OK465
The elevator alone took the aircraft out of the demonstrated flight envelope.
3rd BEA report
At 2 h 10 min 51, the stall warning triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs.
Not really disagreeing, but I believe the application of thrust at that point finished the job of taking the aircraft out of the envelope. They would likely have been able to do it with elevator alone as well, it would have just taken a little longer, particularly since PF was making inputs in both directions at that time. If they had not put in TOGA thrust, it may have kept struggling along until the Captain got back or the airspeeds returned.
Note: The THS had piled on at least one degree of trim by the time the aircraft left the envelope. If it had been stopped at stall warning, it would have been a bit harder to pull all the way into the stall.
The THS behavior you find objectionable occurred as a result of being outside the envelope.
I guess I find it objectionable because it was unnecessary and had the effect of digging the hole the aircraft was in deeper. Not only do you have to rotate the aircraft nose down to recover, you have to run the trim back down to have a successful recovery and that would not be a quick process unless done manually. The fact that the aircraft was driven further into the stall by the THS again made things still worse.
The trim is essentially an AOA control if I understand the relationship between trim position and pitching moments properly. The more nose up trim you have, the more AOA you want the aircraft to fly at. The closer you trim to a stall AOA, the easier it is to pull into a stall.
How often does the Bus need to trim 12+ degrees nose up anyway? Aren't the flaps down when you do it and the cg is well forward as well? Would logical configuration related limits on trim position be appropriate?