Originally Posted by rubik101
This piece of information may well be buried somewhere in this thread, but just where did the pilot get the idea that repeated and full deflection of the rudder would correct any apparent or real upset caused by wake vortex? If it was from AA training dept. then you have to wonder who dreamed up such a scheme in the first place.
If you encounter an unexpected skid situation in your car, perhaps caused by icy conditions and worn tread of the tyres, do you repeatedly apply full steering inputs, first in one direction and then in the other, or do you apply slight and gentle inputs in the direction of the skid?
I know which action is likely to lead my safe recovery and which is liable to end up wrapped around a tree some way off the road.
The pilot was either badly trained, misinformed or plain silly. Either way, he was the major contributor to the accident.
The ice and the tyres contributed to the initial event but did not cause the subsequent crash.
I think your analogy using the icy road and worn tire tread initiation and then the driver’s over-compensation is reasonable – except for the very last sentence. In the AA587 accident scenario, the only “contributing factor” that could even possibly be considered would be the second wake turbulence encounter. However, as they had just (12 seconds earlier) encountered the first wake turbulence, in which the PF reacted perfectly, one would have to speculate as to why the PF would react so dramatically different from just 12 seconds previously. If you check the FDR you’ll see that at the first encounter, the PF used minimal rudder and used moderate, well controlled aileron and elevator. IF there could be considered any difference in magnitude of the displacement of the airplane between the two encounters, it would appear (again by reference to the FDR) that the 2nd encounter produced significantly
less displacement than the first.
Using your analogy it would be like the driver encountering an icy road with little tire tread, starting a skid and handling it perfectly and then seconds later encountering a situation that wasn’t quite as icy, and having the driver go “nuts” with the wheel and brakes.
Originally Posted by Hand Solo
Yes it did come from the American Airlines training department. They were taught to do it, even though Airbus told them it was a bad idea.
Well, that’s not exactly correct either. The AA Advanced Maneuver Training
did, indeed, talk about the use of rudder in certain circumstances. But, there was no reference to maximum use of rudder, except where it mentioned that rudder was available, and that crews shouldn’t be hesitant to use it properly, even if proper use required “full rudder.” However, the predominant references were to “judicial and coordinated use of rudder” throughout that program. I don’t recall now whether AA sought input from the regulator and the manufacturer, or if the regulator and the manufacturer spontaneously volunteered their memo to AA, but the concern mentioned by the regulator and the manufacturer had to do with the use of rudder during a
dynamic recovery from an attitude that was not desired. If there was
too much rudder used in such a dynamic recovery, the likelihood of using too much rudder was a concern on its own, and the potential of countering that initial and overly aggressive input might generate the use of opposite rudder was flagged as an increasing concern. The problem, as I see it, was that no one discussed what
judicial use meant, and no one understood what
over use of the rudder meant, and no one mentioned the
repeated reversal of rudder application. Certainly, no one mentioned the
continued, repeated, rudder reversal, to maximum deflection used by the PF. This is what caused the accident.