Originally Posted by
Capn Bloggs
The purpose of washout (look at the outboard 1/4 of a 747 wing from the rear) is to prevent this entire-wing-stall-at-the-same-time. The entire wing won't stall "at the same time", surely?
Yes absolutely. But if any part of the wing stalls it still has the effect of moving the centre of lift forward purely because of the separation of the airflow from the rear of the wing section.
My 'entire wing' thing was just an example of that.
A deep stall can be induced on any aircraft with enough elevator authority or as a result of design. Recovery from a deep stall can be harder to achieve if the elevator then becomes less effective as per T-Tail aircraft or some other configuration.
Considering that AF447 AoA was somewhere between 35 and 60 degrees you can surmise that the horizontal stabiliser also had a similar AoA, effectively the HS was also stalled. If they had made a large nose down input to attempt recovery that would have the effect of increasing the AoA of the HS past 60 degrees. Coupled with TOGA power I suspect the effect of the ND input would have been negligible.