Originally Posted by
Takwis
If only there was some sort of switch, acted upon by the control column, whereby if a pilot pulled back on the yoke, the switch automatically cut off forward trimming (and vice versa). Pilots wouldn't even have to think about it...it would be instinctive.
Oh, wait! I just checked my MAX FRM. It says there IS such a system! Section 9.2.5.2.1
It goes on to describe the STAB TRIM OVRD switch, to take that column switch out of the loop, in case that it fails. It does NOT mention the fact that the MCAS is wired into that OVRD switch, and defeats the purpose of the column cutout switches. Actually, it doesn't mention MCAS at all...but we already knew that.
So following your sequence, the stab trim is running away and not being overridden - so the stab trim runaway NNC is followed trim back to level then stab trim cut out.
As I have said before the runaway could be due to a now dead rodent that chewed an electric cable. The pilot does not have to know _why_ the stab trim is stepping nose down - only that the pilot wants/needs to stop it and to do that follow the Stab Trim runaway NNC as was done by the first Lion Air flight and was published by Boeing along with the AD after the crashed Lion Air flight. Neither crashed aircraft followed the Stab Trim Runaway NNC correctly.