Originally Posted by
DaveReidUK
The thinking behind that is presumably that it is safer to assume that the higher of two differing AoA signals is the correct one
Not entirely sure they aren't doing that already - on a quick check back through the published info I can't find anything that says it only uses one side AOA, only that
one bad AOA can
trigger it.
Reason I was checking - I compared the MMELs. On NG you can MEL "1 aoa sensor", on MAX you cannot, and no mention of MCAS either.
Availability requirement for MCAS seems to be higher than STS (which
can be MELed), and possibly higher than a single AOA would give?
It was the initial 0.6° nose-down trim application that wasn't certifiable. There's no indication in the Seattle Times article that Boeing are planning to revert to that.
It's been stated that FAA thought 0.6 was the
total authority - maybe as well as that being increased to 2.5 the reset/repeat was added at that point too, possibly because it couldn't pass one of the cert tests without it. Or maybe the reset wasn't documented to, or understood by, the FAA.