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MCAS failure is very similar in appearance and have exactly the same solution.

MCAS doesn't behave like a runaway stabilizer. MCAS adjusts the trim periodically and will back off if you apply opposite trim.

The steps to deal with runaway trim are[1]:

1 Control column . . . . . . . . . . . . . . . . . Hold firmly

2 Autopilot (if engaged) . . . . . . . . . . . . . Disengage

Do not re-engage the autopilot

Control airplane pitch attitude manually with control column and main electric trim as needed.

3 If the runaway stops:

  ■   ■   ■   ■ 

So someone trying to make sense of MCAS would logically stop at step 3 and not actually disable MCAS.

1: http://www.737ng.co.uk/737-800%20Quick%20Reference%20Handboo...



Why did you leave off steps 4 and 5?

4. If the runaway continues: STAB TRIM CUTOUT switches (both) . . . . . . . . . CUTOUT

If the runaway continues: Stabilizer trim wheel . . . . . . . . . . Grasp and hold

I don't see why someone would stop at step 3, given that the MCAS pause cycle is only 5 seconds long.


Why did you leave off steps 4 and 5?

Because that's where many pilots would stop. The "runaway" stops when the pilot inputs opposite trim.




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