DW
Not to mention that the autotrim does not and did not move of its own volition, but moved in response to the consistent and excessive (for the conditions) backpressure on the stick from the PF.
Thatīs DozyWīs Oozlum bird. Either you donīt understand the system in the respective Alt2 Law or you donīt want to know.
Without autotrim only the elevators (already in full NU position by the FCS in an attempt to maintain the trajectory while airspeed decaying) would have been available for SS inputs. Then a further nose up command wouldnīt have changed anything. Although there are no data available (as BEA didnīt discuss that matter in the report) it must be assumed, that the pullup would have been terminated earlier with a higher speed. Without autotrim the mentioned neutral stability (mentioned by BEA) could have not be maintained and a significant nosedrop would have been present.
We still donīt know if it would have saved the day though.
ruderruderrat
the FBW computers would attempt to maintain that trajectory by moving the elevators and hence the stab trim.
HazelNuts39
Agreed. But the culprit is not autotrim, without it the airplane would still have stalled.
If talking about culprit then the law reversion logic comes into my mind. Unlimited Autotrim in ALT2b in conjunction with only BIO-protection seems not a clever idea. Why was the limit of the autotrim in Alt law out-designed in the A330/340 and not retained like in the 320 series? What kind of situation would necessitate an full up THS when careful handling due to the law degradation is necessary?
For BEA the case looks like lost after the aircraft departed the flight envelope. Does that mean, that there was no chance of recovery or that they didnīt look into that matter? THS position and autotrim would play a role when looking into that phase of the flight.