Originally Posted by
dmsdfw
In theory, the MCAS system is a valuable safety aid to prevent the aircraft from stalling. It is designed to trim the nose down before the aircraft stalls if an excessive AoA is reached. However, the problem is that it is vulnerable to being mistriggered if an AoA sensor itself fails in a mode that causes it to read high
What I read over on PPRune (so not authoritative) is that the 737MAX MCAS only reads from a single AOA vane (even though the aircraft is equipped with two). In my layperson’s opinion, that seems like really poor design and if true, I’d wager it becomes the crux of the whole shooting match.
edited to add - Hearing now that redundant MCAS sensors is what the software update aims to fix. It is simply unfathomable how it made it into production, this is Engineering 101.