Originally Posted by
alf5071h
Concentrating on the 'certainly split' region, then this is coincident with change of stab trim.
As you note, which part of the system is driving the trim; which direction - presumably nose down.
Pilot trim switch input, but it is not clear if the AP was disengaged.
Or the AP, auto trim, unlikely re the stick deflection; but if so the direction should be consistent with the selected mode, which was …
Or AP overridden by stick deflection; is this CWS mode, and if so what would the trim be expected to do. Perhaps minimise the stick force as a 'follow up' trim function; but then why does the trim not stop / reverse when the sticks are reversed. The stick 'reversal' is coincident with the split region, where trim reversal might be expected, but with a split, which stick has priority.
We don't know what the pilots felt nor how that might have influenced their perception.
A/P C was NEVER off since cruise until end of record
After G/A, A/P was in G/A P mode and G/A R mode (pitch and roll)
The final seconds it changed from G/A P mode to ALT and ALT HOLD mode, that was somewhere at 3000ft (guess what was dialed in into MCP)
The FDR data does not mention CWS. I don't know the 767 and its behaviour with manual overriding the G/A mode
TRIM changed from ~5 to ~4 Units, that is towards nose down. I believe it followed colums with some delay. Again, I hav no knowledge of 767.
"Stick force": add the forces once the split between CPT and F/O took place. I don't know if it's just a momentary breakout force or if the split produces permanent forces.