Originally Posted by Owain Glyndwr
The HAP mode contains logic that in effect says: “Do not allow pitch to increase if the speed is falling”.
Bechet got no restriction to obtain more than 17 deg of pitch even if he was under high AoA protection 1 sec after selecting TOGA.
True that speed was bizarrely not falling ... especially compared to Asseline who kept his sidestick in the same position for 3 more seconds ...
if flying at or near alphamax with a falling airspeed the last thing one wants to do is allow changes that might take the aircraft over that limit and nearer to alphastall.
If flying at or near alpha max, there is no such thing as "falling airspeed", but there is flying at or near Valphamax.
"Falling airspeed" would be associated to rapid increase of alpha.
If it seems that the pitch rate could be safely increased then the HAP might apply a small nose up correction, but if the pitch rate means that the aircraft is approaching alphamax too rapidly it might need to do the reverse to avoid an overshoot.
It would do that but brief temporary overshoot of alpha max is part of the protection too as demonstrated by the Airbus test pilot.
Originally Posted by Dozy
This is because it's an airliner, not a fighter - HAP mode is designed to maintain stability and trajectory, and Alpha Max is the upper AoA limit of that mode - it is *not* necessarily for use as an escape manoeuvre.
To the contrary it is specifically designed with that in mind.
In fact it can only really be expected to perform that function in concert with either sufficient airspeed
Alpha max is necessarily associated to "sufficient airspeed" called Valphamax.
As the graphs demonstrate (and OG has helped describe), Bechet initially got to a higher AoA in less time, but the overall performance was more or less similar.
Anything between 5 and 10ft is
a lot of performance ... if it's all it takes to survive the bush ...