Dave Therhino
Shuttle - I think you mean per flight. Back when I worked the figure was 1/100 per flight.
I think the real concern is that Boeing programmed their flight software - MCAS
to rely on a potentially unreliable sensor. MCAS was not able (programmed) to detect
the failing sensor. Perhaps MCAS should have had a sanity check on reported AOA.
How one validates such an apparently Ad-hoc piece of software is beyond me.
My previous comment should have indicated that the expectation of an event is in the numbers
that you (NASA or Boeing or FAA) should be calculating with.