The AF447 cree would have seen the FPV drop out the bottom of a HUD and I venture out the bottom of the flight director. That would have told them they had a very high AoA.
If they didn't notice the unusually high attitude they created why would they notice anything els. 447 is a lost cause. The crew was overwhelmed, they didn't see anything, they didn't hear anything. May be the fear factor had set in, they were doing something from below the conscious mind but being a terrestrial specie there was no data to access call it instinct if you like. 447 is a bad example to draw any logical conclusions.