Originally Posted by
A Squared
That is true, but from the descriptions I have read of the MCAS, my understanding is that this is exactly the way the MCAS would behave in an actual high AoA situation, intermittent adjustments of stabilizer position. In other words, the "intermittent" part wasn't a result of the bad AoA data, the erroneous AoA data was consistently and continuously high, and the MCAS was responding as it was designed to respond to a high AOA.
With correct AOA supplied to the MCAS function, it will begin automatic nose down stabilizer insertion when AOA first exceeds the MCAS activation AOA threshold. The amount of stabilizer motion that MCAS will command is a function of speed and the degree to which AOA exceeds the MCAS activation threshold. The flight deck effect is that the pilot will find that as AOA increases, the airplane has and ever increasing tendency to lower the nose to recover. Keep in mind that the stick shaker will also activate giving the pilot both auditory and tactile cues that AOA is above the normal range. Once AOA has dropped below the activation point, MCAS will remove the stabilizer increment that it has inserted. If a maneuver to higher AOA is started from a trim point at a lower, more normal AOA, MCAS will run the stabilizer nose down to aid in recovery and then once recovered to lower AOA will run the stabilizer back nose up so that it ends up close to where it started with the airplane back in trim at the condition from which it started the maneuver.