I realise I am rather late at the 'They followed the FD' dining table, but why does this possibility not feature more in the BEA report? Is it not a horrendously poisonous cocktail to present to a confused crew - an apparently 'computer generated so must be right' driven VS demand, totally seductive, when all else has fallen around your ears? Why not a simple 'Select Vertical mode' inhibit?
Procedure AF for unreliable speed:
Select FD OFF
AF447 crew don't followed the procedure ... sad ...