帅哥
发表于 2008-12-9 15:09:59
An airplane that may be difficult to spin intentionally
in the Utility Category (restricted aft CG and reduced
weight) could have less resistance to spin entry in the
Normal Category (less restricted aft CG and increased
weight). This situation is due to the airplane being able
to generate a higher angle of attack and load factor.
Furthermore, an airplane that is approved for spins in
the Utility Category, but loaded in the Normal
Category, may not recover from a spin that is allowed
to progress beyond the incipient phase.
Common errors in the performance of intentional
spins are:
• Failure to apply full rudder pressure in the desired
spin direction during spin entry.
• Failure to apply and maintain full up-elevator
pressure during spin entry, resulting in a spiral.
• Failure to achieve a fully stalled condition prior to
spin entry.
• Failure to apply full rudder against the spin during
recovery.
• Failure to apply sufficient forward-elevator
pressure during recovery.
• Failure to neutralize the rudder during recovery
after rotation stops, resulting in a possible
secondary spin.
• Slow and overly cautious control movements
during recovery.
• Excessive back-elevator pressure after rotation
stops, resulting in possible secondary stall.
• Insufficient back-elevator pressure during
recovery resulting in excessive airspeed.
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GENERAL
This chapter discusses takeoffs and departure climbs in
tricycle landing gear (nosewheel-type) airplanes under
normal conditions, and under conditions which require
maximum performance. A thorough knowledge of
takeoff principles, both in theory and practice, will
often prove of extreme value throughout a pilot’s
career. It will often prevent an attempted takeoff that
would result in an accident, or during an emergency,
make possible a takeoff under critical conditions when
a pilot with a less well rounded knowledge and technique
would fail.
The takeoff, though relatively simple, often presents
the most hazards of any part of a flight. The importance
of thorough knowledge and faultless technique and
judgment cannot be overemphasized.
It must be remembered that the manufacturer’s recommended
procedures, including airplane configuration and
airspeeds, and other information relevant to takeoffs and
departure climbs in a specific make and model airplane are
contained in the FAA-approved Airplane Flight Manual
and/or Pilot’s Operating Handbook (AFM/POH) for that
airplane. If any of the information in this chapter differs
from the airplane manufacturer’s recommendations as
contained in the AFM/POH, the airplane manufacturer’s
recommendations take precedence.
TERMS AND DEFINITIONS
Although the takeoff and climb is one continuous
maneuver, it will be divided into three separate steps
for purposes of explanation: (1) the takeoff roll, (2) the
lift-off, and (3) the initial climb after becoming airborne.
• Takeoff Roll (ground roll)—the portion of the
takeoff procedure during which the airplane is
accelerated from a standstill to an airspeed that
provides sufficient lift for it to become airborne.
• Lift-off (rotation)—the act of becoming airborne
as a result of the wings lifting the airplane
off the ground or the pilot rotating the nose up,
increasing the angle of attack to start a climb.
• Initial Climb—begins when the airplane leaves
the ground and a pitch attitude has been established
to climb away from the takeoff area.
Normally, it is considered complete when the
airplane has reached a safe maneuvering altitude,
or an en route climb has been established.
5-1
Figure 5-1.Takeoff and climb.
Takeoff
power
Takeoff pitch
attitude
Best climb speed
Safe maneuvering altitude
climb power
En Route
climb
Climb
(3)
Lift-off
(2)
Takeoff
roll
(1)
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5-2
PRIOR TO TAKEOFF
Before taxiing onto the runway or takeoff area, the
pilot should ensure that the engine is operating properly
and that all controls, including flaps and trim tabs,
are set in accordance with the before takeoff checklist.
In addition, the pilot must make certain that the
approach and takeoff paths are clear of other aircraft.
At uncontrolled airports, pilots should announce their
intentions on the common traffic advisory frequency
(CTAF) assigned to that airport. When operating from
an airport with an operating control tower, pilots must
contact the tower operator and receive a takeoff clearance
before taxiing onto the active runway.
It is not recommended to take off immediately behind
another aircraft, particularly large, heavily loaded
transport airplanes, because of the wake turbulence
that is generated.
While taxiing onto the runway, the pilot can select
ground reference points that are aligned with the
runway direction as aids to maintaining directional
control during the takeoff. These may be runway
centerline markings, runway lighting, distant trees,
towers, buildings, or mountain peaks.
NORMAL TAKEOFF
Anormal takeoff is one in which the airplane is headed
into the wind, or the wind is very light. Also, the takeoff
surface is firm and of sufficient length to permit the
airplane to gradually accelerate to normal lift-off and
climb-out speed, and there are no obstructions along
the takeoff path.
There are two reasons for making a takeoff as nearly
into the wind as possible. First, the airplane’s speed
while on the ground is much less than if the takeoff
were made downwind, thus reducing wear and stress
on the landing gear. Second, a shorter ground roll and
therefore much less runway length is required to
develop the minimum lift necessary for takeoff and
climb. Since the airplane depends on airspeed in order
to fly, a headwind provides some of that airspeed, even
with the airplane motionless, from the wind flowing
over the wings.
TAKEOFF ROLL
After taxiing onto the runway, the airplane should be
carefully aligned with the intended takeoff direction,
and the nosewheel positioned straight, or centered.
After releasing the brakes, the throttle should be
advanced smoothly and continuously to takeoff power.
An abrupt application of power may cause the airplane
to yaw sharply to the left because of the torque effects
of the engine and propeller. This will be most apparent
in high horsepower engines. As the airplane starts to
roll forward, the pilot should assure both feet are on
the rudder pedals so that the toes or balls of the feet are
on the rudder portions, not on the brake portions.
Engine instruments should be monitored during the
takeoff roll for any malfunctions.
In nosewheel-type airplanes, pressures on the elevator
control are not necessary beyond those needed to
steady it. Applying unnecessary pressure will only
aggravate the takeoff and prevent the pilot from recognizing
when elevator control pressure is actually
needed to establish the takeoff attitude.
As speed is gained, the elevator control will tend to
assume a neutral position if the airplane is correctly
trimmed. At the same time, directional control should
be maintained with smooth, prompt, positive rudder
corrections throughout the takeoff roll. The effects of
engine torque and P-factor at the initial speeds tend to
pull the nose to the left. The pilot must use whatever
rudder pressure and aileron needed to correct for these
effects or for existing wind conditions to keep the nose
of the airplane headed straight down the runway. The
use of brakes for steering purposes should be avoided,
since this will cause slower acceleration of the airplane’s
speed, lengthen the takeoff distance, and
possibly result in severe swerving.
While the speed of the takeoff roll increases, more
and more pressure will be felt on the flight controls,
particularly the elevators and rudder. If the tail surfaces
are affected by the propeller slipstream, they
become effective first. As the speed continues to
increase, all of the flight controls will gradually
become effective enough to maneuver the airplane
about its three axes. It is at this point, in the taxi to
flight transition, that the airplane is being flown more
than taxied. As this occurs, progressively smaller
rudder deflections are needed to maintain direction.
The feel of resistance to the movement of the controls
and the airplane’s reaction to such movements
are the only real indicators of the degree of control
attained. This feel of resistance is not a measure of
the airplane’s speed, but rather of its controllability.
To determine the degree of controllability, the pilot
must be conscious of the reaction of the airplane to
the control pressures and immediately adjust the
pressures as needed to control the airplane. The pilot
must wait for the reaction of the airplane to the
applied control pressures and attempt to sense the
control resistance to pressure rather than attempt to
control the airplane by movement of the controls.
Balanced control surfaces increase the importance
of this point, because they materially reduce the
intensity of the resistance offered to pressures
exerted by the pilot.
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5-3
At this stage of training, beginning takeoff practice, a
student pilot will normally not have a full appreciation
of the variations of control pressures with the speed of
the airplane. The student, therefore, may tend to move
the controls through wide ranges seeking the pressures
that are familiar and expected, and as a consequence
over-control the airplane. The situation may be aggravated
by the sluggish reaction of the airplane to these
movements. The flight instructor should take measures
to check these tendencies and stress the importance of
the development of feel. The student pilot should be
required to feel lightly for resistance and accomplish
the desired results by applying pressure against it. This
practice will enable the student pilot, as experience is
gained, to achieve a sense of the point when sufficient
speed has been acquired for the takeoff, instead of
merely guessing, fixating on the airspeed indicator, or
trying to force performance from the airplane.
LIFT-OFF
Since a good takeoff depends on the proper takeoff
attitude, it is important to know how this attitude
appears and how it is attained. The ideal takeoff attitude
requires only minimum pitch adjustments
shortly after the airplane lifts off to attain the speed
for the best rate of climb (VY). The pitch
attitude necessary for the airplane to accelerate to VY
speed should be demonstrated by the instructor and
memorized by the student. Initially, the student pilot
may have a tendency to hold excessive back-elevator
pressure just after lift-off, resulting in an abrupt pitchup.
The flight instructor should be prepared for this.
Each type of airplane has a best pitch attitude for
normal lift-off; however, varying conditions may
make a difference in the required takeoff technique.
A rough field, a smooth field, a hard surface runway,
or a short or soft, muddy field, all call for a slightly
different technique, as will smooth air in contrast to
a strong, gusty wind. The different techniques for
those other-than-normal conditions are discussed
later in this chapter.
When all the flight controls become effective during
the takeoff roll in a nosewheel-type airplane, backelevator
pressure should be gradually applied to
raise the nosewheel slightly off the runway, thus
establishing the takeoff or lift-off attitude. This is
often referred to as “rotating.” At this point, the
position of the nose in relation to the horizon should
be noted, then back-elevator pressure applied as
necessary to hold this attitude. The wings must be
kept level by applying aileron pressure as necessary.
The airplane is allowed to fly off the ground while in
the normal takeoff attitude. Forcing it into the air by
applying excessive back-elevator pressure would only
result in an excessively high pitch attitude and may
delay the takeoff. As discussed earlier, excessive and
rapid changes in pitch attitude result in proportionate
changes in the effects of torque, thus making the airplane
more difficult to control.
Although the airplane can be forced into the air, this is
considered an unsafe practice and should be avoided
under normal circumstances. If the airplane is forced
to leave the ground by using too much back-elevator
pressure before adequate flying speed is attained, the
wing’s angle of attack may be excessive, causing the
airplane to settle back to the runway or even to stall.
On the other hand, if sufficient back-elevator pressure
is not held to maintain the correct takeoff attitude after
becoming airborne, or the nose is allowed to lower
excessively, the airplane may also settle back to the
runway. This would occur because the angle of attack
is decreased and lift diminished to the degree where it
will not support the airplane. It is important, then, to
hold the correct attitude constant after rotation or liftoff.
As the airplane leaves the ground, the pilot must
continue to be concerned with maintaining the
wings in a level attitude, as well as holding the
proper pitch attitude. Outside visual scan to
attain/maintain proper airplane pitch and bank attitude
must be intensified at this critical point. The
flight controls have not yet become fully effective,
and the beginning pilot will often have a tendency
to fixate on the airplane’s pitch attitude and/or the
airspeed indicator and neglect the natural tendency
of the airplane to roll just after breaking ground.
During takeoffs in a strong, gusty wind, it is advisable
that an extra margin of speed be obtained before the
airplane is allowed to leave the ground. Atakeoff at the
Figure 5-2. Initial roll and takeoff attitude. normal takeoff speed may result in a lack of positive
A. Initial roll
B. Takeoff attitude
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5-4
control, or a stall, when the airplane encounters a
sudden lull in strong, gusty wind, or other turbulent
air currents. In this case, the pilot should allow the
airplane to stay on the ground longer to attain more
speed; then make a smooth, positive rotation to leave
the ground.
INITIAL CLIMB
Upon lift-off, the airplane should be flying at approximately
the pitch attitude that will allow it to accelerate
to VY. This is the speed at which the airplane will gain
the most altitude in the shortest period of time.
If the airplane has been properly trimmed, some backelevator
pressure may be required to hold this attitude
until the proper climb speed is established. On the
other hand, relaxation of any back-elevator pressure
before this time may result in the airplane settling,
even to the extent that it contacts the runway.
The airplane will pick up speed rapidly after it
becomes airborne. Once a positive rate of climb is
established, the flaps and landing gear can be retracted
(if equipped).
It is recommended that takeoff power be maintained
until reaching an altitude of at least 500 feet above the
surrounding terrain or obstacles. The combination of
VY and takeoff power assures the maximum altitude
gained in a minimum amount of time. This gives the
pilot more altitude from which the airplane can be
safely maneuvered in case of an engine failure or other
emergency.
Since the power on the initial climb is fixed at the takeoff
power setting, the airspeed must be controlled by making
slight pitch adjustments using the elevators. However,
the pilot should not fixate on the airspeed indicator when
making these pitch changes, but should, instead, continue
to scan outside to adjust the airplane’s attitude in relation
to the horizon. In accordance with the principles of attitude
flying, the pilot should first make the necessary
pitch change with reference to the natural horizon and
hold the new attitude momentarily, and then glance at the
airspeed indicator as a check to see if the new attitude is
correct. Due to inertia, the airplane will not accelerate or
decelerate immediately as the pitch is changed. It takes a
little time for the airspeed to change. If the pitch attitude
has been over or under corrected, the airspeed indicator
will show a speed that is more or less than that desired.
When this occurs, the cross-checking and appropriate
pitch-changing process must be repeated until the desired
climbing attitude is established.
When the correct pitch attitude has been attained, it
should be held constant while cross-checking it against
the horizon and other outside visual references. The
airspeed indicator should be used only as a check to
determine if the attitude is correct.
After the recommended climb airspeed has been established,
and a safe maneuvering altitude has been
reached, the power should be adjusted to the recommended
climb setting and the airplane trimmed to
relieve the control pressures. This will make it easier
to hold a constant attitude and airspeed.
During initial climb, it is important that the takeoff
path remain aligned with the runway to avoid drifting
into obstructions, or the path of another aircraft that
may be taking off from a parallel runway. Proper scanning
techniques are essential to a safe takeoff and
climb, not only for maintaining attitude and direction,
but also for collision avoidance in the airport area.
When the student pilot nears the solo stage of flight
training, it should be explained that the airplane’s
takeoff performance will be much different when the
instructor is out of the airplane. Due to decreased
load, the airplane will become airborne sooner and
will climb more rapidly. The pitch attitude that the
student has learned to associate with initial climb
may also differ due to decreased weight, and the
flight controls may seem more sensitive. If the situation
is unexpected, it may result in increased tension
that may remain until after the landing. Frequently,
the existence of this tension and the uncertainty that
develops due to the perception of an “abnormal”
takeoff results in poor performance on the subsequent
landing.
Common errors in the performance of normal takeoffs
and departure climbs are:
• Failure to adequately clear the area prior to taxiing
into position on the active runway.
• Abrupt use of the throttle.
• Failure to check engine instruments for signs of
malfunction after applying takeoff power.
• Failure to anticipate the airplane’s left turning
tendency on initial acceleration.
• Overcorrecting for left turning tendency.
• Relying solely on the airspeed indicator rather
than developed feel for indications of speed and
airplane controllability during acceleration and
lift-off.
• Failure to attain proper lift-off attitude.
• Inadequate compensation for torque/P-factor
during initial climb resulting in a sideslip.
• Over-control of elevators during initial climbout.
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5-5
• Limiting scan to areas directly ahead of the airplane
(pitch attitude and direction), resulting in
allowing a wing (usually the left) to drop
immediately after lift-off.
• Failure to attain/maintain best rate-of-climb airspeed
(VY).
• Failure to employ the principles of attitude flying
during climb-out, resulting in “chasing” the airspeed
indicator.
CROSSWIND TAKEOFF
While it is usually preferable to take off directly into
the wind whenever possible or practical, there will
be many instances when circumstances or judgment
will indicate otherwise. Therefore, the pilot must be
familiar with the principles and techniques involved
in crosswind takeoffs, as well as those for normal
takeoffs. A crosswind will affect the airplane during
takeoff much as it does in taxiing. With this in mind,
it can be seen that the technique for crosswind
correction during takeoffs closely parallels the
crosswind correction techniques used in taxiing.
TAKEOFF ROLL
The technique used during the initial takeoff roll in a
crosswind is generally the same as used in a normal
takeoff, except that aileron control must be held INTO
the crosswind. This raises the aileron on the upwind
wing to impose a downward force on the wing to counteract
the lifting force of the crosswind and prevents
the wing from rising.
As the airplane is taxied into takeoff position, it is essential
that the windsock and other wind direction indicators
be checked so that the presence of a crosswind may be
recognized and anticipated. If a crosswind is indicated,
FULL aileron should be held into the wind as the takeoff
roll is started. This control position should be maintained
while the airplane is accelerating and until the ailerons
start becoming sufficiently effective for maneuvering the
airplane about its longitudinal axis.
With the aileron held into the wind, the takeoff path
must be held straight with the rudder.
Normally, this will require applying downwind rudder
pressure, since on the ground the airplane will tend to
weathervane into the wind. When takeoff power is
applied, torque or P-factor that yaws the airplane to the
left may be sufficient to counteract the weathervaning
tendency caused by a crosswind from the right. On the
other hand, it may also aggravate the tendency to
Figure 5-3. Crosswind takeoff roll and initial climb.
WIND
Apply full aileron into wind
Rudder as needed for direction
Hold aileron into wind
Roll on upwind wheel
Rudder as needed
Hold aileron into wind
Bank into wind
Rudder as needed
Start roll
Takeoff roll
Lift-off
Initial climb
Wings level
with a wind correction
angle
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5-6
swerve left when the wind is from the left. In any case,
whatever rudder pressure is required to keep the airplane
rolling straight down the runway should be
applied.
As the forward speed of the airplane increases and the
crosswind becomes more of a relative headwind, the
mechanical holding of full aileron into the wind should
be reduced. It is when increasing pressure is being felt
on the aileron control that the ailerons are becoming
more effective. As the aileron’s effectiveness increases
and the crosswind component of the relative wind
becomes less effective, it will be necessary to gradually
reduce the aileron pressure. The crosswind component
effect does not completely vanish, so some aileron pressure
will have to be maintained throughout the takeoff
roll to keep the crosswind from raising the upwind wing.
If the upwind wing rises, thus exposing more surface to
the crosswind, a “skipping” action may result. [Figure
5-4]
This is usually indicated by a series of very small
bounces, caused by the airplane attempting to fly
and then settling back onto the runway. During these
bounces, the crosswind also tends to move the airplane
sideways, and these bounces will develop into
side-skipping. This side-skipping imposes severe
side stresses on the landing gear and could result in
structural failure.
It is important, during a crosswind takeoff roll, to hold
sufficient aileron into the wind not only to keep the
upwind wing from rising but to hold that wing down so
that the airplane will, immediately after lift-off, be
sideslipping into the wind enough to counteract drift.
LIFT-OFF
As the nosewheel is being raised off the runway, the
holding of aileron control into the wind may result in
the downwind wing rising and the downwind main
wheel lifting off the runway first, with the remainder
of the takeoff roll being made on that one main wheel.
This is acceptable and is preferable to side-skipping.
If a significant crosswind exists, the main wheels
should be held on the ground slightly longer than in a
normal takeoff so that a smooth but very definite liftoff
can be made. This procedure will allow the airplane
to leave the ground under more positive control
so that it will definitely remain airborne while the
proper amount of wind correction is being established.
More importantly, this procedure will avoid imposing
excessive side-loads on the landing gear and prevent
possible damage that would result from the airplane
settling back to the runway while drifting.
As both main wheels leave the runway and ground
friction no longer resists drifting, the airplane will be
slowly carried sideways with the wind unless adequate
drift correction is maintained by the pilot. Therefore, it
is important to establish and maintain the proper
amount of crosswind correction prior to lift-off by
applying aileron pressure toward the wind to keep the
upwind wing from rising and applying rudder pressure
as needed to prevent weathervaning.
INITIAL CLIMB
If proper crosswind correction is being applied, as soon
as the airplane is airborne, it will be sideslipping into the
wind sufficiently to counteract the drifting effect of the
wind. This sideslipping should be continued
until the airplane has a positive rate of climb. At that time,
the airplane should be turned into the wind to establish
just enough wind correction angle to counteract the wind
and then the wings rolled level. Firm and aggressive use
of the rudders will be required to keep the airplane headed
straight down the runway. The climb with a wind correction
angle should be continued to follow a ground track
aligned with the runway direction. However, because the
force of a crosswind may vary markedly within a few
hundred feet of the ground, frequent checks of actual
ground track should be made, and the wind correction
adjusted as necessary. The remainder of the climb technique
is the same used for normal takeoffs and climbs.
Common errors in the performance of crosswind takeoffs
are:
• Failure to adequately clear the area prior to taxiing
onto the active runway.
• Using less than full aileron pressure into the
wind initially on the takeoff roll.
• Mechanical use of aileron control rather than
sensing the need for varying aileron control
input through feel for the airplane.
No correction
WIND
WIND
Proper correction
Figure 5-4. Crosswind effect.
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• Premature lift-off resulting in side-skipping.
• Excessive aileron input in the latter stage of the
takeoff roll resulting in a steep bank into the wind
at lift-off.
• Inadequate drift correction after lift-off.
GROUND EFFECT ON TAKEOFF
Ground effect is a condition of improved performance
encountered when the airplane is operating
very close to the ground. Ground effect can be
detected and measured up to an altitude equal to one
wingspan above the surface. However,
ground effect is most significant when the airplane
(especially a low-wing airplane) is maintaining a
constant attitude at low airspeed at low altitude (for
example, during takeoff when the airplane lifts off
and accelerates to climb speed, and during the landing
flare before touchdown).
When the wing is under the influence of ground effect,
there is a reduction in upwash, downwash, and wingtip
vortices. As a result of the reduced wingtip vortices,
induced drag is reduced. When the wing is at a height
equal to one-fourth the span, the reduction in induced
drag is about 25 percent, and when the wing is at a
height equal to one-tenth the span, the reduction in
induced drag is about 50 percent. At high speeds where
parasite drag dominates, induced drag is a small part of
the total drag. Consequently, the effects of ground effect
are of greater concern during takeoff and landing.
On takeoff, the takeoff roll, lift-off, and the beginning
of the initial climb are accomplished in the ground
effect area. The ground effect causes local increases in
static pressure, which cause the airspeed indicator and
altimeter to indicate slightly less than they should, and
usually results in the vertical speed indicator indicating
a descent. As the airplane lifts off and climbs out of
the ground effect area, however, the following will
occur.
• The airplane will require an increase in angle of
attack to maintain the same lift coefficient.
• The airplane will experience an increase in
induced drag and thrust required.
• The airplane will experience a pitch-up tendency
and will require less elevator travel because of an
increase in downwash at the horizontal tail.
WIND
Figure 5-5. Crosswind climb flightpath.
Ground effect
decreases
induced drag
Airplane may
fly at lower
indicated
airspeed
Accelerate in
ground effect
to VX or V Y
Ground effect
decreases quickly
with height
Ground effect is
negligible when
height is equal
to wingspan
Ground
Effect
Area
Figure 5-6.Takeoff in ground effect area.
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• The airplane will experience a reduction in static
source pressure as it leaves the ground effect area
and a corresponding increase in indicated airspeed.
Due to the reduced drag in ground effect, the airplane
may seem to be able to take off below the recommended
airspeed. However, as the airplane rises out of
ground effect with an insufficient airspeed, initial
climb performance may prove to be marginal because
of the increased drag. Under conditions of high-density
altitude, high temperature, and/or maximum gross
weight, the airplane may be able to become airborne at
an insufficient airspeed, but unable to climb out of
ground effect. Consequently, the airplane may not be
able to clear obstructions, or may settle back on the
runway. The point to remember is that additional
power is required to compensate for increases in drag
that occur as an airplane leaves ground effect. But during
an initial climb, the engine is already developing
maximum power. The only alternative is to lower pitch
attitude to gain additional airspeed, which will result in
inevitable altitude loss. Therefore, under marginal conditions,
it is important that the airplane takes off at the
recommended speed that will provide adequate initial
climb performance.
Ground effect is important to normal flight operations.
If the runway is long enough, or if no obstacles exist,
ground effect can be used to an advantage by using the
reduced drag to improve initial acceleration.
Additionally, the procedure for takeoff from unsatisfactory
surfaces is to take as much weight on the wings
as possible during the ground run, and to lift off with
the aid of ground effect before true flying speed is
attained. It is then necessary to reduce the angle of
attack to attain normal airspeed before attempting to
fly away from the ground effect area.
SHORT-FIELD TAKEOFF AND
MAXIMUM PERFORMANCE CLIMB
Takeoffs and climbs from fields where the takeoff area
is short or the available takeoff area is restricted by
obstructions require that the pilot operate the airplane
at the limit of its takeoff performance capabilities. To
depart from such an area safely, the pilot must exercise
positive and precise control of airplane attitude and
airspeed so that takeoff and climb performance results
in the shortest ground roll and the steepest angle of
climb.
The achieved result should be consistent with the
performance section of the FAA-approved Airplane
Flight Manual and/or Pilot’s Operating Handbook
(AFM/POH). In all cases, the power setting, flap
setting, airspeed, and procedures prescribed by the
airplane’s manufacturer should be followed.
In order to accomplish a maximum performance takeoff
safely, the pilot must have adequate knowledge in
the use and effectiveness of the best angle-of-climb
speed (VX) and the best rate-of-climb speed (VY) for
the specific make and model of airplane being flown.
The speed for VX is that which will result in the
greatest gain in altitude for a given distance over the
ground. It is usually slightly less than VY which provides
the greatest gain in altitude per unit of time.
The specific speeds to be used for a given airplane
are stated in the FAA-approved AFM/POH. It should
be emphasized that in some airplanes, a deviation of
5 knots from the recommended speed will result in a
significant reduction in climb performance.
Therefore, precise control of airspeed has an important
bearing on the successful execution as well as
the safety of the maneuver.
Climb
at VY
Retract gear
and flaps
Climb
at VX
Rotate at
approximately VX
Figure 5-7. Short-field takeoff.
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TAKEOFF ROLL
Taking off from a short field requires the takeoff to be
started from the very beginning of the takeoff area. At
this point, the airplane is aligned with the intended
takeoff path. If the airplane manufacturer recommends
the use of flaps, they should be extended the proper
amount before starting the takeoff roll. This permits
the pilot to give full attention to the proper technique
and the airplane’s performance throughout the takeoff.
Some authorities prefer to hold the brakes until the
maximum obtainable engine r.p.m. is achieved before
allowing the airplane to begin its takeoff run. However,
it has not been established that this procedure will
result in a shorter takeoff run in all light single-engine
airplanes. Takeoff power should be applied smoothly
and continuously—without hesitation—to accelerate
the airplane as rapidly as possible. The airplane should
be allowed to roll with its full weight on the main
wheels and accelerated to the lift-off speed. As the
takeoff roll progresses, the airplane’s pitch attitude and
angle of attack should be adjusted to that which results
in the minimum amount of drag and the quickest acceleration.
In nosewheel-type airplanes, this will involve
little use of the elevator control, since the airplane is
already in a low drag attitude.
LIFT-OFF
Approaching best angle-of-climb speed (VX), the airplane
should be smoothly and firmly lifted off, or rotated, by
applying back-elevator pressure to an attitude that will
result in the best angle-of-climb airspeed (VX). Since the
airplane will accelerate more rapidly after lift-off, additional
back-elevator pressure becomes necessary to hold a
constant airspeed. After becoming airborne, a wings level
climb should be maintained at VX until obstacles have
been cleared or, if no obstacles are involved, until an altitude
of at least 50 feet above the takeoff surface is attained.
Thereafter, the pitch attitude may be lowered slightly, and
the climb continued at best rate-of-climb speed (VY) until
reaching a safe maneuvering altitude. Remember that an
attempt to pull the airplane off the ground prematurely, or
to climb too steeply, may cause the airplane to settle back
to the runway or into the obstacles. Even if the airplane
remains airborne, the initial climb will remain flat and
climb performance/obstacle clearance ability seriously
degraded until best angle-of-climb airspeed (VX) is
achieved.
The objective is to rotate to the appropriate pitch attitude
at (or near) best angle-of-climb airspeed. It should
be remembered, however, that some airplanes will
have a natural tendency to lift off well before reaching
VX. In these airplanes, it may be necessary to allow the
airplane to lift off in ground effect and then reduce
pitch attitude to level until the airplane accelerates to
best angle-of-climb airspeed with the wheels just clear
of the runway surface. This method is preferable to
forcing the airplane to remain on the ground with forward-
elevator pressure until best angle-of-climb speed
is attained. Holding the airplane on the ground unnecessarily
puts excessive pressure on the nosewheel, may
result in “wheelbarrowing,” and will hinder both
acceleration and overall airplane performance.
INITIAL CLIMB
On short-field takeoffs, the landing gear and flaps
should remain in takeoff position until clear of obstacles
(or as recommended by the manufacturer) and VY
has been established. It is generally unwise for the pilot
to be looking in the cockpit or reaching for landing
gear and flap controls until obstacle clearance is
assured. When the airplane is stabilized at VY, the gear
(if equipped) and then the flaps should be retracted. It
is usually advisable to raise the flaps in increments to
avoid sudden loss of lift and settling of the airplane.
Next, reduce the power to the normal climb setting or
as recommended by the airplane manufacturer.
Common errors in the performance of short-field takeoffs
and maximum performance climbs are:
• Failure to adequately clear the area.
• Failure to utilize all available runway/takeoff
area.
• Failure to have the airplane properly trimmed
prior to takeoff.
• Premature lift-off resulting in high drag.
• Holding the airplane on the ground unnecessarily
with excessive forward-elevator pressure.
• Inadequate rotation resulting in excessive speed
after lift-off.
• Inability to attain/maintain best angle-of-climb
airspeed.
Premature rotation Airplane may lift off
at low airspeed
Airplane may settle
back to the ground
Flight below V
results in shallow
climb
X
Figure 5-8. Effect of premature lift-off.
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5-10
• Fixation on the airspeed indicator during initial
climb.
• Premature retraction of landing gear and/or wing
flaps.
SOFT/ROUGH-FIELD TAKEOFF
AND CLIMB
Takeoffs and climbs from soft fields require the use of
operational techniques for getting the airplane airborne
as quickly as possible to eliminate the drag caused by
tall grass, soft sand, mud, and snow, and may or may
not require climbing over an obstacle. The technique
makes judicious use of ground effect and requires a
feel for the airplane and fine control touch. These same
techniques are also useful on a rough field where it is
advisable to get the airplane off the ground as soon as
possible to avoid damaging the landing gear.
Soft surfaces or long, wet grass usually reduces the airplane’s
acceleration during the takeoff roll so much
that adequate takeoff speed might not be attained if
normal takeoff techniques were employed.
It should be emphasized that the correct takeoff
procedure for soft fields is quite different from
that appropriate for short fields with firm, smooth
surfaces. To minimize the hazards associated with
takeoffs from soft or rough fields, support of the
airplane’s weight must be transferred as rapidly
as possible from the wheels to the wings as the
takeoff roll proceeds. Establishing and maintaining
a relatively high angle of attack or nose-high
pitch attitude as early as possible does this. Wing
flaps may be lowered prior to starting the takeoff
(if recommended by the manufacturer) to provide
additional lift and to transfer the airplane’s weight
from the wheels to the wings as early as possible.
Stopping on a soft surface, such as mud or snow, might
bog the airplane down; therefore, it should be kept in
continuous motion with sufficient power while lining
up for the takeoff roll.
TAKEOFF ROLL
As the airplane is aligned with the takeoff path, takeoff
power is applied smoothly and as rapidly as the powerplant
will accept it without faltering. As the airplane
accelerates, enough back-elevator pressure should be
applied to establish a positive angle of attack and to
reduce the weight supported by the nosewheel.
When the airplane is held at a nose-high attitude
throughout the takeoff run, the wings will, as speed
increases and lift develops, progressively relieve the
wheels of more and more of the airplane’s weight,
thereby minimizing the drag caused by surface irregularities
or adhesion. If this attitude is accurately maintained,
the airplane will virtually fly itself off the ground,
becoming airborne at airspeed slower than a safe climb
speed because of ground effect.
LIFT-OFF
After becoming airborne, the nose should be lowered
very gently with the wheels clear of the surface to
allow the airplane to accelerate to VY, or VX if obstacles
must be cleared. Extreme care must be exercised
immediately after the airplane becomes airborne and
while it accelerates, to avoid settling back onto the surface.
An attempt to climb prematurely or too steeply
may cause the airplane to settle back to the surface as
a result of losing the benefit of ground effect. An
attempt to climb out of ground effect before sufficient
climb airspeed is attained may result in the airplane
being unable to climb further as the ground effect area
is transited, even with full power. Therefore, it is
essential that the airplane remain in ground effect until
at least VX is reached. This requires feel for the airplane,
and a very fine control touch, in order to avoid
over-controlling the elevator as required control pressures
change with airplane acceleration.
INITIAL CLIMB
After a positive rate of climb is established, and the airplane
has accelerated to VY, retract the landing gear and
flaps, if equipped. If departing from an airstrip with wet
snow or slush on the takeoff surface, the gear should not
be retracted immediately. This allows for any wet snow
or slush to be air-dried. In the event an obstacle must be
cleared after a soft-field takeoff, the climb-out is performed
at VX until the obstacle has been cleared. After
reaching this point, the pitch attitude is adjusted to VY
and the gear and flaps are retracted. The power may
then be reduced to the normal climb setting.
Accelerate Raise nosewheel Lift off
Level off in
ground effect
Accelerate
in ground effect
to VX or VY
Figure 5-9. Soft-field takeoff.
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Common errors in the performance of soft/rough field
takeoff and climbs are:
• Failure to adequately clear the area.
• Insufficient back-elevator pressure during initial
takeoff roll resulting in inadequate angle of
attack.
• Failure to cross-check engine instruments for
indications of proper operation after applying
power.
• Poor directional control.
• Climbing too steeply after lift-off.
• Abrupt and/or excessive elevator control while
attempting to level off and accelerate after liftoff.
• Allowing the airplane to “mush” or settle resulting
in an inadvertent touchdown after lift-off.
• Attempting to climb out of ground effect area
before attaining sufficient climb speed.
• Failure to anticipate an increase in pitch attitude
as the airplane climbs out of ground effect.
REJECTED TAKEOFF/ENGINE FAILURE
Emergency or abnormal situations can occur during a
takeoff that will require a pilot to reject the takeoff
while still on the runway. Circumstances such as a
malfunctioning powerplant, inadequate acceleration,
runway incursion, or air traffic conflict may be reasons
for a rejected takeoff.
Prior to takeoff, the pilot should have in mind a
point along the runway at which the airplane
should be airborne. If that point is reached and the
airplane is not airborne, immediate action should
be taken to discontinue the takeoff. Properly
planned and executed, chances are excellent the
airplane can be stopped on the remaining runway
without using extraordinary measures, such as
excessive braking that may result in loss of directional
control, airplane damage, and/or personal
injury.
In the event a takeoff is rejected, the power should be
reduced to idle and maximum braking applied while
maintaining directional control. If it is necessary to
shut down the engine due to a fire, the mixture control
should be brought to the idle cutoff position and the
magnetos turned off. In all cases, the manufacturer’s
emergency procedure should be followed.
What characterizes all power loss or engine failure
occurrences after lift-off is urgency. In most instances,
the pilot has only a few seconds after an engine failure
to decide what course of action to take and to execute
it. Unless prepared in advance to make the proper decision,
there is an excellent chance the pilot will make a
poor decision, or make no decision at all and allow
events to rule.
帅哥
发表于 2008-12-9 15:10:10
In the event of an engine failure on initial climb-out,
the pilot’s first responsibility is to maintain aircraft
control. At a climb pitch attitude without power, the
airplane will be at or near a stalling angle of attack.
At the same time, the pilot may still be holding right
rudder. It is essential the pilot immediately lower the
pitch attitude to prevent a stall and possible spin.
The pilot should establish a controlled glide toward
a plausible landing area (preferably straight ahead
on the remaining runway).
NOISE ABATEMENT
Aircraft noise problems have become a major concern at
many airports throughout the country. Many local communities
have pressured airports into developing specific
operational procedures that will help limit aircraft noise
while operating over nearby areas. For years now, the
FAA, airport managers, aircraft operators, pilots, and special
interest groups have been working together to minimize
aircraft noise for nearby sensitive areas. As a result,
noise abatement procedures have been developed for
many of these airports that include standardized profiles
and procedures to achieve these lower noise goals.
Airports that have noise abatement procedures provide
information to pilots, operators, air carriers, air traffic
facilities, and other special groups that are applicable
to their airport. These procedures are available to the
aviation community by various means. Most of this
information comes from the Airport/Facility Directory,
local and regional publications, printed handouts, operator
bulletin boards, safety briefings, and local air traffic
facilities.
At airports that use noise abatement procedures,
reminder signs may be installed at the taxiway hold
positions for applicable runways. These are to remind
pilots to use and comply with noise abatement procedures
on departure. Pilots who are not familiar with
these procedures should ask the tower or air traffic
facility for the recommended procedures. In any case,
pilots should be considerate of the surrounding community
while operating their airplane to and from such
an airport. This includes operating as quietly, yet safely
as possible.
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5-12
Ch 05.qxd 5/7/04 7:02 AM Page 5-12
PURPOSE AND SCOPE
Ground reference maneuvers and their related factors
are used in developing a high degree of pilot skill.
Although most of these maneuvers are not performed
as such in normal everyday flying, the elements and
principles involved in each are applicable to performance
of the customary pilot operations. They aid the
pilot in analyzing the effect of wind and other forces
acting on the airplane and in developing a fine control
touch, coordination, and the division of attention
necessary for accurate and safe maneuvering of the
airplane.
All of the early part of the pilot’s training has been conducted
at relatively high altitudes, and for the purpose
of developing technique, knowledge of maneuvers,
coordination, feel, and the handling of the airplane in
general. This training will have required that most of
the pilot’s attention be given to the actual handling of
the airplane, and the results of control pressures on the
action and attitude of the airplane.
If permitted to continue beyond the appropriate training
stage, however, the student pilot’s concentration of
attention will become a fixed habit, one that will seriously
detract from the student’s ease and safety as a
pilot, and will be very difficult to eliminate. Therefore,
it is necessary, as soon as the pilot shows proficiency in
the fundamental maneuvers, that the pilot be introduced
to maneuvers requiring outside attention on a practical
application of these maneuvers and the knowledge
gained.
It should be stressed that, during ground reference
maneuvers, it is equally important that basic flying
technique previously learned be maintained. The
flight instructor should not allow any relaxation of the
student’s previous standard of technique simply
because a new factor is added. This requirement
should be maintained throughout the student’s
progress from maneuver to maneuver. Each new
maneuver should embody some advance and include
the principles of the preceding one in order that continuity
be maintained. Each new factor introduced
should be merely a step-up of one already learned so
that orderly, consistent progress can be made.
MANEUVERING BY REFERENCE
TO GROUND OBJECTS
Ground track or ground reference maneuvers are performed
at a relatively low altitude while applying wind
drift correction as needed to follow a predetermined
track or path over the ground. They are designed to
develop the ability to control the airplane, and to recognize
and correct for the effect of wind while dividing
attention among other matters. This requires planning
ahead of the airplane, maintaining orientation in relation
to ground objects, flying appropriate headings to follow
a desired ground track, and being cognizant of other air
traffic in the immediate vicinity.
Ground reference maneuvers should be flown at an altitude
of approximately 600 to 1,000 feet AGL. The
actual altitude will depend on the speed and type of airplane
to a large extent, and the following factors should
be considered.
• The speed with relation to the ground should not
be so apparent that events happen too rapidly.
• The radius of the turn and the path of the airplane
over the ground should be easily noted and
changes planned and effected as circumstances
require.
• Drift should be easily discernable, but not tax the
student too much in making corrections.
• Objects on the ground should appear in their proportion
and size.
• The altitude should be low enough to render any
gain or loss apparent to the student, but in no case
lower than 500 feet above the highest obstruction.
During these maneuvers, both the instructor and the
student should be alert for available forced-landing
fields. The area chosen should be away from communities,
livestock, or groups of people to prevent possible
annoyance or hazards to others. Due to the altitudes at
which these maneuvers are performed, there is little
time available to search for a suitable field for landing
in the event the need arises.
6-1
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6-2
DRIFT AND GROUND
TRACK CONTROL
Whenever any object is free from the ground, it is
affected by the medium with which it is surrounded.
This means that a free object will move in whatever
direction and speed that the medium moves.
For example, if a powerboat is crossing a river and
the river is still, the boat could head directly to a point
on the opposite shore and travel on a straight course
to that point without drifting. However, if the river
were flowing swiftly, the water current would have to
be considered. That is, as the boat progresses forward
with its own power, it must also move upstream at the
same rate the river is moving it downstream. This is
accomplished by angling the boat upstream sufficiently
to counteract the downstream flow. If this is
done, the boat will follow the desired track across
the river from the departure point directly to the
intended destination point. Should the boat not be
headed sufficiently upstream, it would drift with the
current and run aground at some point downstream
on the opposite bank.
As soon as an airplane becomes airborne, it is free of
ground friction. Its path is then affected by the air mass
in which it is flying; therefore, the airplane (like the
boat) will not always track along the ground in the
exact direction that it is headed. When flying with the
longitudinal axis of the airplane aligned with a road, it
may be noted that the airplane gets closer to or farther
from the road without any turn having been made. This
would indicate that the air mass is moving sideward in
relation to the airplane. Since the airplane is flying
within this moving body of air (wind), it moves or
drifts with the air in the same direction and speed, just
like the boat moved with the river current.
When flying straight and level and following a
selected ground track, the preferred method of correcting
for wind drift is to head the airplane (wind
correction angle) sufficiently into the wind to cause
the airplane to move forward into the wind at the
same rate the wind is moving it sideways.
Depending on the wind velocity, this may require a
large wind correction angle or one of only a few
degrees. When the drift has been neutralized, the
airplane will follow the desired ground track.
To understand the need for drift correction during
flight, consider a flight with a wind velocity of 30
knots from the left and 90° to the direction the airplane
is headed. After 1 hour, the body of air in which the
airplane is flying will have moved 30 nautical miles
(NM) to the right. Since the airplane is moving with
this body of air, it too will have drifted 30 NM to the
right. In relation to the air, the airplane moved forward,
but in relation to the ground, it moved forward
as well as 30 NM to the right.
There are times when the pilot needs to correct for drift
while in a turn. Throughout the turn the
wind will be acting on the airplane from constantly
changing angles. The relative wind angle and speed
CURRENT CURRENT
No Current - No Drift With a current the boat drifts
downstream unless corrected.
With proper correction, boat
stays on intended course.
No Wind - No Drift With any wind, the airplane drifts
downwind unless corrected.
With proper correction, airplane
stays on intended course.
WIND WIND
Figure 6-1. Wind drift.
Ch 06.qxd 5/7/04 7:35 AM Page 6-2
6-3
govern the time it takes for the airplane to progress
through any part of a turn. This is due to the constantly
changing groundspeed. When the airplane is headed
into the wind, the groundspeed is decreased; when
headed downwind, the groundspeed is increased.
Through the crosswind portion of a turn, the airplane
must be turned sufficiently into the wind to counteract
drift.
To follow a desired circular ground track, the wind correction
angle must be varied in a timely manner
because of the varying groundspeed as the turn progresses.
The faster the groundspeed, the faster the wind
correction angle must be established; the slower the
groundspeed, the slower the wind correction angle may
be established. It can be seen then that the steepest
bank and fastest rate of turn should be made on the
downwind portion of the turn and the shallowest bank
and slowest rate of turn on the upwind portion.
The principles and techniques of varying the angle of
bank to change the rate of turn and wind correction
angle for controlling wind drift during a turn are the
same for all ground track maneuvers involving
changes in direction of flight.
When there is no wind, it should be simple to fly along
a ground track with an arc of exactly 180° and a constant
radius because the flightpath and ground track
would be identical. This can be demonstrated by
approaching a road at a 90° angle and, when directly
over the road, rolling into a medium-banked turn, then
maintaining the same angle of bank throughout the
180° of turn.
To complete the turn, the rollout should be started at a
point where the wings will become level as the airplane
again reaches the road at a 90° angle and will be
directly over the road just as the turn is completed. This
would be possible only if there were absolutely no
wind and if the angle of bank and the rate of turn
remained constant throughout the entire maneuver.
If the turn were made with a constant angle of bank
and a wind blowing directly across the road, it would
result in a constant radius turn through the air.
However, the wind effects would cause the ground
track to be distorted from a constant radius turn or
semicircular path. The greater the wind velocity, the
greater would be the difference between the desired
ground track and the flightpath. To counteract this
drift, the flightpath can be controlled by the pilot in
such a manner as to neutralize the effect of the wind,
and cause the ground track to be a constant radius
semicircle.
The effects of wind during turns can be demonstrated
after selecting a road, railroad, or other ground reference
that forms a straight line parallel to the wind. Fly
into the wind directly over and along the line and then
make a turn with a constant medium angle of bank for
360° of turn. The airplane will return to a
point directly over the line but slightly downwind from
the starting point, the amount depending on the wind
velocity and the time required to complete the turn.
The path over the ground will be an elongated circle,
although in reference to the air it is a perfect circle.
Straight flight during the upwind segment after completion
of the turn is necessary to bring the airplane
back to the starting position.
20 Knot Wind
Intended ground path
Actual ground path
No Wind
Figure 6-2. Effect of wind during a turn.
Figure 6-3. Effect of wind during turns.
No Wind
Start & Finish
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6-4
A similar 360° turn may be started at a specific point
over the reference line, with the airplane headed
directly downwind. In this demonstration, the effect of
wind during the constant banked turn will drift the airplane
to a point where the line is reintercepted, but the
360° turn will be completed at a point downwind from
the starting point.
Another reference line which lies directly crosswind
may be selected and the same procedure repeated,
showing that if wind drift is not corrected the airplane
will, at the completion of the 360° turn, be headed in
the original direction but will have drifted away from
the line a distance dependent on the amount of wind.
From these demonstrations, it can be seen where and
why it is necessary to increase or decrease the angle of
bank and the rate of turn to achieve a desired track over
the ground. The principles and techniques involved can
be practiced and evaluated by the performance of the
ground track maneuvers discussed in this chapter.
RECTANGULAR COURSE
Normally, the first ground reference maneuver the pilot
is introduced to is the rectangular course.
The rectangular course is a training maneuver in which
the ground track of the airplane is equidistant from all
sides of a selected rectangular area on the ground. The
maneuver simulates the conditions encountered in an
airport traffic pattern. While performing the maneuver,
the altitude and airspeed should be held constant.
The maneuver assists the student pilot in perfecting:
• Practical application of the turn.
• The division of attention between the flightpath,
ground objects, and the handling of the airplane.
• The timing of the start of a turn so that the turn
will be fully established at a definite point over
the ground.
• The timing of the recovery from a turn so that a
definite ground track will be maintained.
• The establishing of a ground track and the determination
of the appropriate “crab” angle.
Like those of other ground track maneuvers, one of the
objectives is to develop division of attention between
the flightpath and ground references, while controlling
the airplane and watching for other aircraft in the
Turn More Than
90° Rollout
with Wind Correction
Established
Complete Turn
at Boundary
Turn Into
Wind
Start Turn at
Boundary
Start Turn
at Boundary
Complete Turn
at Boundary
Turn
Less Than 90°
Complete Turn
at Boundary
Start Turn
at Boundary
No Wind Correction
Enter
45° to Downwind
Exit
No Wind Correction
Turn Into
Wind
Turn Less Than
90° Rollout
With WIind Correction
Established
Turn More
Than 90°
Start Turn at
Boundary
Complete Turn
at Boundary
Track With No Wind Correction
Track With No Wind Correction
DOWNWIND
UPWIND
CROSSWIND
BASE
Figure 6-4. Rectangular course.
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6-5
vicinity. Another objective is to develop recognition of
drift toward or away from a line parallel to the intended
ground track. This will be helpful in recognizing drift
toward or from an airport runway during the various
legs of the airport traffic pattern.
For this maneuver, a square or rectangular field, or an
area bounded on four sides by section lines or roads
(the sides of which are approximately a mile in length),
should be selected well away from other air traffic. The
airplane should be flown parallel to and at a uniform
distance about one-fourth to one-half mile away from
the field boundaries, not above the boundaries. For
best results, the flightpath should be positioned outside
the field boundaries just far enough that they may be
easily observed from either pilot seat by looking out
the side of the airplane. If an attempt is made to fly
directly above the edges of the field, the pilot will have
no usable reference points to start and complete the
turns. The closer the track of the airplane is to the field
boundaries, the steeper the bank necessary at the turning
points. Also, the pilot should be able to see the
edges of the selected field while seated in a normal
position and looking out the side of the airplane during
either a left-hand or right-hand course. The distance of
the ground track from the edges of the field should be
the same regardless of whether the course is flown to
the left or right. All turns should be started when the
airplane is abeam the corner of the field boundaries,
and the bank normally should not exceed 45°. These
should be the determining factors in establishing the
distance from the boundaries for performing the
maneuver.
Although the rectangular course may be entered from
any direction, this discussion assumes entry on a
downwind.
On the downwind leg, the wind is a tailwind and results
in an increased groundspeed. Consequently, the turn
onto the next leg is entered with a fairly fast rate of
roll-in with relatively steep bank. As the turn progresses,
the bank angle is reduced gradually because
the tailwind component is diminishing, resulting in a
decreasing groundspeed.
During and after the turn onto this leg (the equivalent
of the base leg in a traffic pattern), the wind will tend
to drift the airplane away from the field boundary. To
compensate for the drift, the amount of turn will be
more than 90°.
The rollout from this turn must be such that as the
wings become level, the airplane is turned slightly
toward the field and into the wind to correct for drift.
The airplane should again be the same distance from
the field boundary and at the same altitude, as on other
legs. The base leg should be continued until the upwind
leg boundary is being approached. Once more the pilot
should anticipate drift and turning radius. Since drift
correction was held on the base leg, it is necessary to
turn less than 90° to align the airplane parallel to the
upwind leg boundary. This turn should be started with
a medium bank angle with a gradual reduction to a
shallow bank as the turn progresses. The rollout should
be timed to assure paralleling the boundary of the field
as the wings become level.
While the airplane is on the upwind leg, the next field
boundary should be observed as it is being approached,
to plan the turn onto the crosswind leg. Since the wind
is a headwind on this leg, it is reducing the airplane’s
groundspeed and during the turn onto the crosswind
leg will try to drift the airplane toward the field. For
this reason, the roll-in to the turn must be slow and the
bank relatively shallow to counteract this effect. As the
turn progresses, the headwind component decreases,
allowing the groundspeed to increase. Consequently,
the bank angle and rate of turn are increased gradually
to assure that upon completion of the turn the crosswind
ground track will continue the same distance
from the edge of the field. Completion of the turn with
the wings level should be accomplished at a point
aligned with the upwind corner of the field.
Simultaneously, as the wings are rolled level, the
proper drift correction is established with the airplane
turned into the wind. This requires that the turn be less
than a 90° change in heading. If the turn has been made
properly, the field boundary will again appear to be
one-fourth to one-half mile away. While on the crosswind
leg, the wind correction angle should be adjusted
as necessary to maintain a uniform distance from the
field boundary.
As the next field boundary is being approached, the
pilot should plan the turn onto the downwind leg. Since
a wind correction angle is being held into the wind and
away from the field while on the crosswind leg, this
next turn will require a turn of more than 90°. Since
the crosswind will become a tailwind, causing the
groundspeed to increase during this turn, the bank initially
should be medium and progressively increased
as the turn proceeds. To complete the turn, the rollout
must be timed so that the wings become level at a point
aligned with the crosswind corner of the field just as
the longitudinal axis of the airplane again becomes
parallel to the field boundary. The distance from the
field boundary should be the same as from the other
sides of the field.
Usually, drift should not be encountered on the upwind
or the downwind leg, but it may be difficult to find a
situation where the wind is blowing exactly parallel to
the field boundaries. This would make it necessary to
use a slight wind correction angle on all the legs. It is
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important to anticipate the turns to correct for groundspeed,
drift, and turning radius. When the wind is
behind the airplane, the turn must be faster and steeper;
when it is ahead of the airplane, the turn must be
slower and shallower. These same techniques apply
while flying in airport traffic patterns.
Common errors in the performance of rectangular
courses are:
• Failure to adequately clear the area.
• Failure to establish proper altitude prior to
entry. (Typically entering the maneuver while
descending.)
• Failure to establish appropriate wind correction
angle resulting in drift.
• Gaining or losing altitude.
• Poor coordination. (Typically skidding in turns
from a downwind heading and slipping in turns
from an upwind heading.)
• Abrupt control usage.
• Inability to adequately divide attention between
airplane control and maintaining ground track.
• Improper timing in beginning and recovering
from turns.
• Inadequate visual lookout for other aircraft.
S-TURNS ACROSS A ROAD
An S-turn across a road is a practice maneuver in
which the airplane’s ground track describes semicircles
of equal radii on each side of a selected straight
line on the ground. The straight line may
be a road, fence, railroad, or section line that lies perpendicular
to the wind, and should be of sufficient
length for making a series of turns. A constant altitude
should be maintained throughout the maneuver.
S-turns across a road present one of the most elementary
problems in the practical application of the turn
and in the correction for wind drift in turns. While the
application of this maneuver is considerably less
advanced in some respects than the rectangular course,
it is taught after the student has been introduced to that
maneuver in order that the student may have a knowledge
of the correction for wind drift in straight flight
along a reference line before the student attempt to
correct for drift by playing a turn.
The objectives of S-turns across a road are to develop
the ability to compensate for drift during turns, orient
the flightpath with ground references, follow an
assigned ground track, arrive at specified points on
assigned headings, and divide the pilot’s attention. The
Steep
Bank
Shallow Bank
Shallow Bank
Steep
Bank
Moderate Bank
Moderate Bank
Wings Level
Entry
Figure 6-5. S-Turns.
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maneuver consists of crossing the road at a 90° angle
and immediately beginning a series of 180° turns of
uniform radius in opposite directions, re-crossing the
road at a 90° angle just as each 180° turn is completed.
To accomplish a constant radius ground track requires
a changing roll rate and angle of bank to establish the
wind correction angle. Both will increase or decrease
as groundspeed increases or decreases.
The bank must be steepest when beginning the turn on
the downwind side of the road and must be shallowed
gradually as the turn progresses from a downwind
heading to an upwind heading. On the upwind side, the
turn should be started with a relatively shallow bank
and then gradually steepened as the airplane turns from
an upwind heading to a downwind heading.
In this maneuver, the airplane should be rolled from
one bank directly into the opposite just as the reference
line on the ground is crossed.
Before starting the maneuver, a straight ground reference
line or road that lies 90° to the direction of the
wind should be selected, then the area checked to
ensure that no obstructions or other aircraft are in the
immediate vicinity. The road should be approached
from the upwind side, at the selected altitude on a
downwind heading. When directly over the road, the
first turn should be started immediately. With the airplane
headed downwind, the groundspeed is greatest
and the rate of departure from the road will be rapid;
so the roll into the steep bank must be fairly rapid to
attain the proper wind correction angle. This prevents
the airplane from flying too far from the road and
from establishing a ground track of excessive radius.
During the latter portion of the first 90° of turn when
the airplane’s heading is changing from a downwind
heading to a crosswind heading, the groundspeed
becomes less and the rate of departure from the road
decreases. The wind correction angle will be at the
maximum when the airplane is headed directly crosswind.
After turning 90°, the airplane’s heading becomes
more and more an upwind heading, the groundspeed
will decrease, and the rate of closure with the road
will become slower. If a constant steep bank were
maintained, the airplane would turn too quickly for
the slower rate of closure, and would be headed perpendicular
to the road prematurely. Because of the
decreasing groundspeed and rate of closure while
approaching the upwind heading, it will be necessary
to gradually shallow the bank during the remaining
90° of the semicircle, so that the wind correction
angle is removed completely and the wings become
level as the 180° turn is completed at the moment the
road is reached.
At the instant the road is being crossed again, a turn in
the opposite direction should be started. Since the airplane
is still flying into the headwind, the groundspeed
is relatively slow. Therefore, the turn will have to be
started with a shallow bank so as to avoid an excessive
rate of turn that would establish the maximum wind
correction angle too soon. The degree of bank should
be that which is necessary to attain the proper wind
correction angle so the ground track describes an arc
the same size as the one established on the downwind
side.
Since the airplane is turning from an upwind to a
downwind heading, the groundspeed will increase
and after turning 90°, the rate of closure with the road
will increase rapidly. Consequently, the angle of bank
and rate of turn must be progressively increased so
that the airplane will have turned 180° at the time it
reaches the road. Again, the rollout must be timed so
the airplane is in straight-and-level flight directly
over and perpendicular to the road.
Throughout the maneuver a constant altitude should
be maintained, and the bank should be changing
constantly to effect a true semicircular ground track.
Often there is a tendency to increase the bank too
rapidly during the initial part of the turn on the
upwind side, which will prevent the completion of
the 180° turn before re-crossing the road. This is
apparent when the turn is not completed in time for
the airplane to cross the road at a perpendicular
angle. To avoid this error, the pilot must visualize the
desired half circle ground track, and increase the
bank during the early part of this turn. During the latter
part of the turn, when approaching the road, the
pilot must judge the closure rate properly and
increase the bank accordingly, so as to cross the road
perpendicular to it just as the rollout is completed.
Common errors in the performance of S-turns across a
road are:
• Failure to adequately clear the area.
• Poor coordination.
• Gaining or losing altitude.
• Inability to visualize the half circle ground track.
• Poor timing in beginning and recovering from
turns.
• Faulty correction for drift.
• Inadequate visual lookout for other aircraft.
TURNS AROUND A POINT
Turns around a point, as a training maneuver, is a
logical extension of the principles involved in the
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performance of S-turns across a road. Its purposes as
a training maneuver are:
• To further perfect turning technique.
• To perfect the ability to subconsciously control
the airplane while dividing attention between the
flightpath and ground references.
• To teach the student that the radius of a turn is a
distance which is affected by the degree of bank
used when turning with relation to a definite
object.
• To develop a keen perception of altitude.
• To perfect the ability to correct for wind drift
while in turns.
In turns around a point, the airplane is flown in two or
more complete circles of uniform radii or distance
from a prominent ground reference point using a maximum
bank of approximately 45° while maintaining a
constant altitude.
The factors and principles of drift correction that are
involved in S-turns are also applicable in this maneuver.
As in other ground track maneuvers, a constant
radius around a point will, if any wind exists, require a
constantly changing angle of bank and angles of wind
correction. The closer the airplane is to a direct downwind
heading where the groundspeed is greatest, the
steeper the bank and the faster the rate of turn required
to establish the proper wind correction angle. The
more nearly it is to a direct upwind heading where the
groundspeed is least, the shallower the bank and the
slower the rate of turn required to establish the proper
wind correction angle. It follows, then, that throughout
the maneuver the bank and rate of turn must be
gradually varied in proportion to the groundspeed.
The point selected for turns around a point should
be prominent, easily distinguished by the pilot, and
yet small enough to present precise reference.
Isolated trees, crossroads, or other similar
small landmarks are usually suitable.
To enter turns around a point, the airplane should be
flown on a downwind heading to one side of the
selected point at a distance equal to the desired radius
of turn. In a high-wing airplane, the distance from the
point must permit the pilot to see the point throughout
the maneuver even with the wing lowered in a bank. If
the radius is too large, the lowered wing will block the
pilot’s view of the point.
When any significant wind exists, it will be necessary to
roll into the initial bank at a rapid rate so that the steep-
Steepest
Bank
Shallowest
Bank
Steeper
Bank
Shallower
Bank
Upwind Half of Circle
Downwind Half of Circle
Figure 6-6.Turns around a point.
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est bank is attained abeam of the point when the airplane
is headed directly downwind. By entering the maneuver
while heading directly downwind, the steepest bank can
be attained immediately. Thus, if a maximum bank of
45° is desired, the initial bank will be 45° if the airplane
is at the correct distance from the point. Thereafter, the
bank is shallowed gradually until the point is reached
where the airplane is headed directly upwind. At this
point, the bank should be gradually steepened until the
steepest bank is again attained when heading downwind
at the initial point of entry.
Just as S-turns require that the airplane be turned into
the wind in addition to varying the bank, so do turns
around a point. During the downwind half of the circle,
the airplane’s nose is progressively turned toward the
inside of the circle; during the upwind half, the nose is
progressively turned toward the outside. The downwind
half of the turn around the point may be compared to the
downwind side of the S-turn across a road; the upwind
half of the turn around a point may be compared to the
upwind side of the S-turn across a road.
As the pilot becomes experienced in performing turns
around a point and has a good understanding of the
effects of wind drift and varying of the bank angle and
wind correction angle as required, entry into the
maneuver may be from any point. When entering the
maneuver at a point other than downwind, however,
the radius of the turn should be carefully selected, taking
into account the wind velocity and groundspeed so
that an excessive bank is not required later on to maintain
the proper ground track. The flight instructor
should place particular emphasis on the effect of an
incorrect initial bank. This emphasis should continue
in the performance of elementary eights.
Common errors in the performance of turns around a
point are:
• Failure to adequately clear the area.
• Failure to establish appropriate bank on entry.
• Failure to recognize wind drift.
• Excessive bank and/or inadequate wind correction
angle on the downwind side of the circle
resulting in drift towards the reference point.
• Inadequate bank angle and/or excessive wind
correction angle on the upwind side of the circle
resulting in drift away from the reference point.
• Skidding turns when turning from downwind to
crosswind.
• Slipping turns when turning from upwind to
crosswind.
• Gaining or losing altitude.
• Inadequate visual lookout for other aircraft.
• Inability to direct attention outside the airplane
while maintaining precise airplane control.
ELEMENTARY EIGHTS
An “eight” is a maneuver in which the airplane
describes a path over the ground more or less in the
shape of a figure “8”. In all eights except “lazy eights”
the path is horizontal as though following a marked
path over the ground. There are various types of eights,
progressing from the elementary types to very difficult
types in the advanced maneuvers. Each has its special
use in teaching the student to solve a particular
problem of turning with relation to the Earth, or an
object on the Earth’s surface. Each type, as they
advance in difficulty of accomplishment, further
perfects the student’s coordination technique and
requires a higher degree of subconscious flying ability.
Of all the training maneuvers available to the
instructor, only eights require the progressively
higher degree of conscious attention to outside
objects. However, the real importance of eights is in
the requirement for the perfection and display of
subconscious flying.
Elementary eights, specifically eights along a road,
eights across a road, and eights around pylons, are
variations of turns around a point, which use two
points about which the airplane circles in either
direction. Elementary eights are designed for the following
purposes.
• To perfect turning technique.
• To develop the ability to divide attention between
the actual handling of controls and an outside
objective.
• To perfect the knowledge of the effect of angle of
bank on radius of turn.
• To demonstrate how wind affects the path of the
airplane over the ground.
• To gain experience in the visualization of the
results of planning before the execution of the
maneuver.
• To train the student to think and plan ahead of the
airplane.
EIGHTS ALONG A ROAD
An eight along a road is a maneuver in which the
ground track consists of two complete adjacent circles
of equal radii on each side of a straight road or other
reference line on the ground. The ground track resembles
a figure 8.
Like the other ground reference maneuvers, its
objective is to develop division of attention while
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compensating for drift, maintaining orientation with
ground references, and maintaining a constant
altitude.
Although eights along a road may be performed with
the wind blowing parallel to the road or directly across
the road, for simplification purposes, only the latter situation
is explained since the principles involved in
either case are common.
A reference line or road which is perpendicular to the
wind should be selected and the airplane flown parallel
to and directly above the road. Since the wind is blowing
across the flightpath, the airplane will require some
wind correction angle to stay directly above the road
during the initial straight and level portion. Before
starting the maneuver, the area should be checked to
ensure clearance of obstructions and avoidance of
other aircraft.
Usually, the first turn should be made toward a downwind
heading starting with a medium bank. Since the
airplane will be turning more and more directly downwind,
the groundspeed will be gradually increasing and
the rate of departing the road will tend to become
faster. Thus, the bank and rate of turn is increased to
establish a wind correction angle to keep the airplane
from exceeding the desired distance from the road
when 180° of change in direction is completed. The
steepest bank is attained when the airplane is headed
directly downwind.
As the airplane completes 180° of change in direction,
it will be flying parallel to and using a wind correction
angle toward the road with the wind acting directly
perpendicular to the ground track. At this point, the
pilot should visualize the remaining 180° of ground
track required to return to the same place over the road
from which the maneuver started.
While the turn is continued toward an upwind heading,
the wind will tend to keep the airplane from reaching
the road, with a decrease in groundspeed and rate of
closure. The rate of turn and wind correction angle are
decreased proportionately so that the road will be
reached just as the 360° turn is completed. To accomplish
this, the bank is decreased so that when headed
directly upwind, it will be at the shallowest angle. In
the last 90° of the turn, the bank may be varied to correct
any previous errors in judging the returning rate
and closure rate. The rollout should be timed so that
the airplane will be straight and level over the starting
point, with enough drift correction to hold it over the
road.
After momentarily flying straight and level along the
road, the airplane is then rolled into a medium bank
turn in the opposite direction to begin the circle on the
upwind side of the road. The wind will still be decreasing
the groundspeed and trying to drift the airplane
back toward the road; therefore, the bank must be
decreased slowly during the first 90° change in direction
in order to reach the desired distance from the
road and attain the proper wind correction angle when
180° change in direction has been completed.
As the remaining 180° of turn continues, the wind
becomes more of a tailwind and increases the airplane’s
groundspeed. This causes the rate of closure
to become faster; consequently, the angle of bank
and rate of turn must be increased further to attain
sufficient wind correction angle to keep the airplane
from approaching the road too rapidly. The bank will
be at its steepest angle when the airplane is headed
directly downwind.
In the last 90° of the turn, the rate of turn should be
reduced to bring the airplane over the starting point on
the road. The rollout must be timed so the airplane will
be straight and level, turned into the wind, and flying
parallel to and over the road.
The measure of a student’s progress in the performance
of eights along a road is the smoothness and accuracy of
the change in bank used to counteract drift. The sooner
the drift is detected and correction applied, the smaller
will be the required changes. The more quickly the
student can anticipate the corrections needed, the
less obvious the changes will be and the more attention
can be diverted to the maintenance of altitude and operation
of the airplane.
Errors in coordination must be eliminated and a constant
altitude maintained. Flying technique must not
be allowed to suffer from the fact that the student’s
attention is diverted. This technique should improve as
the student becomes able to divide attention between
the operation of the airplane controls and following a
designated flightpath.
Shallower
Bank
Shallowest
Bank Steep
Bank
Shallowest
Bank
Steeper
Bank
Steepest
Bank
Figure 6-7. Eights along a road.
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EIGHTS ACROSS A ROAD
This maneuver is a variation of eights along a road and
involves the same principles and techniques. The primary
difference is that at the completion of each loop
of the figure eight, the airplane should cross an intersection
of roads or a specific point on a straight road.
The loops should be across the road and the wind
should be perpendicular to the road. Each time the road
is crossed, the crossing angle should be the same and
the wings of the airplane should be level. The eights
also may be performed by rolling from one bank
immediately to the other, directly over the road.
EIGHTS AROUND PYLONS
This training maneuver is an application of the same
principles and techniques of correcting for wind drift
as used in turns around a point and the same objectives
as other ground track maneuvers. In this case, two
points or pylons on the ground are used as references,
and turns around each pylon are made in opposite
directions to follow a ground track in the form of a
figure 8.
Steeper
Bank
Shallower
Bank
Shallowest
Bank
Steeper
Bank
Shallowest
Bank
Shallower
Bank
Steepest
Bank
Steepest
Bank
Figure 6-8. Eights across a road.
Steeper
Bank
Shallower
Bank
Shallowest
Bank
Steeper
Bank
Shallowest
Bank
Shallower
Bank
Steepest
Bank
Steepest
Bank
Figure 6-9. Eights around pylons.
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The pattern involves flying downwind between the
pylons and upwind outside of the pylons. It may
include a short period of straight-and-level flight while
proceeding diagonally from one pylon to the other.
The pylons selected should be on a line 90° to the
direction of the wind and should be in an area away
from communities, livestock, or groups of people, to
avoid possible annoyance or hazards to others. The
area selected should be clear of hazardous obstructions
and other air traffic. Throughout the maneuver a constant
altitude of at least 500 feet above the ground
should be maintained.
The eight should be started with the airplane on a
downwind heading when passing between the pylons.
The distance between the pylons and the wind velocity
will determine the initial angle of bank required to
maintain a constant radius from the pylons during each
turn. The steepest banks will be necessary just after
each turn entry and just before the rollout from each
turn where the airplane is headed downwind and the
groundspeed is greatest; the shallowest banks will be
when the airplane is headed directly upwind and the
groundspeed is least.
The rate of bank change will depend on the wind
velocity, the same as it does in S-turns and turns
around a point, and the bank will be changing continuously
during the turns. The adjustment of the bank
angle should be gradual from the steepest bank to the
shallowest bank as the airplane progressively heads
into the wind, followed by a gradual increase until the
steepest bank is again reached just prior to rollout. If
the airplane is to proceed diagonally from one turn to
the other, the rollout from each turn must be completed
on the proper heading with sufficient wind correction
angle to ensure that after brief straight-and-level flight,
the airplane will arrive at the point where a turn of the
same radius can be made around the other pylon. The
straight-and-level flight segments must be tangent to
both circular patterns.
Common errors in the performance of elementary
eights are:
• Failure to adequately clear the area.
• Poor choice of ground reference points.
• Improper maneuver entry considering wind
direction and ground reference points.
• Incorrect initial bank.
• Poor coordination during turns.
• Gaining or losing altitude.
• Loss of orientation.
• Abrupt rather than smooth changes in bank angle
to counteract wind drift in turns.
• Failure to anticipate needed drift correction.
• Failure to apply needed drift correction in a
timely manner.
• Failure to roll out of turns on proper heading.
• Inability to divide attention between reference
points on the ground, airplane control, and scanning
for other aircraft.
EIGHTS-ON-PYLONS (PYLON EIGHTS)
The pylon eight is the most advanced and most difficult
of the low altitude flight training maneuvers.
Because of the various techniques involved, the pylon
eight is unsurpassed for teaching, developing, and testing
subconscious control of the airplane.
As the pylon eight is essentially an advanced
maneuver in which the pilot’s attention is directed
at maintaining a pivotal position on a selected pylon,
with a minimum of attention within the cockpit, it
should not be introduced until the instructor is assured
that the student has a complete grasp of the fundamentals.
Thus, the prerequisites are the ability to make a coordinated
turn without gain or loss of altitude, excellent feel of
the airplane, stall recognition, relaxation with low altitude
maneuvering, and an absence of the error of over
concentration.
Like eights around pylons, this training maneuver also
involves flying the airplane in circular paths, alternately
left and right, in the form of a figure 8 around
two selected points or pylons on the ground. Unlike
eights around pylons, however, no attempt is made to
maintain a uniform distance from the pylon. In eightson-
pylons, the distance from the pylons varies if there
is any wind. Instead, the airplane is flown at such a
precise altitude and airspeed that a line parallel to the
airplane’s lateral axis, and extending from the pilot’s
eye, appears to pivot on each of the pylons. [Figure 6-
10] Also, unlike eights around pylons, in the performance
of eights-on-pylons the degree of bank increases
as the distance from the pylon decreases.
The altitude that is appropriate for the airplane being
flown is called the pivotal altitude and is governed by
the groundspeed. While not truly a ground track
maneuver as were the preceding maneuvers, the objective
is similar—to develop the ability to maneuver the
airplane accurately while dividing one’s attention
between the flightpath and the selected points on the
ground.
In explaining the performance of eights-on-pylons, the
term “wingtip” is frequently considered as being synonymous
with the proper reference line, or pivot
point on the airplane. This interpretation is not
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always correct. High-wing, low-wing, sweptwing, and
tapered wing airplanes, as well as those with tandem or
side-by-side seating, will all present different angles from
the pilot’s eye to the wingtip. Therefore, in
the correct performance of eights-on-pylons, as in other
maneuvers requiring a lateral reference, the pilot should
use a sighting reference line that, from eye level, parallels
the lateral axis of the airplane.
Closest to
the Pylon
Lowest
Groundspeed
Lowest Pivotal
Altitude
High Groundspeed
High Pivotal Altitude
Entry
Figure 6-10. Eights-on-pylons.
Figure 6-11. Line of sight.
Lateral Axis
Line of Sight
Lateral Axis
Line of Sight
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6-14
The sighting point or line, while not necessarily on the
wingtip itself, may be positioned in relation to the
wingtip (ahead, behind, above, or below), but even
then it will differ for each pilot, and from each seat in
the airplane. This is especially true in tandem (fore and
aft) seat airplanes. In side-by-side type airplanes, there
will be very little variation in the sighting lines for different
persons if those persons are seated so that the
eyes of each are at approximately the same level.
An explanation of the pivotal altitude is also essential.
There is a specific altitude at which, when the airplane
turns at a given groundspeed, a projection of the sighting
reference line to the selected point on the ground
will appear to pivot on that point. Since different airplanes
fly at different airspeeds, the groundspeed will
be different. Therefore, each airplane will have its own
pivotal altitude. The pivotal altitude does
not vary with the angle of bank being used unless the
bank is steep enough to affect the groundspeed. A rule
of thumb for estimating pivotal altitude in calm wind is
to square the true airspeed and divide by 15 for miles
per hour (m.p.h.) or 11.3 for knots.
Distance from the pylon affects the angle of bank.
At any altitude above that pivotal altitude, the projected
reference line will appear to move rearward
in a circular path in relation to the pylon.
Conversely, when the airplane is below the pivotal
altitude, the projected reference line will appear to
move forward in a circular path.
To demonstrate this, the airplane is flown at normal
cruising speed, and at an altitude estimated to be below
the proper pivotal altitude, and then placed in a
medium-banked turn. It will be seen that the projected
reference line of sight appears to move forward along
the ground (pylon moves back) as the airplane turns.
A climb is then made to an altitude well above the pivotal
altitude, and when the airplane is again at normal
cruising speed, it is placed in a medium-banked turn.
At this higher altitude, the projected reference line of
sight now appears to move backward across the
ground (pylon moves forward) in a direction opposite
that of flight.
After the high altitude extreme has been demonstrated,
the power is reduced, and a descent at cruising speed
begun in a continuing medium bank around the pylon.
The apparent backward travel of the projected reference
line with respect to the pylon will slow down as
altitude is lost, stop for an instant, then start to reverse
itself, and would move forward if the descent were
allowed to continue below the pivotal altitude.
The altitude at which the line of sight apparently
ceased to move across the ground was the pivotal
altitude. If the airplane descended below the pivotal
altitude, power should be added to maintain airspeed
while altitude is regained to the point at which the
projected reference line moves neither backward nor
forward but actually pivots on the pylon. In this way
the pilot can determine the pivotal altitude of the airplane.
The pivotal altitude is critical and will change with
variations in groundspeed. Since the headings
throughout the turns continually vary from directly
downwind to directly upwind, the groundspeed will
constantly change. This will result in the proper pivotal
altitude varying slightly throughout the eight.
Therefore, adjustment is made for this by climbing or
descending, as necessary, to hold the reference line or
point on the pylons. This change in altitude will be
dependent on how much the wind affects the groundspeed.
The instructor should emphasize that the elevators are
the primary control for holding the pylons. Even a very
slight variation in altitude effects a double correction,
since in losing altitude, speed is gained, and even a
slight climb reduces the airspeed. This variation in altitude,
although important in holding the pylon, in most
cases will be so slight as to be barely perceptible on a
sensitive altimeter.
Before beginning the maneuver, the pilot should select
two points on the ground along a line which lies 90° to
the direction of the wind. The area in which the
maneuver is to be performed should be checked for
obstructions and any other air traffic, and it should be
located where a disturbance to groups of people, livestock,
or communities will not result.
The selection of proper pylons is of importance to
good eights-on-pylons. They should be sufficiently
prominent to be readily seen by the pilot when completing
the turn around one pylon and heading for the
next, and should be adequately spaced to provide time
AIRSPEED
KNOTS MPH
APPROXIMATE
PIVOTAL
ALTITUDE
87
91
96
100
104
109
113
100
105
110
115
120
125
130
670
735
810
885
960
1050
1130
Figure 6-12. Speed vs. pivotal altitude.
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for planning the turns and yet not cause unnecessary
straight-and-level flight between the pylons. The
selected pylons should also be at the same elevation,
since differences of over a very few feet will necessitate
climbing or descending between each turn.
For uniformity, the eight is usually begun by flying
diagonally crosswind between the pylons to a point
downwind from the first pylon so that the first turn
can be made into the wind. As the airplane
approaches a position where the pylon appears to be
just ahead of the wingtip, the turn should be started
by lowering the upwind wing to place the pilot’s line
of sight reference on the pylon. As the turn is continued,
the line of sight reference can be held on the
pylon by gradually increasing the bank. The reference
line should appear to pivot on the pylon. As the airplane
heads into the wind, the groundspeed
decreases; consequently, the pivotal altitude is lower
and the airplane must descend to hold the reference
line on the pylon. As the turn progresses on the
upwind side of the pylon, the wind becomes more of
a crosswind. Since a constant distance from the pylon
is not required on this maneuver, no correction to
counteract drifting should be applied during the turns.
If the reference line appears to move ahead of the
pylon, the pilot should increase altitude. If the reference
line appears to move behind the pylon, the pilot
should decrease altitude. Varying rudder pressure to
yaw the airplane and force the wing and reference
line forward or backward to the pylon is a dangerous
technique and must not be attempted.
As the airplane turns toward a downwind heading,
the rollout from the turn should be started to allow
the airplane to proceed diagonally to a point on the
downwind side of the second pylon. The rollout
must be completed in the proper wind correction
angle to correct for wind drift, so that the airplane
will arrive at a point downwind from the second
pylon the same distance it was from the first pylon
at the beginning of the maneuver.
Upon reaching that point, a turn is started in the opposite
direction by lowering the upwind wing to again place
the pilot’s line of sight reference on the pylon. The turn
Too High
Pivotal Altitude
Too Low
Figure 6-13. Effect of different altitudes on pivotal altitude.
Ch 06.qxd 5/10/04 5:55 AM Page 6-15
6-16
is then continued just as in the turn around the first
pylon but in the opposite direction.
With prompt correction, and a very fine control
touch, it should be possible to hold the projection of
the reference line directly on the pylon even in a stiff
wind. Corrections for temporary variations, such as
those caused by gusts or inattention, may be made by
shallowing the bank to fly relatively straight to bring
forward a lagging wing, or by steepening the bank
temporarily to turn back a wing which has crept
ahead. With practice, these corrections will become
so slight as to be barely noticeable. These variations
are apparent from the movement of the wingtips long
before they are discernable on the altimeter.
Pylon eights are performed at bank angles ranging
from shallow to steep. The student
should understand that the bank chosen will not alter
the pivotal altitude. As proficiency is gained, the
instructor should increase the complexity of the
maneuver by directing the student to enter at a distance
from the pylon that will result in a specific bank angle
at the steepest point in the pylon turn.
The most common error in attempting to hold a pylon
is incorrect use of the rudder. When the projection of
the reference line moves forward with respect to the
pylon, many pilots will tend to press the inside rudder
to yaw the wing backward. When the reference line
moves behind the pylon, they will press the outside
rudder to yaw the wing forward. The rudder is to be
used only as a coordination control.
Other common errors in the performance of eights-onpylons
(pylon eights) are:
• Failure to adequately clear the area.
• Skidding or slipping in turns (whether trying to
hold the pylon with rudder or not).
• Excessive gain or loss of altitude.
• Over concentration on the pylon and failure to
observe traffic.
• Poor choice of pylons.
• Not entering the pylon turns into the wind.
• Failure to assume a heading when flying
between pylons that will compensate sufficiently
for drift.
• Failure to time the bank so that the turn entry is
completed with the pylon in position.
• Abrupt control usage.
• Inability to select pivotal altitude.
Pylon
Pivotal
Altitude
60° ° °
Figure 6-14. Bank angle vs. pivotal altitude.
Ch 06.qxd 5/7/04 7:35 AM Page 6-16
帅哥
发表于 2008-12-9 15:11:30
AIRPORT TRAFFIC
PATTERNS AND OPERATIONS
Just as roads and streets are needed in order to utilize
automobiles, airports or airstrips are needed to utilize
airplanes. Every flight begins and ends at an airport or
other suitable landing field. For that reason, it is
essential that the pilot learn the traffic rules, traffic
procedures, and traffic pattern layouts that may be in
use at various airports.
When an automobile is driven on congested city streets,
it can be brought to a stop to give way to conflicting traffic;
however, an airplane can only be slowed down.
Consequently, specific traffic patterns and traffic control
procedures have been established at designated airports.
The traffic patterns provide specific routes for takeoffs,
departures, arrivals, and landings. The exact nature of
each airport traffic pattern is dependent on the runway in
use, wind conditions, obstructions, and other factors.
Control towers and radar facilities provide a means of
adjusting the flow of arriving and departing aircraft,
and render assistance to pilots in busy terminal areas.
Airport lighting and runway marking systems are used
frequently to alert pilots to abnormal conditions and
hazards, so arrivals and departures can be made safely.
Airports vary in complexity from small grass or sod
strips to major terminals having many paved runways
and taxiways. Regardless of the type of airport, the
pilot must know and abide by the rules and general
operating procedures applicable to the airport being
used. These rules and procedures are based not only on
logic or common sense, but also on courtesy, and their
objective is to keep air traffic moving with maximum
safety and efficiency. The use of any traffic pattern,
service, or procedure does not alter the responsibility
of pilots to see and avoid other aircraft.
STANDARD AIRPORT
TRAFFIC PATTERNS
To assure that air traffic flows into and out of an airport
in an orderly manner, an airport traffic pattern is established
appropriate to the local conditions, including the
direction and placement of the pattern, the altitude to
be flown, and the procedures for entering and leaving
the pattern. Unless the airport displays approved visual
markings indicating that turns should be made to the
right, the pilot should make all turns in the pattern to
the left.
When operating at an airport with an operating control
tower, the pilot receives, by radio, a clearance to
approach or depart, as well as pertinent information
about the traffic pattern. If there is not a control tower,
it is the pilot’s responsibility to determine the direction
of the traffic pattern, to comply with the appropriate
traffic rules, and to display common courtesy toward
other pilots operating in the area.
The pilot is not expected to have extensive knowledge
of all traffic patterns at all airports, but if the pilot is
familiar with the basic rectangular pattern, it will be
easy to make proper approaches and departures from
most airports, regardless of whether they have control
towers. At airports with operating control towers, the
tower operator may instruct pilots to enter the traffic
pattern at any point or to make a straight-in approach
without flying the usual rectangular pattern. Many
other deviations are possible if the tower operator and
the pilot work together in an effort to keep traffic
moving smoothly. Jets or heavy airplanes will
frequently be flying wider and/or higher patterns than
lighter airplanes, and in many cases will make a
straight-in approach for landing.
Compliance with the basic rectangular traffic pattern
reduces the possibility of conflicts at airports without
an operating control tower. It is imperative that the pilot
form the habit of exercising constant vigilance in the
vicinity of airports even though the air traffic appears
to be light.
The standard rectangular traffic pattern is illustrated in
figure 7-1 (on next page). The traffic pattern altitude is
usually 1,000 feet above the elevation of the airport surface.
The use of a common altitude at a given airport is the
key factor in minimizing the risk of collisions at airports
without operating control towers.
It is recommended that while operating in the traffic
pattern at an airport without an operating control
tower the pilot maintain an airspeed that conforms
with the limits established by Title 14 of the Code of
Federal Regulations (14 CFR) part 91 for such an airport:
no more than 200 knots (230 miles per hour
(m.p.h.)). In any case, the speed should be adjusted,
7-1
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7-2
Figure 7-1.Traffic patterns.
LEFT-HAND
TRAFFIC PATTERN
Entry
Crosswind
Departure
Final
Base
Downwind
RIGHT-HAND
TRAFFIC PATTERN
Crosswind
Final
Base
Downwind
Entry
Departure
帅哥
发表于 2008-12-9 15:11:48
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7-3
when practicable, so that it is compatible with the
speed of other airplanes in the pattern.
When entering the traffic pattern at an airport without
an operating control tower, inbound pilots are expected
to observe other aircraft already in the pattern and to
conform to the traffic pattern in use. If other aircraft
are not in the pattern, then traffic indicators on the
ground and wind indicators must be checked to determine
which runway and traffic pattern direction should
be used. Many airports have L-shaped
traffic pattern indicators displayed with a segmented
circle adjacent to the runway. The short member of the
L shows the direction in which the traffic pattern turns
should be made when using the runway parallel to the
long member. These indicators should be checked
while at a distance well away from any pattern that
might be in use, or while at a safe height well above
generally used pattern altitudes. When the proper traffic
pattern direction has been determined, the pilot
should then proceed to a point well clear of the pattern
before descending to the pattern altitude.
When approaching an airport for landing, the traffic pattern
should be entered at a 45° angle to the downwind
leg, headed toward a point abeam of the midpoint of the
runway to be used for landing. Arriving airplanes should
be at the proper traffic pattern altitude before entering
the pattern, and should stay clear of the traffic flow until
established on the entry leg. Entries into traffic patterns
while descending create specific collision hazards and
should always be avoided.
The entry leg should be of sufficient length to provide
a clear view of the entire traffic pattern, and to allow
the pilot adequate time for planning the intended path
in the pattern and the landing approach.
The downwind leg is a course flown parallel to the
landing runway, but in a direction opposite to the
intended landing direction. This leg should be
approximately 1/2 to 1 mile out from the landing runway,
and at the specified traffic pattern altitude.
During this leg, the before landing check should be
completed and the landing gear extended if
retractable. Pattern altitude should be maintained
until abeam the approach end of the landing runway.
At this point, power should be reduced and a descent
begun. The downwind leg continues past a point
abeam the approach end of the runway to a point
approximately 45° from the approach end of the runway,
and a medium bank turn is made onto the base
leg.
The base leg is the transitional part of the traffic pattern
between the downwind leg and the final approach
leg. Depending on the wind condition, it is established
at a sufficient distance from the approach end of the
landing runway to permit a gradual descent to the
intended touchdown point. The ground track of the airplane
while on the base leg should be perpendicular to
the extended centerline of the landing runway,
although the longitudinal axis of the airplane may not
be aligned with the ground track when it is necessary
to turn into the wind to counteract drift. While on the
base leg, the pilot must ensure, before turning onto the
final approach, that there is no danger of colliding with
another aircraft that may be already on the final
approach.
The final approach leg is a descending flightpath starting
from the completion of the base-to-final turn and
extending to the point of touchdown. This is probably
the most important leg of the entire pattern, because
here the pilot’s judgment and procedures must be the
sharpest to accurately control the airspeed and descent
angle while approaching the intended touchdown
point.
As stipulated in 14 CFR part 91, aircraft while on
final approach to land or while landing, have the
right-of-way over other aircraft in flight or operating
on the surface. When two or more aircraft are
approaching an airport for the purpose of landing, the
aircraft at the lower altitude has the right-of-way.
Pilots should not take advantage of this rule to cut in
front of another aircraft that is on final approach to
land, or to overtake that aircraft.
The upwind leg is a course flown parallel to the landing
runway, but in the same direction to the intended
landing direction. The upwind leg continues past a
point abeam of the departure end of the runway to
where a medium bank 90° turn is made onto the
crosswind leg.
The upwind leg is also the transitional part of the traffic
pattern when on the final approach and a go-around
Figure 7-2.Traffic pattern indicators. is initiated and climb attitude is established. When a
Windsock
Segmented Circle
Traffic Pattern Indicator
(indicates location of base leg)
Ch 07.qxd 5/7/04 7:54 AM Page 7-3
7-4
safe altitude is attained, the pilot should commence a
shallow bank turn to the upwind side of the airport.
This will allow better visibility of the runway for
departing aircraft.
The departure leg of the rectangular pattern is a
straight course aligned with, and leading from, the
takeoff runway. This leg begins at the point the airplane
leaves the ground and continues until the 90°
turn onto the crosswind leg is started.
On the departure leg after takeoff, the pilot should continue
climbing straight ahead, and, if remaining in the
traffic pattern, commence a turn to the crosswind leg
beyond the departure end of the runway within 300 feet
of pattern altitude. If departing the traffic pattern, continue
straight out or exit with a 45° turn (to the left
when in a left-hand traffic pattern; to the right when in
a right-hand traffic pattern) beyond the departure end
of the runway after reaching pattern altitude.
The crosswind leg is the part of the rectangular pattern
that is horizontally perpendicular to the extended centerline
of the takeoff runway and is entered by making
approximately a 90° turn from the upwind leg. On the
crosswind leg, the airplane proceeds to the downwind
leg position.
Since in most cases the takeoff is made into the wind,
the wind will now be approximately perpendicular to
the airplane’s flightpath. As a result, the airplane will
have to be turned or headed slightly into the wind
while on the crosswind leg to maintain a ground track
that is perpendicular to the runway centerline extension.
Additional information on airport operations can be
found in the Aeronautical Information Manual (AIM).
Ch 07.qxd 5/7/04 7:54 AM Page 7-4
NORMAL APPROACH AND LANDING
A normal approach and landing involves the use of
procedures for what is considered a normal situation;
that is, when engine power is available, the wind is
light or the final approach is made directly into the
wind, the final approach path has no obstacles, and the
landing surface is firm and of ample length to
gradually bring the airplane to a stop. The selected
landing point should be beyond the runway’s approach
threshold but within the first one-third portion of
the runway.
The factors involved and the procedures described for
the normal approach and landing also have applications
to the other-than-normal approaches and landings
which are discussed later in this chapter. This being the
case, the principles of normal operations are explained
first and must be understood before proceeding to the
more complex operations. So that the pilot may better
understand the factors that will influence judgment and
procedures, that last part of the approach pattern and
the actual landing will be divided into five phases: the
base leg, the final approach, the roundout, the
touchdown, and the after-landing roll.
It must be remembered that the manufacturer’s
recommended procedures, including airplane
configuration and airspeeds, and other information
relevant to approaches and landings in a specific make
and model airplane are contained in the FAA-approved
Airplane Flight Manual and/or Pilot’s Operating
Handbook (AFM/POH) for that airplane. If any of the
information in this chapter differs from the airplane
manufacturer’s recommendations as contained in
the AFM/POH, the airplane manufacturer’s
recommendations take precedence.
BASE LEG
The placement of the base leg is one of the more
important judgments made by the pilot in any landing
approach. The pilot must accurately judge
the altitude and distance from which a gradual descent
will result in landing at the desired spot. The distance
will depend on the altitude of the base leg, the effect of
wind, and the amount of wing flaps used. When there is
a strong wind on final approach or the flaps will be
used to produce a steep angle of descent, the base leg
must be positioned closer to the approach end of the
runway than would be required with a light wind or no
Figure 8-1. Base leg and final approach.
帅哥
发表于 2008-12-9 15:12:09
8-1
Ch 08.qxd 5/7/04 8:08 AM Page 8-1
flaps. Normally, the landing gear should be extended
and the before landing check completed prior
to reaching the base leg.
After turning onto the base leg, the pilot should start
the descent with reduced power and airspeed of
approximately 1.4 VSO. (VSO—the stalling speed
with power off, landing gears and flaps down.) For
example, if VSO is 60 knots, the speed should be 1.4
times 60, or 84 knots. Landing flaps may be partially
lowered, if desired, at this time. Full flaps are not
recommended until the final approach is established.
Drift correction should be established and
maintained to follow a ground track perpendicular
to the extension of the centerline of the runway on
which the landing is to be made. Since the final
approach and landing will normally be made into
the wind, there will be somewhat of a crosswind
during the base leg. This requires that the airplane be
angled sufficiently into the wind to prevent drifting
farther away from the intended landing spot.
The base leg should be continued to the point where a
medium to shallow-banked turn will align the
airplane’s path directly with the centerline of the
landing runway. This descending turn should be
completed at a safe altitude that will be dependent
upon the height of the terrain and any obstructions
along the ground track. The turn to the final approach
should also be sufficiently above the airport elevation
to permit a final approach long enough for the pilot to
accurately estimate the resultant point of touchdown,
while maintaining the proper approach airspeed. This
will require careful planning as to the starting point
and the radius of the turn. Normally, it is recommended
that the angle of bank not exceed a medium bank
because the steeper the angle of bank, the higher the
airspeed at which the airplane stalls. Since the base-tofinal
turn is made at a relatively low altitude, it is
important that a stall not occur at this point. If an
extremely steep bank is needed to prevent
overshooting the proper final approach path, it is
advisable to discontinue the approach, go around, and
plan to start the turn earlier on the next approach rather
than risk a hazardous situation.
FINAL APPROACH
After the base-to-final approach turn is completed, the
longitudinal axis of the airplane should be aligned with
the centerline of the runway or landing surface, so that
drift (if any) will be recognized immediately. On a
normal approach, with no wind drift, the longitudinal
axis should be kept aligned with the runway centerline
throughout the approach and landing. (The proper way
to correct for a crosswind will be explained under the
section, Crosswind Approach and Landing. For now,
only an approach and landing where the wind is
straight down the runway will be discussed.)
After aligning the airplane with the runway centerline,
the final flap setting should be completed and the pitch
attitude adjusted as required for the desired rate of
descent. Slight adjustments in pitch and power may
be necessary to maintain the descent attitude and the
desired approach airspeed. In the absence of the
manufacturer’s recommended airspeed, a speed
equal to 1.3 VSO should be used. If VSO is 60 knots,
the speed should be 78 knots. When the pitch
attitude and airspeed have been stabilized, the
airplane should be retrimmed to relieve the
pressures being held on the controls.
The descent angle should be controlled throughout the
approach so that the airplane will land in the center
of the first third of the runway. The descent angle is
affected by all four fundamental forces that act on an
airplane (lift, drag, thrust, and weight). If all the
forces are constant, the descent angle will be constant
in a no-wind condition. The pilot can control these
forces by adjusting the airspeed, attitude, power, and
drag (flaps or forward slip). The wind also plays a
prominent part in the gliding distance over the
ground ; naturally, the pilot does not have
control over the wind but may correct for its effect
on the airplane’s descent by appropriate pitch and
power adjustments.
Increased Airspeed Flightpath
Normal Best Glide Speed
Flightpath
Figure 8-2. Effect of headwind on final approach.
8-2
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8-3
Considering the factors that affect the descent angle on
the final approach, for all practical purposes at a given
pitch attitude there is only one power setting for one
airspeed, one flap setting, and one wind condition.
A change in any one of these variables will require
an appropriate coordinated change in the other controllable
variables. For example, if the pitch attitude
is raised too high without an increase of power, the
airplane will settle very rapidly and touch down
short of the desired spot. For this reason, the pilot
should never try to stretch a glide by applying backelevator
pressure alone to reach the desired landing
spot. This will shorten the gliding distance if power is
not added simultaneously. The proper angle of descent
and airspeed should be maintained by coordinating
pitch attitude changes and power changes.
The objective of a good final approach is to descend at
an angle and airspeed that will permit the airplane to
reach the desired touchdown point at an airspeed
which will result in minimum floating just before
touchdown; in essence, a semi-stalled condition. To
accomplish this, it is essential that both the descent
angle and the airspeed be accurately controlled. Since
on a normal approach the power setting is not fixed as
in a power-off approach, the power and pitch attitude
should be adjusted simultaneously as necessary, to
control the airspeed, and the descent angle, or to attain
the desired altitudes along the approach path. By lowering
the nose and reducing power to keep approach
airspeed constant, a descent at a higher rate can be
made to correct for being too high in the approach.
This is one reason for performing approaches with partial
power; if the approach is too high, merely lower
the nose and reduce the power. When the approach is
too low, add power and raise the nose.
USE OF FLAPS
The lift/drag factors may also be varied by the pilot to
adjust the descent through the use of landing flaps.
Flap extension during landings
provides several advantages by:
• Producing greater lift and permitting lower
landing speed.
• Producing greater drag, permitting a steep
descent angle without airspeed increase.
• Reducing the length of the landing roll.
Flap extension has a definite effect on the airplane’s
pitch behavior. 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 loads 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 airplane has a tendency to balloon
No Flaps
Half Flaps
Full Flaps
With: Constant Airspeed
Constant Power
Flatter Descent Angle
Steeper Descent Angle
With: Constant Airspeed
Constant Power
No Flaps Half Flaps Full Flaps
Figure 8-3. Effect of flaps on the landing point.
Figure 8-4. Effect of flaps on the approach angle.
Ch 08.qxd 5/7/04 8:08 AM Page 8-3
up with initial flap deflection because of the lift
increase. The nosedown pitching moment, however,
tends to offset the balloon. Flap deflection beyond 15°
produces a large increase in drag. Also, deflection
beyond 15° produces a significant noseup pitching
moment in high-wing airplanes because the resulting
downwash increases the airflow over the horizontal tail.
The time of flap extension and the 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 descent angle. Consequently, the
deflection of flaps at certain positions in the landing
pattern has definite advantages. Incremental deflection
of flaps on downwind, base leg, and final approach
allow smaller adjustment of pitch and power compared
to extension of full flaps all at one time.
When the flaps are lowered, the airspeed will decrease
unless the power is increased or the pitch attitude
lowered. On final approach, therefore, the pilot must
estimate where the airplane will land through
discerning judgment of the descent angle. If it appears
that the airplane is going to overshoot the desired
landing spot, more flaps may be used if not fully
extended or the power reduced further, and the pitch
attitude lowered. This will result in a steeper approach.
If the desired landing spot is being undershot and a
shallower approach is needed, both power and pitch
attitude should be increased to readjust the descent
angle. Never retract the flaps to correct for undershooting
since that will suddenly decrease the lift and cause
the airplane to sink even more rapidly.
The airplane must be retrimmed on the final approach
to compensate for the change in aerodynamic forces.
With the reduced power and with a slower airspeed,
the airflow produces less lift on the wings and less
downward force on the horizontal stabilizer, resulting
in a significant nosedown tendency. The elevator must
then be trimmed more noseup.
It will be found that the roundout, touchdown, and
landing roll are much easier to accomplish when they
are preceded by a proper final approach with precise
control of airspeed, attitude, power, and drag resulting
in a stabilized descent angle.
ESTIMATING HEIGHT AND MOVEMENT
During the approach, roundout, and touchdown, vision
is of prime importance. To provide a wide scope of
vision and to foster good judgment of height and
movement, the pilot’s head should assume a natural,
straight-ahead position. The pilot’s visual focus should
not be fixed on any one side or any one spot ahead of
the airplane, but should be changing slowly from a
point just over the airplane’s nose to the desired
touchdown zone and back again, while maintaining a
deliberate awareness of distance from either side of
the runway within the pilot’s peripheral field of vision.
Accurate estimation of distance is, besides being a
matter of practice, dependent upon how clearly objects
are seen; it requires that the vision be focused properly
in order that the important objects stand out as clearly
as possible.
Speed blurs objects at close range. For example,
most everyone has noted this in an automobile
moving at high speed. Nearby objects seem to merge
together in a blur, while objects farther away stand
out clearly. The driver subconsciously focuses the
eyes sufficiently far ahead of the automobile to see
objects distinctly.
The distance at which the pilot’s vision is focused
should be proportionate to the speed at which the
airplane is traveling over the ground. Thus, as speed is
reduced during the roundout, the distance ahead of the
airplane at which it is possible to focus should be
brought closer accordingly.
If the pilot attempts to focus on a reference that is too
close or looks directly down, the reference will
become blurred, and the reaction will be
either too abrupt or too late. In this case, the pilot’s
tendency will be to overcontrol, round out high, and
make full-stall, drop-in landings. When the pilot
focuses too far ahead, accuracy in judging the
closeness of the ground is lost and the consequent
reaction will be too slow since there will not appear to
be a necessity for action. This will result in the
airplane flying into the ground nose first. The change
of visual focus from a long distance to a short distance
requires a definite time interval and even though the
time is brief, the airplane’s speed during this interval is
such that the airplane travels an appreciable distance,
both forward and downward toward the ground.
Figure 8-5. Focusing too close blurs vision.
If the focus is changed gradually, being brought progressively
closer as speed is reduced, the time interval
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8-5
and the pilot’s reaction will be reduced, and the whole
landing process smoothed out.
ROUNDOUT (FLARE)
The roundout is a slow, smooth transition from a normal
approach attitude to a landing attitude, gradually
rounding out the flightpath to one that is parallel with,
and within a very few inches above, the runway. When
the airplane, in a normal descent, approaches within
what appears to be 10 to 20 feet above the ground, the
roundout or flare should be started, and once started
should be a continuous process until the airplane
touches down on the ground.
帅哥
发表于 2008-12-9 15:12:29
As the airplane reaches a height above the ground
where a timely change can be made into the proper
landing attitude, back-elevator pressure should be
gradually applied to slowly increase the pitch attitude
and angle of attack. This will cause the
airplane’s nose to gradually rise toward the desired
landing attitude. The angle of attack should be
increased at a rate that will allow the airplane to continue
settling slowly as forward speed decreases.
When the angle of attack is increased, the lift is momentarily
increased, which decreases the rate of descent.
Since power normally is reduced to idle during the
roundout, the airspeed will also gradually decrease.
This will cause lift to decrease again, and it must be
controlled by raising the nose and further increasing the
angle of attack. During the roundout, the airspeed is
being decreased to touchdown speed while the lift is
being controlled so the airplane will settle gently onto
the landing surface. The roundout should be executed
at a rate that the proper landing attitude and the proper
touchdown airspeed are attained simultaneously just as
the wheels contact the landing surface.
The rate at which the roundout is executed depends on
the airplane’s height above the ground, the rate of
descent, and the pitch attitude. A roundout started
excessively high must be executed more slowly than
one from a lower height to allow the airplane to
descend to the ground while the proper landing attitude
is being established. The rate of rounding out must also
be proportionate to the rate of closure with the ground.
When the airplane appears to be descending very
slowly, the increase in pitch attitude must be made at a
correspondingly slow rate.
Visual cues are important in flaring at the proper altitude
and maintaining the wheels a few inches above
the runway until eventual touchdown. Flare cues are
primarily dependent on the angle at which the pilot’s
central vision intersects the ground (or runway) ahead
and slightly to the side. Proper depth perception is a
factor in a successful flare, but the visual cues used
most are those related to changes in runway or terrain
perspective and to changes in the size of familiar
objects near the landing area such as fences, bushes,
trees, hangars, and even sod or runway texture. The
pilot should direct central vision at a shallow downward
angle of from 10° to 15° toward the runway as
the roundout/flare is initiated.
Maintaining the same viewing angle causes the point
Increase
Angle of
Attack
Increase
Angle of
Attack
Increase
Angle of
Attack
78 Knots
70 Knots
65 Knots
60 Knots
10° to 15°
Figure 8-7.To obtain necessary visual cues, the pilot should look toward the runway at a shallow angle.
Figure 8-6. Changing angle of attack during roundout.
Ch 08.qxd 5/7/04 8:08 AM Page 8-5
of visual interception with the runway to move
progressively rearward toward the pilot as the airplane
loses altitude. This is an important visual cue in
assessing the rate of altitude loss. Conversely, forward
movement of the visual interception point will indicate
an increase in altitude, and would mean that the pitch
angle was increased too rapidly, resulting in an over
flare. Location of the visual interception point in
conjunction with assessment of flow velocity of nearby
off-runway terrain, as well as the similarity of
appearance of height above the runway ahead of the
airplane (in comparison to the way it looked when the
airplane was taxied prior to takeoff) is also used to
judge when the wheels are just a few inches above
the runway.
The pitch attitude of the airplane in a full-flap approach
is considerably lower than in a no-flap approach. To
attain the proper landing attitude before touching
down, the nose must travel through a greater pitch
change when flaps are fully extended. Since the roundout
is usually started at approximately the same height
above the ground regardless of the degree of flaps
used, the pitch attitude must be increased at a faster
rate when full flaps are used; however, the roundout
should still be executed at a rate proportionate to the
airplane’s downward motion.
Once the actual process of rounding out is started, the
elevator control should not be pushed forward. If too
much back-elevator pressure has been exerted, this
pressure should be either slightly relaxed or held
constant, depending on the degree of the error. In some
cases, it may be necessary to advance the throttle
slightly to prevent an excessive rate of sink, or a stall, all
of which would result in a hard, drop-in type landing.
It is recommended that the student pilot form the habit
of keeping one hand on the throttle throughout the
approach and landing, should a sudden and unexpected
hazardous situation require an immediate application
of power.
TOUCHDOWN
The touchdown is the gentle settling of the airplane
onto the landing surface. The roundout and touchdown
should be made with the engine idling, and the airplane
at minimum controllable airspeed, so that the airplane
will touch down on the main gear at approximately
stalling speed. As the airplane settles, the proper
landing attitude is attained by application of whatever
back-elevator pressure is necessary.
Some pilots may try to force or fly the airplane onto
the ground without establishing the proper landing
attitude. The airplane should never be flown on
the runway with excessive speed. It is paradoxical that
the way to make an ideal landing is to try to hold the
airplane’s wheels a few inches off the ground as
long as possible with the elevators. In most cases,
when the wheels are within 2 or 3 feet off the
ground, the airplane will still be settling too fast for
a gentle touchdown; therefore, this descent must be
retarded by further back-elevator pressure. Since
the airplane is already close to its stalling speed and
is settling, this added back-elevator pressure will
only slow up the settling instead of stopping it. At
the same time, it will result in the airplane touching
the ground in the proper landing attitude, and the
main wheels touching down first so that little or no
weight is on the nosewheel.
After the main wheels make initial contact with the
ground, back-elevator pressure should be held to
maintain a positive angle of attack for aerodynamic
braking, and to hold the nosewheel off the ground until
the airplane decelerates. As the airplane’s momentum
decreases, back-elevator pressure may be gradually
relaxed to allow the nosewheel to gently settle onto the
runway. This will permit steering with the nosewheel.
At the same time, it will cause a low angle of attack
and negative lift on the wings to prevent floating or
skipping, and will allow the full weight of the airplane
to rest on the wheels for better braking action.
Near-Zero Rate of Descent
15 Feet
2 to 3 Feet 1 Foot
Figure 8-8. A well executed roundout results in attaining the proper landing attitude.
8-6
Ch 08.qxd 5/7/04 8:08 AM Page 8-6
8-7
It is extremely important that the touchdown occur
with the airplane’s longitudinal axis exactly parallel to
the direction in which the airplane is moving along the
runway. Failure to accomplish this imposes severe side
loads on the landing gear. To avoid these side stresses,
the pilot should not allow the airplane to touch down
while turned into the wind or drifting.
AFTER-LANDING ROLL
The landing process must never be considered complete
until the airplane decelerates to the normal taxi
speed during the landing roll or has been brought to a
complete stop when clear of the landing area. Many
accidents have occurred as a result of pilots abandoning
their vigilance and positive control after getting the
airplane on the ground.
帅哥
发表于 2008-12-9 15:12:53
The pilot must be alert for directional control difficulties
immediately upon and after touchdown due to the
ground friction on the wheels. The friction creates a pivot
point on which a moment arm can act. Loss of directional
control may lead to an aggravated, uncontrolled, tight
turn on the ground, or a ground loop. The combination
of centrifugal force acting on the center of gravity (CG)
and ground friction of the main wheels resisting it during
the ground loop may cause the airplane to tip or lean
enough for the outside wingtip to contact the ground.
This may even impose a sideward force, which could
collapse the landing gear.
The rudder serves the same purpose on the ground as it
does in the air—it controls the yawing of the airplane.
The effectiveness of the rudder is dependent on the airflow,
which depends on the speed of the airplane. As
the speed decreases and the nosewheel has been lowered
to the ground, the steerable nose provides more
positive directional control.
The brakes of an airplane serve the same primary
purpose as the brakes of an automobile—to reduce
speed on the ground. In airplanes, they may also be
used as an aid in directional control when more positive
control is required than could be obtained with
rudder or nosewheel steering alone.
To use brakes, on an airplane equipped with toe brakes,
the pilot should slide the toes or feet up from the rudder
pedals to the brake pedals. If rudder pressure is
being held at the time braking action is needed, that
pressure should not be released as the feet or toes are
being slid up to the brake pedals, because control may
be lost before brakes can be applied.
Putting maximum weight on the wheels after touchdown
is an important factor in obtaining optimum
braking performance. During the early part of rollout,
some lift may continue to be generated by the wing.
After touchdown, the nosewheel should be lowered to
the runway to maintain directional control. During
deceleration, the nose may be pitched down by braking
and the weight transferred to the nosewheel from the
main wheels. This does not aid in braking action, so
back pressure should be applied to the controls without
lifting the nosewheel off the runway. This will enable
the pilot to maintain directional control while keeping
weight on the main wheels.
Careful application of the brakes can be initiated after
the nosewheel is on the ground and directional control
is established. Maximum brake effectiveness is just
short of the point where skidding occurs. If the brakes
are applied so hard that skidding takes place, braking
becomes ineffective. Skidding can be stopped by releasing
the brake pressure. Also, braking effectiveness is not
enhanced by alternately applying and reapplying brake
pressure. The brakes should be applied firmly and
smoothly as necessary.
During the ground roll, the airplane’s direction of
movement can be changed by carefully applying pressure
on one brake or uneven pressures on each brake in
the desired direction. Caution must be exercised when
applying brakes to avoid overcontrolling.
The ailerons serve the same purpose on the ground as
they do in the air—they change the lift and drag components
of the wings. During the after-landing roll,
they should be used to keep the wings level in much
the same way they were used in flight. If a wing starts
to rise, aileron control should be applied toward that
wing to lower it. The amount required will depend on
speed because as the forward speed of the airplane
decreases, the ailerons will become less effective.
Procedures for using ailerons in crosswind conditions
are explained further in this chapter, in the Crosswind
Approach and Landing section.
After the airplane is on the ground, back-elevator pressure
may be gradually relaxed to place normal weight on
the nosewheel to aid in better steering. If available
runway permits, the speed of the airplane should be
allowed to dissipate in a normal manner. Once the
airplane has slowed sufficiently and has turned on to
the taxiway and stopped, the pilot should retract the
flaps and clean up the airplane. Many accidents have
occurred as a result of the pilot unintentionally operating
the landing gear control and retracting the gear instead
of the flap control when the airplane was still
rolling. The habit of positively identifying both of these
controls, before actuating them, should be formed from
the very beginning of flight training and continued in all
future flying activities.
STABILIZED APPROACH CONCEPT
A stabilized approach is one in which the pilot establishes
and maintains a constant angle glidepath
Ch 08.qxd 5/7/04 8:08 AM Page 8-7
8-8
towards a predetermined point on the landing runway.
It is based on the pilot’s judgment of certain visual
clues, and depends on the maintenance of a constant
final descent airspeed and configuration.
An airplane descending on final approach at a constant
rate and airspeed will be traveling in a straight line
toward a spot on the ground ahead. This spot will not
be the spot on which the airplane will touch down,
because some float will inevitably occur during the
roundout (flare). Neither will it be the spot
toward which the airplane’s nose is pointed, because
the airplane is flying at a fairly high angle of attack,
and the component of lift exerted parallel to the Earth’s
surface by the wings tends to carry the airplane forward
horizontally.
The point toward which the airplane is progressing is
termed the “aiming point.” It is the point
on the ground at which, if the airplane maintains a
constant glidepath, and was not flared for landing, it
would strike the ground. To a pilot moving straight
ahead toward an object, it appears to be stationary. It
does not “move.” This is how the aiming point can be
distinguished—it does not move. However, objects in
front of and beyond the aiming point do appear to move
as the distance is closed, and they appear to move in
opposite directions. During instruction in landings, one
of the most important skills a student pilot must acquire
is how to use visual cues to accurately determine the
true aiming point from any distance out on final
approach. From this, the pilot will not only be able to
determine if the glidepath will result in an undershoot
or overshoot, but, taking into account float during
roundout, the pilot will be able to predict the touchdown
point to within a very few feet.
For a constant angle glidepath, the distance between
the horizon and the aiming point will remain constant.
If a final approach descent has been established but the
distance between the perceived aiming point and the
horizon appears to increase (aiming point moving
down away from the horizon), then the true aiming
point, and subsequent touchdown point, is farther
down the runway. If the distance between the perceived
aiming point and the horizon decreases (aiming
point moving up toward the horizon), the true aiming
point is closer than perceived.
When the airplane is established on final approach, the
shape of the runway image also presents clues as to
what must be done to maintain a stabilized approach
to a safe landing.
A runway, obviously, is normally shaped in the form
of an elongated rectangle. When viewed from the
air during the approach, the phenomenon known as
perspective causes the runway to assume the shape of
a trapezoid with the far end looking narrower than the
approach end, and the edge lines converging ahead.
If the airplane continues down the glidepath at a
constant angle (stabilized), the image the pilot sees
will still be trapezoidal but of proportionately larger
dimensions. In other words, during a stabilized
approach the runway shape does not change. [Figure
8-10]
If the approach becomes shallower, however, the
runway will appear to shorten and become wider.
Conversely, if the approach is steepened, the runway
will appear to become longer and narrower.
The objective of a stabilized approach is to select an
appropriate touchdown point on the runway, and
adjust the glidepath so that the true aiming point and
the desired touchdown point basically coincide.
Immediately after rolling out on final approach, the
pilot should adjust the pitch attitude and power so that
the airplane is descending directly toward the aiming
point at the appropriate airspeed. The airplane should
Distance Traveled in Flare
Touchdown
Aiming Point (Descent Angle Intersects Ground)
Figure 8-9. Stabilized approach.
Ch 08.qxd 5/7/04 8:08 AM Page 8-8
be in the landing configuration, and trimmed for
“hands off” flight. With the approach set up in this
manner, the pilot will be free to devote full attention
toward outside references. The pilot should not stare at
any one place, but rather scan from one point to
another, such as from the aiming point to the horizon,
to the trees and bushes along the runway, to an area
well short of the runway, and back to the aiming point.
In this way, the pilot will be more apt to perceive a
deviation from the desired glidepath, and whether or
not the airplane is proceeding directly toward the
aiming point.
If the pilot perceives any indication that the aiming
point on the runway is not where desired, an adjustment
must be made to the glidepath. This in turn will move
the aiming point. For instance, if the pilot perceives that
the aiming point is short of the desired touchdown
point and will result in an undershoot, an increase in
pitch attitude and engine power is warranted. Aconstant
airspeed must be maintained. The pitch and power
change, therefore, must be made smoothly and
simultaneously. This will result in a shallowing of
the glidepath with the resultant aiming point moving
towards the desired touchdown point. Conversely,
if the pilot perceives that the aiming point is farther
down the runway than the desired touchdown point
and will result in an overshoot, the glidepath should be
steepened by a simultaneous decrease in pitch attitude
and power. Once again, the airspeed must be held constant.
It is essential that deviations from the desired
glidepath be detected early, so that only slight and
infrequent adjustments to glidepath are required.
帅哥
发表于 2008-12-9 15:13:10
3°Approach Angle
4000' x 100' Runway
1600' From Threshold
105' Altitude
Same Runway, Same Approach Angle
800' From Threshold
52' Altitude
Same Runway, Same Approach Angle
400' From Threshold
26' Altitude
Figure 8-10. Runway shape during stabilized approach.
Too High
Proper Descent Angle
Too Low
Figure 8-11. Change in runway shape if approach becomes
narrow or steep.
8-9
Ch 08.qxd 5/7/04 8:08 AM Page 8-9
8-10
The closer the airplane gets to the runway, the larger
(and possibly more frequent) the required corrections
become, resulting in an unstabilized approach.
Common errors in the performance of normal
approaches and landings are:
• Inadequate wind drift correction on the base leg.
• Overshooting or undershooting the turn onto
final approach resulting in too steep or too shallow
a turn onto final approach.
• Flat or skidding turns from base leg to final
approach as a result of overshooting/inadequate
wind drift correction.
• Poor coordination during turn from base to final
approach.
• Failure to complete the landing checklist in a
timely manner.
• Unstabilized approach.
• Failure to adequately compensate for flap extension.
• Poor trim technique on final approach.
• Attempting to maintain altitude or reach the runway
using elevator alone.
• Focusing too close to the airplane resulting in a
too high roundout.
• Focusing too far from the airplane resulting in a
too low roundout.
• Touching down prior to attaining proper landing
attitude.
• Failure to hold sufficient back-elevator pressure
after touchdown.
• Excessive braking after touchdown.
INTENTIONAL SLIPS
A slip occurs when the bank angle of an airplane is too
steep for the existing rate of turn. Unintentional slips
are most often the result of uncoordinated
rudder/aileron application. Intentional slips, however,
are used to dissipate altitude without increasing airspeed,
and/or to adjust airplane ground track during a
crosswind. Intentional slips are especially useful in
forced landings, and in situations where obstacles must
be cleared during approaches to confined areas. A slip
can also be used as an emergency means of rapidly
reducing airspeed in situations where wing flaps are
inoperative or not installed.
A slip is a combination of forward movement and
sideward (with respect to the longitudinal axis of the
airplane) movement, the lateral axis being inclined
and the sideward movement being toward the low
end of this axis (low wing). An airplane in a slip is in
fact flying sideways. This results in a change in the
direction the relative wind strikes the airplane. Slips
are characterized by a marked increase in drag and
corresponding decrease in airplane climb, cruise, and
glide performance. It is the increase in drag, however,
that makes it possible for an airplane in a slip to
descend rapidly without an increase in airspeed.
Most airplanes exhibit the characteristic of positive
static directional stability and, therefore, have a natural
tendency to compensate for slipping. An intentional
slip, therefore, requires deliberate cross-controlling
ailerons and rudder throughout the maneuver.
A“sideslip” is entered by lowering a wing and applying
just enough opposite rudder to prevent a turn. In a
sideslip, the airplane’s longitudinal axis remains parallel
to the original flightpath, but the airplane no
longer flies straight ahead. Instead the horizontal
component of wing lift forces the airplane also to
move somewhat sideways toward the low wing.
The amount of slip, and therefore the
rate of sideward movement, is determined by the bank
angle. The steeper the bank—the greater the degree of
slip. As bank angle is increased, however, additional
opposite rudder is required to prevent turning.
A “forward slip” is one in which the airplane’s
direction of motion continues the same as before the
slip was begun. Assuming the airplane is originally
in straight flight, the wing on the side toward which
Direction of Movement
Relative Wind
Sideslip
Figure 8-12. Sideslip.
Ch 08.qxd 5/7/04 8:08 AM Page 8-10
8-11
the slip is to be made should be lowered by use of the
ailerons. Simultaneously, the airplane’s nose must be
yawed in the opposite direction by applying opposite
rudder so that the airplane’s longitudinal axis is at an
angle to its original flightpath. The
degree to which the nose is yawed in the opposite
direction from the bank should be such that the
original ground track is maintained. In a forward slip,
the amount of slip, and therefore the sink rate, is
determined by the bank angle. The steeper the bank—
the steeper the descent.
In most light airplanes, the steepness of a slip is
limited by the amount of rudder travel available. In
both sideslips and forward slips, the point may be
reached where full rudder is required to maintain
heading even though the ailerons are capable of further
steepening the bank angle. This is the practical slip
limit, because any additional bank would cause the
airplane to turn even though full opposite rudder is
being applied. If there is a need to descend more
rapidly even though the practical slip limit has been
reached, lowering the nose will not only increase the
sink rate but will also increase airspeed. The increase
in airspeed increases rudder effectiveness permitting
a steeper slip. Conversely, when the nose is raised,
rudder effectiveness decreases and the bank angle must
be reduced.
Discontinuing a slip is accomplished by leveling the
wings and simultaneously releasing the rudder
pressure while readjusting the pitch attitude to the
normal glide attitude. If the pressure on the rudder is
released abruptly, the nose will swing too quickly into
line and the airplane will tend to acquire excess speed.
Because of the location of the pitot tube and static
vents, airspeed indicators in some airplanes may have
considerable error when the airplane is in a slip. The
pilot must be aware of this possibility and recognize a
properly performed slip by the attitude of the airplane,
the sound of the airflow, and the feel of the flight
controls. Unlike skids, however, if an airplane in a slip
is made to stall, it displays very little of the yawing
tendency that causes a skidding stall to develop into a
spin. The airplane in a slip may do little more than tend
to roll into a wings level attitude. In fact, in some
airplanes stall characteristics may even be improved.
GO-AROUNDS
(REJECTED LANDINGS)
Whenever landing conditions are not satisfactory, a
go-around is warranted. There are many factors that
can contribute to unsatisfactory landing conditions.
Situations such as air traffic control requirements,
unexpected appearance of hazards on the runway,
overtaking another airplane, wind shear,
wake turbulence, mechanical failure and/or an
unstabilized approach are all examples of reasons to
discontinue a landing approach and make another
approach under more favorable conditions. The
assumption that an aborted landing is invariably the
consequence of a poor approach, which in turn is due
to insufficient experience or skill, is a fallacy. The
go-around is not strictly an emergency procedure. It
is a normal maneuver that may at times be used in an
emergency situation. Like any other normal maneuver,
the go-around must be practiced and perfected. The flight
instructor should emphasize early on, and the student
pilot should be made to understand, that the go-around
maneuver is an alternative to any approach
and/or landing.
Although the need to discontinue a landing may arise
at any point in the landing process, the most critical
go-around will be one started when very close to the
ground. Therefore, the earlier a condition that warrants a
go-around is recognized, the safer the go-around/rejected
landing will be. The go-around maneuver is not
inherently dangerous in itself. It becomes dangerous
only when delayed unduly or executed improperly.
Delay in initiating the go-around normally stems from
two sources: (1) landing expectancy, or set—the
anticipatory belief that conditions are not as
threatening as they are and that the approach will
surely be terminated with a safe landing, and (2)
pride—the mistaken belief that the act of going around
is an admission of failure—failure to execute the
approach properly. The improper execution of the goaround
maneuver stems from a lack of familiarity with
the three cardinal principles of the procedure: power,
attitude, and configuration.
帅哥
发表于 2008-12-9 15:13:28
POWER
Power is the pilot’s first concern. The instant the
pilot decides to go around, full or maximum allowable
takeoff power must be applied smoothly and
without hesitation, and held until flying speed and
controllability are restored. Applying only partial
power in a go-around is never appropriate. The pilot
Direction of Movement
Relative Wind
Forward Slip
Figure 8-13. Forward slip.
Ch 08.qxd 5/7/04 8:08 AM Page 8-11
must be aware of the degree of inertia that must be
overcome, before an airplane that is settling towards
the ground can regain sufficient airspeed to become
fully controllable and capable of turning safely or
climbing. The application of power should be smooth
as well as positive. Abrupt movements of the throttle
in some airplanes will cause the engine to falter.
Carburetor heat should be turned off for maximum
power.
ATTITUDE
Attitude is always critical when close to the ground,
and when power is added, a deliberate effort on the part
of the pilot will be required to keep the nose from
pitching up prematurely. The airplane executing a goaround
must be maintained in an attitude that permits a
buildup of airspeed well beyond the stall point before
any effort is made to gain altitude, or to execute a turn.
Raising the nose too early may produce a stall from
which the airplane could not be recovered if the
go-around is performed at a low altitude.
A concern for quickly regaining altitude during a goaround
produces a natural tendency to pull the nose up.
The pilot executing a go-around must accept the fact
that an airplane will not climb until it can fly, and it
will not fly below stall speed. In some circumstances,
it may be desirable to lower the nose briefly to gain
airspeed. As soon as the appropriate climb airspeed and
pitch attitude are attained, the pilot should “rough
trim” the airplane to relieve any adverse control pressures.
Later, more precise trim adjustments can be
made when flight conditions have stabilized.
CONFIGURATION
In cleaning up the airplane during the go-around, the
pilot should be concerned first with flaps and secondly
with the landing gear (if retractable). When the decision
is made to perform a go-around, takeoff power
should be applied immediately and the pitch attitude
changed so as to slow or stop the descent. After the
descent has been stopped, the landing flaps may be
partially retracted or placed in the takeoff position as
recommended by the manufacturer. Caution must be
used, however, in retracting the flaps. Depending on
the airplane’s altitude and airspeed, it may be wise to
retract the flaps intermittently in small increments to
allow time for the airplane to accelerate progressively
as they are being raised. Asudden and complete retraction
of the flaps could cause a loss of lift resulting in
the airplane settling into the ground.
Unless otherwise specified in the AFM/POH, it is generally
recommended that the flaps be retracted (at least
partially) before retracting the landing gear—for two
reasons. First, on most airplanes full flaps produce
more drag than the landing gear; and second, in case
the airplane should inadvertently touch down as the
go-around is initiated, it is most desirable to have the
landing gear in the down-and-locked position. After a
positive rate of climb is established, the landing gear
can be retracted.
When takeoff power is applied, it will usually be necessary
to hold considerable pressure on the controls to
maintain straight flight and a safe climb attitude. Since
the airplane has been trimmed for the approach (a low
power and low airspeed condition), application of
maximum allowable power will require considerable
control pressure to maintain a climb pitch attitude. The
addition of power will tend to raise the airplane’s nose
suddenly and veer to the left. Forward elevator pressure
must be anticipated and applied to hold the nose in a
safe climb attitude. Right rudder pressure must be
increased to counteract torque and P-factor, and to keep
the nose straight. The airplane must be held in the proper
flight attitude regardless of the amount of control
pressure that is required. Trim should be used to
relieve adverse control pressures and assist the pilot in
maintaining a proper pitch attitude. On airplanes that
produce high control pressures when using maximum
power on go-arounds, pilots should use caution when
reaching for the flap handle. Airplane control may
become critical during this high workload phase.
Retract Remaining
Positive Rate Flaps
of Climb, Retract
Gear, Climb
at VY
500'
Cr uise Climb
Timely Decision to
Make Go-Around Apply Max Power
Adjust Pitch Attitude
Allow Airspeed to Increase
Assume Climb Atttude
Flaps to
Intermediate
Figure 8-14. Go-around procedure.
8-12
Ch 08.qxd 5/7/04 8:08 AM Page 8-12
8-13
The landing gear should be retracted only after the initial
or rough trim has been accomplished and when it is
certain the airplane will remain airborne. During the
initial part of an extremely low go-around, the airplane
may settle onto the runway and bounce. This situation
is not particularly dangerous if the airplane is kept
straight and a constant, safe pitch attitude is maintained.
The airplane will be approaching safe flying
speed rapidly and the advanced power will cushion any
secondary touchdown.
If the pitch attitude is increased excessively in an effort
to keep the airplane from contacting the runway, it may
cause the airplane to stall. This would be especially
likely if no trim correction is made and the flaps
remain fully extended. The pilot should not attempt to
retract the landing gear until after a rough trim is
accomplished and a positive rate of climb is established.
GROUND EFFECT
Ground effect is a factor in every landing and every
takeoff in fixed-wing airplanes. Ground effect can also
be an important factor in go-arounds. If the go-around
is made close to the ground, the airplane may be in the
ground effect area. Pilots are often lulled into a sense
of false security by the apparent “cushion of air” under
the wings that initially assists in the transition from an
approach descent to a climb. This “cushion of air,”
however, is imaginary. The apparent increase in airplane
performance is, in fact, due to a reduction in
induced drag in the ground effect area. It is “borrowed”
performance that must be repaid when the airplane
climbs out of the ground effect area. The pilot must
factor in ground effect when initiating a go-around
close to the ground. An attempt to climb prematurely
may result in the airplane not being able to climb, or
even maintain altitude at full power.
Common errors in the performance of go-arounds
(rejected landings) are:
• Failure to recognize a condition that warrants a
rejected landing.
• Indecision.
• Delay in initiating a go-round.
• Failure to apply maximum allowable power in a
timely manner.
• Abrupt power application.
• Improper pitch attitude.
• Failure to configure the airplane appropriately.
• Attempting to climb out of ground effect prematurely.
• Failure to adequately compensate for torque/Pfactor.
CROSSWIND
APPROACH AND LANDING
Many runways or landing areas are such that landings
must be made while the wind is blowing across rather
than parallel to the landing direction. All pilots should
be prepared to cope with these situations when they
arise. The same basic principles and factors involved
in a normal approach and landing apply to a crosswind
approach and landing; therefore, only the additional
procedures required for correcting for wind drift are
discussed here.
Crosswind landings are a little more difficult to perform
than crosswind takeoffs, mainly due to different
problems involved in maintaining accurate control of
the airplane while its speed is decreasing rather than
increasing as on takeoff.
There are two usual methods of accomplishing a crosswind
approach and landing—the crab method and the
wing-low (sideslip) method. Although the crab method
may be easier for the pilot to maintain during final
approach, it requires a high degree of judgment and
timing in removing the crab immediately prior to
touchdown. The wing-low method is recommended in
most cases, although a combination of both methods
may be used.
CROSSWIND FINAL APPROACH
The crab method is executed by establishing a heading
(crab) toward the wind with the wings level so that the
airplane’s ground track remains aligned with the centerline
of the runway. This crab angle is
maintained until just prior to touchdown, when the
longitudinal axis of the airplane must be aligned with
the runway to avoid sideward contact of the wheels
with the runway. If a long final approach is being
flown, the pilot may use the crab method until just
before the roundout is started and then smoothly
change to the wing-low method for the remainder of
the landing.
Figure 8-15. Crabbed approach.
The wing-low (sideslip) method will compensate for a
crosswind from any angle, but more important, it
Ch 08.qxd 5/7/04 8:08 AM Page 8-13
enables the pilot to simultaneously keep the airplane’s
ground track and longitudinal axis aligned with the
runway centerline throughout the final approach,
roundout, touchdown, and after-landing roll. This
prevents the airplane from touching down in a sideward
motion and imposing damaging side loads on
the landing gear.
To use the wing-low method, the pilot aligns the airplane’s
heading with the centerline of the runway,
notes the rate and direction of drift, and then promptly
applies drift correction by lowering the upwind wing.
The amount the wing must be lowered
depends on the rate of drift. When the wing is lowered,
the airplane will tend to turn in that direction. It is then
necessary to simultaneously apply sufficient opposite
rudder pressure to prevent the turn and keep the airplane’s
longitudinal axis aligned with the runway. In
other words, the drift is controlled with aileron, and
the heading with rudder. The airplane will now be
sideslipping into the wind just enough that both the
resultant flightpath and the ground track are aligned
with the runway. If the crosswind diminishes, this
crosswind correction is reduced accordingly, or the
airplane will begin slipping away from the desired
approach path.
To correct for strong crosswind, the slip into the wind
is increased by lowering the upwind wing a considerable
amount. As a consequence, this will result in a
greater tendency of the airplane to turn. Since turning
is not desired, considerable opposite rudder must be
applied to keep the airplane’s longitudinal axis aligned
with the runway. In some airplanes, there may not be
sufficient rudder travel available to compensate for the
strong turning tendency caused by the steep bank. If
the required bank is such that full opposite rudder will
not prevent a turn, the wind is too strong to safely land
the airplane on that particular runway with those wind
conditions. Since the airplane’s capability will be
exceeded, it is imperative that the landing be made on
Figure 8-16. Sideslip approach.
Figure 8-17. Crosswind approach and landing.
帅哥
发表于 2008-12-9 15:13:49
8-14
Ch 08.qxd 5/7/04 8:08 AM Page 8-14
8-15
a more favorable runway either at that airport or at an
alternate airport.
Flaps can and should be used during most approaches
since they tend to have a stabilizing effect on the airplane.
The degree to which flaps should be extended
will vary with the airplane’s handling characteristics,
as well as the wind velocity.
CROSSWIND ROUNDOUT (FLARE)
Generally, the roundout can be made like a normal
landing approach, but the application of a crosswind
correction is continued as necessary to prevent
drifting.
Since the airspeed decreases as the roundout progresses,
the flight controls gradually become less
effective. As a result, the crosswind correction being
held will become inadequate. When using the winglow
method, it is necessary to gradually increase the
deflection of the rudder and ailerons to maintain the
proper amount of drift correction.
Do not level the wings; keep the upwind wing down
throughout the roundout. If the wings are leveled, the
airplane will begin drifting and the touchdown will
occur while drifting. Remember, the primary objective
is to land the airplane without subjecting it to any side
loads that result from touching down while drifting.
CROSSWIND TOUCHDOWN
If the crab method of drift correction has been used
throughout the final approach and roundout, the crab
must be removed the instant before touchdown by
applying rudder to align the airplane’s longitudinal
axis with its direction of movement. This requires
timely and accurate action. Failure to accomplish this
will result in severe side loads being imposed on the
landing gear.
If the wing-low method is used, the crosswind correction
(aileron into the wind and opposite rudder)
should be maintained throughout the roundout, and
the touchdown made on the upwind main wheel.
During gusty or high wind conditions, prompt adjustments
must be made in the crosswind correction to
assure that the airplane does not drift as the airplane
touches down.
As the forward momentum decreases after initial
contact, the weight of the airplane will cause the
downwind main wheel to gradually settle onto the
runway.
In those airplanes having nosewheel steering interconnected
with the rudder, the nosewheel may not be
aligned with the runway as the wheels touch down
because opposite rudder is being held in the crosswind
correction. To prevent swerving in the direction the
nosewheel is offset, the corrective rudder pressure
must be promptly relaxed just as the nosewheel
touches down.
CROSSWIND AFTER-LANDING ROLL
Particularly during the after-landing roll, special
attention must be given to maintaining directional
control by the use of rudder or nosewheel steering,
while keeping the upwind wing from rising by the use
of aileron.
When an airplane is airborne, it moves with the air
mass in which it is flying regardless of the airplane’s
heading and speed. When an airplane is on the ground,
it is unable to move with the air mass (crosswind)
because of the resistance created by ground friction on
the wheels.
Characteristically, an airplane has a greater profile or
side area, behind the main landing gear than forward
of it does. With the main wheels acting as a pivot point
and the greater surface area exposed to the crosswind
behind that pivot point, the airplane will tend to turn or
weathervane into the wind.
Wind acting on an airplane during crosswind landings
is the result of two factors. One is the natural wind,
which acts in the direction the air mass is traveling, while
the other is induced by the movement of the airplane and
acts parallel to the direction of movement. Consequently,
a crosswind has a headwind component acting along
the airplane’s ground track and a crosswind component
acting 90° to its track. The resultant or relative wind is
somewhere between the two components. As the
airplane’s forward speed decreases during the afterlanding
roll, the headwind component decreases and the
relative wind has more of a crosswind component. The
greater the crosswind component, the more difficult it is
to prevent weathervaning.
Retaining control on the ground is a critical part of the
after-landing roll, because of the weathervaning effect
of the wind on the airplane. Additionally, tire side load
from runway contact while drifting frequently generates
roll-overs in tricycle geared airplanes. The basic
factors involved are cornering angle and side load.
Cornering angle is the angular difference between the
heading of a tire and its path. Whenever a load bearing
tire’s path and heading diverge, a side load is created.
It is accompanied by tire distortion. Although side load
differs in varying tires and air pressures, it is completely
independent of speed, and through a considerable
range, is directional proportional to the cornering angle
and the weight supported by the tire. As little as 10° of
cornering angle will create a side load equal to half the
Ch 08.qxd 5/7/04 8:08 AM Page 8-15
supported weight; after 20° the side load does not
increase with increasing cornering angle. For each
high-wing, tricycle geared airplane, there is a cornering
angle at which roll-over is inevitable. The roll-over
axis being the line linking the nose and main wheels.
At lesser angles, the roll-over may be avoided by use
of ailerons, rudder, or steerable nosewheel but not
brakes.
While the airplane is decelerating during the afterlanding
roll, more and more aileron is applied to keep
the upwind wing from rising. Since the airplane is
slowing down, there is less airflow around the ailerons
and they become less effective. At the same time, the
relative wind is becoming more of a crosswind and
exerting a greater lifting force on the upwind wing.
When the airplane is coming to a stop, the aileron control
must be held fully toward the wind.
MAXIMUM SAFE CROSSWIND VELOCITIES
Takeoffs and landings in certain crosswind conditions
are inadvisable or even dangerous. If the
crosswind is great enough to warrant an extreme drift
correction, a hazardous landing condition may result.
Therefore, the takeoff and landing capabilities with
respect to the reported surface wind conditions and the
available landing directions must be considered.
Figure 8-18. Crosswind chart.
Before an airplane is type certificated by the Federal
Aviation Administration (FAA), it must be flight tested
to meet certain requirements. Among these is the
demonstration of being satisfactorily controllable with
no exceptional degree of skill or alertness on the part
of the pilot in 90° crosswinds up to a velocity equal to
0.2 VSO. This means a windspeed of two-tenths of the
airplane’s stalling speed with power off and landing
gear/flaps down. Regulations require that the demonstrated
crosswind velocity be included on a placard in
airplanes certificated after May 3, 1962.
The headwind component and the crosswind component
for a given situation can be determined by reference
to a crosswind component chart. It is
imperative that pilots determine the maximum
crosswind component of each airplane they fly, and
avoid operations in wind conditions that exceed the
capability of the airplane.
Figure 8-19. Crosswind component chart.
Common errors in the performance of crosswind
approaches and landings are:
• Attempting to land in crosswinds that exceed the
airplane’s maximum demonstrated crosswind
component.
• Inadequate compensation for wind drift on the
turn from base leg to final approach, resulting in
undershooting or overshooting.
• Inadequate compensation for wind drift on final
approach.
• Unstabilized approach.
• Failure to compensate for increased drag during
sideslip resulting in excessive sink rate and/or
too low an airspeed.
• Touchdown while drifting.
60
50
40
30
20
10
0
Wind Velocity – MPH
20 40 60 80 100
Wind Angle – Degrees
Direct
Crosswind
8-16
60
50
40
30
20
10
0
Headwind Component
10 20 30 40 50 60
Crosswind Component
0° 10°
20°
30°
40°
50°
60°
70°
80°
90°
WIND VELOCITY
Ch 08.qxd 5/7/04 8:08 AM Page 8-16
• Excessive airspeed on touchdown.
• Failure to apply appropriate flight control inputs
during rollout.
• Failure to maintain direction control on rollout.
• Excessive braking.
TURBULENT AIR
APPROACH AND LANDING
Power-on approaches at an airspeed slightly above the
normal approach speed should be used for landing in
turbulent air. This provides for more positive control
of the airplane when strong horizontal wind gusts, or
up and down drafts, are experienced. Like other
power-on approaches (when the pilot can vary the
amount of power), a coordinated combination of both
pitch and power adjustments is usually required. As in
most other landing approaches, the proper approach
attitude and airspeed require a minimum roundout and
should result in little or no floating during the landing.
To maintain good control, the approach in turbulent air
with gusty crosswind may require the use of partial
wing flaps. With less than full flaps, the airplane will
be in a higher pitch attitude. Thus, it will require less
of a pitch change to establish the landing attitude, and
the touchdown will be at a higher airspeed to ensure
more positive control. The speed should not be so
excessive that the airplane will float past the desired
landing area.
One procedure is to use the normal approach speed
plus one-half of the wind gust factors. If the normal
speed is 70 knots, and the wind gusts increase 15 knots,
airspeed of 77 knots is appropriate. In any case, the airspeed
and the amount of flaps should be as the airplane
manufacturer recommends.
An adequate amount of power should be used to maintain
the proper airspeed and descent path throughout
the approach, and the throttle retarded to idling position
only after the main wheels contact the landing surface.
Care must be exercised in closing the throttle before the
pilot is ready for touchdown. In this situation, the sudden
or premature closing of the throttle may cause a sudden
increase in the descent rate that could result in a hard
landing.
Landings from power approaches in turbulence should
be such that the touchdown is made with the airplane
in approximately level flight attitude. The pitch attitude
at touchdown should be only enough to prevent the
nosewheel from contacting the surface before the main
wheels have touched the surface. After touchdown, the
pilot should avoid the tendency to apply forward pressure
on the yoke as this may result in wheelbarrowing
and possible loss of control. The airplane should be
allowed to decelerate normally, assisted by careful use
of wheel brakes. Heavy braking should be avoided until
the wings are devoid of lift and the airplane’s full
weight is resting on the landing gear.
SHORT-FIELD APPROACH
AND LANDING
Short-field approaches and landings require the use of
procedures for approaches and landings at fields with a
relatively short landing area or where an approach is
made over obstacles that limit the available landing area.
As in short-field takeoffs, it is
one of the most critical of the maximum performance
operations. It requires that the pilot fly the airplane at
one of its crucial performance capabilities while close to
the ground in order to safely land within confined areas.
This low-speed type of power-on approach is closely
related to the performance of flight at minimum
controllable airspeeds.
8-17
Effective Runway
Length
Obstacle Clearance
Figure 8-20. Landing over an obstacle.
Ch 08.qxd 5/7/04 8:08 AM Page 8-17
To land within a short-field or a confined area, the pilot
must have precise, positive control of the rate of
descent and airspeed to produce an approach that will
clear any obstacles, result in little or no floating during
the roundout, and permit the airplane to be stopped in
the shortest possible distance.
The procedures for landing in a short-field or for landing
approaches over obstacles, as recommended in the
AFM/POH, should be used. A stabilized approach is
essential. These procedures
generally involve the use of full flaps, and the final
approach started from an altitude of at least 500 feet
higher than the touchdown area. A wider than normal
pattern should be used so that the airplane can be
properly configured and trimmed. In the absence of
the manufacturer’s recommended approach speed, a
speed of not more than 1.3 VSO should be used. For
example, in an airplane that stalls at 60 knots with
power off, and flaps and landing gear extended, the
approach speed should not be higher than 78 knots. In
gusty air, no more than one-half the gust factor should
be added. An excessive amount of airspeed could result
in a touchdown too far from the runway threshold or
an after-landing roll that exceeds the available landing
area.
After the landing gear and full flaps have been
extended, the pilot should simultaneously adjust the
power and the pitch attitude to establish and maintain
the proper descent angle and airspeed. A coordinated
combination of both pitch and power adjustments is
required. When this is done properly, very little change
in the airplane’s pitch attitude and power setting is
necessary to make corrections in the angle of descent
and airspeed.
The short-field approach and landing is in reality an
accuracy approach to a spot landing. The procedures
previously outlined in the section on the stabilized
approach concept should be used. If it appears that
the obstacle clearance is excessive and touchdown
will occur well beyond the desired spot, leaving
insufficient room to stop, power may be reduced
while lowering the pitch attitude to steepen the
descent path and increase the rate of descent. If it
appears that the descent angle will not ensure safe
clearance of obstacles, power should be increased
while simultaneously raising the pitch attitude to
shallow the descent path and decrease the rate of
descent. Care must be taken to avoid an excessively
low airspeed. If the speed is allowed to become too
slow, an increase in pitch and application of full power
Non-Obstacle Clearance Effective Runway Length
Figure 8-21. Landing on a short-field.
Figure 8-22. Stabilized approach.
8-18
Stabilized
Ch 08.qxd 5/7/04 8:08 AM Page 8-18
may only result in a further rate of descent. This occurs
when the angle of attack is so great and creating so
much drag that the maximum available power is
insufficient to overcome it. This is generally referred
to as operating in the region of reversed command
or operating on the back side of the power curve.
Because the final approach over obstacles is made at a
relatively steep approach angle and close to the airplane’s
stalling speed, the initiation of the roundout or
flare must be judged accurately to avoid flying into the
ground, or stalling prematurely and sinking rapidly. A
lack of floating during the flare, with sufficient control
to touch down properly, is one verification that the
approach speed was correct.
Touchdown should occur at the minimum controllable
airspeed with the airplane in approximately the pitch
attitude that will result in a power-off stall when the
throttle is closed. Care must be exercised to avoid closing
the throttle too rapidly before the pilot is ready for
touchdown, as closing the throttle may result in an
immediate increase in the rate of descent and a hard
landing.
Upon touchdown, the airplane should be held in this
positive pitch attitude as long as the elevators remain
effective. This will provide aerodynamic braking to
assist in deceleration.
Immediately upon touchdown, and closing the throttle,
appropriate braking should be applied to minimize the
after-landing roll. The airplane should be stopped
within the shortest possible distance consistent with
safety and controllability. If the proper approach speed
has been maintained, resulting in minimum float
during the roundout, and the touchdown made at
minimum control speed, minimum braking will be
required.
Common errors in the performance of short-field
approaches and landings are:
• Failure to allow enough room on final to set up
the approach, necessitating an overly steep
approach and high sink rate.
• Unstabilized approach.
• Undue delay in initiating glidepath corrections.
• Too low an airspeed on final resulting in inability
to flare properly and landing hard.
• Too high an airspeed resulting in floating on
roundout.
• Prematurely reducing power to idle on roundout
resulting in hard landing.
• Touchdown with excessive airspeed.
• Excessive and/or unnecessary braking after
touchdown.
• Failure to maintain directional control.
SOFT-FIELD APPROACH
AND LANDING
Landing on fields that are rough or have soft surfaces,
such as snow, sand, mud, or tall grass requires unique
procedures. When landing on such surfaces, the
objective is to touch down as smoothly as possible,
and at the slowest possible landing speed. The pilot
must control the airplane in a manner that the wings
support the weight of the airplane as long as practical,
to minimize drag and stresses imposed on the
landing gear by the rough or soft surface.
The approach for the soft-field landing is similar to the
normal approach used for operating into long, firm
landing areas. The major difference between the two is
Figure 8-23. Unstabilized approach.
Unstabilized
8-19
Ch 08.qxd 5/7/04 8:08 AM Page 8-19
that, during the soft-field landing, the airplane is held
1 to 2 feet off the surface in ground effect as long as
possible. This permits a more gradual dissipation of
forward speed to allow the wheels to touch down gently
at minimum speed. This technique minimizes the
nose-over forces that suddenly affect the airplane at
the moment of touchdown. Power can be used
throughout the level-off and touchdown to ensure
touchdown at the slowest possible airspeed, and the
airplane should be flown onto the ground with the
weight fully supported by the wings.
The use of flaps during soft-field landings will aid in
touching down at minimum speed and is recommended
whenever practical. In low-wing airplanes, the flaps
may suffer damage from mud, stones, or slush thrown
up by the wheels. If flaps are used, it is generally inadvisable
to retract them during the after-landing roll
because the need for flap retraction is usually less
important than the need for total concentration on
maintaining full control of the airplane.
The final approach airspeed used for short-field landings
is equally appropriate to soft-field landings. The
use of higher approach speeds may result in excessive
float in ground effect, and floating makes a smooth,
controlled touchdown even more difficult. There is,
however, no reason for a steep angle of descent unless
obstacles are present in the approach path.
Touchdown on a soft or rough field should be made at
the lowest possible airspeed with the airplane in a
nose-high pitch attitude. In nosewheel-type airplanes,
after the main wheels touch the surface, the pilot
should hold sufficient back-elevator pressure to keep
the nosewheel off the surface. Using back-elevator
pressure and engine power, the pilot can control the
rate at which the weight of the airplane is transferred
from the wings to the wheels.
Field conditions may warrant that the pilot maintain a
flight condition in which the main wheels are just
touching the surface but the weight of the airplane is
still being supported by the wings, until a suitable taxi
surface is reached. At any time during this transition
phase, before the weight of the airplane is being supported
by the wheels, and before the nosewheel is on
the surface, the pilot should be able to apply full
power and perform a safe takeoff (obstacle clearance
and field length permitting) should the pilot elect to
abandon the landing. Once committed to a landing,
the pilot should gently lower the nosewheel to the
surface. A slight addition of power usually will aid in
easing the nosewheel down.
The use of brakes on a soft field is not needed and
should be avoided as this may tend to impose a heavy
load on the nose gear due to premature or hard contact
with the landing surface, causing the nosewheel to dig
in. The soft or rough surface itself will provide sufficient
reduction in the airplane’s forward speed. Often it
will be found that upon landing on a very soft field, the
pilot will need to increase power to keep the airplane
moving and from becoming stuck in the soft surface.
Common errors in the performance of soft-field
approaches and landings are:
• Excessive descent rate on final approach.
• Excessive airspeed on final approach.
• Unstabilized approach.
• Roundout too high above the runway surface.
• Poor power management during roundout and
touchdown.
• Hard touchdown.
• Inadequate control of the airplane weight transfer
from wings to wheels after touchdown.
• Allowing the nosewheel to “fall” to the runway
after touchdown rather than controlling its
descent.
Figure 8-24. Soft/rough field approach and landing.
8-20
Ground Effect
Transition
Area
Ch 08.qxd 5/7/04 8:08 AM Page 8-20
8-21
POWER-OFF ACCURACY
APPROACHES
Power-off accuracy approaches are approaches and
landings made by gliding with the engine idling,
through a specific pattern to a touchdown beyond and
within 200 feet of a designated line or mark on the runway.
The objective is to instill in the pilot the judgment
and procedures necessary for accurately flying the airplane,
without power, to a safe landing.
The ability to estimate the distance an airplane will glide
to a landing is the real basis of all power-off accuracy
approaches and landings. This will largely determine the
amount of maneuvering that may be done from a given
altitude. In addition to the ability to estimate distance, it
requires the ability to maintain the proper glide while
maneuvering the airplane.
With experience and practice, altitudes up to approximately
1,000 feet can be estimated with fair accuracy,
while above this level the accuracy in judgment of height
above the ground decreases, since all features tend to
merge. The best aid in perfecting the ability to judge
height above this altitude is through the indications of the
altimeter and associating them with the general
appearance of the Earth.
The judgment of altitude in feet, hundreds of feet, or
thousands of feet is not as important as the ability to
estimate gliding angle and its resultant distance. The
pilot who knows the normal glide angle of the airplane
can estimate with reasonable accuracy, the approximate
spot along a given ground path at which the airplane
will land, regardless of altitude. The pilot, who also has
the ability to accurately estimate altitude, can judge
how much maneuvering is possible during the glide,
which is important to the choice of landing areas in an
actual emergency.
The objective of a good final approach is to descend at
an angle that will permit the airplane to reach the
desired landing area, and at an airspeed that will result
in minimum floating just before touchdown. To
accomplish this, it is essential that both the descent
angle and the airspeed be accurately controlled.
Unlike a normal approach when the power setting is
variable, on a power-off approach the power is fixed at
the idle setting. Pitch attitude is adjusted to control the
airspeed. This will also change the glide or descent
angle. By lowering the nose to keep the approach airspeed
constant, the descent angle will steepen. If the airspeed is
too high, raise the nose, and when the airspeed is too low,
lower the nose. If the pitch attitude is raised too high, the
airplane will settle rapidly due to a slow airspeed and
insufficient lift. For this reason, never try to stretch a glide
to reach the desired landing spot.
Uniform approach patterns such as the 90°, 180°, or
360° power-off approaches are described further in this
chapter. Practice in these approaches provides the pilot
with a basis on which to develop judgment in gliding
distance and in planning an approach.
The basic procedure in these approaches involves closing
the throttle at a given altitude, and gliding to a key
position. This position, like the pattern itself, must not
be allowed to become the primary objective; it is
merely a convenient point in the air from which the
pilot can judge whether the glide will safely terminate
at the desired spot. The selected key position should be
one that is appropriate for the available altitude and the
wind condition. From the key position, the pilot must
constantly evaluate the situation.
It must be emphasized that, although accurate spot
touchdowns are important, safe and properly executed
approaches and landings are vital. The pilot must never
sacrifice a good approach or landing just to land on the
desired spot.
90° POWER-OFF APPROACH
The 90° power-off approach is made from a base leg and
requires only a 90° turn onto the final approach. The
approach path may be varied by positioning the base leg
closer to or farther out from the approach end of the runway
according to wind conditions.
The glide from the key position on the base leg through
the 90° turn to the final approach is the final part of all
accuracy landing maneuvers.
The 90° power-off approach usually begins from a
rectangular pattern at approximately 1,000 feet above
the ground or at normal traffic pattern altitude. The
airplane should be flown onto a downwind leg at the
same distance from the landing surface as in a normal
traffic pattern. The before landing checklist should be
completed on the downwind leg, including extension
of the landing gear if the airplane is equipped with
retractable gear.
After a medium-banked turn onto the base leg is completed,
the throttle should be retarded slightly and the
airspeed allowed to decrease to the normal base-leg
speed. On the base leg, the airspeed,
wind drift correction, and altitude should be maintained
while proceeding to the 45° key position. At this
position, the intended landing spot will appear to be
on a 45° angle from the airplane’s nose.
The pilot can determine the strength and direction of
the wind from the amount of crab necessary to hold the
desired ground track on the base leg. This will help in
planning the turn onto the final approach and in lowering
the correct amount of flaps.
Ch 08.qxd 5/7/04 8:08 AM Page 8-21
At the 45° key position, the throttle should be closed
completely, the propeller control (if equipped)
advanced to the full increase r.p.m. position, and altitude
maintained until the airspeed decreases to the
manufacturer’s recommended glide speed. In the
absence of a recommended speed, use 1.4 VSO. When
this airspeed is attained, the nose should be lowered to
maintain the gliding speed and the controls retrimmed.
The base-to-final turn should be planned and accomplished
so that upon rolling out of the turn the airplane
will be aligned with the runway centerline. When on
final approach, the wing flaps are lowered and the
pitch attitude adjusted, as necessary, to establish the
proper descent angle and airspeed (1.3 VSO), then the
controls retrimmed. Slight adjustments in pitch attitude
or flaps setting may be necessary to control the glide
Light Wind
Medium Wind
Strong Wind
Figure 8-25. Plan the base leg for wind conditions.
Figure 8-26. 90° power-off approach.
8-22
45°
Power Reduced
Base Leg Speed
Close Throttle
Established 1.4 V
Base Key
Position
Lower Partial Flaps
Maintain 1.4 V
Lower Full Flaps
(As Needed)
Establish 1.3 V
S0
S0
S0
Ch 08.qxd 5/7/04 8:08 AM Page 8-22
8-23
angle and airspeed. However, NEVER TRY TO
STRETCH THE GLIDE OR RETRACT THE FLAPS
to reach the desired landing spot. The final approach
may be made with or without the use of slips.
After the final approach glide has been established, full
attention is then given to making a good, safe landing
rather than concentrating on the selected landing spot.
The base-leg position and the flap setting already
determined the probability of landing on the spot. In
any event, it is better to execute a good landing 200
feet from the spot than to make a poor landing precisely
on the spot.
180° POWER-OFF APPROACH
The 180° power-off approach is executed by gliding
with the power off from a given point on a downwind
leg to a preselected landing spot. It is an
extension of the principles involved in the 90° poweroff
approach just described. Its objective is to further
develop judgment in estimating distances and glide
ratios, in that the airplane is flown without power from
a higher altitude and through a 90° turn to reach the
base-leg position at a proper altitude for executing the
90° approach.
The 180° power-off approach requires more planning
and judgment than the 90° power-off approach. In the
execution of 180° power-off approaches, the airplane
is flown on a downwind heading parallel to the landing
runway. The altitude from which this type of approach
should be started will vary with the type of airplane,
but it should usually not exceed 1,000 feet above the
ground, except with large airplanes. Greater accuracy
in judgment and maneuvering is required at higher
altitudes.
When abreast of or opposite the desired landing spot,
the throttle should be closed and altitude maintained
while decelerating to the manufacturer’s recommended
glide speed, or 1.4 VSO. The point at which the throttle
is closed is the downwind key position.
The turn from the downwind leg to the base leg should
be a uniform turn with a medium or slightly steeper
bank. The degree of bank and amount of this initial
turn will depend upon the glide angle of the airplane
and the velocity of the wind. Again, the base leg should
be positioned as needed for the altitude, or wind condition.
Position the base leg to conserve or dissipate
altitude so as to reach the desired landing spot.
The turn onto the base leg should be made at an altitude
high enough and close enough to permit the
airplane to glide to what would normally be the
base key position in a 90° power-off approach.
Although the key position is important, it must not be
overemphasized nor considered as a fixed point on
the ground. Many inexperienced pilots may gain a
conception of it as a particular landmark, such as a
tree, crossroad, or other visual reference, to be
reached at a certain altitude. This will result in a
mechanical conception and leave the pilot at a total
Figure 8-27. 180° power-off approach.
Medium or
Steeper Bank
Lower Partial Flaps
Maintain 1.4 Vs0
Lower Full Flaps
(as Needed)
Establish 1.3 Vs0
Key Position
Close Throttle
Normal Glide Speed
90°
Downwind Leg
Key Position
Ch 08.qxd 5/7/04 8:08 AM Page 8-23
8-24
loss any time such objects are not present. Both altitude
and geographical location should be varied as
much as is practical to eliminate any such conception.
After reaching the base key position, the approach and
landing are the same as in the 90° power-off approach.
360° POWER-OFF APPROACH
The 360° power-off approach is one in which the airplane
glides through a 360° change of direction to
the preselected landing spot. The entire pattern is
designed to be circular, but the turn may be shallowed,
steepened, or discontinued at any point to adjust the
accuracy of the flightpath.
The 360° approach is started from a position over the
approach end of the landing runway or slightly to the
side of it, with the airplane headed in the proposed
landing direction and the landing gear and flaps
retracted.
It is usually initiated from approximately 2,000 feet or
more above the ground—where the wind may vary significantly
from that at lower altitudes. This must be
taken into account when maneuvering the airplane to a
point from which a 90° or 180° power-off approach
can be completed.
After the throttle is closed over the intended point of
landing, the proper glide speed should immediately be
established, and a medium-banked turn made in the
desired direction so as to arrive at the downwind key
position opposite the intended landing spot. At or just
beyond the downwind key position, the landing gear
may be extended if the airplane is equipped with
retractable gear. The altitude at the downwind key
position should be approximately 1,000 to 1,200 feet
above the ground.
After reaching that point, the turn should be continued
to arrive at a base-leg key position, at an altitude of
about 800 feet above the terrain. Flaps may be used at
this position, as necessary, but full flaps should not be
used until established on the final approach.
The angle of bank can be varied as needed throughout
the pattern to correct for wind conditions and to align
the airplane with the final approach. The turn-to-final
should be completed at a minimum altitude of 300 feet
above the terrain.
Common errors in the performance of power-off accuracy
approaches are:
• Downwind leg too far from the runway/landing
area.
• Overextension of downwind leg resulting from
tailwind.
• Inadequate compensation for wind drift on base
leg.
• Skidding turns in an effort to increase gliding
distance.
Figure 8-28. 360° power-off approach.
Normal Glide Speed
Normal Glide
Speed
Lower Partial Flaps
Maintain 1.4 Vs0
Lower Flaps
as Needed
Establish 1.3 Vs0
Key Position
Key Position
Close Throttle,
Retract Flaps
Ch 08.qxd 5/7/04 8:08 AM Page 8-24
• Failure to lower landing gear in retractable gear
airplanes.
• Attempting to “stretch” the glide during undershoot.
• Premature flap extension/landing gear extension.
• Use of throttle to increase the glide instead of
merely clearing the engine.
• Forcing the airplane onto the runway in order to
avoid overshooting the designated landing spot.
EMERGENCY APPROACHES AND
LANDINGS (SIMULATED)
From time to time on dual flights, the instructor should
give simulated emergency landings by retarding the
throttle and calling “simulated emergency landing.”
The objective of these simulated emergency landings
is to develop the pilot’s accuracy, judgment, planning,
procedures, and confidence when little or no power is
available.
A simulated emergency landing may be given with the
airplane in any configuration. When the instructor calls
“simulated emergency landing,” the pilot should
immediately establish a glide attitude and ensure that
the flaps and landing gear are in the proper configuration
for the existing situation. When the proper glide
speed is attained, the nose should then be lowered and
the airplane trimmed to maintain that speed.
Aconstant gliding speed should be maintained because
variations of gliding speed nullify all attempts at accuracy
in judgment of gliding distance and the landing
spot. The many variables, such as altitude, obstruction,
wind direction, landing direction, landing surface and
gradient, and landing distance requirements of the
airplane will determine the pattern and approach procedures
to use.
Utilizing any combination of normal gliding maneuvers,
from wings level to spirals, the pilot should eventually
arrive at the normal key position at a normal traffic pattern
altitude for the selected landing area. From this
point on, the approach will be as nearly as possible a
normal power-off approach.
With the greater choice of fields afforded by higher
altitudes, the inexperienced pilot may be inclined to
delay making a decision, and with considerable altitude
in which to maneuver, errors in maneuvering and
estimation of glide distance may develop.
All pilots should learn to determine the wind direction
and estimate its speed from the windsock at the airport,
smoke from factories or houses, dust, brush fires, and
windmills.
Once a field has been selected, the student pilot should
always be required to indicate it to the instructor.
Normally, the student should be required to plan and
fly a pattern for landing on the field first elected until
the instructor terminates the simulated emergency
Figure 8-29. Remain over intended landing area.
Retract Flaps
Base Key Point
Lower Flaps
Spiral Over
Landing Field
8-25
Ch 08.qxd 5/7/04 8:08 AM Page 8-25
landing. This will give the instructor an opportunity to
explain and correct any errors; it will also give the student
an opportunity to see the results of the errors.
However, if the student realizes during the approach
that a poor field has been selected—one that would
obviously result in disaster if a landing were to be
made—and there is a more advantageous field within
gliding distance, a change to the better field should be
permitted. The hazards involved in these last-minute
decisions, such as excessive maneuvering at very low
altitudes, should be thoroughly explained by the
instructor.
Slipping the airplane, using flaps, varying the position
of the base leg, and varying the turn onto final
approach should be stressed as ways of correcting for
misjudgment of altitude and glide angle.
Eagerness to get down is one of the most common
faults of inexperienced pilots during simulated emergency
landings. In giving way to this, they forget about
speed and arrive at the edge of the field with too much
speed to permit a safe landing. Too much speed may be
just as dangerous as too little; it results in excessive
floating and overshooting the desired landing spot. It
should be impressed on the students that they cannot
dive at a field and expect to land on it.
During all simulated emergency landings, the engine
should be kept warm and cleared. During a simulated
emergency landing, either the instructor or the student
should have complete control of the throttle. There
should be no doubt as to who has control since many
near accidents have occurred from such misunderstandings.
Every simulated emergency landing approach should
be terminated as soon as it can be determined whether
a safe landing could have been made. In no case
should it be continued to a point where it creates an
undue hazard or an annoyance to persons or property
on the ground.
In addition to flying the airplane from the point of
simulated engine failure to where a reasonable safe
landing could be made, the student should also be
taught certain emergency cockpit procedures. The
habit of performing these cockpit procedures should
be developed to such an extent that, when an engine
failure actually occurs, the student will check the critical
items that would be necessary to get the engine
operating again while selecting a field and planning
an approach. Combining the two operations—
accomplishing emergency procedures and planning
Figure 8-30. Sample emergency checklist.
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Ch 08.qxd 5/7/04 8:08 AM Page 8-26
and flying the approach—will be difficult for the student
during the early training in emergency landings.
There are definite steps and procedures to be followed
in a simulated emergency landing. Although they may
differ somewhat from the procedures used in an actual
emergency, they should be learned thoroughly by the
student, and each step called out to the instructor. The
use of a checklist is strongly recommended. Most
airplane manufacturers provide a checklist of the
appropriate items.
Critical items to be checked should include the position
of the fuel tank selector, the quantity of fuel in the
tank selected, the fuel pressure gauge to see if the electric
fuel pump is needed, the position of the mixture
control, the position of the magneto switch, and the use
of carburetor heat. Many actual emergency landings
have been made and later found to be the result of the
fuel selector valve being positioned to an empty tank
while the other tank had plenty of fuel. It may be wise
to change the position of the fuel selector valve even
though the fuel gauge indicates fuel in all tanks
because fuel gauges can be inaccurate. Many actual
emergency landings could have been prevented if
the pilots had developed the habit of checking these
critical items during flight training to the extent that
it carried over into later flying.
Instruction in emergency procedures should not be limited
to simulated emergency landings caused by power
failures. Other emergencies associated with the operation
of the airplane should be explained, demonstrated, and
practiced if practicable. Among these emergencies are
such occurrences as fire in flight, electrical or hydraulic
system malfunctions, unexpected severe weather
conditions, engine overheating, imminent fuel
exhaustion, and the emergency operation of airplane
systems and equipment.
FAULTY APPROACHES
AND LANDINGS
LOW FINAL APPROACH
When the base leg is too low, insufficient power is used,
landing flaps are extended prematurely, or the velocity of
the wind is misjudged, sufficient altitude may be lost,
which will cause the airplane to be well below the proper
final approach path. In such a situation, the pilot would
have to apply considerable power to fly the airplane (at
an excessively low altitude) up to the runway threshold.
When it is realized the runway will not be reached
unless appropriate action is taken, power must be
applied immediately to maintain the airspeed while the
pitch attitude is raised to increase lift and stop the
descent. When the proper approach path has been
intercepted, the correct approach attitude should be
reestablished and the power reduced and a stabilized
approach maintained. DO NOT increase
the pitch attitude without increasing the power, since
the airplane will decelerate rapidly and may approach
the critical angle of attack and stall. DO NOT retract
the flaps; this will suddenly decrease lift and cause the
airplane to sink more rapidly. If there is any doubt
about the approach being safely completed, it is advisable
to EXECUTE AN IMMEDIATE GO-AROUND.
HIGH FINAL APPROACH
When the final approach is too high, lower the flaps as
required. Further reduction in power may be necessary,
while lowering the nose simultaneously to maintain
approach airspeed and steepen the approach path.
When the proper approach path has been
intercepted, adjust the power as required to maintain a
Figure 8-31. Right and wrong methods of correction for low final approach.
8-27
Normal Approach Path
Add Power
Nose Up
Hold Altitude
Wrong (Dragging it in with
High Power / High Pitch Altitude)
Intercept Normal Glidepath
Resume Normal Approach
Ch 08.qxd 5/7/04 8:08 AM Page 8-27
stabilized approach. When steepening the approach
path, however, care must be taken that the descent does
not result in an excessively high sink rate. If a high sink
rate is continued close to the surface, it may be difficult
to slow to a proper rate prior to ground contact. Any
sink rate in excess of 800 - 1,000 feet per minute is considered
excessive. A go-around should be initiated if
the sink rate becomes excessive.
SLOW FINAL APPROACH
When the airplane is flown at a slower-than-normal
airspeed on the final approach, the pilot’s judgment of
the rate of sink (descent) and the height of roundout
will be difficult. During an excessively slow approach,
the wing is operating near the critical angle of attack
and, depending on the pitch attitude changes and control
usage, the airplane may stall or sink rapidly, contacting
the ground with a hard impact.