Machinbird,
It is clear that the silent trim was not helpful in that stressful situation, and you've eloquently explained that.
But I am going further.
The trim should have stopped, or should have never happen during the Stall.
The a/c computers determined that the a/c was in a Stall, and sounded the alarm for 53 seconds.
During those very 53 seconds, the autotrim moved silently the THS to its extreme position of -13 degrees of max NU.
It is clear that there was a logical disconnect between the Stall and Autotrim. Had there been a logical connection, with a locking of the THS in Neutral, it would have certainly helped the pilots, the recovery from Stall.
During the rest of the descent, the Stall Warning sounded another 8 times, and the THS has remained in its max NU during all those 8 Stall Warnings.
Should the THS have returned to Neutral at the first Stall Warning out of those 8, the recovery would have been helped.
Originally Posted by
Machinbird
3Hole
Don't you see a problem with an aircraft with an automatic trim system that trims silently? For years we have had alerting devices on THS trim movement (clackers & whoolers) to let you know the thing is moving. Then comes the new guy on the block with a "better" idea. (Airbus)
Couldn't they have seen the trim moving in their peripheral vision? Maybe, maybe not. There were serious problems in the cockpit that night that demanded attention.
If someone in the cockpit had noted that trim running up, they could have stopped it just like you would in a 707. Grab the trim wheel. Without all that nose up trim, the PF would have had serious trouble holding the nose up against the natural aerodynamic tendencies of the basic aircraft to drop its nose as it slowed. The PNF could have largely overridden the inept handling of the PF if it had occurred to him.
But no one saw the trim move. No one heard it move. If they had thought about it, they should have anticipated it moving, but they had other problems and it bit them.
We have now lost two Airbus aircraft due to lack of crew awareness of trim position and (other problems). Fixing the trim system to provide better motion alerting should be easy. It has plenty of precedents and it is not rocket sciences.