Originally posted by RR_NDB ...
I'm assuming crew never identified the UAS.
Well, they did. Or at least the PNF announced the loss of speeds and later the change to ALT Law.
From IR#3 .. At 2 h 10 min 10, the PF's nose-up inputs increased the angle of attack and the stall warning triggered twice transitorily. Probably in reaction to this warning, the PNF exclaimed "what is that?". The PF then said "We haven't got good … We haven't got a good display … of speed" and the PNF "We've lost the speeds". The angle of attack recorded was around 5°, for a theoretical stall warning threshold trigger value of slightly over 4°.
The crew identified the loss of the speed displays but neither of the two copilots called out the associated procedure. The "Unreliable IAS" emergency manoeuvre requires as a first step to disconnect the automatic flight controls and disengage the Flight Directors. The two copilots had only been trained for the emergency manoeuvre at lower levels, in the course of which the pitch attitude to adopt is 10° or 15°.
Page 54/55 of BEA Interim Report No.3 provides detail on what should have been done under the heading:-
1.17.4 Air France crew operational instructions
The real question should be why the PF believed he could manoeuvre the A/C at FL350+ the same way he had been trained to do at below FL100. Ultimately what was done right/wrong and by whom boils down to bad CRM associated with as yet undetermined Human Factors. I do find it "a bit of a stretch" to blame the systems/human interface when many similar situations have been successfully handled by other crews. All this crew were required to do is detailed in AF SOPs.