Originally Posted by
CurtainTwitcher
Not quite correct, the Speed Trim System (STS) will trim in opposition to control column movement. B737 pilots get used to seeing the trim wheel move without a trim input and accept this as normal. I believe this is a very subtle form of conditioning that is likely to be relevant to at least the Lionair JT610 accident.
STS is subject to column cutout such that large column motion in opposition to STS stabilizer command will stop STS command. Not true with MCAS. This is an important differnce between these two automatic stabilizer control functions.