Originally Posted by
737 Driver
First of all, we must recognize that MCAS is currently being redesigned and whatever techniques that are discussed here may be entirely moot by the time the MAX is cleared for operations. That being said, and assuming the MCAS design as it existed at the time of the MAX grounding, the short answer is that an "AOA Disagree" message can occur in situations where an unwanted MCAS activation would not happen. MCAS requires a number of conditions to be present before it kicks in, and disconnecting the electric trim prematurely potentially introduces other hazards into the operation. If the pilot was concerned about the potential for an unwanted MCAS activation, the two clear avenues to inhibit MCAS is to engage the autopilot or extend the flaps. Use of the autopilot was precluded in the accident aircraft due to the effects of the erroneous stall signal.
Sorry to push you on this, but that is not a clear answer. What precisely is the procedure that the ET302 pilots should have followed? ie What would you have done? That is not in any way suggesting the the ET302 followed the correct procedure.