Originally Posted by
surplus1
Would any of the experts please answer some dumb questions for me.
1. How exactly does the NTSB know that the PF pulled the yoke full back and held it there?
Yes, I know they have the DFDR - but what on the DFDR trace shows that the pilot pulled and held the yoke full back? Is it the position of the elevator as recorded or is it something else that tells them that? If so, what precisely?
NTSB Docket Item
Figure A2.1 page 18 (of the pdf) shows plots of both elevator and COLUMN position. Section 2.3 of the main body of the text contains:
General FDR data observations include:
...
2. The control column and elevator position were noted to move approximately 1/2 full travel in the aft/trailing edge up direction within 2 seconds of stick shaker activation.[7]
They were noted to again move aft/trailing edge up, to near full deflection, in the sequence of events after initial stick pusher activation, and finally to full deflection for the last 6 seconds of the recording.
It appears that the DFDR did not have the facility to record control column forces as opposed to positions (thats a relatively recent requirement for FDRs). So no-one is ever going to meet your apparent standards of proof that the control column was "pulled". Maybe it moved full aft of it's own accord? But the only logical conclusion is that the pilot flying the aircraft was moving the control column. Especially since it did the opposite of what the stick pusher would have had it do if there were no pilot intervention.