However, if the PF (or the 'system') stalls the aircraft at altitude and can't recover because the controls won't respond or the instruments don't indicate a stall or the PF's training is lacking; then IMHO that is NOT pilot error.
Of course it's not.
An opinion:
Is that that there are basic software design misconceptions, with regard to the interface between humans (pilots) and the aircraft automation, built into certain commercial passenger aircraft. These misconceptions have been compounded and endorsed (perhaps in misguided good faith) by certain airline operators who believe that they can reduce their 'pilot training' costs by using aircraft that can 'fly themselves'.
These airline operators would have a philosophy something like this:
Why waste money on over-training pilots if the aircraft automation can handle the aircraft in flight? We can just train our pilots to fully believe in the aircraft automated systems can't we? The systems cannot go wrong can they?
But maybe they can...
This aircraft went down 3.5 minutes after the AP disengaged and handed control to the PF, without apparently giving any indication to the PF as to why the AP disengaged.
A supposedly highly sophisticated aircraft automation system just gives up in a flight situation which it cannot handle and gives control to the humans on the flight deck without any indication as to why it did this? WTF!
Is there an SOP for the pilots to deal with this situation?
If so, can the SOP be effectively executed in less than 3.5 minutes (or before the aircraft falls out of the sky) and if not, why not?
These questions really bother me.
I cannot imagine how those guys on the flight deck felt or what they thought when confronted with this situation, not to mention what the passengers/CC went through, if they were (God forbid) ever really aware of their situation...
So how about we take all the software writers who conceived this system, the beancounters who drove it's implimentation and the managers who approved it, put them all on the same type aircraft in a identical situation (with the managers in the drivers seats) and just say 'OK, you have control guys'...