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Old 5th Jul 2012, 15:53
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PJ2
 
Join Date: Mar 2003
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A procedural question from a non-pilot.

I assume that a stall warning requires a prompt response, while an event such as UAS requires a more considered response [and resort to a checklist].

If so, shouldn't the initial response to a stall warning be a memory item? With any caveats about ignoring stall warnings being part of that memory item.
From Day One of flight training, recognition of the stall in the airplane one is training in is a high priority item. The "Approach to the Stall" is a common exercise when transitioning to new aircraft types. The "approach to stall" is not the actual stall, either in the simulator or the aircraft as the case may be. No one stalls airplanes in transition or type-rating courses. It is the recognition of the impending stall that is taught.

Regulatory bodies may or may not require that the approach-to-stall exercise be part of recurrent training on one's current aircraft. In Canada, current regulations do not require the approach to the stall exercise in fly-by-wire aircraft after the initial type-rating is complete. One may go years without seeing the exercise again unless it is informally inserted into the sim exercise by a keen instructor. Usually sim time is so compressed with required exercises that such things as manual flying and so on aren't usually done.

On the memorized aspect of the stall response, you're right - the stall warning requires an immediate response and yes, the aircraft-specific response would be memorized - but it's memorized the same sense as one might "memorize", say, the skid-response in a car...it's not just "memorized mechanically" but should be "visceral" - ie, instant and automatic.

Two reasons why this may not be the current state of affairs are, 1) aircraft today are so reliable and so well-designed that getting oneself into such a corner is an extremely rare event, and 2) because of such reliability, the "approach to the stall" exercise has been de-emphasized (and not just for Airbus aircraft) so pilots today who may not have exerienced anything but a high degree of automation may not, (emphasis here) have the same appreciation of the danger of the stall as the previous group who grew up on cable-and-pulley aircraft that could and did stall. A sense that one's airplane "cannot stall" because of automated protections is completely foreign to me and to an entire generation of guys who are now retired/retiring but I wonder in what way the stall is currently perceived as a serious and ever-present threat if one loses airspeed? There have been at least a dozen accidents in the last eight or so years as a result of stalling one's transport aircraft. That's unusual and I think a trend.

The avoidance of the stall would be/should be innate as once again, avoiding a stall is absolutely fundamental to flying any airplane. Type-specific responses to the stall warning, (which indicates an approach to stall, and not the fact that the airplane is stalled) would be part of the FCOM for the aircraft. Typically, such responses used to focus on a minimum loss of altitude first, while "powering out" of the condition. At high altitude, the guidance was that the pitch attitude may have to be slightly below the horizon for recovery. TOGA (take off/go around) thrust was always applied as part of the memorized drill.

Since AF447, this response has been re-visited and, I think, far more intelligently designed due to the recognition that the stall is not an airspeed problem, it is an AoA [angle of attack] problem, and the first reaction now is to reduce the wing's AoA to unstall the wing, then recover with power. Increasing thrust with under-slung engines tends to pitch the aircraft up, countering the required response, so adding thrust is a secondary response now. These responses will be memorized and, I suspect, practised far more frequently now.

The sections of the FCOM I cited in the previous post would be those seen on the ECAM and would be accomplished after all memory items were completed by the crew.

The standard response has always been to respect the stall warning, period. The one caution could be confusing to someone who hadn't received thorough training but the two should never be confused to the extent that doubt is produced as to what to do if a stall warning occurs.

I hope this helps.

Last edited by PJ2; 5th Jul 2012 at 15:57.
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