Originally Posted by
Grebe
OK - but 9 seconds at .27= 2.43 degrees - Thats a lot- thats outrageous at almost any speed- welcome to significant negative G ...
Actually, not terribly outrageous - if you are really, truly recovering from a low-speed stall. More likely than not, the aircraft winds up in the low-speed stall region because the pilots were not paying enough attention to the airspeed and either the pilot or the automation was putting in nose up trim to compensate. In this situation, the pilot has to lower the nose to break the stall, level the wings, apply power (potentially generating a big nose up moment), and aggressively trim nose down to put the stab back where it should have been in the first place. And this for pretty much any airliner I have flown.
That being said, it was still a terrible design to have an unknown "background" system input this much stab trim. Assuming the MAX does fly again, this large MCAS input will still be needed in an actual low-speed stall to address the control force issue at high AOA. Keep in mind that in an actual stall, MCAS is offsetting a lightening of the control forces, and
not forcing the nose down. However, as I currently understand the system, when the pilots reduce the AOA to break the stall there would no longer be a nose up moment generated by the engine nacelles and the MCAS input would then effectively convert to a large nose down moment. That seems to imply that the pilots would not need to put in nearly as much nose down trim as they would in a 737NG stall recovery and would thus change the look and feel of the maneuver.