Originally Posted by
hans brinker
I won't even try to dispute the technical part of your analysis. Having said that:
- The captain was (most probably) the only pilot with feet on the pedals.
- Those pedals ended up deflected to the left.
- The airplane turned to the left, and after rotation banked to the left.
- The captain commented the aircraft banked left, but not did comment the rudder pedals deflected uncommanded.
And while I cannot understand how a 20K hour pilot can make such a basic mistake, I feel it is more likely than a failure leading to an uncommanded input that wasn't recognized by the pilot.
I would absolutely agree with you, however, there are pesky data points that are out of order and that may be an artifact, but do not appear to be so, and if they are not an artifact, then there was a potential back drive of the surface to the rudder pedals. Should not happen, but then many things should not happen yet do. Other than that set of data points, I would be suggesting this is a crew cognitive error, but then, there are these pesky data points....
If someone has a rational explanation for that, I should be happy. Without a rational explanation that determines they are artifacts "I am troubled".
Low-frequency sampling can throw up artifacts, but the rate of input change needed to achieve such a sampling rate artifact would be somewhat beyond my creaky bones nowdays, faster than landing a Pitts S1, or downwind hover taxi of an R-22... all usually fun for tap dancing. Rough order, the guys feet would be moving between the 8Hz data points sufficient to get the surface recorded at a place that is then nowhere near the next sample of the pedal position. That is a 2-3" amplitude reversal at around 2 times sampling rate or 16Hz or so. Even Gregory Hines would have issues doing that for the Ethiopian Shim Sham Sand Dance... james Devine may be able to do it, he can get 38 taps per second out, which is toe/heel, and 2 feet, which is around 8.5Hz then.... so, there is some odd data there.