If the airplane has not attained a positive

rate of climb, there is always the chance it may settle

back onto the runway with the gear retracted. This is

especially so in cases of premature lift-off. The pilot

should also remember that leaning forward to reach the

landing gear selector may result in inadvertent forward

pressure on the yoke, which will cause the airplane to

descend.

As the landing gear retracts, airspeed will increase and

the airplane’s pitch attitude may change. The gear may

take several seconds to retract. Gear retraction and

locking (and gear extension and locking) is

accompanied by sound and feel that are unique to the

specific make and model airplane. The pilot should

become familiar with the sounds and feel of normal

gear retraction so that any abnormal gear operation can

be readily discernable. Abnormal landing gear

retraction is most often a clear sign that the gear

extension cycle will also be abnormal.

APPROACH AND LANDING 

The operating loads placed on the landing gear at

higher airspeeds may cause structural damage due to

the forces of the airstream. Limiting speeds, therefore,

are established for gear operation to protect the gear

components from becoming overstressed during flight.

These speeds are not found on the airspeed indicator.

They are published in the AFM/POH for the particular

airplane and are usually listed on placards in the

cockpit. [Figure 11-11] The maximum landing

extended speed (VLE ) is the maximum speed at which

the airplane can be flown with the landing gear

extended. The maximum landing gear operating speed

(VLO) is the maximum speed at which the landing gear

may be operated through its cycle.

The landing gear is extended by placing the gear

selector switch in the GEAR DOWN position. As the

landing gear extends, the airspeed will decrease and

the pitch attitude may increase. During the several

seconds it takes for the gear to extend, the pilot

should be attentive to any abnormal sounds or feel.

The pilot should confirm that the landing gear has

extended and locked by the normal sound and feel of

the system operation as well as by the gear position

indicators in the cockpit. Unless the landing gear has

been previously extended to aid in a descent to traffic

pattern altitude, the landing gear should be extended

by the time the airplane reaches a point on the downwind leg that is opposite the point of intended

landing. The pilot should establish a standard

procedure consisting of a specific position on the

downwind leg at which to lower the landing gear.

Strict adherence to this procedure will aid the pilot in

avoiding unintentional gear up landings.

Figure 11-11. Placarded gear speeds in the cockpit.

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11-14

Operation of an airplane equipped with a retractable

landing gear requires the deliberate, careful, and

continued use of an appropriate checklist. When on

the downwind leg, the pilot should make it a habit to

complete the landing gear checklist for that airplane.

This accomplishes two purposes. It ensures that

action has been taken to lower the gear, and it

increases the pilot’s awareness so that the gear down

indicators can be rechecked prior to landing.

Unless good operating practices dictate otherwise, the

landing roll should be completed and the airplane

clear of the runway before any levers or switches are

operated. This will accomplish the following: The

landing gear strut safety switches will be actuated,

deactivating the landing gear retract system. After

rollout and clearing the runway, the pilot will be able

to focus attention on the after landing checklist and to

identify the proper controls.

Pilots transitioning to retractable gear airplanes should

be aware that the most common pilot operational

factors involved in retractable gear airplane accidents

are:

• Neglected to extend landing gear.

• Inadvertently retracted landing gear.

• Activated gear, but failed to check gear position.

• Misused emergency gear system.

• Retracted gear prematurely on takeoff.

• Extended gear too late. 

In order to minimize the chances of a landing gear

related mishap, the pilot should:

• Use an appropriate checklist. (A condensed

checklist mounted in view of the pilot as a

reminder for its use and easy reference can be

especially helpful.)

• Be familiar with, and periodically review, the

landing gear emergency extension procedures for

the particular airplane.

• Be familiar with the landing gear warning horn

and warning light systems for the particular

airplane. Use the horn system to cross-check the

warning light system when an unsafe condition

is noted.

• Review the procedure for replacing light bulbs

in the landing gear warning light displays for the

particular airplane, so that you can properly

replace a bulb to determine if the bulb(s) in the

display is good. Check to see if spare bulbs are

available in the airplane spare bulb supply as part

of the preflight inspection.

• Be familiar with and aware of the sounds and

feel of a properly operating landing gear system.

TRANSITION TRAINING

Transition to a complex airplane or a high

performance airplane should be accomplished through

a structured course of training administered by a

competent and qualified flight instructor. The training

should be accomplished in accordance with a ground

and flight training syllabus. [Figure 11-12] 

This sample syllabus for transition training is to be

considered flexible. The arrangement of the subject

matter may be changed and the emphasis may be

shifted to fit the qualifications of the transitioning

pilot, the airplane involved, and the circumstances of

the training situation, provided the prescribed

proficiency standards are achieved. These standards

are contained in the practical test standards

appropriate for the certificate that the transitioning

pilot holds or is working towards.

The training times indicated in the syllabus are based

on the capabilities of a pilot who is currently active

and fully meets the present requirements for the

issuance of at least a private pilot certificate. The time

periods may be reduced for pilots with higher

qualifications or increased for pilots who do not meet

the current certification requirements or who have had

little recent flight experience.

Ch 11.qxd 5/7/04 8:50 AM Page 11-14
11-15

1. Operations sections of

 flight manual

2. Line inspection

3. Cockpit familiarization

1. Flight training maneuvers

2. Takeoffs, landings and

 go-arounds

1. Aircraft loading, limitations

 and servicing

2. Instruments, radio and 

 special equipment

3. Aircraft systems

1. Emergency operations

2. Control by reference to

 instruments

3. Use of radio and autopilot

As assigned by flight instructor

1. Performance section of

 flight manual

2. Cruise control

3. Review

1. Short and soft-field

 takeoffs and landings

2. Maximum performance

 operations

As assigned by flight instructor

Ground Instruction Flight Instruction Directed Practice*

1 Hour—CHECKOUT

1 Hour 1 Hour

1 Hour 1 Hour 1 Hour

1 Hour 1 Hour 1 Hour

* The directed practice indicated may be conducted solo or with a safety pilot at the discretion of the instructor.

Figure 11-12.Transition training syllabus.

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11-16

Ch 11.qxd 5/7/04 8:50 AM Page 11-16
MULTIENGINE FLIGHT

This chapter is devoted to the factors associated with

the operation of small multiengine airplanes. For the

purpose of this handbook, a “small” multiengine airplane is a reciprocating or turbopropeller-powered

airplane with a maximum certificated takeoff weight

of 12,500 pounds or less. This discussion assumes a

conventional design with two engines—one mounted

on each wing. Reciprocating engines are assumed

unless otherwise noted. The term “light-twin,”

although not formally defined in the regulations, is

used herein as a small multiengine airplane with a

maximum certificated takeoff weight of 6,000 pounds

or less.

There are several unique characteristics of multiengine

airplanes that make them worthy of a separate class rating. Knowledge of these factors and proficient flight

skills are a key to safe flight in these airplanes. This

chapter deals extensively with the numerous aspects of

one engine inoperative (OEI) flight. However, pilots

are strongly cautioned not to place undue emphasis

on mastery of OEI flight as the sole key to flying

multiengine airplanes safely. The inoperative engine

information that follows is extensive only because

this chapter emphasizes the differences between flying

multiengine airplanes as contrasted to single-engine

airplanes.

The modern, well-equipped multiengine airplane can

be remarkably capable under many circumstances. But,

as with single-engine airplanes, it must be flown prudently by a current and competent pilot to achieve the

highest possible level of safety.

This chapter contains information and guidance on the

performance of certain maneuvers and procedures in

small multiengine airplanes for the purposes of flight

training and pilot certification testing. The final

authority on the operation of a particular make and

model airplane, however, is the airplane manufacturer.

Both the flight instructor and the student should be

aware that if any of the guidance in this handbook conflicts with the airplane manufacturer’s recommended

procedures and guidance as contained in the FAAapproved Airplane Flight Manual and/or Pilot’s

Operating Handbook (AFM/POH), it is the airplane

manufacturer’s guidance and procedures that take

precedence.

GENERAL

The basic difference between operating a multiengine

airplane and a single-engine airplane is the potential

problem involving an engine failure. The penalties for

loss of an engine are twofold: performance and control.

The most obvious problem is the loss of 50 percent

of power, which reduces climb performance 80 to 90

percent, sometimes even more. The other is the control problem caused by the remaining thrust, which

is now asymmetrical. Attention to both these factors

is crucial to safe OEI flight. The performance and

systems redundancy of a multiengine airplane is a

safety advantage only to a trained and proficient

pilot.

TERMS AND DEFINITIONS

Pilots of single-engine airplanes are already familiar

with many performance “V” speeds and their definitions. Twin-engine airplanes have several additional

V speeds unique to OEI operation. These speeds are

differentiated by the notation “SE”, for single engine.

A review of some key V speeds and several new V

speeds unique to twin-engine airplanes follows.

• VR – Rotation speed. The speed at which back

pressure is applied to rotate the airplane to a takeoff attitude.

• VLOF – Lift-off speed. The speed at which the

airplane leaves the surface. (Note: some manufacturers reference takeoff performance data to

VR, others to VLOF.)

• VX – Best angle of climb speed. The speed at

which the airplane will gain the greatest altitude

for a given distance of forward travel.

• VXSE – Best angle-of-climb speed with one

engine inoperative.

• VY – Best rate of climb speed. The speed at

which the airplane will gain the most altitude for

a given unit of time.

• VYSE – Best rate-of-climb speed with one engine

inoperative. Marked with a blue radial line on

most airspeed indicators. Above the single-engine

absolute ceiling, VYSE yields the minimum rate of

sink.

• VSSE – Safe, intentional one-engine-inoperative

speed. Originally known as safe single-engine

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Ch 12.qxd 5/7/04 9:54 AM Page 12-1
speed. Now formally defined in Title 14 of the

Code of Federal Regulations (14 CFR) part 23,

Airworthiness Standards, and required to be

established and published in the AFM/POH. It is

the minimum speed to intentionally render the

critical engine inoperative.

• VMC – Minimum control speed with the critical

engine inoperative. Marked with a red radial line

on most airspeed indicators. The minimum speed

at which directional control can be maintained

under a very specific set of circumstances outlined

in 14 CFR part 23, Airworthiness Standards.

Under the small airplane certification regulations

currently in effect, the flight test pilot must be able

to (1) stop the turn that results when the critical

engine is suddenly made inoperative within 20°

of the original heading, using maximum rudder

deflection and a maximum of 5° bank, and (2)

thereafter, maintain straight flight with not

more than a 5° bank. There is no requirement in

this determination that the airplane be capable

of climbing at this airspeed. VMC only

addresses directional control. Further discussion of VMC as determined during airplane certification and demonstrated in pilot training

follows in minimum control airspeed (VMC)

demonstration. [Figure 12-1]

Figure 12-1. Airspeed indicator markings for a multiengine

airplane.

Unless otherwise noted, when V speeds are given in

the AFM/POH, they apply to sea level, standard day

conditions at maximum takeoff weight. Performance

speeds vary with aircraft weight, configuration, and

atmospheric conditions. The speeds may be stated in

statute miles per hour (m.p.h.) or knots (kts), and they

may be given as calibrated airspeeds (CAS) or indicated airspeeds (IAS). As a general rule, the newer

AFM/POHs show V speeds in knots indicated airspeed

(KIAS). Some V speeds are also stated in knots calibrated airspeed (KCAS) to meet certain regulatory

requirements. Whenever available, pilots should operate the airplane from published indicated airspeeds.

With regard to climb performance, the multiengine

airplane, particularly in the takeoff or landing configuration, may be considered to be a single-engine

airplane with its powerplant divided into two units.

There is nothing in 14 CFR part 23 that requires a

multiengine airplane to maintain altitude while in

the takeoff or landing configuration with one engine

inoperative. In fact, many twins are not required to

do this in any configuration, even at sea level.

The current 14 CFR part 23 single-engine climb

performance requirements for reciprocating enginepowered multiengine airplanes are as follows.

• More than 6,000 pounds maximum weight

and/or VSO more than 61 knots: the singleengine rate of climb in feet per minute (f.p.m.) at

5,000 feet MSL must be equal to at least .027

VSO

2. For airplanes type certificated February 4,

1991, or thereafter, the climb requirement is

expressed in terms of a climb gradient, 1.5 percent. The climb gradient is not a direct equivalent of the .027 VSO

2 formula. Do not confuse the

date of type certification with the airplane’s

model year. The type certification basis of many

multiengine airplanes dates back to CAR 3 (the

Civil Aviation Regulations, forerunner of today’s

Code of Federal Regulations).

• 6,000 pounds or less maximum weight and VSO

61 knots or less: the single-engine rate of climb

at 5,000 feet MSL must simply be determined.

The rate of climb could be a negative number.

There is no requirement for a single-engine

positive rate of climb at 5,000 feet or any other

altitude. For light-twins type certificated

February 4, 1991, or thereafter, the singleengine climb gradient (positive or negative) is

simply determined.

Rate of climb is the altitude gain per unit of time, while

climb gradient is the actual measure of altitude gained

per 100 feet of horizontal travel, expressed as a percentage. An altitude gain of 1.5 feet per 100 feet of

travel (or 15 feet per 1,000, or 150 feet per 10,000) is a

climb gradient of 1.5 percent.

There is a dramatic performance loss associated with

the loss of an engine, particularly just after takeoff.

Any airplane’s climb performance is a function of

thrust horsepower which is in excess of that required

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Ch 12.qxd 5/7/04 9:54 AM Page 12-2
for level flight. In a hypothetical twin with each engine

producing 200 thrust horsepower, assume that the total

level-flight thrust horsepower required is 175. In this

situation, the airplane would ordinarily have a reserve

of 225 thrust horsepower available for climb. Loss of

one engine would leave only 25 (200 minus 175) thrust

horsepower available for climb, a drastic reduction.

Sea level rate-of-climb performance losses of at least

80 to 90 percent, even under ideal circumstances, are

typical for multiengine airplanes in OEI flight.

OPERATION OF SYSTEMS

This section will deal with systems that are generally

found on multiengine airplanes. Multiengine airplanes

share many features with complex single-engine airplanes. There are certain systems and features covered

here, however, that are generally unique to airplanes

with two or more engines.

PROPELLERS

The propellers of the multiengine airplane may outwardly appear to be identical in operation to the

constant-speed propellers of many single-engine

airplanes, but this is not the case. The propellers of

multiengine airplanes are featherable, to minimize

drag in the event of an engine failure. Depending

upon single-engine performance, this feature often

permits continued flight to a suitable airport following

an engine failure. To feather a propeller is to stop

engine rotation with the propeller blades streamlined

with the airplane’s relative wind, thus to minimize

drag. [Figure 12-2]

Feathering is necessary because of the change in parasite drag with propeller blade angle. [Figure 12-3]

When the propeller blade angle is in the feathered

position, the change in parasite drag is at a minimum

and, in the case of a typical multiengine airplane, the

added parasite drag from a single feathered propeller

is a relatively small contribution to the airplane total

drag.

At the smaller blade angles near the flat pitch position,

the drag added by the propeller is very large. At these

small blade angles, the propeller windmilling at high

r.p.m. can create such a tremendous amount of drag that

the airplane may be uncontrollable. The propeller windmilling at high speed in the low range of blade angles

can produce an increase in parasite drag which may be

as great as the parasite drag of the basic airplane.

As a review, the constant-speed propellers on almost

all single-engine airplanes are of the non-feathering,

oil-pressure-to-increase-pitch design. In this design,

increased oil pressure from the propeller governor

drives the blade angle towards high pitch, low r.p.m.

In contrast, the constant-speed propellers installed

on most multiengine airplanes are full feathering,

counterweighted, oil-pressure-to-decrease-pitch

designs. In this design, increased oil pressure from the

propeller governor drives the blade angle towards low

pitch, high r.p.m.—away from the feather blade angle.

In effect, the only thing that keeps these propellers

from feathering is a constant supply of high pressure

engine oil. This is a necessity to enable propeller feathering in the event of a loss of oil pressure or a propeller

governor failure.

Full

Feathered

90°

High

Pitch

Low

Pitch

Figure 12-2. Feathered propeller.

Change in

Equivalent

Parasite

Drag

Propeller Blade Angle

0 15 30 45 60 90

PROPELLER DRAG CONTRIBUTION

Windmilling

Propeller

Stationary

Propeller Feathered

Position

Flat Blade Position

Figure 12-3. Propeller drag contribution.

12-3

Ch 12.qxd 5/7/04 9:54 AM Page 12-3
The aerodynamic forces alone acting upon a windmilling propeller tend to drive the blades to low pitch,

high r.p.m. Counterweights attached to the shank of

each blade tend to drive the blades to high pitch, low

r.p.m. Inertia, or apparent force called centrifugal force

acting through the counterweights is generally slightly

greater than the aerodynamic forces. Oil pressure from

the propeller governor is used to counteract the counterweights and drives the blade angles to low pitch,

high r.p.m. A reduction in oil pressure causes the r.p.m.

to be reduced from the influence of the counterweights.

[Figure 12-4]

To feather the propeller, the propeller control is

brought fully aft. All oil pressure is dumped from the

governor, and the counterweights drive the propeller

blades towards feather. As centrifugal force acting on

the counterweights decays from decreasing r.p.m.,

additional forces are needed to completely feather the

blades. This additional force comes from either a

spring or high pressure air stored in the propeller

dome, which forces the blades into the feathered position. The entire process may take up to 10 seconds.

Feathering a propeller only alters blade angle and stops

engine rotation. To completely secure the engine, the

pilot must still turn off the fuel (mixture, electric boost

pump, and fuel selector), ignition, alternator/generator,

and close the cowl flaps. If the airplane is pressurized,

there may also be an air bleed to close for the failed

engine. Some airplanes are equipped with firewall

shutoff valves that secure several of these systems

with a single switch.

Completely securing a failed engine may not be necessary or even desirable depending upon the failure

mode, altitude, and time available. The position of the

fuel controls, ignition, and alternator/generator

switches of the failed engine has no effect on aircraft

performance. There is always the distinct possibility

of manipulating the incorrect switch under conditions

of haste or pressure.

To unfeather a propeller, the engine must be rotated

so that oil pressure can be generated to move the

propeller blades from the feathered position. The

ignition is turned on prior to engine rotation with the

throttle at low idle and the mixture rich. With the

propeller control in a high r.p.m. position, the starter

is engaged. The engine will begin to windmill, start,

and run as oil pressure moves the blades out of

feather. As the engine starts, the propeller r.p.m.

should be immediately reduced until the engine has

had several minutes to warm up; the pilot should

monitor cylinder head and oil temperatures.

Should the r.p.m. obtained with the starter be insufficient to unfeather the propeller, an increase in airspeed

Counterweight

Action

Aerodynamic Force

Hydraulic Force

High-pressure oil enters the cylinder through the center of 

the propeller shaft and piston rod. The propeller control 

regulates the flow of high-pressure oil from a governor.

A hydraulic piston in the hub of the propeller is connected 

to each blade by a piston rod. This rod is attached to forks 

that slide over the pitch-change pin mounted in the root of 

each blade.

The oil pressure moves the piston toward the front of the 

cylinder, moving the piston rod and forks forward.

The forks push the pitch-change pin of each blade 

toward the front of the hub, causing the blades to twist 

toward the low-pitch position.

A nitrogen pressure charge or mechanical spring in 

the front of the hub opposes the oil pressure, and 

causes the propeller to move toward high-pitch.

Counterweights also cause the blades to move toward 

the high-pitch and feather positions. The counterweights counteract the aerodynamic twisting force that 

tries to move the blades toward a low-pitch angle.

Nitrogen Pressure or Spring

Force, and Counterweight Action

Figure 12-4. Pitch change forces.

12-4

Ch 12.qxd 5/7/04 9:54 AM Page 12-4
from a shallow dive will usually help. In any event, the

AFM/POH procedures should be followed for the

exact unfeathering procedure. Both feathering and

starting a feathered reciprocating engine on the ground

are strongly discouraged by manufacturers due to the

excessive stress and vibrations generated.

As just described, a loss of oil pressure from the propeller governor allows the counterweights, spring

and/or dome charge to drive the blades to feather.

Logically then, the propeller blades should feather

every time an engine is shut down as oil pressure falls

to zero. Yet, this does not occur. Preventing this is a

small pin in the pitch changing mechanism of the

propeller hub that will not allow the propeller blades

to feather once r.p.m. drops below approximately

800. The pin senses a lack of centrifugal force from

propeller rotation and falls into place, preventing the

blades from feathering. Therefore, if a propeller is to

be feathered, it must be done before engine r.p.m.

decays below approximately 800. On one popular

model of turboprop engine, the propeller blades do,

in fact, feather with each shutdown. This propeller is

not equipped with such centrifugally-operated pins,

due to a unique engine design.

An unfeathering accumulator is an optional device that

permits starting a feathered engine in flight without the

use of the electric starter. An accumulator is any device

that stores a reserve of high pressure. On multiengine

airplanes, the unfeathering accumulator stores a small

reserve of engine oil under pressure from compressed

air or nitrogen. To start a feathered engine in flight,

the pilot moves the propeller control out of the

feather position to release the accumulator pressure.

The oil flows under pressure to the propeller hub and

drives the blades toward the high r.p.m., low pitch

position, whereupon the propeller will usually begin

to windmill. (On some airplanes, an assist from the

electric starter may be necessary to initiate rotation

and completely unfeather the propeller.) If fuel and

ignition are present, the engine will start and run.

For airplanes used in training, this saves much electric starter and battery wear. High oil pressure from

the propeller governor recharges the accumulator

just moments after engine rotation begins.

PROPELLER SYNCHRONIZATION

Many multiengine airplanes have a propeller synchronizer (prop sync) installed to eliminate the annoying

“drumming” or “beat” of propellers whose r.p.m. are

close, but not precisely the same. To use prop sync, the

propeller r.p.m. are coarsely matched by the pilot and

the system is engaged. The prop sync adjusts the r.p.m.

of the “slave” engine to precisely match the r.p.m. of

the “master” engine, and then maintains that relationship. The prop sync should be disengaged when the

pilot selects a new propeller r.p.m., then re-engaged

after the new r.p.m. is set. The prop sync should always

be off for takeoff, landing, and single-engine operation. The AFM/POH should be consulted for system

description and limitations.

A variation on the propeller synchronizer is the propeller synchrophaser. Prop sychrophase acts much

like a synchronizer to precisely match r.p.m., but the

synchrophaser goes one step further. It not only

matches r.p.m. but actually compares and adjusts the

positions of the individual blades of the propellers in

their arcs. There can be significant propeller noise and

vibration reductions with a propeller synchrophaser.

From the pilot’s perspective, operation of a propeller

synchronizer and a propeller syncrophaser are very

similar. A synchrophaser is also commonly referred to

as prop sync, although that is not entirely correct

nomenclature from a technical standpoint.

As a pilot aid to manually synchronizing the

propellers, some twins have a small gauge mounted

in or by the tachometer(s) with a propeller symbol

on a disk that spins. The pilot manually fine tunes

the engine r.p.m. so as to stop disk rotation, thereby

synchronizing the propellers. This is a useful backup

to synchronizing engine r.p.m. using the audible

propeller beat. This gauge is also found installed

with most propeller synchronizer and synchrophase

systems. Some synchrophase systems use a knob for

the pilot to control the phase angle.

FUEL CROSSFEED

Fuel crossfeed systems are also unique to multiengine

airplanes. Using crossfeed, an engine can draw fuel

from a fuel tank located in the opposite wing.

On most multiengine airplanes, operation in the crossfeed mode is an emergency procedure used to extend

airplane range and endurance in OEI flight. There are

a few models that permit crossfeed as a normal, fuel

balancing technique in normal operation, but these are

not common. The AFM/POH will describe crossfeed

limitations and procedures, which vary significantly

among multiengine airplanes.

Checking crossfeed operation on the ground with a

quick repositioning of the fuel selectors does nothing

more than ensure freedom of motion of the handle. To

actually check crossfeed operation, a complete, functional crossfeed system check should be accomplished.

To do this, each engine should be operated from its

crossfeed position during the runup. The engines

should be checked individually, and allowed to run at

moderate power (1,500 r.p.m. minimum) for at least 1

minute to ensure that fuel flow can be established from

the crossfeed source. Upon completion of the check,

each engine should be operated for at least 1 minute at

moderate power from the main (takeoff) fuel tanks to

reconfirm fuel flow prior to takeoff.

12-5

Ch 12.qxd 5/7/04 9:54 AM Page 12-5
12-6

This suggested check is not required prior to every

flight. Infrequently used, however, crossfeed lines are

ideal places for water and debris to accumulate unless

they are used from time to time and drained using their

external drains during preflight. Crossfeed is ordinarily not used for completing single-engine flights when

an alternate airport is readily at hand, and it is never

used during takeoff or landings.

COMBUSTION HEATER

Combustion heaters are common on multiengine

airplanes. A combustion heater is best described as

a small furnace that burns gasoline to produce

heated air for occupant comfort and windshield

defogging. Most are thermostatically operated, and

have a separate hour meter to record time in service

for maintenance purposes. Automatic overtemperature

protection is provided by a thermal switch mounted on

the unit, which cannot be accessed in flight. This

requires the pilot or mechanic to actually visually

inspect the unit for possible heat damage in order to

reset the switch.

When finished with the combustion heater, a cool

down period is required. Most heaters require that outside air be permitted to circulate through the unit for at

least 15 seconds in flight, or that the ventilation fan be

operated for at least 2 minutes on the ground. Failure

to provide an adequate cool down will usually trip the

thermal switch and render the heater inoperative until

the switch is reset.

FLIGHT DIRECTOR/AUTOPILOT

Flight director/autopilot (FD/AP) systems are common

on the better-equipped multiengine airplanes. The

system integrates pitch, roll, heading, altitude, and

radio navigation signals in a computer. The outputs,

called computed commands, are displayed on a flight

command indicator, or FCI. The FCI replaces the

conventional attitude indicator on the instrument

panel. The FCI is occasionally referred to as a flight

director indicator (FDI), or as an attitude director

indicator (ADI). The entire flight director/autopilot

system is sometimes called an integrated flight control system (IFCS) by some manufacturers. Others

may use the term “automatic flight control system

(AFCS).”

The FD/AP system may be employed at three different

levels.

• Off (raw data).

• Flight director (computed commands).

• Autopilot.

With the system off, the FCI operates as an ordinary

attitude indicator. On most FCIs, the command bars

are biased out of view when the flight director is off.

The pilot maneuvers the airplane as though the system

were not installed.

To maneuver the airplane using the flight director, the

pilot enters the desired modes of operation (heading,

altitude, nav intercept, and tracking) on the FD/AP

mode controller. The computed flight commands are

then displayed to the pilot through either a single-cue

or dual-cue system in the FCI. On a single-cue system,

the commands are indicated by “V” bars. On a

dual-cue system, the commands are displayed on

two separate command bars, one for pitch and one

for roll. To maneuver the airplane using computed

commands, the pilot “flies” the symbolic airplane

of the FCI to match the steering cues presented.

On most systems, to engage the autopilot the flight

director must first be operating. At any time thereafter,

the pilot may engage the autopilot through the mode

controller. The autopilot then maneuvers the airplane

to satisfy the computed commands of the flight

director.

Like any computer, the FD/AP system will only do

what it is told. The pilot must ensure that it has been

properly programmed for the particular phase of flight

desired. The armed and/or engaged modes are usually

displayed on the mode controller or separate annunciator lights. When the airplane is being hand-flown, if

the flight director is not being used at any particular

moment, it should be off so that the command bars are

pulled from view.

Prior to system engagement, all FD/AP computer and

trim checks should be accomplished. Many newer

systems cannot be engaged without the completion of

a self-test. The pilot must also be very familiar with

various methods of disengagement, both normal and

emergency. System details, including approvals and

limitations, can be found in the supplements section

of the AFM/POH. Additionally, many avionics manufacturers can provide informative pilot operating

guides upon request.

YAW DAMPER

The yaw damper is a servo that moves the rudder in

response to inputs from a gyroscope or accelerometer

that detects yaw rate. The yaw damper minimizes

motion about the vertical axis caused by turbulence.

(Yaw dampers on sweptwing airplanes provide

another, more vital function of damping dutch roll

characteristics.) Occupants will feel a smoother ride,

particularly if seated in the rear of the airplane, when

the yaw damper is engaged. The yaw damper should

be off for takeoff and landing. There may be additional

restrictions against its use during single-engine operation. Most yaw dampers can be engaged independently

of the autopilot.

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12-7

ALTERNATOR/GENERATOR

Alternator or generator paralleling circuitry matches

the output of each engine’s alternator/generator so that

the electrical system load is shared equally between

them. In the event of an alternator/generator failure,

the inoperative unit can be isolated and the entire

electrical system powered from the remaining one.

Depending upon the electrical capacity of the alternator/generator, the pilot may need to reduce the

electrical load (referred to as load shedding) when

operating on a single unit. The AFM/POH will contain

system description and limitations.

NOSE BAGGAGE COMPARTMENT

Nose baggage compartments are common on multiengine

airplanes (and are even found on a few single-engine

airplanes). There is nothing strange or exotic about a

nose baggage compartment, and the usual guidance

concerning observation of load limits applies. They

are mentioned here in that pilots occasionally neglect

to secure the latches properly, and therein lies the

danger. When improperly secured, the door will open

and the contents may be drawn out, usually into the

propeller arc, and usually just after takeoff. Even when

the nose baggage compartment is empty, airplanes

have been lost when the pilot became distracted by the

open door. Security of the nose baggage compartment

latches and locks is a vital preflight item.

Most airplanes will continue to fly with a nose baggage door open. There may be some buffeting from

the disturbed airflow and there will be an increase in

noise. Pilots should never become so preoccupied

with an open door (of any kind) that they fail to fly

the airplane.

Inspection of the compartment interior is also an

important preflight item. More than one pilot has been

surprised to find a supposedly empty compartment

packed to capacity or loaded with ballast. The tow

bars, engine inlet covers, windshield sun screens, oil

containers, spare chocks, and miscellaneous small

hand tools that find their way into baggage compartments should be secured to prevent damage from

shifting in flight.

ANTI-ICING/DEICING

Anti-icing/deicing equipment is frequently installed on

multiengine airplanes and consists of a combination of

different systems. These may be classified as either

anti-icing or deicing, depending upon function. The

presence of anti-icing and deicing equipment, even

though it may appear elaborate and complete, does not

necessarily mean that the airplane is approved for

flight in icing conditions. The AFM/POH, placards,

and even the manufacturer should be consulted for

specific determination of approvals and limitations.

Anti-icing equipment is provided to prevent ice from

forming on certain protected surfaces. Anti-icing

equipment includes heated pitot tubes, heated or nonicing static ports and fuel vents, propeller blades with

electrothermal boots or alcohol slingers, windshields

with alcohol spray or electrical resistance heating,

windshield defoggers, and heated stall warning lift

detectors. On many turboprop engines, the “lip”

surrounding the air intake is heated either electrically

or with bleed air. In the absence of AFM/POH guidance

to the contrary, anti-icing equipment is actuated prior to

flight into known or suspected icing conditions.

Deicing equipment is generally limited to pneumatic

boots on wing and tail leading edges. Deicing equipment is installed to remove ice that has already formed

on protected surfaces. Upon pilot actuation, the boots

inflate with air from the pneumatic pumps to break off

accumulated ice. After a few seconds of inflation, they

are deflated back to their normal position with the

assistance of a vacuum. The pilot monitors the buildup

of ice and cycles the boots as directed in the

AFM/POH. An ice light on the left engine nacelle

allows the pilot to monitor wing ice accumulation at

night.

Other airframe equipment necessary for flight in icing

conditions includes an alternate induction air source

and an alternate static system source. Ice tolerant

antennas will also be installed.

In the event of impact ice accumulating over normal

engine air induction sources, carburetor heat (carbureted engines) or alternate air (fuel injected engines)

should be selected. Ice buildup on normal induction

sources can be detected by a loss of engine r.p.m. with

fixed-pitch propellers and a loss of manifold pressure

with constant-speed propellers. On some fuel injected

engines, an alternate air source is automatically

activated with blockage of the normal air source.

An alternate static system provides an alternate source

of static air for the pitot-static system in the unlikely

event that the primary static source becomes blocked.

In non-pressurized airplanes, most alternate static

sources are plumbed to the cabin. On pressurized airplanes, they are usually plumbed to a non-pressurized

baggage compartment. The pilot must activate the

alternate static source by opening a valve or a fitting in

the cockpit. Upon activation, the airspeed indicator,

altimeter, and the vertical speed indicator (VSI) will be

affected and will read somewhat in error. A correction

table is frequently provided in the AFM/POH.

Anti-icing/deicing equipment only eliminates ice from

the protected surfaces. Significant ice accumulations

may form on unprotected areas, even with proper use

of anti-ice and deice systems. Flight at high angles of

Ch 12.qxd 5/7/04 9:54 AM Page 12-7
12-8

attack or even normal climb speeds will permit significant ice accumulations on lower wing surfaces, which

are unprotected. Many AFM/POHs mandate minimum

speeds to be maintained in icing conditions. Degradation

of all flight characteristics and large performance losses

can be expected with ice accumulations. Pilots should

not rely upon the stall warning devices for adequate stall

warning with ice accumulations.

Ice will accumulate unevenly on the airplane. It will

add weight and drag (primarily drag), and decrease

thrust and lift. Even wing shape affects ice accumulation; thin airfoil sections are more prone to ice

accumulation than thick, highly-cambered sections.

For this reason certain surfaces, such as the horizontal

stabilizer, are more prone to icing than the wing. With

ice accumulations, landing approaches should be made

with a minimum wing flap setting (flap extension

increases the angle of attack of the horizontal stabilizer)

and with an added margin of airspeed. Sudden and large

configuration and airspeed changes should be avoided.

Unless otherwise recommended in the AFM/POH, the

autopilot should not be used in icing conditions.

Continuous use of the autopilot will mask trim and

handling changes that will occur with ice accumulation. Without this control feedback, the pilot may not

be aware of ice accumulation building to hazardous

levels. The autopilot will suddenly disconnect when it

reaches design limits and the pilot may find the airplane

has assumed unsatisfactory handling characteristics.

The installation of anti-ice/deice equipment on airplanes without AFM/POH approval for flight into icing

conditions is to facilitate escape when such conditions

are inadvertently encountered. Even with AFM/POH

approval, the prudent pilot will avoid icing conditions

to the maximum extent practicable, and avoid extended

flight in any icing conditions. No multiengine airplane

is approved for flight into severe icing conditions, and

none are intended for indefinite flight in continuous

icing conditions.

PERFORMANCE AND LIMITATIONS

Discussion of performance and limitations requires the

definition of several terms.

• Accelerate-stop distance is the runway length

required to accelerate to a specified speed (either

VR or VLOF, as specified by the manufacturer),

experience an engine failure, and bring the airplane to a complete stop.

• Accelerate-go distance is the horizontal distance required to continue the takeoff and climb

to 50 feet, assuming an engine failure at VR or

VLOF, as specified by the manufacturer.

• Climb gradient is a slope most frequently

expressed in terms of altitude gain per 100 feet

of horizontal distance, whereupon it is stated as

a percentage. A 1.5 percent climb gradient is an

altitude gain of one and one-half feet per 100 feet

of horizontal travel. Climb gradient may also be

expressed as a function of altitude gain per nautical mile, or as a ratio of the horizontal distance

to the vertical distance (50:1, for example).

Unlike rate of climb, climb gradient is affected

by wind. Climb gradient is improved with a

headwind component, and reduced with a tailwind component. [Figure 12-5]

• The all-engine service ceiling of multiengine

airplanes is the highest altitude at which the airplane can maintain a steady rate of climb of 100

f.p.m. with both engines operating. The airplane

has reached its absolute ceiling when climb is

no longer possible. 

• The single-engine service ceiling is reached

when the multiengine airplane can no longer

maintain a 50 f.p.m. rate of climb with one engine

inoperative, and its single-engine absolute ceiling when climb is no longer possible.

The takeoff in a multiengine airplane should be

planned in sufficient detail so that the appropriate

action is taken in the event of an engine failure. The

pilot should be thoroughly familiar with the airplane’s

performance capabilities and limitations in order to

make an informed takeoff decision as part of the preflight planning. That decision should be reviewed as

the last item of the “before takeoff” checklist.

In the event of an engine failure shortly after takeoff,

the decision is basically one of continuing flight or

landing, even off-airport. If single-engine climb

performance is adequate for continued flight, and

the airplane has been promptly and correctly configured, the climb after takeoff may be continued. If

single-engine climb performance is such that climb

is unlikely or impossible, a landing will have to be

made in the most suitable area. To be avoided above

all is attempting to continue flight when it is not

within the airplane’s performance capability to do

so. [Figure 12-6]

Takeoff planning factors include weight and balance,

airplane performance (both single and multiengine),

runway length, slope and contamination, terrain and

obstacles in the area, weather conditions, and pilot

proficiency. Most multiengine airplanes have

AFM/POH performance charts and the pilot should

be highly proficient in their use. Prior to takeoff, the

multiengine pilot should ensure that the weight and

balance limitations have been observed, the runway

Ch 12.qxd 5/7/04 9:54 AM Page 12-8
length is adequate, the normal flightpath will clear obstacles and terrain, and that a definitive course of action has

been planned in the event of an engine failure.

The regulations do not specifically require that the

runway length be equal to or greater than the accelerate-stop distance. Most AFM/POHs publish

accelerate-stop distances only as an advisory. It

becomes a limitation only when published in the

limitations section of the AFM/POH. Experienced

multiengine pilots, however, recognize the safety

margin of runway lengths in excess of the bare minimum required for normal takeoff. They will insist

on runway lengths of at least accelerate-stop distance as a matter of safety and good operating

practice.

50 ft Brake VR / VLOF

Release

Accelerate-Stop Distance

Accelerate-Go Distance

500 ft

Brake VLOF

Release

5,000 ft

10:1 or 10 Percent Climb Gradient

Figure 12-5. Accelerate-stop distance, accelerate-go distance, and climb gradient.

Figure 12-6. Area of decision.

12-9

VXSE

VYSE

Gear Up and Loss of One Engine

Best Rate of Climb

Best Angle of Climb

Decision Area

VR / VLOF

Brake

Release

ENGINE FAILURE AFTER LIFT-OFF

Ch 12.qxd 5/7/04 9:54 AM Page 12-9
The multiengine pilot must keep in mind that the

accelerate-go distance, as long as it is, has only

brought the airplane, under ideal circumstances, to a

point a mere 50 feet above the takeoff elevation. To

achieve even this meager climb, the pilot had to instantaneously recognize and react to an unanticipated

engine failure, retract the landing gear, identify and

feather the correct engine, all the while maintaining

precise airspeed control and bank angle as the airspeed

is nursed to VYSE. Assuming flawless airmanship thus

far, the airplane has now arrived at a point little more

than one wingspan above the terrain, assuming it was

absolutely level and without obstructions.

With (for the purpose of illustration) a net 150 f.p.m.

rate of climb at a 90-knot VYSE, it will take approximately 3 minutes to climb an additional 450 feet to reach

500 feet AGL. In doing so, the airplane will have

traveled an additional 5 nautical miles beyond the

original accelerate-go distance, with a climb gradient

of about 1.6 percent. A turn of any consequence, such

as to return to the airport, will seriously degrade the

already marginal climb performance.

Not all multiengine airplanes have published accelerate-go distances in their AFM/POH, and fewer still

publish climb gradients. When such information is

published, the figures will have been determined under

ideal flight testing conditions. It is unlikely that this

performance will be duplicated in service conditions.

The point of the foregoing is to illustrate the marginal

climb performance of a multiengine airplane that

suffers an engine failure shortly after takeoff, even

under ideal conditions. The prudent multiengine

pilot should pick a point in the takeoff and climb

sequence in advance. If an engine fails before this point,

the takeoff should be rejected, even if airborne, for a

landing on whatever runway or surface lies essentially

ahead. If an engine fails after this point, the pilot should

promptly execute the appropriate engine failure procedure and continue the climb, assuming the performance

capability exists. As a general recommendation, if the

landing gear has not been selected up, the takeoff

should be rejected, even if airborne.

As a practical matter for planning purposes, the option

of continuing the takeoff probably does not exist unless

the published single-engine rate-of-climb performance

is at least 100 to 200 f.p.m. Thermal turbulence, wind

gusts, engine and propeller wear, or poor technique in

airspeed, bank angle, and rudder control can easily

negate even a 200 f.p.m. rate of climb.

WEIGHT AND BALANCE

The weight and balance concept is no different than

that of a single-engine airplane. The actual execution,

however, is almost invariably more complex due to a

number of new loading areas, including nose and aft

baggage compartments, nacelle lockers, main fuel

tanks, aux fuel tanks, nacelle fuel tanks, and numerous

seating options in a variety of interior configurations.

The flexibility in loading offered by the multiengine

airplane places a responsibility on the pilot to address

weight and balance prior to each flight.

The terms “empty weight, licensed empty weight,

standard empty weight, and basic empty weight” as

they appear on the manufacturer’s original weight and

balance documents are sometimes confused by pilots.

In 1975, the General Aviation Manufacturers

Association (GAMA) adopted a standardized format

for AFM/POHs. It was implemented by most

manufacturers in model year 1976. Airplanes whose

manufacturers conform to the GAMA standards utilize

the following terminology for weight and balance:

Standard empty weight

+ Optional equipment

= Basic empty weight

Standard empty weight is the weight of the standard

airplane, full hydraulic fluid, unusable fuel, and full

oil. Optional equipment includes the weight of all

equipment installed beyond standard. Basic empty

weight is the standard empty weight plus optional

equipment. Note that basic empty weight includes no

usable fuel, but full oil.

Airplanes manufactured prior to the GAMA format

generally utilize the following terminology for weight

and balance, although the exact terms may vary somewhat:

Empty weight

+ Unusable fuel

= Standard empty weight

Standard empty weight

+ Optional equipment

= Licensed empty weight

Empty weight is the weight of the standard airplane,

full hydraulic fluid and undrainable oil. Unusable fuel

is the fuel remaining in the airplane not available to

the engines. Standard empty weight is the empty

weight plus unusable fuel. When optional equipment

is added to the standard empty weight, the result is

licensed empty weight. Licensed empty weight,

therefore, includes the standard airplane, optional

equipment, full hydraulic fluid, unusable fuel, and

undrainable oil.

The major difference between the two formats

(GAMA and the old) is that basic empty weight

includes full oil, and licensed empty weight does not.

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Oil must always be added to any weight and balance

utilizing a licensed empty weight.

When the airplane is placed in service, amended

weight and balance documents are prepared by appropriately rated maintenance personnel to reflect changes

in installed equipment. The old weight and balance

documents are customarily marked “superseded” and

retained in the AFM/POH. Maintenance personnel are

under no regulatory obligation to utilize the GAMA

terminology, so weight and balance documents

subsequent to the original may use a variety of

terms. Pilots should use care to determine whether

or not oil has to be added to the weight and balance

calculations or if it is already included in the figures

provided.

The multiengine airplane is where most pilots

encounter the term “zero fuel weight” for the first time.

Not all multiengine airplanes have a zero fuel weight

limitation published in their AFM/POH, but many do.

Zero fuel weight is simply the maximum allowable

weight of the airplane and payload, assuming there is

no usable fuel on board. The actual airplane is not

devoid of fuel at the time of loading, of course. This is

merely a calculation that assumes it was. If a zero fuel

weight limitation is published, then all weight in

excess of that figure must consist of usable fuel. The

purpose of a zero fuel weight is to limit load forces on

the wing spars with heavy fuselage loads.

Assume a hypothetical multiengine airplane with the

following weights and capacities:

Basic empty weight . . . . . . . . . . . . . . . . .3,200 lb.

Zero fuel weight . . . . . . . . . . . . . . . . . . . .4,400 lb.

Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.

Maximum usable fuel . . . . . . . . . . . . . . . .180 gal.

1. Calculate the useful load:

Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.

Basic empty weight . . . . . . . . . . . . . . . . .-3,200 lb.

Useful load . . . . . . . . . . . . . . . . . . . . . . . .2,000 lb.

The useful load is the maximum combination of usable

fuel, passengers, baggage, and cargo that the airplane

is capable of carrying.

2. Calculate the payload:

Zero fuel weight . . . . . . . . . . . . . . . . . . . . 4,400 lb.

Basic empty weight . . . . . . . . . . . . . . . . . -3,200 lb.

Payload . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,200 lb.

The payload is the maximum combination of passengers, baggage, and cargo that the airplane is capable

of carrying. A zero fuel weight, if published, is the

limiting weight.

3. Calculate the fuel capacity at maximum payload

(1,200 lb.):

Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.

Zero fuel weight . . . . . . . . . . . . . . . . . . .-4,400 lb.

Fuel allowed . . . . . . . . . . . . . . . . . . . . . . . .800 lb.

Assuming maximum payload, the only weight permitted in excess of the zero fuel weight must consist of

usable fuel. In this case, 133.3 gallons.

4. Calculate the payload at maximum fuel capacity

(180 gal.):

Basic empty weight . . . . . . . . . . . . . . . . .3,200 lb.

Maximum usable fuel . . . . . . . . . . . . . . .+1,080 lb.

Weight with max. fuel . . . . . . . . . . . . . . .4,280 lb.

Maximum takeoff weight . . . . . . . . . . . . .5,200 lb.

Weight with max. fuel . . . . . . . . . . . . . . .-4,280 lb.

Payload allowed . . . . . . . . . . . . . . . . . . . . .920 lb.

Assuming maximum fuel, the payload is the difference

between the weight of the fueled airplane and the maximum takeoff weight.

Some multiengine airplanes have a ramp weight,

which is in excess of the maximum takeoff weight. The

ramp weight is an allowance for fuel that would be

burned during taxi and runup, permitting a takeoff at

full maximum takeoff weight. The airplane must

weigh no more than maximum takeoff weight at the

beginning of the takeoff roll.

A maximum landing weight is a limitation against

landing at a weight in excess of the published value.

This requires preflight planning of fuel burn to ensure

that the airplane weight upon arrival at destination will

be at or below the maximum landing weight. In the

event of an emergency requiring an immediate landing, the pilot should recognize that the structural

margins designed into the airplane are not fully

available when over landing weight. An overweight

landing inspection may be advisable—the service

manual or manufacturer should be consulted.

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Although the foregoing problems only dealt with

weight, the balance portion of weight and balance

is equally vital. The flight characteristics of the

multiengine airplane will vary significantly with

shifts of the center of gravity (CG) within the

approved envelope.

At forward CGs, the airplane will be more stable, with

a slightly higher stalling speed, a slightly slower

cruising speed, and favorable stall characteristics.

At aft CGs, the airplane will be less stable, with a

slightly lower stalling speed, a slightly faster cruising

speed, and less desirable stall characteristics. Forward

CG limits are usually determined in certification by

elevator/stabilator authority in the landing roundout. Aft CG limits are determined by the minimum

acceptable longitudinal stability. It is contrary to the

airplane’s operating limitations and the Code of

Federal Regulations (CFR) to exceed any weight

and balance parameter.

Some multiengine airplanes may require ballast to

remain within CG limits under certain loading conditions. Several models require ballast in the aft baggage

compartment with only a student and instructor on

board to avoid exceeding the forward CG limit.

When passengers are seated in the aft-most seats of

some models, ballast or baggage may be required in

the nose baggage compartment to avoid exceeding

the aft CG limit. The pilot must direct the seating of

passengers and placement of baggage and cargo to

achieve a center of gravity within the approved

envelope. Most multiengine airplanes have general

loading recommendations in the weight and balance

section of the AFM/POH. When ballast is added, it

must be securely tied down and it must not exceed

the maximum allowable floor loading.

Some airplanes make use of a special weight and

balance plotter. It consists of several movable parts

that can be adjusted over a plotting board on which

the CG envelope is printed. The reverse side of the

typical plotter contains general loading recommendations for the particular airplane. A pencil line plot

can be made directly on the CG envelope imprinted

on the working side of the plotting board. This plot

can easily be erased and recalculated anew for each

flight. This plotter is to be used only for the make

and model airplane for which it was designed.

GROUND OPERATION

Good habits learned with single-engine airplanes are

directly applicable to multiengine airplanes for preflight and engine start. Upon placing the airplane in

motion to taxi, the new multiengine pilot will notice

several differences, however. The most obvious is

the increased wingspan and the need for even

greater vigilance while taxiing in close quarters.

Ground handling may seem somewhat ponderous

and the multiengine airplane will not be as nimble

as the typical two- or four-place single-engine airplane.

As always, use care not to ride the brakes by keeping

engine power to a minimum. One ground handling

advantage of the multiengine airplane over singleengine airplanes is the differential power capability.

Turning with an assist from differential power minimizes both the need for brakes during turns and the

turning radius.

The pilot should be aware, however, that making a

sharp turn assisted by brakes and differential power

can cause the airplane to pivot about a stationary

inboard wheel and landing gear. This is abuse for

which the airplane was not designed and should be

guarded against.

Unless otherwise directed by the AFM/POH, all

ground operations should be conducted with the cowl

flaps fully open. The use of strobe lights is normally

deferred until taxiing onto the active runway.

NORMAL AND CROSSWIND 

TAKEOFF AND CLIMB

With the “before takeoff” checklist complete and

air traffic control (ATC) clearance received, the airplane should be taxied into position on the runway

centerline. If departing from an airport without an

operating control tower, a careful check for

approaching aircraft should be made along with a

radio advisory on the appropriate frequency. Sharp

turns onto the runway combined with a rolling

takeoff are not a good operating practice and may

be prohibited by the AFM/POH due to the possibility

of “unporting” a fuel tank pickup. (The takeoff itself

may be prohibited by the AFM/POH under any circumstances below certain fuel levels.) The flight controls

should be positioned for a crosswind, if present.

Exterior lights such as landing and taxi lights, and

wingtip strobes should be illuminated immediately

prior to initiating the takeoff roll, day or night. If

holding in takeoff position for any length of time,

particularly at night, the pilot should activate all

exterior lights upon taxiing into position.

Takeoff power should be set as recommended in the

AFM/POH. With normally aspirated (non-turbocharged) engines, this will be full throttle. Full

throttle is also used in most turbocharged engines.

There are some turbocharged engines, however,

that require the pilot to set a specific power setting,

usually just below red line manifold pressure. This

yields takeoff power with less than full throttle travel.

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Turbocharged engines often require special consideration. Throttle motion with turbocharged engines

should be exceptionally smooth and deliberate. It is

acceptable, and may even be desirable, to hold the

airplane in position with brakes as the throttles are

advanced. Brake release customarily occurs after significant boost from the turbocharger is established. This

prevents wasting runway with slow, partial throttle

acceleration as the engine power is increased. If runway

length or obstacle clearance is critical, full power should

be set before brake release, as specified in the performance charts.

As takeoff power is established, initial attention should

be divided between tracking the runway centerline and

monitoring the engine gauges. Many novice multiengine pilots tend to fixate on the airspeed indicator

just as soon as the airplane begins its takeoff roll.

Instead, the pilot should confirm that both engines

are developing full-rated manifold pressure and

r.p.m., and that the fuel flows, fuel pressures, exhaust

gas temperatures (EGTs), and oil pressures are matched

in their normal ranges. A directed and purposeful scan

of the engine gauges can be accomplished well before

the airplane approaches rotation speed. If a crosswind is

present, the aileron displacement in the direction of the

crosswind may be reduced as the airplane accelerates.

The elevator/stabilator control should be held neutral

throughout.

Full rated takeoff power should be used for every takeoff. Partial power takeoffs are not recommended.

There is no evidence to suggest that the life of modern

reciprocating engines is prolonged by partial power

takeoffs. Paradoxically, excessive heat and engine

wear can occur with partial power as the fuel metering

system will fail to deliver the slightly over-rich

mixture vital for engine cooling during takeoff.

There are several key airspeeds to be noted during the

takeoff and climb sequence in any twin. The first speed

to consider is VMC. If an engine fails below VMC while

the airplane is on the ground, the takeoff must be

rejected. Directional control can only be maintained by

promptly closing both throttles and using rudder and

brakes as required. If an engine fails below VMC while

airborne, directional control is not possible with the

remaining engine producing takeoff power. On takeoffs, therefore, the airplane should never be airborne

before the airspeed reaches and exceeds VMC. Pilots

should use the manufacturer’s recommended rotation

speed (VR) or lift-off speed (VLOF). If no such speeds

are published, a minimum of VMC plus 5 knots should

be used for VR.

The rotation to a takeoff pitch attitude is done

smoothly. With a crosswind, the pilot should ensure

that the landing gear does not momentarily touch the

runway after the airplane has lifted off, as a side drift

will be present. The rotation may be accomplished

more positively and/or at a higher speed under these

conditions. However, the pilot should keep in mind

that the AFM/POH performance figures for acceleratestop distance, takeoff ground roll, and distance to clear

an obstacle were calculated at the recommended VR

and/or VLOF speed.

After lift-off, the next consideration is to gain altitude as rapidly as possible. After leaving the ground,

altitude gain is more important than achieving an

excess of airspeed. Experience has shown that

excessive speed cannot be effectively converted into

altitude in the event of an engine failure. Altitude

gives the pilot time to think and react. Therefore, the

airplane should be allowed to accelerate in a shallow

climb to attain VY, the best all-engine rate-of-climb

speed. VY should then be maintained until a safe

single-engine maneuvering altitude, considering

terrain and obstructions, is achieved.

To assist the pilot in takeoff and initial climb profile,

some AFM/POHs give a “50-foot” or “50-foot barrier”

speed to use as a target during rotation, lift-off, and

acceleration to VY.

Landing gear retraction should normally occur after a

positive rate of climb is established. Some

AFM/POHs direct the pilot to apply the wheel brakes

momentarily after lift-off to stop wheel rotation prior

to landing gear retraction. If flaps were extended for

takeoff, they should be retracted as recommended in

the AFM/POH.

Once a safe single-engine maneuvering altitude has

been reached, typically a minimum of 400-500 feet

AGL, the transition to an enroute climb speed should

be made. This speed is higher than VY and is usually

maintained to cruising altitude. Enroute climb speed

gives better visibility, increased engine cooling, and a

higher groundspeed. Takeoff power can be reduced, if

desired, as the transition to enroute climb speed is

made.

Some airplanes have a climb power setting published

in the AFM/POH as a recommendation (or sometimes

as a limitation), which should then be set for enroute

climb. If there is no climb power setting published, it is

customary, but not a requirement, to reduce manifold

pressure and r.p.m. somewhat for enroute climb. The

propellers are usually synchronized after the first

power reduction and the yaw damper, if installed,

engaged. The AFM/POH may also recommend leaning

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12-14

the mixtures during climb. The “climb” checklist

should be accomplished as traffic and work load allow.

[Figure 12-7]

LEVEL OFF AND CRUISE

Upon leveling off at cruising altitude, the pilot should

allow the airplane to accelerate at climb power until

cruising airspeed is achieved, then cruise power and

r.p.m. should be set. To extract the maximum cruise

performance from any airplane, the power setting

tables provided by the manufacturer should be closely

followed. If the cylinder head and oil temperatures are

within their normal ranges, the cowl flaps may be

closed. When the engine temperatures have stabilized,

the mixtures may be leaned per AFM/POH recommendations. The remainder of the “cruise” checklist should

be completed by this point.

Fuel management in multiengine airplanes is often

more complex than in single-engine airplanes.

Depending upon system design, the pilot may need to

select between main tanks and auxiliary tanks, or

even employ fuel transfer from one tank to another.

In complex fuel systems, limitations are often found

restricting the use of some tanks to level flight only,

or requiring a reserve of fuel in the main tanks for

descent and landing. Electric fuel pump operation can

vary widely among different models also, particularly

during tank switching or fuel transfer. Some fuel

pumps are to be on for takeoff and landing; others are

to be off. There is simply no substitute for thorough

systems and AFM/POH knowledge when operating

complex aircraft.

NORMAL APPROACH AND LANDING

Given the higher cruising speed (and frequently, altitude) of multiengine airplanes over most single-engine

airplanes, the descent must be planned in advance. A

hurried, last minute descent with power at or near idle

is inefficient and can cause excessive engine cooling.

It may also lead to passenger discomfort, particularly

if the airplane is unpressurized. As a rule of thumb, if

terrain and passenger conditions permit, a maximum

of a 500 f.p.m. rate of descent should be planned.

Pressurized airplanes can plan for higher descent rates,

if desired.

In a descent, some airplanes require a minimum EGT,

or may have a minimum power setting or cylinder

head temperature to observe. In any case, combinations of very low manifold pressure and high

r.p.m. settings are strongly discouraged by engine

manufacturers. If higher descent rates are necessary,

the pilot should consider extending partial flaps or

lowering the landing gear before retarding the power

excessively. The “descent” checklist should be initiated

upon leaving cruising altitude and completed before

arrival in the terminal area. Upon arrival in the terminal

area, pilots are encouraged to turn on their landing

and recognition lights when operating below

10,000 feet, day or night, and especially when

operating within 10 miles of any airport or in conditions

of reduced visibility.

Figure 12-7.Takeoff and climb profile.

Lift-off

Published VR or VLOF

if not Published,

VMC + 5 Knots

Positive Rate - Gear Up 

Climb at VY

500 ft

1. Accelerate to Cruise Climb

2. Set Climb Power

3. Climb Checklist

Ch 12.qxd 5/7/04 9:54 AM Page 12-14
The traffic pattern and approach are typically flown at

somewhat higher indicated airspeeds in a multiengine

airplane contrasted to most single-engine airplanes.

The pilot may allow for this through an early start on

the “before landing” checklist. This provides time for

proper planning, spacing, and thinking well ahead of

the airplane. Many multiengine airplanes have partial

flap extension speeds above VFE, and partial flaps can

be deployed prior to traffic pattern entry. Normally, the

landing gear should be selected and confirmed down

when abeam the intended point of landing as the downwind leg is flown. [Figure 12-8]

The Federal Aviation Administration (FAA) recommends a stabilized approach concept. To the greatest

extent practical, on final approach and within 500 feet

AGL, the airplane should be on speed, in trim, configured for landing, tracking the extended centerline

of the runway, and established in a constant angle of

descent towards an aim point in the touchdown

zone. Absent unusual flight conditions, only minor

corrections will be required to maintain this approach

to the roundout and touchdown.

The final approach should be made with power and

at a speed recommended by the manufacturer; if a recommended speed is not furnished, the speed should be

no slower than the single-engine best rate-of-climb

speed (VYSE) until short final with the landing assured,

but in no case less than critical engine-out minimum

control speed (VMC). Some multiengine pilots prefer

to delay full flap extension to short final with the landing assured. This is an acceptable technique with appropriate experience and familiarity with the airplane.

In the roundout for landing, residual power is gradually reduced to idle. With the higher wing loading of

multiengine airplanes and with the drag from two

windmilling propellers, there will be minimal float.

Full stall landings are generally undesirable in twins. The

airplane should be held off as with a high performance

single-engine model, allowing touchdown of the main

wheels prior to a full stall.

Under favorable wind and runway conditions, the

nosewheel can be held off for best aerodynamic braking. Even as the nosewheel is gently lowered to the

runway centerline, continued elevator back pressure

will greatly assist the wheel brakes in stopping the

airplane.

If runway length is critical, or with a strong crosswind,

or if the surface is contaminated with water, ice or

snow, it is undesirable to rely solely on aerodynamic

braking after touchdown. The full weight of the airplane should be placed on the wheels as soon as

practicable. The wheel brakes will be more effective

than aerodynamic braking alone in decelerating the

airplane.

Once on the ground, elevator back pressure should be

used to place additional weight on the main wheels and

to add additional drag. When necessary, wing flap

retraction will also add additional weight to the wheels

and improve braking effectivity. Flap retraction during

the landing rollout is discouraged, however, unless

there is a clear, operational need. It should not be

accomplished as routine with each landing.

Some multiengine airplanes, particularly those of the

cabin class variety, can be flown through the roundout

and touchdown with a small amount of power. This is

an acceptable technique to prevent high sink rates and

to cushion the touchdown. The pilot should keep in

mind, however, that the primary purpose in landing is

to get the airplane down and stopped. This technique

should only be attempted when there is a generous

Approaching Traffic Pattern

1. Descent Checklist

2. Reduce to Traffic Pattern Airspeed and Altitude

Downwind

1. Flaps - Approach Position

2. Gear Down

3. Before Landing Checklist

Base Leg

1. Gear-Check Down

2. Check for Conflicting

 Traffic

Final

1. Gear-Check Down

2. Flaps-Landing Position

Airspeed- 1.3 Vs0 or

Manufacturers Recommended

Figure 12-8. Normal two-engine approach and landing.

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12-16

margin of runway length. As propeller blast flows

directly over the wings, lift as well as thrust is produced.

The pilot should taxi clear of the runway as soon as

speed and safety permit, and then accomplish the “after

landing” checklist. Ordinarily, no attempt should be

made to retract the wing flaps or perform other checklist duties until the airplane has been brought to a halt

when clear of the active runway. Exceptions to this

would be the rare operational needs discussed above,

to relieve the weight from the wings and place it on the

wheels. In these cases, AFM/POH guidance should be

followed. The pilot should not indiscriminately reach

out for any switch or control on landing rollout. An

inadvertent landing gear retraction while meaning to

retract the wing flaps may result.

CROSSWIND APPROACH 

AND LANDING

The multiengine airplane is often easier to land in a

crosswind than a single-engine airplane due to its

higher approach and landing speed. In any event, the

principles are no different between singles and twins.

Prior to touchdown, the longitudinal axis must be

aligned with the runway centerline to avoid landing

gear side loads.

The two primary methods, crab and wing-low, are

typically used in conjunction with each other. As

soon as the airplane rolls out onto final approach, the

crab angle to track the extended runway centerline is

established. This is coordinated flight with adjustments to heading to compensate for wind drift either

left or right. Prior to touchdown, the transition to a

sideslip is made with the upwind wing lowered and

opposite rudder applied to prevent a turn. The airplane

touches down on the landing gear of the upwind wing

first, followed by that of the downwind wing, and

then the nose gear. Follow-through with the flight

controls involves an increasing application of aileron

into the wind until full control deflection is reached.

The point at which the transition from the crab to the

sideslip is made is dependent upon pilot familiarity

with the airplane and experience. With high skill and

experience levels, the transition can be made during

the roundout just before touchdown. With lesser skill

and experience levels, the transition is made at

increasing distances from the runway. Some multiengine airplanes (as some single-engine airplanes)

have AFM/POH limitations against slips in excess of

a certain time period; 30 seconds, for example. This is

to prevent engine power loss from fuel starvation as

the fuel in the tank of the lowered wing flows towards

the wingtip, away from the fuel pickup point. This

time limit must be observed if the wing-low method

is utilized.

Some multiengine pilots prefer to use differential

power to assist in crosswind landings. The asymmetrical thrust produces a yawing moment little

different from that produced by the rudder. When

the upwind wing is lowered, power on the upwind

engine is increased to prevent the airplane from

turning. This alternate technique is completely

acceptable, but most pilots feel they can react to

changing wind conditions quicker with rudder and

aileron than throttle movement. This is especially

true with turbocharged engines where the throttle

response may lag momentarily. The differential

power technique should be practiced with an

instructor familiar with it before being attempted

alone.

SHORT-FIELD TAKEOFF AND CLIMB

The short-field takeoff and climb differs from the

normal takeoff and climb in the airspeeds and initial

climb profile. Some AFM/POHs give separate

short-field takeoff procedures and performance

charts that recommend specific flap settings and airspeeds. Other AFM/POHs do not provide separate

short-field procedures. In the absence of such specific

procedures, the airplane should be operated only as

recommended in the AFM/POH. No operations should

be conducted contrary to the recommendations in the

AFM/POH.

On short-field takeoffs in general, just after rotation

and lift-off, the airplane should be allowed to accelerate to VX, making the initial climb over obstacles at

VX and transitioning to VY as obstacles are cleared.

[Figure 12-9]

Figure 12-9. Short-field takeoff and climb.

VX

VY

50 ft

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12-17

When partial flaps are recommended for short-field

takeoffs, many light-twins have a strong tendency to

become airborne prior to VMC plus 5 knots. Attempting

to prevent premature lift-off with forward elevator

pressure results in wheelbarrowing. To prevent this,

allow the airplane to become airborne, but only a few

inches above the runway. The pilot should be prepared

to promptly abort the takeoff and land in the event of

engine failure on takeoff with landing gear and flaps

extended at airspeeds below VX.

Engine failure on takeoff, particularly with obstructions, is compounded by the low airspeeds and steep

climb attitudes utilized in short-field takeoffs. VX and

VXSE are often perilously close to VMC, leaving scant

margin for error in the event of engine failure as VXSE

is assumed. If flaps were used for takeoff, the engine

failure situation becomes even more critical due to the

additional drag incurred. If VX is less than 5 knots

higher than VMC, give strong consideration to reducing

useful load or using another runway in order to

increase the takeoff margins so that a short-field

technique will not be required.

SHORT-FIELD APPROACH 

AND LANDING

The primary elements of a short-field approach and

landing do not differ significantly from a normal

approach and landing. Many manufacturers do not

publish short-field landing techniques or performance

charts in the AFM/POH. In the absence of specific

short-field approach and landing procedures, the

airplane should be operated as recommended in the

AFM/POH. No operations should be conducted

contrary to the AFM/POH recommendations.

The emphasis in a short-field approach is on configuration (full flaps), a stabilized approach with a constant

angle of descent, and precise airspeed control. As part

of a short-field approach and landing procedure,

some AFM/POHs recommend a slightly slower than

normal approach airspeed. If no such slower speed is

published, use the AFM/POH-recommended normal

approach speed.

Full flaps are used to provide the steepest approach

angle. If obstacles are present, the approach should be

planned so that no drastic power reductions are

required after they are cleared. The power should be

smoothly reduced to idle in the roundout prior to

touchdown. Pilots should keep in mind that the propeller blast blows over the wings, providing some lift

in addition to thrust. Significantly reducing power just

after obstacle clearance usually results in a sudden,

high sink rate that may lead to a hard landing.

After the short-field touchdown, maximum stopping

effort is achieved by retracting the wing flaps, adding

back pressure to the elevator/stabilator, and applying

heavy braking. However, if the runway length permits,

the wing flaps should be left in the extended position

until the airplane has been stopped clear of the runway.

There is always a significant risk of retracting the landing gear instead of the wing flaps when flap retraction

is attempted on the landing rollout.

Landing conditions that involve either a short-field,

high-winds or strong crosswinds are just about the only

situations where flap retraction on the landing rollout

should be considered. When there is an operational

need to retract the flaps just after touchdown, it must

be done deliberately, with the flap handle positively

identified before it is moved.

GO-AROUND

When the decision to go around is made, the throttles

should be advanced to takeoff power. With adequate

airspeed, the airplane should be placed in a climb pitch

attitude. These actions, which are accomplished

simultaneously, will arrest the sink rate and place the

airplane in the proper attitude for transition to a

climb. The initial target airspeed will be VY, or VX if

obstructions are present. With sufficient airspeed, the

flaps should be retracted from full to an intermediate

position and the landing gear retracted when there is

a positive rate of climb and no chance of runway

contact. The remaining flaps should then be

retracted. [Figure 12-10]

Figure 12-10. Go-around procedure.

Retract Remaining

Flaps Positive Rate

of Climb, Retract

Gear, Climb

at VY

500'

Cruise Climb

Timely Decision to

Make Go-Around Apply Max Power

Adjust Pitch Attitude

to Arrest Sink Rate

Flaps to

Intermediate

Ch 12.qxd 5/7/04 9:54 AM Page 12-17
12-18

If the go-around was initiated due to conflicting traffic

on the ground or aloft, the pilot should maneuver to the

side, so as to keep the conflicting traffic in sight. This

may involve a shallow bank turn to offset and then parallel the runway/landing area.

If the airplane was in trim for the landing approach

when the go-around was commenced, it will soon require

a great deal of forward elevator/stabilator pressure as the

airplane accelerates away in a climb. The pilot should

apply appropriate forward pressure to maintain the

desired pitch attitude. Trim should be commenced immediately. The “balked landing” checklist should be

reviewed as work load permits.

Flaps should be retracted before the landing gear for

two reasons. First, on most airplanes, full flaps produce

more drag than the extended landing gear. Secondly,

the airplane will tend to settle somewhat with flap

retraction, and the landing gear should be down in the

event of an inadvertent, momentary touchdown.

Many multiengine airplanes have a landing gear retraction speed significantly less than the extension speed.

Care should be exercised during the go-around not to

exceed the retraction speed. If the pilot desires to

return for a landing, it is essential to re-accomplish the

entire “before landing” checklist. An interruption to a

pilot’s habit patterns, such as a go-around, is a classic

scenario for a subsequent gear up landing.

The preceding discussion of go-arounds assumes that

the maneuver was initiated from normal approach

speeds or faster. If the go-around was initiated from a

low airspeed, the initial pitch up to a climb attitude must

be tempered with the necessity of maintaining adequate

flying speed throughout the maneuver. Examples of

where this applies include go-arounds initiated from the

landing roundout or recovery from a bad bounce as well

as a go-around initiated due to an inadvertent approach

to a stall. The first priority is always to maintain control

and obtain adequate flying speed. A few moments of

level or near level flight may be required as the airplane

accelerates up to climb speed.

REJECTED TAKEOFF

A takeoff can be rejected for the same reasons a takeoff

in a single-engine airplane would be rejected. Once the

decision to reject a takeoff is made, the pilot should

promptly close both throttles and maintain directional

control with the rudder, nosewheel steering, and

brakes. Aggressive use of rudder, nosewheel steering,

and brakes may be required to keep the airplane on

the runway. Particularly, if an engine failure is not

immediately recognized and accompanied by

prompt closure of both throttles. However, the primary objective is not necessarily to stop the airplane

in the shortest distance, but to maintain control of

the airplane as it decelerates. In some situations, it

may be preferable to continue into the overrun area

under control, rather than risk directional control loss,

landing gear collapse, or tire/brake failure in an

attempt to stop the airplane in the shortest possible

distance. 

ENGINE FAILURE AFTER LIFT-OFF

A takeoff or go-around is the most critical time to suffer an engine failure. The airplane will be slow, close

to the ground, and may even have landing gear and

flaps extended. Altitude and time will be minimal.

Until feathered, the propeller of the failed engine will

be windmilling, producing a great deal of drag and

yawing tendency. Airplane climb performance will be

marginal or even non-existent, and obstructions may

lie ahead. Add the element of surprise and the need for

a plan of action before every takeoff is obvious.

With loss of an engine, it is paramount to maintain

airplane control and comply with the manufacturer’s

recommended emergency procedures. Complete failure of one engine shortly after takeoff can be broadly

categorized into one of three following scenarios.

1. Landing gear down. [Figure 12-11] If the

engine failure occurs prior to selecting the landing gear to the UP position, close both throttles

and land on the remaining runway or overrun.

Depending upon how quickly the pilot reacts to

the sudden yaw, the airplane may run off the

side of the runway by the time action is taken.

There are really no other practical options. As

discussed earlier, the chances of maintaining

directional control while retracting the flaps (if

extended), landing gear, feathering the propeller,

and accelerating are minimal. On some airplanes

with a single-engine-driven hydraulic pump,

failure of that engine means the only way to

raise the landing gear is to allow the engine to

windmill or to use a hand pump. This is not a

viable alternative during takeoff.

2. Landing gear control selected up, singleengine climb performance inadequate.

[Figure 12-12] When operating near or above

the single-engine ceiling and an engine failure is

experienced shortly after lift-off, a landing must

be accomplished on whatever essentially lies

ahead. There is also the option of continuing

ahead, in a descent at VYSE with the remaining

engine producing power, as long as the pilot

is not tempted to remain airborne beyond the

airplane’s performance capability. Remaining

airborne, bleeding off airspeed in a futile

attempt to maintain altitude is almost invariably

fatal. Landing under control is paramount. The

greatest hazard in a single-engine takeoff is

attempting to fly when it is not within the perCh 12.qxd 5/7/04 9:54 AM Page 12-18
12-19

formance capability of the airplane to do so. An

accident is inevitable.

Analysis of engine failures on takeoff reveals a very

high success rate of off-airport engine inoperative

landings when the airplane is landed under control.

Analysis also reveals a very high fatality rate in stallspin accidents when the pilot attempts flight beyond

the performance capability of the airplane.

As mentioned previously, if the airplane’s landing gear

retraction mechanism is dependent upon hydraulic

pressure from a certain engine-driven pump, failure

of that engine can mean a loss of hundreds of feet of

altitude as the pilot either windmills the engine to

provide hydraulic pressure to raise the gear or raises

it manually with a backup pump.

3. Landing gear control selected up, singleengine climb performance adequate. [Figure

12-13] If the single-engine rate of climb is

adequate, the procedures for continued flight

should be followed. There are four areas of

concern: control, configuration, climb, and

checklist.

• CONTROL— The first consideration following

engine failure during takeoff is control of the airplane. Upon detecting an engine failure, aileron

should be used to bank the airplane and rudder

pressure applied, aggressively if necessary, to

counteract the yaw and roll from asymmetrical

thrust. The control forces, particularly on the

rudder, may be high. The pitch attitude for VYSE

will have to be lowered from that of VY.

Figure 12-11. Engine failure on takeoff, landing gear down.

If Engine Failure Occurs at

or Before Lift-off, Abort the

Takeoff.

If Failure of Engine Occurs After Lift-off:

1. Maintain Directional Control

2. Close Both Throttles

Figure 12-12. Engine failure on takeoff, inadequate climb performance.

Liftoff

Engine Failure

Descend at VYSE

Land Under Control

On or Off Runway

Over Run Area

Ch 12.qxd 5/7/04 9:54 AM Page 12-19
At least 5° of bank should be used, if necessary,

to stop the yaw and maintain directional control.

This initial bank input is held only momentarily,

just long enough to establish or ensure directional control. Climb performance suffers when

bank angles exceed approximately 2 or 3°, but

obtaining and maintaining VYSE and directional

control are paramount. Trim should be adjusted

to lower the control forces.

• CONFIGURATION—The memory items from

the “engine failure after takeoff” checklist

[Figure 12-14] should be promptly executed to

configure the airplane for climb. The specific

procedures to follow will be found in the

AFM/POH and checklist for the particular airplane. Most will direct the pilot to assume VYSE,

set takeoff power, retract the flaps and landing

gear, identify, verify, and feather the failed

engine. (On some airplanes, the landing gear is

to be retracted before the flaps.)

The “identify” step is for the pilot to initially

identify the failed engine. Confirmation on the

engine gauges may or may not be possible,

depending upon the failure mode. Identification

should be primarily through the control inputs

required to maintain straight flight, not the

engine gauges. The “verify” step directs the pilot

to retard the throttle of the engine thought to have

failed. No change in performance when the suspected throttle is retarded is verification that the

correct engine has been identified as failed. The

corresponding propeller control should be

brought fully aft to feather the engine.

• CLIMB—As soon as directional control is established and the airplane configured for climb, the

bank angle should be reduced to that producing

best climb performance. Without specific

guidance for zero sideslip, a bank of 2° and

one-third to one-half ball deflection on the

slip/skid indicator is suggested. VYSE is maintained with pitch control. As turning flight

reduces climb performance, climb should be

made straight ahead, or with shallow turns to

avoid obstacles, to an altitude of at least 400

feet AGL before attempting a return to

the airport.

Obstruction Clearance

Altitude or Above

At 500' or Obstruction Clearance Altitude:

7. Engine Failure Checklist

 Circle and Land

3. Drag - Reduce - Gear, Flaps

4. Identify - Inoperative Engine

5. Verify - Inoperative Engine

6. Feather - Inoperative Engine

If Failure of Engine Occurs After Liftoff:

1. Maintain Directional Control - VYSE, 

 Heading, Bank into Operating Engine

2. Power - Increase or Set for Takeoff

Figure 12-13. Landing gear up—adequate climb performance.

Figure 12-14.Typical “engine failure after takeoff” emergency

checklist.

12-20

 ENGINE FAILURE AFTER TAKEOFF

Airspeed . . . . . . . . . . . . . . . . . . . Maintain VYSE

Mixtures . . . . . . . . . . . . . . . . . . . RICH

Propellers . . . . . . . . . . . . . . . . . .HIGH RPM

Throttles . . . . . . . . . . . . . . . . . . . FULL POWER

Flaps . . . . . . . . . . . . . . . . . . . . . . . UP

Landing Gear . . . . . . . . . . . . . . . UP

Identify . . . . . . . . . . . . . . . . . . . . Determine failed

engine

Verify Close throttle of

failed engine

Propeller . . . . . . . . . . . . . . . . . . . FEATHER

Trim Tabs . . . . . . . . . . . . . . . . . . . ADJUST

Failed Engine . . . . . . . . . . . . . . . SECURE

As soon as practical . . . . . . . . . . LAND

Bold - faced items require immediate action and 

are to be accomplished from memory.

. . . . . . . . . . . . . . . . . . . . . . . .

Ch 12.qxd 5/7/04 9:55 AM Page 12-20
12-21

• CHECKLIST—Having accomplished the

memory items from the “engine failure after

takeoff” checklist, the printed copy should be

reviewed as time permits. The “securing failed

engine” checklist [Figure 12-15] should then be

accomplished. Unless the pilot suspects an

engine fire, the remaining items should be

accomplished deliberately and without undue

haste. Airplane control should never be sacrificed

to execute the remaining checklists. The priority

items have already been accomplished from

memory.

Figure 12-15. Typical “securing failed engine” emergency

checklist.

Other than closing the cowl flap of the failed engine,

none of these items, if left undone, adversely affects

airplane climb performance. There is a distinct possibility

of actuating an incorrect switch or control if the procedure is rushed. The pilot should concentrate on flying

the airplane and extracting maximum performance. If

ATC facilities are available, an emergency should be

declared.

The memory items in the “engine failure after takeoff”

checklist may be redundant with the airplane’s existing

configuration. For example, in the third takeoff scenario,

the gear and flaps were assumed to already be retracted,

yet the memory items included gear and flaps. This is

not an oversight. The purpose of the memory items is

to either initiate the appropriate action or to confirm

that a condition exists. Action on each item may not

be required in all cases. The memory items also

apply to more than one circumstance. In an engine

failure from a go-around, for example, the landing

gear and flaps would likely be extended when the

failure occurred.

The three preceding takeoff scenarios all include the

landing gear as a key element in the decision to land or

continue. With the landing gear selector in the DOWN

position, for example, continued takeoff and climb is

not recommended. This situation, however, is not justification to retract the landing gear the moment the

airplane lifts off the surface on takeoff as a normal

procedure. The landing gear should remain selected

down as long as there is usable runway or overrun

available to land on. The use of wing flaps for takeoff

virtually eliminates the likelihood of a single-engine

climb until the flaps are retracted.

There are two time-tested memory aids the pilot may

find useful in dealing with engine-out scenarios. The

first, “Dead foot–dead engine” is used to assist in identifying the failed engine. Depending on the failure

mode, the pilot won’t be able to consistently identify

the failed engine in a timely manner from the engine

gauges. In maintaining directional control, however,

rudder pressure will be exerted on the side (left or right)

of the airplane with the operating engine. Thus, the

“dead foot” is on the same side as the “dead engine.”

Variations on this saying include “Idle foot–idle

engine” and “Working foot–working engine.”

The second memory aid has to do with climb performance. The phrase “Raise the dead” is a reminder that

the best climb performance is obtained with a very

shallow bank, about 2° toward the operating engine.

Therefore, the inoperative, or “dead” engine should be

“raised” with a very slight bank.

Not all engine power losses are complete failures.

Sometimes the failure mode is such that partial power

may be available. If there is a performance loss when

the throttle of the affected engine is retarded, the pilot

should consider allowing it to run until altitude and airspeed permit safe single-engine flight, if this can be

done without compromising safety. Attempts to save a

malfunctioning engine can lead to a loss of the entire

airplane.

ENGINE FAILURE DURING FLIGHT

Engine failures well above the ground are handled

differently than those occurring at lower speeds and

altitudes. Cruise airspeed allows better airplane control, and altitude may permit time for a possible

diagnosis and remedy of the failure. Maintaining

airplane control, however, is still paramount.

Airplanes have been lost at altitude due to apparent

fixation on the engine problem to the detriment of

flying the airplane.

Not all engine failures or malfunctions are catastrophic

in nature (catastrophic meaning a major mechanical

failure that damages the engine and precludes further

engine operation). Many cases of power loss are

related to fuel starvation, where restoration of power

may be made with the selection of another tank. An

orderly inventory of gauges and switches may reveal

the problem. Carburetor heat or alternate air can be

selected. The affected engine may run smoothly on just

one magneto or at a lower power setting. Altering the

 SECURING FAILED ENGINE

Mixture . . . . . . . . . . . . . . . . . . . . . . . IDLE CUT OFF

Magnetos . . . . . . . . . . . . . . . . . . . . . OFF

Alternator . . . . . . . . . . . . . . . . . . . . . OFF

Cowl Flap . . . . . . . . . . . . . . . . . . . . . CLOSE

Boost Pump . . . . . . . . . . . . . . . . . . . .OFF

Fuel Selector . . . . . . . . . . . . . . . . . . OFF

Prop Sync . . . . . . . . . . . . . . . . . . . . . OFF

Electrical Load . . . . . . . . . . . . . . . . . . . Reduce

Crossfeed . . . . . . . . . . . . . . . . . . . . . Consider

Ch 12.qxd 5/7/04 9:55 AM Page 12-21
12-22

mixture may help. If fuel vapor formation is suspected,

fuel boost pump operation may be used to eliminate

flow and pressure fluctuations.

Although it is a natural desire among pilots to save an

ailing engine with a precautionary shutdown, the

engine should be left running if there is any doubt as to

needing it for further safe flight. Catastrophic failure

accompanied by heavy vibration, smoke, blistering

paint, or large trails of oil, on the other hand, indicate

a critical situation. The affected engine should be

feathered and the “securing failed engine” checklist

completed. The pilot should divert to the nearest suitable airport and declare an emergency with ATC for

priority handling.

Fuel crossfeed is a method of getting fuel from a tank

on one side of the airplane to an operating engine on

the other. Crossfeed is used for extended single-engine

operation. If a suitable airport is close at hand, there is

no need to consider crossfeed. If prolonged flight on a

single-engine is inevitable due to airport non-availability, then crossfeed allows use of fuel that would

otherwise be unavailable to the operating engine. It

also permits the pilot to balance the fuel consumption

to avoid an out-of-balance wing heaviness.

AFM/POH procedures for crossfeed vary widely.

Thorough fuel system knowledge is essential if crossfeed is to be conducted. Fuel selector positions and fuel

boost pump usage for crossfeed differ greatly among

multiengine airplanes. Prior to landing, crossfeed

should be terminated and the operating engine returned

to its main tank fuel supply.

If the airplane is above its single-engine absolute

ceiling at the time of engine failure, it will slowly

lose altitude. The pilot should maintain VYSE to minimize the rate of altitude loss. This “drift down” rate

will be greatest immediately following the failure

and will decrease as the single-engine ceiling is

approached. Due to performance variations caused

by engine and propeller wear, turbulence, and pilot

technique, the airplane may not maintain altitude

even at its published single-engine ceiling. Any further

rate of sink, however, would likely be modest.

An engine failure in a descent or other low power

setting can be deceiving. The dramatic yaw and performance loss will be absent. At very low power

settings, the pilot may not even be aware of a failure.

If a failure is suspected, the pilot should advance both

engine mixtures, propellers, and throttles significantly,

to the takeoff settings if necessary, to correctly identify

the failed engine. The power on the operative engine

can always be reduced later.

ENGINE INOPERATIVE APPROACH

AND LANDING

The approach and landing with one engine inoperative

is essentially the same as a two-engine approach and

landing. The traffic pattern should be flown at similar

altitudes, airspeeds, and key positions as a two-engine

approach. The differences will be the reduced power

available and the fact that the remaining thrust is

asymmetrical. A higher-than-normal power setting

will be necessary on the operative engine.

With adequate airspeed and performance, the landing

gear can still be extended on the downwind leg. In

which case it should be confirmed DOWN no later

than abeam the intended point of landing. Performance

permitting, initial extension of wing flaps (10°, typically) and a descent from pattern altitude can also be

initiated on the downwind leg. The airspeed should be

no slower than VYSE. The direction of the traffic pattern, and therefore the turns, is of no consequence as

far as airplane controllability and performance are

concerned. It is perfectly acceptable to make turns

toward the failed engine.

On the base leg, if performance is adequate, the flaps

may be extended to an intermediate setting (25°, typically). If the performance is inadequate, as measured

by a decay in airspeed or high sink rate, delay further

flap extension until closer to the runway. VYSE is still

the minimum airspeed to maintain.

On final approach, a normal, 3° glidepath to a landing

is desirable. VASI or other vertical path lighting aids

should be utilized if available. Slightly steeper

approaches may be acceptable. However, a long, flat,

low approach should be avoided. Large, sudden power

applications or reductions should also be avoided.

Maintain VYSE until the landing is assured, then slow

to 1.3 VSO or the AFM/POH recommended speed. The

final flap setting may be delayed until the landing is

assured, or the airplane may be landed with partial

flaps.

The airplane should remain in trim throughout. The

pilot must be prepared, however, for a rudder trim

change as the power of the operating engine is reduced

to idle in the roundout just prior to touchdown. With

drag from only one windmilling propeller, the airplane

will tend to float more than on a two-engine approach.

Precise airspeed control therefore is essential, especially

when landing on a short, wet and/or slippery surface.

Some pilots favor resetting the rudder trim to neutral

on final and compensating for yaw by holding rudder

pressure for the remainder of the approach. This eliminates the rudder trim change close to the ground as

Ch 12.qxd 5/7/04 9:55 AM Page 12-22
the throttle is closed during the roundout for landing.

This technique eliminates the need for groping for the

rudder trim and manipulating it to neutral during final

approach, which many pilots find to be highly distracting. AFM/POH recommendations or personal

preference should be used.

Single-engine go-arounds must be avoided. As a practical matter in single-engine approaches, once the airplane is on final approach with landing gear and flaps

extended, it is committed to land. If not on the intended

runway, then on another runway, a taxiway, or grassy

infield. The light-twin does not have the performance

to climb on one engine with landing gear and flaps

extended. Considerable altitude will be lost while

maintaining VYSE and retracting landing gear and

flaps. Losses of 500 feet or more are not unusual. If the

landing gear has been lowered with an alternate means

of extension, retraction may not be possible, virtually

negating any climb capability.

ENGINE INOPERATIVE 

FLIGHT PRINCIPLES

Best single-engine climb performance is obtained at

VYSE with maximum available power and minimum

drag. After the flaps and landing gear have been

retracted and the propeller of the failed engine feathered, a key element in best climb performance is

minimizing sideslip.

With a single-engine airplane or a multiengine airplane

with both engines operative, sideslip is eliminated

when the ball of the turn and bank instrument is centered. This is a condition of zero sideslip, and the

airplane is presenting its smallest possible profile to

the relative wind. As a result, drag is at its minimum.

Pilots know this as coordinated flight.

In a multiengine airplane with an inoperative engine,

the centered ball is no longer the indicator of zero

sideslip due to asymmetrical thrust. In fact, there is no

instrument at all that will directly tell the pilot the

flight conditions for zero sideslip. In the absence of a

yaw string, minimizing sideslip is a matter of placing

the airplane at a predetermined bank angle and ball

position. The AFM/POH performance charts for single-engine flight were determined at zero sideslip. If

this performance is even to be approximated, the zero

sideslip technique must be utilized.

There are two different control inputs that can be used

to counteract the asymmetrical thrust of a failed

engine: (1) yaw from the rudder, and (2) the horizontal

component of lift that results from bank with the

ailerons. Used individually, neither is correct. Used

together in the proper combination, zero sideslip and

best climb performance are achieved.

Three different scenarios of airplane control inputs are

presented below. Neither of the first two is correct.

They are presented to illustrate the reasons for the zero

sideslip approach to best climb performance.

1. Engine inoperative flight with wings level and

ball centered requires large rudder input towards

the operative engine. [Figure 12-16] The result is

a moderate sideslip towards the inoperative

engine. Climb performance will be reduced by

the moderate sideslip. With wings level, VMC will

be significantly higher than published as there is

no horizontal component of lift available to help

the rudder combat asymmetrical thrust.

Figure 12-16. Wings level engine-out flight.

Rudder Force

Yaw

String

Fin Effect

Due to Sideslip

Slipstream

Wings level, ball centered, airplane slips toward dead engine.

Results: high drag, large control surface deflections required,

and rudder and fin in opposition due to sideslip.

12-23

Ch 12.qxd 5/7/04 9:55 AM Page 12-23
2. Engine inoperative flight using ailerons alone

requires an 8 - 10° bank angle towards the operative engine. [Figure 12-17] This assumes no

rudder input. The ball will be displaced well

towards the operative engine. The result is a

large sideslip towards the operative engine.

Climb performance will be greatly reduced by

the large sideslip.

3. Rudder and ailerons used together in the proper

combination will result in a bank of approximately 2° towards the operative engine. The

ball will be displaced approximately one-third

to one-half towards the operative engine. The

result is zero sideslip and maximum climb performance. [Figure 12-18] Any attitude other

than zero sideslip increases drag, decreasing

performance. VMC under these circumstances

will be higher than published, as less than the

5° bank certification limit is employed.

The precise condition of zero sideslip (bank angle and

ball position) varies slightly from model to model, and

with available power and airspeed. If the airplane is

not equipped with counter-rotating propellers, it will

also vary slightly with the engine failed due to P-factor.

The foregoing zero sideslip recommendations apply to

Yaw

String

Excess bank toward operating engine, no rudder input.

Result: large sideslip toward operating engine and greatly

reduced climb performance.

12-24

Rudder Force

Yaw

String

Bank toward operating engine, no sideslip. Results: much

lower drag and smaller control surface deflections.

Figure 12-17. Excessive bank engine-out flight. Figure 12-18. Zero sideslip engine-out flight.

Ch 12.qxd 5/7/04 9:55 AM Page 12-24
12-25

reciprocating engine multiengine airplanes flown at

VYSE with the inoperative engine feathered. The zero

sideslip ball position for straight flight is also the zero

sideslip position for turning flight.

When bank angle is plotted against climb performance

for a hypothetical twin, zero sideslip results in the best

(however marginal) climb performance or the least rate

of descent. Zero bank (all rudder to counteract yaw)

degrades climb performance as a result of moderate

sideslip. Using bank angle alone (no rudder) severely

degrades climb performance as a result of a large

sideslip. 

The actual bank angle for zero sideslip varies among

airplanes from one and one-half to two and one-half

degrees. The position of the ball varies from one-third

to one-half of a ball width from instrument center.

For any multiengine airplane, zero sideslip can be confirmed through the use of a yaw string. A yaw string is

a piece of string or yarn approximately 18 to 36 inches

in length, taped to the base of the windshield, or to the

nose near the windshield, along the airplane centerline.

In two-engine coordinated flight, the relative wind will

cause the string to align itself with the longitudinal axis

of the airplane, and it will position itself straight up the

center of the windshield. This is zero sideslip.

Experimentation with slips and skids will vividly display

the location of the relative wind. Adequate altitude and

flying speed must be maintained while accomplishing

these maneuvers.

With an engine set to zero thrust (or feathered) and the

airplane slowed to VYSE, a climb with maximum power

on the remaining engine will reveal the precise bank

angle and ball deflection required for zero sideslip and

best climb performance. Zero sideslip will again be

indicated by the yaw string when it aligns itself vertically on the windshield. There will be very minor

changes from this attitude depending upon the

engine failed (with noncounter-rotating propellers),

power available, airspeed and weight; but without

more sensitive testing equipment, these changes are

difficult to detect. The only significant difference

would be the pitch attitude required to maintain VYSE

under different density altitude, power available, and

weight conditions.

If a yaw string is attached to the airplane at the time

of a VMC demonstration, it will be noted that VMC

occurs under conditions of sideslip. VMC was not

determined under conditions of zero sideslip during

aircraft certification and zero sideslip is not part of a

VMC demonstration for pilot certification.

To review, there are two different sets of bank angles

used in one-engine-inoperative flight.

• To maintain directional control of a multiengine

airplane suffering an engine failure at low speeds

(such as climb), momentarily bank at least 5°,

and a maximum of 10° towards the operative

engine as the pitch attitude for VYSE is set. This

maneuver should be instinctive to the proficient

multiengine pilot and take only 1 to 2 seconds to

attain. It is held just long enough to assure directional control as the pitch attitude for VYSE is

assumed.

• To obtain the best climb performance, the airplane must be flown at VYSE and zero sideslip,

with the failed engine feathered and maximum

available power from the operating engine. Zero

sideslip is approximately 2° of bank toward the

operating engine and a one-third to one-half ball

deflection, also toward the operating engine. The

precise bank angle and ball position will vary

somewhat with make and model and power

available. If above the airplane’s single-engine

ceiling, this attitude and configuration will result

in the minimum rate of sink.

In OEI flight at low altitudes and airspeeds such as the

initial climb after takeoff, pilots must operate the airplane

so as to guard against the three major accident factors:

(1) loss of directional control, (2) loss of performance,

and (3) loss of flying speed. All have equal potential to

be lethal. Loss of flying speed will not be a factor,

however, when the airplane is operated with due regard

for directional control and performance.

SLOW FLIGHT

There is nothing unusual about maneuvering during

slow flight in a multiengine airplane. Slow flight may

be conducted in straight-and-level flight, turns, in the

clean configuration, landing configuration, or at any

other combination of landing gear and flaps. Pilots

should closely monitor cylinder head and oil temperatures during slow flight. Some high performance

multiengine airplanes tend to heat up fairly quickly

under some conditions of slow flight, particularly in

the landing configuration.

Simulated engine failures should not be conducted during slow flight. The airplane will be well below VSSE

and very close to VMC. Stability, stall warning or stall

avoidance devices should not be disabled while

maneuvering during slow flight.

STALLS

Stall characteristics vary among multiengine airplanes

just as they do with single-engine airplanes, and

therefore, it is important to be familiar with them. The

application of power upon stall recovery, however,

has a significantly greater effect during stalls in a

Ch 12.qxd 5/7/04 9:55 AM Page 12-25
12-26

twin than a single-engine airplane. In the twin, an

application of power blows large masses of air from

the propellers directly over the wings, producing a

significant amount of lift in addition to the expected

thrust. The multiengine airplane, particularly at light

operating weights, typically has a higher thrust-toweight ratio, making it quicker to accelerate out of a

stalled condition.

In general, stall recognition and recovery training in

twins is performed similar to any high performance

single-engine airplane. However, for twins, all stall

maneuvers should be planned so as to be completed at

least 3,000 feet AGL.

Single-engine stalls or stalls with significantly more

power on one engine than the other should not be

attempted due to the likelihood of a departure from

controlled flight and possible spin entry. Similarly,

simulated engine failures should not be performed during stall entry and recovery.

POWER-OFF STALLS 

(APPROACH AND LANDING)

Power-off stalls are practiced to simulate typical

approach and landing scenarios. To initiate a power-off

stall maneuver, the area surrounding the airplane

should first be cleared for possible traffic. The airplane

should then be slowed and configured for an approach

and landing. A stabilized descent should be established

(approximately 500 f.p.m.) and trim adjusted. The pilot

should then transition smoothly from the stabilized

descent attitude, to a pitch attitude that will induce a

stall. Power is reduced further during this phase, and

trimming should cease at speeds slower than takeoff.

When the airplane reaches a stalled condition, the

recovery is accomplished by simultaneously reducing

the angle of attack with coordinated use of the flight

controls and smoothly applying takeoff or specified

power. The flap setting should be reduced from full to

approach, or as recommended by the manufacturer.

Then with a positive rate of climb, the landing gear is

selected up. The remaining flaps are then retracted as a

climb has commenced. This recovery process should

be completed with a minimum loss of altitude, appropriate to the aircraft characteristics.

The airplane should be accelerated to VX (if simulated

obstacles are present) or VY during recovery and climb.

Considerable forward elevator/stabilator pressure will

be required after the stall recovery as the airplane accelerates to VX or VY. Appropriate trim input should be

anticipated.

Power-off stalls may be performed with wings level, or

from shallow and medium banked turns. When recovering from a stall performed from turning flight, the

angle of attack should be reduced prior to leveling the

wings. Flight control inputs should be coordinated.

It is usually not advisable to execute full stalls in

multiengine airplanes because of their relatively high

wing loading. Stall training should be limited to

approaches to stalls and when a stall condition occurs.

Recoveries should be initiated at the onset, or decay of

control effectiveness, or when the first physical

indication of the stall occurs.

POWER-ON STALLS 

(TAKEOFF AND DEPARTURE)

Power-on stalls are practiced to simulate typical

takeoff scenarios. To initiate a power-on stall

maneuver, the area surrounding the airplane should

always be cleared to look for potential traffic. The

airplane is slowed to the manufacturer’s recommended

lift-off speed. The airplane should be configured in the

takeoff configuration. Trim should be adjusted for this

speed. Engine power is then increased to that recommended in the AFM/POH for the practice of power-on

stalls. In the absence of a recommended setting, use

approximately 65 percent of maximum available

power while placing the airplane in a pitch attitude that

will induce a stall. Other specified (reduced) power

settings may be used to simulate performance at higher

gross weights and density altitudes.

When the airplane reaches a stalled condition, the

recovery is made by simultaneously lowering the

angle of attack with coordinated use of the flight

controls and applying power as appropriate.

However, if simulating limited power available for

high gross weight and density altitude situations, the

power during the recovery should be limited to that

specified. The recovery should be completed with a

minimum loss of altitude, appropriate to aircraft characteristics.

The landing gear should be retracted when a positive

rate of climb is attained, and flaps retracted, if flaps

were set for takeoff. The target airspeed on recovery is

VX if (simulated) obstructions are present, or VY. The

pilot should anticipate the need for nosedown trim as

the airplane accelerates to VX or VY after recovery.

Power-on stalls may be performed from straight flight

or from shallow and medium banked turns. When

recovering from a power-on stall performed from turning flight, the angle of attack should be reduced prior

to leveling the wings, and the flight control inputs

should be coordinated.

SPIN AWARENESS

No multiengine airplane is approved for spins, and

their spin recovery characteristics are generally very

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poor. It is therefore necessary to practice spin avoidance and maintain a high awareness of situations that

can result in an inadvertent spin.

In order to spin any airplane, it must first be stalled. At

the stall, a yawing moment must be introduced. In a

multiengine airplane, the yawing moment may be

generated by rudder input or asymmetrical thrust. It

follows, then, that spin awareness be at its greatest

during VMC demonstrations, stall practice, slow

flight, or any condition of high asymmetrical thrust,

particularly at low speed/high angle of attack. Singleengine stalls are not part of any multiengine training

curriculum.

A situation that may inadvertently degrade into a spin

entry is a simulated engine failure introduced at an

inappropriately low speed. No engine failure should

ever be introduced below safe, intentional one-engineinoperative speed (VSSE). If no VSSE is published, use

VYSE. The “necessity” of simulating engine failures

at low airspeeds is erroneous. Other than training

situations, the multiengine airplane is only operated

below VSSE for mere seconds just after lift-off or

during the last few dozen feet of altitude in preparation

for landing.

For spin avoidance when practicing engine failures,

the flight instructor should pay strict attention to the

maintenance of proper airspeed and bank angle as the

student executes the appropriate procedure. The

instructor should also be particularly alert during stall

and slow flight practice. Forward center-of-gravity

positions result in favorable stall and spin avoidance

characteristics, but do not eliminate the hazard.

When performing a VMC demonstration, the instructor

should also be alert for any sign of an impending stall.

The student may be highly focused on the directional

control aspect of the maneuver to the extent that

impending stall indications go unnoticed. If a VMC

demonstration cannot be accomplished under existing

conditions of density altitude, it may, for training purposes, be done utilizing the rudder blocking technique

described in the following section.

As very few twins have ever been spin-tested (none

are required to), the recommended spin recovery

techniques are based only on the best information

available. The departure from controlled flight may

be quite abrupt and possibly disorienting. The direction of an upright spin can be confirmed from the turn

needle or the symbolic airplane of the turn coordinator,

if necessary. Do not rely on the ball position or other

instruments.

If a spin is entered, most manufacturers recommend

immediately retarding both throttles to idle, applying

full rudder opposite the direction of rotation, and

applying full forward elevator/stabilator pressure (with

ailerons neutral). These actions should be taken as near

simultaneously as possible. The controls should then

be held in that position. Recovery, if possible, will take

considerable altitude. The longer the delay from entry

until taking corrective action, the less likely that recovery will be successful.

ENGINE INOPERATIVE—LOSS OF

DIRECTIONAL CONTROL 

DEMONSTRATION

An engine inoperative—loss of directional control

demonstration, often referred to as a “VMC demonstration,” is a required task on the practical test for a

multiengine class rating. A thorough knowledge of

the factors that affect VMC, as well as its definition,

is essential for multiengine pilots, and as such an

essential part of that required task. VMC is a speed

established by the manufacturer, published in the

AFM/POH, and marked on most airspeed indicators

with a red radial line. The multiengine pilot must

understand that VMC is not a fixed airspeed under all

conditions. VMC is a fixed airspeed only for the very

specific set of circumstances under which it was

determined during aircraft certification. [Figure 12-19]

In reality, VMC varies with a variety of factors as

outlined below. The VMC noted in practice and

demonstration, or in actual single-engine operation,

could be less or even greater than the published

value, depending upon conditions and technique.

In aircraft certification, VMC is the sea level calibrated

airspeed at which, when the critical engine is suddenly

made inoperative, it is possible to maintain control of

the airplane with that engine still inoperative and then

maintain straight flight at the same speed with an angle

of bank of not more than 5°.

The foregoing refers to the determination of VMC under

“dynamic” conditions. This technique is only used by

highly experienced flight test pilots during aircraft certification. It is never to be attempted outside of these

circumstances.

In aircraft certification, there is also a determination of

VMC under “static,” or steady-state conditions. If there

is a difference between the dynamic and static speeds,

the higher of the two is published as VMC. The static

determination is simply the ability to maintain straight

flight at VMC with a bank angle of not more than 5°. This

more closely resembles the VMC demonstration required

in the practical test for a multiengine class rating.

The AFM/POH-published VMC is determined with the

“critical” engine inoperative. The critical engine is the

Ch 12.qxd 5/7/04 9:55 AM Page 12-27
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engine whose failure has the most adverse effect on

directional control. On twins with each engine rotating

in conventional, clockwise rotation as viewed from the

pilot’s seat, the critical engine will be the left engine.

Multiengine airplanes are subject to P-factor just as

single-engine airplanes are. The descending propeller

blade of each engine will produce greater thrust than

the ascending blade when the airplane is operated

under power and at positive angles of attack. The

descending propeller blade of the right engine is also

a greater distance from the center of gravity, and

therefore has a longer moment arm than the descending propeller blade of the left engine. As a result,

failure of the left engine will result in the most

asymmetrical thrust (adverse yaw) as the right

engine will be providing the remaining thrust.

[Figure 12-19]

Many twins are designed with a counter-rotating right

engine. With this design, the degree of asymmetrical

thrust is the same with either engine inoperative. No

engine is more critical than the other, and a VMC

demonstration may be performed with either engine

windmilling.

In aircraft certification, dynamic VMC is determined

under the following conditions.

• Maximum available takeoff power. VMC

increases as power is increased on the operating

engine. With normally aspirated engines, VMC is

highest at takeoff power and sea level, and

decreases with altitude. With turbocharged

engines, takeoff power, and therefore VMC,

remains constant with increases in altitude up to

the engine’s critical altitude (the altitude where

the engine can no longer maintain 100 percent

power). Above the critical altitude, VMC

decreases just as it would with a normally aspirated engine, whose critical altitude is sea level.

VMC tests are conducted at a variety of altitudes.

The results of those tests are then extrapolated to

a single, sea level value.

• Windmilling propeller. VMC increases with

increased drag on the inoperative engine. VMC is

highest, therefore, when the critical engine propeller is windmilling at the low pitch, high

r.p.m. blade angle. VMC is determined with the

critical engine propeller windmilling in the

takeoff position, unless the engine is equipped

with an autofeather system.

• Most unfavorable weight and center-of-gravity

position. VMC increases as the center of gravity

is moved aft. The moment arm of the rudder is

reduced, and therefore its effectivity is reduced,

as the center of gravity is moved aft. At the same

time, the moment arm of the propeller blade is

increased, aggravating asymmetrical thrust.

Invariably, the aft-most CG limit is the most

unfavorable CG position. Currently, 14 CFR

part 23 calls for VMC to be determined at the

most unfavorable weight. For twins certificated under CAR 3 or early 14 CFR part 23,

the weight at which VMC was determined was

not specified. VMC increases as weight is

reduced. [Figure 12-20]

• Landing gear retracted. VMC increases when

the landing gear is retracted. Extended landing

gear aids directional stability, which tends to

decrease VMC.

Figure 12-19. Forces created during single-engine operation.

C L C L

D2 D1

Arm Arm

Inoperative

Engine

Inoperative

Engine

Operative

Engine

Operative

Engine

(Critical Engine)

Ch 12.qxd 5/7/04 9:55 AM Page 12-28
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• Wing flaps in the takeoff position. For most

twins, this will be 0° of flaps.

• Cowl flaps in the takeoff position.

• Airplane trimmed for takeoff.

• Airplane airborne and the ground effect negligible.

• Maximum of 5° angle of bank. VMC is highly

sensitive to bank angle. To prevent claims of

an unrealistically low VMC speed in aircraft

certification, the manufacturer is permitted to

use a maximum of a 5° bank angle toward the

operative engine. The horizontal component of

lift generated by the bank assists the rudder in

counteracting the asymmetrical thrust of the

operative engine. The bank angle works in the

manufacturer’s favor in lowering VMC.

VMC is reduced significantly with increases in bank

angle. Conversely, VMC increases significantly with

decreases in bank angle. Tests have shown that VMC

may increase more than 3 knots for each degree of

bank angle less than 5°. Loss of directional control

may be experienced at speeds almost 20 knots above

published VMC when the wings are held level.

The 5° bank angle maximum is a regulatory limit

imposed upon manufacturers in aircraft certification.

The 5° bank does not inherently establish zero sideslip

or best single-engine climb performance. Zero sideslip,

and therefore best single-engine climb performance,

occurs at bank angles significantly less than 5°. The

determination of VMC in certification is solely concerned with the minimum speed for directional control

under a very specific set of circumstances, and has

nothing to do with climb performance, nor is it the

optimum airplane attitude or configuration for climb

performance.

During dynamic VMC determination in aircraft certification, cuts of the critical engine using the mixture

control are performed by flight test pilots while

gradually reducing the speed with each attempt. VMC

is the minimum speed at which directional control

could be maintained within 20° of the original entry

heading when a cut of the critical engine was made.

During such tests, the climb angle with both engines

operating was high, and the pitch attitude following

the engine cut had to be quickly lowered to regain

the initial speed. Pilots should never attempt to

demonstrate VMC with an engine cut from high

power, and never intentionally fail an engine at

speeds less than VSSE.

The actual demonstration of VMC and recovery in flight

training more closely resembles static VMC determination in aircraft certification. For a demonstration,

the pilot should select an altitude that will allow

completion of the maneuver at least 3,000 feet AGL.

The following description assumes a twin with

noncounter-rotating engines, where the left engine

is critical.

With the landing gear retracted and the flaps set to the

takeoff position, the airplane should be slowed to

approximately 10 knots above VSSE or VYSE

(whichever is higher) and trimmed for takeoff. For the

remainder of the maneuver, the trim setting should not

be altered. An entry heading should be selected and

high r.p.m. set on both propeller controls. Power on the

left engine should be throttled back to idle as the right

engine power is advanced to the takeoff setting. The

landing gear warning horn will sound as long as a

Figure 12-20. Effect of CG location on yaw.

A

B

Inoperative

Engine

Operative

Engine

B x R = A x T

Inoperative

Engine

Operative

Engine

A

R

B

R

T T

Ch 12.qxd 5/7/04 9:55 AM Page 12-29
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throttle is retarded. The pilots should continue to carefully listen, however, for the stall warning horn, if so

equipped, or watch for the stall warning light. The left

yawing and rolling moment of the asymmetrical thrust

is counteracted primarily with right rudder. A bank

angle of 5° (a right bank, in this case) should also be

established.

While maintaining entry heading, the pitch attitude is

slowly increased to decelerate at a rate of 1 knot per

second (no faster). As the airplane slows and control

effectivity decays, the increasing yawing tendency

should be counteracted with additional rudder pressure. Aileron displacement will also increase in order

to maintain 5° of bank. An airspeed is soon reached

where full right rudder travel and a 5° right bank can

no longer counteract the asymmetrical thrust, and the

airplane will begin to yaw uncontrollably to the left.

The moment the pilot first recognizes the uncontrollable yaw, or experiences any symptom associated

with a stall, the operating engine throttle should be

sufficiently retarded to stop the yaw as the pitch

attitude is decreased. Recovery is made with a minimum

loss of altitude to straight flight on the entry heading at

VSSE or VYSE, before setting symmetrical power. The

recovery should not be attempted by increasing power

on the windmilling engine alone.

To keep the foregoing description simple, there were

several important background details that were not

covered. The rudder pressure during the demonstration

can be quite high. In certification, 150 pounds of force

is permitted before the limiting factor becomes rudder

pressure, not rudder travel. Most twins will run out of

rudder travel long before 150 pounds of pressure is

required. Still, it will seem considerable.

Maintaining altitude is not a criterion in accomplishing this maneuver. This is a demonstration of

controllability, not performance. Many airplanes will

lose (or gain) altitude during the demonstration. Begin

the maneuver at an altitude sufficient to allow completion

by 3,000 feet AGL.

As discussed earlier, with normally aspirated engines,

VMC decreases with altitude. Stalling speed (VS),

however, remains the same. Except for a few models,

published VMC is almost always higher than VS. At

sea level, there is usually a margin of several knots

between VMC and VS, but the margin decreases with

altitude, and at some altitude, VMC and VS are the

same. [Figure 12-21]

Should a stall occur while the airplane is under asymmetrical power, particularly high asymmetrical power,

a spin entry is likely. The yawing moment induced

from asymmetrical thrust is little different from that

induced by full rudder in an intentional spin in the

appropriate model of single-engine airplane. In this

case, however, the airplane will depart controlled

flight in the direction of the idle engine, not in the

direction of the applied rudder. Twins are not required

to demonstrate recoveries from spins, and their spin

recovery characteristics are generally very poor.

Where VS is encountered at or before VMC, the departure from controlled flight may be quite sudden, with

strong yawing and rolling tendencies to the inverted

position, and a spin entry. Therefore, during a VMC

demonstration, if there are any symptoms of an

impending stall such as a stall warning light or horn,

airframe or elevator buffet, or rapid decay in control

effectiveness, the maneuver should be terminated

immediately, the angle of attack reduced as the throttle

is retarded, and the airplane returned to the entry

airspeed. It should be noted that if the pilots are

wearing headsets, the sound of a stall warning horn

will tend to be masked.

The VMC demonstration only shows the earliest onset

of a loss of directional control. It is not a loss of control of the airplane when performed in accordance with

the foregoing procedures. A stalled condition should

never be allowed to develop. Stalls should never be

performed with asymmetrical thrust and the VMC

demonstration should never be allowed to degrade into

a single-engine stall. A VMC demonstration that is

allowed to degrade into a single-engine stall with high

asymmetrical thrust is very likely to result in a loss of

control of the airplane.

An actual demonstration of VMC may not be possible

under certain conditions of density altitude, or with

airplanes whose VMC is equal to or less than VS. Under

those circumstances, as a training technique, a demonstration of VMC may be safely conducted by artificially

limiting rudder travel to simulate maximum available

rudder. Limiting rudder travel should be accomplished

at a speed well above VS (approximately 20 knots). Density Altitude

Indicated Airspeed

Stall

Occurs

First

Yaw

Occurs 

First

Recovery

May Be

Difficult

Altitude Where

VMC = Stall Speed

Engine-Out

Power-On

Stall Speed (VS)

VMC

Figure 12-21. Graph depicting relationship of VMC to VS.

Ch 12.qxd 5/7/04 9:55 AM Page 12-30
The rudder limiting technique avoids the hazards of

spinning as a result of stalling with high asymmetrical

power, yet is effective in demonstrating the loss of

directional control.

The VMC demonstration should never be performed

from a high pitch attitude with both engines operating

and then reducing power on one engine. The preceding

discussion should also give ample warning as to why

engine failures are never to be performed at low airspeeds. An unfortunate number of airplanes and pilots

have been lost from unwarranted simulated engine

failures at low airspeeds that degenerated into loss of

control of the airplane. VSSE is the minimum airspeed

at which any engine failure should be simulated.

MULTIENGINE TRAINING 

CONSIDERATIONS

Flight training in a multiengine airplane can be safely

accomplished if both the instructor and the student are

cognizant of the following factors.

• No flight should ever begin without a thorough

preflight briefing of the objectives, maneuvers,

expected student actions, and completion standards.

• A clear understanding must be reached as to how

simulated emergencies will be introduced, and

what action the student is expected to take.

The introduction, practice, and testing of emergency

procedures has always been a sensitive subject.

Surprising a multiengine student with an emergency

without a thorough briefing beforehand has no place

in flight training. Effective training must be carefully

balanced with safety considerations. Simulated engine

failures, for example, can very quickly become actual

emergencies or lead to loss of the airplane when

approached carelessly. Pulling circuit breakers can

lead to a subsequent gear up landing. Stall-spin accidents in training for emergencies rival the number of

stall-spin accidents from actual emergencies. 

All normal, abnormal, and emergency procedures can

and should be introduced and practiced in the airplane

as it sits on the ground, power off. In this respect, the

airplane is used as a cockpit procedures trainer (CPT),

ground trainer, or simulator. The value of this training

should never be underestimated. The engines do not

have to be operating for real learning to occur. Upon

completion of a training session, care should be taken

to return items such as switches, valves, trim, fuel selectors, and circuit breakers to their normal positions.

Pilots who do not use a checklist effectively will be at

a significant disadvantage in multiengine airplanes.

Use of the checklist is essential to safe operation of

airplanes and no flight should be conducted without

one. The manufacturer’s checklist or an aftermarket

checklist for the specific make, model, and model year

should be used. If there is a procedural discrepancy

between the checklist and AFM/POH, then the

AFM/POH always takes precedence.

Certain immediate action items (such as the response

to an engine failure in a critical phase of flight) should

be committed to memory. After they are accomplished,

and as work load permits, the pilot should verify the

action taken with a printed checklist.

Simulated engine failures during the takeoff ground

roll should be accomplished with the mixture control.

The simulated failure should be introduced at a speed

no greater than 50 percent of VMC. If the student does

not react promptly by retarding both throttles, the

instructor can always pull the other mixture.

The FAA recommends that all in-flight simulated

engine failures below 3,000 feet AGL be introduced

with a smooth reduction of the throttle. Thus, the

engine is kept running and is available for instant use,

if necessary. Throttle reduction should be smooth

rather than abrupt to avoid abusing the engine and possibly causing damage. All inflight engine failures must

be conducted at VSSE or above.

If the engines are equipped with dynamic crankshaft

counterweights, it is essential to make throttle reductions

for simulated failures smoothly. Other areas leading to

dynamic counterweight damage include high r.p.m. and

low manifold pressure combinations, overboosting, and

propeller feathering. Severe damage or repetitive abuse

to counterweights will eventually lead to engine failure.

Dynamic counterweights are found on larger, more

complex engines—instructors should check with

maintenance personnel or the engine manufacturer to

determine if their engines are so equipped.

When an instructor simulates an engine failure, the

student should respond with the appropriate memory

items and retard the propeller control towards the

FEATHER position. Assuming zero thrust will be set,

the instructor should promptly move the propeller

control forward and set the appropriate manifold

pressure and r.p.m. It is vital that the student be kept

informed of the instructor’s intentions. At this point

the instructor may state words to the effect, “I have the

right engine; you have the left. I have set zero thrust

and the right engine is simulated feathered.” There

should never be any ambiguity as to who is operating

what systems or controls.

Following a simulated engine failure, the instructor

should continue to care for the “failed” engine just as

the student cares for the operative engine. If zero thrust

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is set to simulate a feathered propeller, the cowl flap

should be closed and the mixture leaned. An occasional

clearing of the engine is also desirable. If possible,

avoid high power applications immediately following

a prolonged cool-down at a zero-thrust power setting.

The flight instructor must impress on the student multiengine pilot the critical importance of feathering the

propeller in a timely manner should an actual engine

failure situation be encountered. Awindmilling propeller,

in many cases, has given the improperly trained

multiengine pilot the mistaken perception that the

failed engine is still developing useful thrust, resulting

in a psychological reluctance to feather, as feathering

results in the cessation of propeller rotation. The flight

instructor should spend ample time demonstrating

the difference in the performance capabilities of the

airplane with a simulated feathered propeller (zero

thrust) as opposed to a windmilling propeller.

All actual propeller feathering should be performed at

altitudes and positions where safe landings on established airports could be readily accomplished.

Feathering and restart should be planned so as to be

completed no lower than 3,000 feet AGL. At certain

elevations and with many popular multiengine training

airplanes, this may be above the single-engine service

ceiling, and level flight will not be possible. 

Repeated feathering and unfeathering is hard on the

engine and airframe, and should be done only as

absolutely necessary to ensure adequate training. The

FAA’s practical test standards for a multiengine class

rating requires the feathering and unfeathering of one

propeller during flight in airplanes in which it is safe to

do so.

While much of this chapter has been devoted to the

unique flight characteristics of the multiengine airplane with one engine inoperative, the modern,

well-maintained reciprocating engine is remarkably

reliable. Simulated engine failures at extremely low

altitudes (such as immediately after lift-off) and/or

below VSSE are undesirable in view of the non-existent

safety margins involved. The high risk of simulating

an engine failure below 200 feet AGL does not warrant

practicing such maneuvers.

For training in maneuvers that would be hazardous in

flight, or for initial and recurrent qualification in an

advanced multiengine airplane, a simulator training

center or manufacturer’s training course should be

given consideration. Comprehensive training manuals

and classroom instruction are available along with system training aids, audio/visuals, and flight training

devices and simulators. Training under a wide variety

of environmental and aircraft conditions is available

through simulation. Emergency procedures that would

be either dangerous or impossible to accomplish in an

airplane can be done safely and effectively in a flight

training device or simulator. The flight training device

or simulator need not necessarily duplicate the specific make and model of airplane to be useful. Highly

effective instruction can be obtained in training

devices for other makes and models as well as generic

training devices.

The majority of multiengine training is conducted in

four to six-place airplanes at weights significantly less

than maximum. Single-engine performance, particularly at low density altitudes, may be deceptively good.

To experience the performance expected at higher

weights, altitudes, and temperatures, the instructor

should occasionally artificially limit the amount of

manifold pressure available on the operative engine.

Airport operations above the single-engine ceiling can

also be simulated in this manner. Loading the airplane

with passengers to practice emergencies at maximum

takeoff weight is not appropriate.

The use of the touch-and-go landing and takeoff in

flight training has always been somewhat controversial.

The value of the learning experience must be weighed

against the hazards of reconfiguring the airplane for

takeoff in an extremely limited time as well as the loss

of the follow-through ordinarily experienced in a full

stop landing. Touch and goes are not recommended

during initial aircraft familiarization in multiengine

airplanes.

If touch and goes are to be performed at all, the student

and instructor responsibilities need to be carefully

briefed prior to each flight. Following touchdown, the

student will ordinarily maintain directional control

while keeping the left hand on the yoke and the right

hand on the throttles. The instructor resets the flaps

and trim and announces when the airplane has been

reconfigured. The multiengine airplane needs considerably more runway to perform a touch and go than a

single-engine airplane. A full stop-taxi back landing is

preferable during initial familiarization. Solo touch

and goes in twins are strongly discouraged.

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