Originally Posted by
bsieker
- Do all these things have to happen exactly in order? That would mean MCAS would never do more than one trim increment unless the pilot uses the manually-operated electric trim in between? How do we know that?
- Where does the information come from that MCAS undoes its nose-down input when AoA returns below activation threshold? STS does something like that, but I have not seen anything to that effect about MCAS.
- How would MCAS determine the "trimmed position" of the stabilizer? And would MCAS really never operate if the stabilizer were moved to this "trimmed position" (assuming there is an engineering definition)?
So you say, but how do you know? And if that is so, why weren't operators told?
Bernd
Bernd - As for your first two points above, you have it right. MCAS does not know where “trim” is, but it does two things related to trim. First, it will undo what it does in response to high AOA when AOA reduces provided the crew has not activated trim themselves. Second, it makes the assumption that if the crew does make their own trim inputs, they know better and will provide sufficient trim inputs to command the stabilizer to the proper trimmed position.
I cannot speak to the pilot training / education history. My knowledge is of the system operation.