AF 447 Thread No. 9

[Lyman]

CONFiture..

You say... 2) ALT LAW + Autotrim amplify the severity of the stall.
Sidestick neutral, the THS would have rolled the same way.

I cannot prove it but I do not think the THS made the STALL more severe, so much as it made the STALL Entry different...., taking away the two cues an aircraft must retain to warn of STALL with the airframe. Without Trim, the a/c likely would have STALLED prior to power and lift ceilings, instead of after, so the a/c started its descent with the nose held high, having transitioned to fully Stalled with no change in Angle of Attack, and the slow loss of the remaining lift occurred due momentum, not loss of lift, nor power.

Buffet was unnoticed (or confused) because of turb, and also the aforementioned transitional bleeding of lift, eliminating this most necessary warning.

With the combination of THS and elevators, I believe the tail kept the nose up through the STALL, and beyond, foreclosing the a/c natural tendency to descend at the break....with no THS the pilot may have lost tail authority sooner, even with full NU, without the THS. He might have encountered secondary STALL with his persistence, but he would have had to ignore the NOSE drop...