ARTICLE: Rethinking Stall Training
The FAA and aviation safety organizations are pushing hard for improvements in pilot training and specifically stall recovery training. Unfortunately the last commercial air carrier accident, which was a stall related accident, resulted in Congress raising the minimum flight hours to 1500 for new hire pilots as if that was the solution to preventing future staff related mishaps – get real! The FAA, forced to comply with Congress, at least made a change to AC 120-29 regarding stall training outlining some core principles that should be in the training program:
- Reduction of Angle of Attack
- Evaluation criteria for a recovery from a stall or approach to a stall
- Realistic scenarios that could be encountered in real operations including ones with autopilot engaged
- Treating approach to stall sane as full stall
- Stick usher training into flight training scenarios
One of the areas that should be addressed by the FAA and the industry jointly is how to best conduct stall training, both in the early stages of initial training and later to pilots who are flying sophisticated Fly by Wire (FBW) aircraft. How do we teach airline pilots to handle the aircraft when it’s close to the edge of the flight envelope?
Here are some points to consider:
- The stall training curriculum should ensure that the proper first steps are taught. During basic training, pilots are taught to recover from a stall by dealing with the attitude first, accepting some height loss then applying power. However air carrier pilots, who spend most of their time in controlled airspace, have been taught that they should apply power first, then adjust attitude if necessary to minimize altitude loss. Maybe this technique was taught and supported by the FAA because it was assumed pilots would be reacting to a stall warning, rather than waiting for the actual stall. Plus there was the controlled airspace factor and vertical separation. It was interesting to note that in the post Colgan accident analysis it was re-discovered that the “power-then-attitude” stall recovery technique was not the one that the manufacturer test pilots were required to demonstrate for certification it was “attitude-then-power” recovery. So it would appear that the FAA inadvertently authorized a line training technique different than the one they required for type certification.
- Angle of Attack is a key reference for stall recovery – ask any Navy or Marine aviator who flew aboard a carrier – airspeed and angle of attack was etched into their flight training program from day one. AOA was prominently displayed in every airplane and it should also be displayed on every commercial airplane be it on the HUD or MFD for pilots to see.
- Stall Recovery training, both high altitudes and low altitude stalls, should be an annual recurrent training requirement – think of it as important as the annual flight physical.
- Training must be tailored to the type of airplane being flown. For example a B737 doesn’t auto-trim with AP-OFF. When handling the aircraft, the pilot has feed-back from the yoke and that is important for the recovery. When the pilot applies forward stick inputs to recover from the stall, the pilot can “recognize” the amount of force needed and also the need (or not) for trimming the aircraft. Airbus Aircraft will switch from “Normal Law” to “Alternate Law” and eventually to “Direct Law.” So the pilot, in reaction to a Stall auto-warning, has to think about all the reversions, has to cancel the AP/ATHR disengagement aural warnings, and has to recover from the stall. A stall in a FBW aircraft means you are in a degraded mode. Without feed-back on the stick, with thrust in a certain set, unreliable speed indications and a flow of ECAM warnings it is a huge challenge.
The essential question to answer is why pilots pull up when there is a stall warning – get back to the basics. At the on-set of the buffet, or when the stall warning goes off, reduce the back pressure, move the stick forward and add power. This reduces the angle of attack and un-stalls the wing.Share this article: