Originally Posted by
Svarin
The airplane pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs.
The climb is not correlated with the initial left nose-up input. 10 seconds between the two. Time for PRIM2 to return to Normal. I posit these nose-down inputs were an unsuccessful reaction to the zoom-climb/pitch-up (manual THS should have been used then, easy to say now of course), and not the initiators of the following :
The vertical speed, which had reached 7000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left.
From the BEA Note:
The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started
to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The
vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied
between 12 degrees right and 10 degrees left. The speed displayed on the left side increased
sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the
recorded angle of attack was around 4 degrees.
So, what does it tell us ?
So we know pretty safely AoA was 4°, speed was >215 kts.
If we now assume a pitch of >10° (see first quote),
this gives a FPA of >6° at ~400kts TAS.
This equals a V/S of >4000 fpm.
Taking this together it does not seem that the depleted energy was the reason for the reduction of the climb rate.
There is only one way how with the data points we have the V/S can have gone down to 700 fpm if speed was >215 kts an AoA was 4°. And that is that the Pitch must have reduced after the initial Pitch Up.
Therefore I conclude that the Nose Down input of the pilots have not been unsuccessful. They might have yielded slower response than expected or resulted in confusing somatogravic results but going purely by the facts I tend to disagree with your scenario that the control system did not follow the Nose down commands.
Edit:
The somatogravic point is the one which is the most intreaguing for me.
If they accidentally overcontrolled the aircraft leading to the initial climb, (e.g. due to mxing up with Roll correction input) then started to deplete energy due to the steep climb, a sudden and significant lowering of the nose (reducng V/S from 7000 to 700 fpm would fall into this category) would give a 'falling sensation'. Being relatively close to the stall speed, a subsequent pull up reaction to any pitch would lead to a reasonable 1g result, because there is no more lift available.
This 1g fits well into the normal range of things and would feel like normal attitude again. in complete darkness with no external references I'm afraid these sensations can play nasty tricks on you. Once your personal G force reference system is shifted (Falling vs. stable 1g), its difficult to go back to the original one. Re- aligning this personal reference system with the instruments in a situation where you are not sure which instruments are working properly might not be easy.
During and post stall any NU input will yield </=1g and thus feel benign.