Mister O
At 2 h 10 min 51 , the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, of around 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight. The PF continued to make nose-up inputs.
Is there any need to postulate a malign machine ?
Also, once in the descent with ROD constant, it would have felt like 1g through the seat of your pants. If the ROD increased with ND input, the sudden resurrection of the stall warner plus the feeling of lightness can't have helped convince that was the right thing to do.
FWIW, from the perspective of one who has now and again been behind an aircraft (luckily without fatal result ...)
If you are stalled, and in that stalled state
the stall warning is not sounding, HAL would seem to be a part of the problem, not part of the solution. (The core problem remains ... "What, you stalled this airplane in cruise flight?"
but bear with me.)
If you've lost confidence in X (in this case airspeed), what confidence have you in
a stall warning
or
what you might perceive as a spurious stall warning while you attempt to catch back up to the aircraft?
At what point did any member of the cockpit crew first determine "We are stalled, we must unstall this airplane?"
I'll offer a guess. It was the Captain, when he came back in and at the moment before he ordered the throttle reduction. Hopefully that guess will be confirmed or buried when a more detailed report is issued.
I confess a bias: having learned how to use an AoA guage in my dim and distant past, my opinion is that being able to see AoA, and use it as a cross check, might well have alerted the flying crew to what was going on a while before the great descent began, and acted as a trigger to a more prompt recovery.