Originally Posted by
RetiredF4
A mixup (PF wants to push and pulls instead) is out of the world.
...
Situation.... agrevated by a nose high position,....
It is natural behaviour to pull more and longer than needed and not to push hard and long enough to get a desired unload of the AC, at least in fast flying jets.
How often does an air transport pilot push (not relax) on the SS and feel less than 1 G? And how often in an unplanned situation under stress?
The combination of Alternate 2, turbulence and ice crystals - likely present - were IMO considerable factors.
The way human (and animal) mechanical and control mechanisms work is that the control is conditioned by feedback coming from the object of the action, from the motion, and the result of the motion.
A simple experiment/example is the opening of an umbrella. If there is no wind, I can open the umbrella with a quick, short action. In wind, I need a
stronger, and prolonged opening action, until I defeat the wind's reaction, and see the umbrella opened.
A similar behavior is shown by an experiment with a dog, or cat,, for instance an attempt to pull a toy from my hand. There will be a
stronger, and prolonged action of the dog, or cat, if I don't release the toy immediately.
It's clearly a reflex built deeply in our motion control systems.
Back to the A/C, the A/C was in turbulent air, and thus the A/C's response to a certain control, could be delayed by the countering effect of the random direction and force of the turbulent air motion.
Additionally, it was instrument based flying, and the perception of the A/C response was through the instruments. Was that as fast as normal visual perception reflex?
If the PF's first action on the stick encountered such a delayed perception of the A/C response, the natural reflex - referred above - is that the action will be
stronger, and prolonged, until the A/C is responding to the stick action.
An additional element, which could amplify the effect of the reflex is how the duration of the action on the stick is translated into the actuating of the control surface action.
Is the excursion/amplitude of the actuating of a control surface proportional to the duration of a certain stick action?
If that's the case, it's clear, that the longer duration, is equivalent to a stronger action on the stick, which adds to the already stronger stick action driven by the reflex.
Deprogramming the reflex mentioned above, and reprogramming the pilot's hand control reflex mechanisms when is at the A/C controls only, requires training, and practice, which may be different from one individual to another.... How stress worked in blurring the new reflex, with the old/natural reflex?
An additional perception factor was the angle of the ice crystals - likely present - hitting the windshield. Where they in an angle giving the perception that the A/C is nose down?
I hope that a transcript of the full cockpit sound recordings will be made available with the next BEA report, along with data from data recordings.