Originally Posted by
Genghis the Engineer
Proper failsafe wants three AoA sensors, then if any one is out of alignment, you disregard it and take the mean of the other two.
Two sensors is not really any better than one in a safety critical system like that, as if they're reading differently, you don't automatically know which one is wrong.
G
Two sensors indicating high A of A --> stab trim (MCAS) input
Discrepancy between sensors --> no stab trim input (but possibly reduced stall protection).