Recovery
If ground contact is not a factor
At buffet or stick shaker:
.
Apply maximum thrust
.
Smoothly decrease pitch
attitude to approximately 5°
above the horizon
.
Level wings
.
Accelerate to maneuvering
speed for flap position
.
Stop descent and return to
target altitude
.
At altitudes above 20,000 feet, pitch attitudes less than 5° may be necessary to achieve
shaker or buffet trim speed
If ground contact is a factor
At buffet or stick shaker:
.
Apply maximum thrust
.
Smoothly adjust attitude asneeded to avoid terrain
.
Level wings
.
Accelerate to maneuvering speed for flap position
.
Level off at target altitude.
Copyright . The Boeing Company. See title page for details.
FCT 737 (TM) October 31, 2006
737 Flight Crew Training Manual
Command Speed
As the airplane is decelerated to the desired initial condition for the approach to stall, set command speed to the maneuver speed for each selected flap setting. For the approach to stall in the landing configuration, set command speed to VREF 30
+ 5 knots.
Initial Buffet-Stall Warning-Stall Buffet
The approach to stall recovery maneuver is entered with thrust that achieves an
airspeed decrease of approximately 1 knot per second. During the initial stages of a stall, local airflow separation results in initial buffet giving natural warning of an approach to stall. A stall warning is considered to be any warning readily identifiable by the pilot, either artificial (stick shaker) or initial buffet. Recovery from an approach to stall is initiated at the earliest recognizable stall warning, initial buffet or stick shaker.
Lateral and Directional Control
Lateral control is maintained with ailerons. Rudder control should not be used because it causes yaw and the resultant roll is undesirable.
Effect of Flaps
Flaps are used to increase low speed performance capability. The leading edge devices ensure that the inboard wing stalls before the outboard wing. This causes the nose of the airplane to pitch down at the onset of the stall.
Effect of Speedbrakes
For any airspeed, the angle of attack is higher with speedbrakes up. This increases initial buffet speed and stick shaker speed but has a lesser effect on actual stall speed.
Entry
To save time, thrust levers may be closed to allow a more rapid deceleration. Target thrust for the configuration should be set approaching selected speed.
Some thrust is used during entry to provide positive engine acceleration for the recovery. The airplane is maintained in trim while decelerating. Level flight or a slight rate of climb is desired.
Landing Gear
If the entry has been made with the landing gear extended, do not retract it until after the recovery.
737 Flight Crew Training Manual
Flaps
Do not retract flaps during the recovery. Retracting the flaps from the landing position, especially when near the ground, causes an altitude loss during the recovery.
Recovery
Recover from approach to a stall with one of the following recommended recovery techniques.
Ground Contact Not a Factor
At the first indication of stall (buffet or stick shaker) smoothly apply maximum thrust, smoothly decrease the pitch attitude to approximately 5 degrees above the horizon and level the wings. As the engines accelerate, counteract the nose up pitch tendency with positive forward control column pressure and nose down trim. (At altitudes above 20,000 feet, pitch attitudes of less than 5 degrees may be necessary to achieve acceptable acceleration.)
Accelerate to maneuvering speed and stop the rate of descent. Correct back to the target altitude.
Ground Contact a Factor
At the first indication of stall (buffet or stick-shaker) smoothly advance the thrust levers to maximum thrust and adjust the pitch attitude as needed to avoid the ground. Simultaneously level the wings. Control pitch as smoothly as possible. As the engines accelerate, the airplane nose pitches up. To assist in pitch control, add more nose down trim as the thrust increases. Avoid abrupt control inputs that may induce a secondary stall. Use intermittent stick shaker as the upper limit for pitch attitude for recovery when ground contact is a factor.
When ground contact is no longer a factor, continue to adjust pitch as required to maintain level flight or a slight climb while accelerating to maneuvering speed for the existing flap position.
Autopilot Engaged
If an approach to a stall is encountered with the autopilot engaged, apply limit thrust and allow the airplane to return to the normal speed. At high altitude, it may be necessary to initiate a descent to regain maneuvering speed. If autopilot response is not acceptable, it should be disengaged.
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