Originally Posted by
jdawg
Obviously you perform a trim runaway memory item once pitch starts wandering against your commands. Didn't think we needed to cover that here.
The Stabilizer Trim System (STS ... onto which MCAS was grafted) wanders against my commands, and every 737 pilot's commands, every single takeoff. Multiple times. As the aircraft accelerates to flaps up speed, the STS is, not continually, but periodically, trimming nose up to maintain the speed it was previously trimmed for. Every single takeoff generates multiple STS trims, in the opposite direction to that desired by the pilot. When the trim moves, driven by the STS, the pilot trims in the opposite direction...habitually.
When the trim moves nose down "by itself", the pilots will naturally respond by trimming nose up. Probably barely noticing it. It looks just like the STS they work against every single takeoff... because it IS the STS...except that it is moving in the opposite direction. So much so, that the surviving crew wrote it up that way. It does NOT look like the stab trim runaway we were (once, long ago) trained for. Boeing could not have masked the problem any more effectively if they had tried.
If I "perform[ed] a trim runaway memory item once pitch starts wandering against [my] commands", I would do so every single flight.
I'll do it tomorrow, just for the heck of it.