Ray, et al,
There is no need to invoke an illusion to account for the pilot's nose-down action.
Consider the inadvertent GA mode, not recognised; aircraft starts to pitch up and thrust increases.
The pilot's objective is to continue the descent; the pilot 'naturaly' pushes forward on the stick (opposing the GA pitchup stick force), forgetting that the AP is still engaged; i.e. overpowers the AP without disengaging.
An unknown factor is the mechanism of AP / auto trim movement in this condition. Either:
- Overpowering a normal pitch mode, the trim could react to oppose the pilot stick input, but not necessarily for GA mode.
- If the 767 (this version) enters CWS mode with overpower, then trim follow-up action is more likely; the trim movement and direction aids the pilots stick input.
Thus the erroneous nose down stick input could have been a subconscious, automatic, or startle response to the unseen GA mode, which was then aided by nose down trim.
Does the 767 have a CWS mode, is this activated by overpowering the AP ?
What would the trim do when overpowering the AP, particularly in CWS mode if fitted and activated ?
'Rather a device/automation that shall prevent such CFIT in future, as it seems to work in military aircraft.'
Already tested as a proposal for EGPWS auto pull up for obstacle / unauthorised location (after 9/11); rejected due to civil certification requirements. Also that AP 'muscle' is usually much less than the human input - pilots can override the AP - back to square 1; what happens if the AP is owerpowered.