faa-h-8083-3a-3of7, FSX, FAA
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I
NTRODUCTION
The maintenance of lift and control of an airplane in
flight requires a certain minimum airspeed. This
critical airspeed depends on certain factors, such as
gross weight, load factors, and existing density altitude.
The minimum speed below which further controlled
flight is impossible is called the stalling speed. An
important feature of pilot training is the development
of the ability to estimate the margin of safety above the
stalling speed. Also, the ability to determine the
characteristic responses of any airplane at different
airspeeds is of great importance to the pilot. The
student pilot, therefore, must develop this awareness in
order to safely avoid stalls and to operate an airplane
correctly and safely at slow airspeeds.
Maneuvering during slow flight should be performed
using both instrument indications and outside visual
reference. Slow flight should be practiced from straight
glides, straight-and-level flight, and from medium
banked gliding and level flight turns. Slow flight at
approach speeds should include slowing the airplane
smoothly and promptly from cruising to approach
speeds without changes in altitude or heading, and
determining and using appropriate power and trim
settings. Slow flight at approach speed should also
include configuration changes, such as landing gear
and flaps, while maintaining heading and altitude.
FLIGHT AT MINIMUM CONTROLLABLE
AIRSPEED
This maneuver demonstrates the flight characteristics
and degree of controllability of the airplane at its
minimum
flying speed. By definition, the term “flight
at minimum controllable airspeed” means a speed at
which any further increase in angle of attack or load
factor, or reduction in power will cause an immediate
stall. Instruction in flight at minimum controllable
airspeed should be introduced at reduced power
settings, with the airspeed sufficiently above the stall to
permit maneuvering, but close enough to the stall to
sense the characteristics of flight at very low
airspeed—which are sloppy controls, ragged response
to control inputs, and difficulty maintaining altitude.
Maneuvering at minimum controllable airspeed should
be performed using both instrument indications and
outside visual reference. It is important that pilots form
the habit of frequent reference to the flight instruments,
especially the airspeed indicator, while flying at very
low airspeeds. However, a “feel” for the airplane at
very low airspeeds must be developed to avoid
inadvertent stalls and to operate the airplane
with precision.
S
LOW FLIGHT
Slow flight could be thought of, by some, as a speed
that is less than cruise. In pilot training and testing,
however, slow flight is broken down into two distinct
elements: (1) the establishment, maintenance of, and
maneuvering of the airplane at airspeeds and in
configurations appropriate to takeoffs, climbs,
descents, landing approaches and go-arounds, and, (2)
maneuvering at the slowest airspeed at which the
airplane is capable of maintaining controlled flight
without indications of a stall—usually 3 to 5 knots
above stalling speed.
FLIGHT AT LESS THAN CRUISE AIRSPEEDS
Maneuvering during slow flight demonstrates the flight
characteristics and degree of controllability of an
airplane at less than cruise speeds. The ability to
determine the characteristic control responses at the
lower airspeeds appropriate to takeoffs, departures,
and landing approaches is a critical factor in
stall awareness.
To begin the maneuver, the throttle is gradually
reduced from cruising position. While the airspeed is
decreasing, the position of the nose in relation to the
horizon should be noted and should be raised as
necessary to maintain altitude.
As airspeed decreases
,
control effectiveness decreases
disproportionately. For instance, there may be a certain
loss of effectiveness when the airspeed is reduced from
30 to 20 m.p.h. above the stalling speed, but there will
normally be a much greater loss as the airspeed is
further reduced to 10 m.p.h. above stalling. The
objective of maneuvering during slow flight is to
develop the pilot’s sense of feel and ability to use the
controls correctly, and to improve proficiency in
performing maneuvers that require slow airspeeds.
When the airspeed reaches the maximum allowable for
landing gear operation, the landing gear (if equipped
with retractable gear) should be extended and all gear
down checks performed. As the airspeed reaches the
maximum allowable for flap operation, full flaps
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SLOW FLIGHT
performance of slow flight. The pilot must understand
that, at speed less than minimum drag speed, the
airspeed is unstable and will continue to decay if
allowed to do so.
Low airspeed
High angle of attack
High power setting
Maintain altitude
When the attitude, airspeed, and power have been
stabilized in straight flight, turns should be practiced
to determine the airplane’s controllability characteris-
tics at this minimum speed. During the turns, power
and pitch attitude may need to be increased to
maintain the airspeed and altitude. The objective is to
acquaint the pilot with the lack of maneuverability at
minimum speeds, the danger of incipient stalls, and
the tendency of the airplane to stall as the bank is
increased. A stall may also occur as a result of abrupt
or rough control movements when flying at this
critical airspeed.
Figure 4-1. Slow flight—Low airspeed, high angle of attack,
high power, and constant altitude
.
should be lowered and the pitch attitude adjusted to
maintain altitude. [Figure 4-1] Additional power will
be required as the speed further decreases to maintain
the airspeed just above a stall. As the speed decreases
further, the pilot should note the feel of the flight
controls, especially the elevator. The pilot should also
note the sound of the airflow as it falls off in tone level.
Abruptly raising the flaps while at minimum
controllable airspeed will result in lift suddenly
being lost, causing the airplane to lose altitude or
perhaps stall.
As airspeed is reduced, the flight controls become less
effective and the normal nosedown tendency is
reduced. The elevators become less responsive and
coarse control movements become necessary to retain
control of the airplane. The slipstream effect produces
a strong yaw so the application of rudder is required to
maintain coordinated flight. The secondary effect of
applied rudder is to induce a roll, so aileron is required
to keep the wings level. This can result in flying with
crossed controls.
Once flight at minimum controllable airspeed is set up
properly for level flight, a descent or climb at
minimum controllable airspeed can be established by
adjusting the power as necessary to establish the
desired rate of descent or climb. The beginning pilot
should note the increased yawing tendency at mini-
mum control airspeed at high power settings with flaps
fully extended. In some airplanes, an attempt to climb
at such a slow airspeed may result in a
loss
of altitude,
even with maximum power applied.
During these changing flight conditions, it is important
to retrim the airplane as often as necessary to
compensate for changes in control pressures. If the
airplane has been trimmed for cruising speed, heavy
aft control pressure will be needed on the elevators,
making precise control impossible. If too much speed
is lost, or too little power is used, further back pressure
on the elevator control may result in a loss of altitude
or a stall. When the desired pitch attitude and
minimum control airspeed have been established, it is
important to continually cross-check the attitude
indicator, altimeter, and airspeed indicator, as well as
outside references to ensure that accurate control is
being maintained.
Common errors in the performance of slow flight are:
• Failure to adequately clear the area.
• Inadequate back-elevator pressure as power is
reduced, resulting in altitude loss.
• Excessive back-elevator pressure as power is
reduced, resulting in a climb, followed by a rapid
reduction in airspeed and “mushing.”
The pilot should understand that when flying more
slowly than
minimum drag speed (LD/
MAX
)
the
airplane will exhibit a characteristic known as “
speed
instability
.” If the airplane is disturbed by even the
slightest turbulence, the airspeed will decrease. As
airspeed decreases, the total drag also increases
resulting in a further loss in airspeed. The total drag
continues to rise and the speed continues to fall. Unless
more power is applied and/or the nose is lowered,
the speed will continue to decay right down to the
stall. This is an extremely important factor in the
• Inadequate compensation for adverse yaw during
turns.
• Fixation on the airspeed indicator.
• Failure to anticipate changes in lift as flaps are
extended or retracted.
• Inadequate power management.
• Inability to adequately divide attention between
airplane control and orientation.
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2.0
1.5
1.0
.5
-4
0
5 10 15 20
Angle of Attack in Degrees
Figure 4-2. Critical angle of attack and stall.
S
TALLS
A stall occurs when the smooth airflow over the
airplane’s wing is disrupted, and the lift degenerates
rapidly. This is caused when the wing exceeds its
critical angle of attack. This can occur at any airspeed,
in any attitude, with any power setting. [Figure 4-2]
The practice of stall recovery and the development of
awareness of stalls are of primary importance in pilot
training. The objectives in performing intentional stalls
are to familiarize the pilot with the conditions that
produce stalls, to assist in recognizing an approaching
stall, and to develop the habit of taking prompt
preventive or corrective action.
•ision is useful in detecting a stall condition by
noting the attitude of the airplane. This sense can
only be relied on when the stall is the result of an
unusual attitude of the airplane. Since the airplane
can also be stalled from a normal attitude, vision
in this instance would be of little help in detecting
the approaching stall.
• Hearing is also helpful in sensing a stall condition.
In the case of fixed-pitch propeller airplanes in a
power-on condition, a change in sound due to loss
of revolutions per minute (r.p.m.) is particularly
noticeable. The lessening of the noise made by the
air flowing along the airplane structure as airspeed
decreases is also quite noticeable, and when the
stall is almost complete, vibration and incident
noises often increase greatly.
Intentional stalls should be performed at an altitude
that will provide adequate height above the ground for
recovery and return to normal level flight. Though it
depends on the degree to which a stall has progressed,
most stalls require some loss of altitude during
recovery. The longer it takes to recognize the
approaching stall, the more complete the stall is likely
to become, and the greater the loss of altitude to
be expected.
RECOGNITION OF STALLS
Pilots must recognize the flight conditions that are
conducive to stalls and know how to apply the
necessary corrective action. They should learn to
recognize an approaching stall by sight, sound, and
feel. The following cues may be useful in recognizing
the approaching stall.
• Kinesthesia, or the sensing of changes in direction
or speed of motion, is probably the most important
and the best indicator to the trained and
experienced pilot. If this sensitivity is properly
developed, it will warn of a decrease in speed
or the beginning of a settling or mushing of
the airplane.
• Feel is an important sense in recognizing the onset
of a stall. The feeling of control pressures is very
important. As speed is reduced, the resistance to
pressures on the controls becomes progressively
less. Pressures exerted on the controls tend to
become movements of the control surfaces. The
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lag between these movements and the response of
the airplane becomes greater, until in a complete
stall all controls can be moved with almost no
resistance, and with little immediate effect on the
airplane. Just before the stall occurs, buffeting,
uncontrollable pitching, or vibrations may begin.
immediately. Since the basic cause of a stall is always
an excessive angle of attack, the cause must first be
eliminated by releasing the back-elevator pressure that
was necessary to attain that angle of attack or by
moving the elevator control forward. This lowers the
nose and returns the wing to an effective angle of
attack. The amount of elevator control pressure or
movement used depends on the design of the airplane,
the severity of the stall, and the proximity of the
ground. In some airplanes, a moderate movement of
the elevator control—perhaps slightly forward of
neutral—is enough, while in others a forcible push to
the full forward position may be required. An
excessive negative load on the wings caused by
excessive forward movement of the elevator may
impede, rather than hasten, the stall recovery. The
object is to reduce the angle of attack but only enough
to allow the wing to regain lift.
Several types of stall warning indicators have been
developed to warn pilots of an approaching stall. The
use of such indicators is valuable and desirable, but the
reason for practicing stalls is to learn to recognize stalls
without the benefit of warning devices.
FUNDAMENTALS OF STALL RECOVERY
During the practice of intentional stalls, the real
objective is not to learn how to stall an airplane, but to
learn how to recognize an approaching stall and take
prompt corrective action. [Figure 4-3] Though the
recovery actions must be taken in a coordinated
manner, they are broken down into three actions here
for explanation purposes.
Second, the maximum allowable power should be
applied to increase the airplane’s airspeed and assist in
reducing the wing’s angle of attack. The throttle
should be promptly, but smoothly, advanced to the
maximum allowable power. The flight instructor
First, at the indication of a stall, the pitch attitude and
angle of attack must be decreased positively and
Stall Recognition
• High angle of attack
• Airframe buffeting or shaking
• Warning horn or light
• Loss of lift
Stall Recovery
• Reduce angle of attack
• Add power
Figure 4-3. Stall recognition and recovery.
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should emphasize, however, that power is not essential
for a safe stall recovery if sufficient altitude is
available. Reducing the angle of attack is the only way
of recovering from a stall regardless of the amount of
power used.
this way, the pilot can become familiar with the
indications of an approaching stall without actually
stalling the airplane. Once the pilot becomes
comfortable with this procedure, the airplane should
be slowed in such a manner that it stalls in as near a
level pitch attitude as is possible. The student pilot
must not be allowed to form the impression that in all
circumstances, a high pitch attitude is necessary to
exceed the critical angle of attack, or that in all
circumstances, a level or near level pitch attitude is
indicative of a low angle of attack. Recovery should be
practiced first
without
the addition of power, by merely
relieving enough back-elevator pressure that the stall
is broken and the airplane assumes a normal glide
attitude. The instructor should also introduce the
student to a secondary stall at this point. Stall
recoveries should then be practiced with the addition
of power to determine how effective power will be in
executing a safe recovery and minimizing altitude loss.
Stall accidents usually result from an inadvertent stall
at a low altitude in which a recovery was not
accomplished prior to contact with the surface. As a
preventive measure, stalls should be practiced at an
altitude which will allow recovery no lower than 1,500
feet AGL. To recover with a minimum loss of altitude
requires a reduction in the angle of attack (lowering
the airplane’s pitch attitude), application of power, and
termination of the descent without entering another
(secondary) stall.
Although stall recoveries should be practiced without,
as well as with the use of power, in most actual stalls
the application of more power, if available, is an
integral part of the stall recovery. Usually, the greater
the power applied, the less the loss of altitude.
Maximum allowable power applied at the instant of a
stall will usually not cause overspeeding of an engine
equipped with a fixed-pitch propeller, due to the heavy
air load imposed on the propeller at slow airspeeds.
However, it will be necessary to reduce the power as
airspeed is gained after the stall recovery so the
airspeed will not become excessive. When performing
intentional stalls, the tachometer indication should
never be allowed to exceed the red line (maximum
allowable r.p.m.) marked on the instrument.
Third, straight-and-level flight should be regained with
coordinated use of all controls.
Practice in both power-on and power-off stalls is
important because it simulates stall conditions that
could occur during normal flight maneuvers. For
example, the power-on stalls are practiced to show
what could happen if the airplane were climbing at an
excessively nose-high attitude immediately after
takeoff or during a climbing turn. The power-off
turning stalls are practiced to show what could happen
if the controls are improperly used during a turn from
the base leg to the final approach. The power-off
straight-ahead stall simulates the attitude and flight
characteristics of a particular airplane during the final
approach and landing.
USE OF AILERONS/RUDDER IN STALL
RECOVERY
Different types of airplanes have different stall
characteristics. Most airplanes are designed so that the
wings will stall progressively outward from the wing
roots (where the wing attaches to the fuselage) to the
wingtips. This is the result of designing the wings in a
manner that the wingtips have less angle of incidence
than the wing roots. [Figure 4-4] Such a design feature
causes the wingtips to have a smaller angle of attack
than the wing roots during flight.
Usually, the first few practices should include only
approaches to stalls, with recovery initiated as soon as
the first buffeting or partial loss of control is noted. In
Figure 4-4. Wingtip washout.
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