wingletflyer . . ."I am also searching a clue suggesting that the A/T system was designed to switch to the correct RA in case of false reading. So far nothing...
Don't you see a semantics problem with your statement? What logic would apply in differentiating whether RA1 or RA2 is reading correct altitude? How would RA1 "know" that its value was incorrect? How would RA2 "know" that its value was correct?
I think that what you want to research is if one RA becomes
inoperative [red flag] that control will be switched to the other RA?