Joined: 11 Dec 2005
|Posted: Sat Feb 23, 2008 5:23 pm Post subject: 737-300 Recovery from a Fully Developed Stall
|An airplane may be stalled in any attitude (nose high, nose low, high angle of bank) or any airspeed (turning, accelerated stall). It is not always intuitively obvious that the airplane is stalled. An airplane stall is characterized by any one (or a combination) of the following conditions:
- Buffeting, which could be heavy
- Lack of pitch authority
- Lack of roll control
- Inability to arrest descent rate
These conditions are usually accompanied by a continous stall warning. A stall must not be confused with the stall warning that alerts the pilot to an approaching stall. Recovery from an approach to stall is not the same as recovery from an actual stall. An approach to stall is a controlled flight maneuver; a stall is an out-of-control, but recoverable, condition.
Anytime the airplane enters a fully developed stall, the autopilot and autothrottle should be disconnected. To recover from a stall, angle of attack must be reduced below the stalling angle. Nose down pitch control must be applied and maintained untill the wings are unstalled. Application of forward control column and the use of some nose-down stabilizer trim should provide sufficient elevator control to produce a nose-down pitch rate. Under certain conditions, on airplanes with underwing-mounted engines, it may be necessary to reduce thrust in order to prevent the angle of attack from continuing to increase. Once the wing is unstalled, upset recovery actions may be taken and thrust reapplied as needed.
If normal pitch control inputs do not stop an increasing pitch rate in a nose high situation, rolling the airplane to a bank angle that starts the nose down may be effective. Finally, if normal pitch control then roll control is ineffective, careful rudder input in the direction of the desired roll may be required to initiate a rolling maneuver recovery. Only a small amount of rudder is needed. Too much rudder applied too quickly or held too long may result in a loss of lateral and directional control.