Curiously my colleagues and I were comparing the differences between the Boeing A/T system and the Airbus Alpha protections. In this case, as the speed came back towards the stall, would the Airbus Alpha protections kick in to giver TOGA power? Bearing in mind the protections are NOT a function of Auto Thrust.
As WS says, not quite right...
The Airbus (A320 anyway - rest are similar if not identical) power up is ATHR
The action of going to full power is called "Alpha Floor"... WS says this occurs at VLS which, whilst it has ATHR implications (if engaged) is not Alpha Floor. Alpha Floor kicks in "at some point" prior Alpha Max (Stall), "at some point" being variable e.g. a rapid increase in Alpha (cf rapid reduction in speed) will see it kick in earlier, than gently coming back to Alpha Max.
Crucially, when related to this incident, Alpha Floor is disabled <100R on landing... as somebody found out early in the A320 days
So whether an Airbus would have gone for Alpha Floor would depend on what (Rad) Alt the speed decayed to the (unknown
) Alpha Floor threshold.
Also interesting is the A v B flying control logic. There is talk (not really interested in discussing if true or not until the AAIB report) that the 777 stalled at @10'. There might be good reason for doing that, but the Airbus would not allow it... as it hit Alpha Max (stall AoA) it would have lowered the nose to maintain Alpha Max [in Normal Law]. In the ultimate case of "hopping over a hedge" onto a "better surface" there is a small chance that the B philosophy might just prove better here
I think the Alpha Floor etc. argument is likely somewhat spurious though... these are ATHR modes, and the AAIB have already stated the ATHR was demanding a power increase and not getting it... so at a simple level, why would Alpha Floor (or it's equivalent) get power? We shall have to wait and see where the "systems" failed, and if there is a chance that factors such as "other modes" might have bypassed the problem
I trust the above is seen, as intended, as a systems discussion,
not speculation on Thursday...
NoD