Autotrim
Excuse my lack of knowledge, but on a recent jumpseat flight aboard a 737-200 I discovered the world of autotrim. Well I think I did anyway. During the approach the trim wheel appeared to wind itself. On landing and vacating the active rwy, the trim wheel unwound itself.
My question is how does this work? I am used to the trim in a C172 where the Pilot in command makes adjustments on the trim wheel to release the pressure required on the yoke. I guess the autotrim senses excessive movement of the yoke and automatically adjusts elevator trim tabs?
An explanation would be appreciated.