Originally Posted by
FCeng84
InfrequentFlyer - When MCAS was introduced to address less than desirable Cm-alpha characteristics it was recognized that it would need to be able to apply airplane nose down stabilizer motion while the column was being pulled past its cutout switch activation point. I do not know all of the details, however I do know that some wiring was added to allow the MCAS command to get to the stabilizer even with a large column pull. This "path around the column cutout switch" is not activated for STS commands, rather only for MCAS commands. Note as stated earlier that MCAS commands take priority over STS commands.
MCAS is active only when flaps are up and its commands are a function of AOA regardless of speed. This allows MCAS to be active for flaps up stalls as well as higher speed high AOA maneuvers such as wind up turns.
"such as wind up turns" Obviously no airline crew is going to do a windup turn, a test flight procedure, hopefully
But they do or used to do steep turns in the simulator which should be a data point on the windup turn flight test info. Never have heard of anyone doing a real (on purpose) steep turn in airline flying. Can you relate that data point to a hazardous AOA and other envelope positions that would make Boeing and the FAA decide to protect the human from it's effects, which most probably they would never see in the airplane and only see it in the simulator if anyone still does steep turns in the simulator. Yet, the autopilot would not need any MCAS help. It would just move the stick back or forward, irrelevant of stick force, to command an attitude that complied with what it wanted the performance instruments to show. But we still have to deal with an autopilot that can be commanded to come close to or enter the straight and level MCAS envelope. MCAS won't help it but the autopilot will move the stick as required, uncaring what the stick force is, to command the required control inputs. But put a human in the loop and we have to help him. What about telling him what to be aware of as @Gums voodoo folks used to do?