I know that no one has asked, but … after reading the recent posts and looking again at the NTSB animation, I’d like to offer my thoughts … but before I do there are 2 things I need to explain:
1. Proprioception is awareness of the position of one’s body in time and a defined space; and the proprioceptors are located in subcutaneous tissues of muscles, tendons, joints that respond to stimuli applied to the body. There is conscious and subconscious proprioception – in a simplified description, one is recognized, processed by the brain, and recognizes a solution or response … and the other is not processed by the brain, the body simply responds … much like quickly jerking your hand away from a hot stove, or blinking your eye if it is threatened.
2. Anyone who flew the B727 very likely received a substantial amount of training on how to recover from a “dutch-roll.” And you probably recall that the primary control response was the aileron (control wheel) and the process was to recognize the direction of bank and apply a large amount of aileron opposite the roll, and immediately return the control to the neutral position. When the airplane began to roll in direction of your last aileron correction, and as soon as the airplane passed wings-level, again apply a large amount of aileron (control wheel) against the rising wing – or opposite the roll – and immediately return the controls to neutral. It’s the “return to neutral” part that is every bit as important as the control insertion to stop the “dutch-roll.” This is what all maximum control applications during certification require … return the control to the neutral position.
OK – now for my thoughts on the AA587 circumstance.
We know about the rudder sensitivity (if we call it that – but even then, the rudder shouldn’t have been all that much of an “unknown” to someone who’s flown the airplane as long as this crew had flown it) and we know that the F/O had quite successfully transitioned the first wingtip vortex (in fact, looking at the animation again – one could call it quite professionally – in that he allowed the inherent stability of the airplane to do it’s “thing”), but I think that encounter really heightened that F/O’s “fear factor” to the point that he was operating on “the panic bubble” – where he was not yet quite panicked, but he was right at the edge. Remember the F/O questioning the Captain about the ATC clearance, asking if the Captain was “comfortable” with the takeoff following distance? I believe the F/O was showing preliminary signs of nervousness, even before they pushed the throttles forward for takeoff. And I don’t think he had rid himself of that nervousness – I think it was peppering the back of his mind throughout the climb-out.
Pilots typically set up a mental regimen by which they fly (which might be described as …“scan – mentally process – feel – mentally process – scan – mentally choose a response – physically respond – scan – mentally process – feel the motion – visually confirm the motion cue – mentally process – etc.”). I think the F/O was riveted on flying the departure and controlling the airplane – and doing so more intently than he normally would. I think he was spending a lot of subconscious effort being concerned about where the JAL747 was ahead of them WHILE concentrating on his departure – still nervous but still performing. Then – bang, they encountered the 1st vortex. It jostled the airplane a bit – and I think the F/O did just what he was trained to do – keep the controls essentially neutral – correcting minor deviations as necessary – most notably, applying a very minor roll correction. And the vortex was successfully transitioned … but … and here’s the real BUT… I think that first event escalated the fear the F/O had been forcing down and brought it right up to scream in his face! I call it “the panic bubble.” He wasn’t panicked – yet. But he was nowhere near the calm F/O that questioned the Captain before the takeoff roll.
Had they not encountered that 2nd vortex, the F/O very likely would have taken a couple of deep breaths and, within the following 5 to 10 minutes, calmed down to the point that everything would have seemed to have been, and likely would have been, “back to normal.” I think he was beginning to mentally process what had just happened (what he saw, felt, heard … what controls he used, how much input, held for how long, any repetition required, etc.) as he began a turn to stay on the departure course … and he knew he had to continue the departure. I think the Captain noticed a change in his F/O – probably not overt … but a change nonetheless – and I think that was the reason he attempted to calm the F/O, and probably himself, by nonchalantly asking “a little turbulence there, eh?” just after the encounter subsided. But I believe that attempt at “down playing” what had just happened didn’t penetrate the F/O’s “panic bubble.”
He knew he had to maintain pitch, bank, heading, altitude, climb rate, airspeed, etc., follow the published departure AND follow ATC instructions – but I think he was more concerned about the JAL747 that he was following. I think those things grew and grew in significance and the panic bubble was growing, not reducing. Now he was trying to recall just how bad that turbulence had been and how bad it could have been. How close was that other airplane? In short, he was mentally pushed to the limits – but he was still trying to perform his duties of flying the airplane. However, before he could get things back into the regular process with which he was familiar … yep … BANG … 2nd vortex encounter. But here, the F/O was spooled up – quite a bit – and now, the panic bubble burst, and his response was one of panic – his proprioception receptors (recognition not requiring processing by the brain) fired, and knowing his airplane was being forced into more of a left bank – and having already established a 23° left bank – just like snapping your hand away from a hot stove, this F/O slammed a right control wheel and a corresponding right rudder control input – almost to the stops. Whether the following and all subsequent control applications (both wheel and rudder) were a result of his proprioception or his realization that what he just did was likely too much – I can’t say … but when you’re responding out of panic, there isn’t much room for recognizing magnitude and incorporating finesse.