The MCAS function becomes active when the airplane Angle of Attack exceeds a threshold based on airspeed and altitude. Stabilizer incremental commands are limited to 2.5 degrees and are provided at a rate of 0.27 degrees per second. The magnitude of the stabilizer input is lower at high Mach number and greater at low Mach numbers. The function is reset once angle of attack falls below the Angle of Attack threshold or if manual stabilizer commands are provided by the flight crew. If the original elevated AOA condition persists, the MCAS function commands another incremental stabilizer nose down command according to current aircraft Mach number at actuation.
I have seen the above description of MCAS function in multiple places, but cannot find the original source, so apologies for the lack of attribution, though I think it came from Boeing.
Can ANYONE confirm there is an ALTITUDE 'limit' on MCAS operation? It has been stated that MCAS is only operational when the flaps are retracted (confirmed by Lion Air data) and AP is NOT engaged (i.e. manual flight).
The statement above includes a 'threshold' that must be exceeded in terms of both altitude and speed. Anyone got anything to confirm this?
- GY