THS trim
@ Rudder
Go find hundreds of posts on the AF447 threads that discuss THS control laws.
The THS only goes as far as it needs to so as to provide full elevator deflection both directions. So it's HAL rolling the big trim wheel like we used to to relieve stick/yoke forces for the desired AoA or gee or pitch attitude..
Only reason the AF447 THS trimmed to the limit was the pilot held back stick for a long time, and HAL obliged. You and I would have rolled the wheel back manually in the old days. Maybe we would have realized it was full back, maybe not.
I can see some conditions requiring full trim of the stabilizer, but rarely. Things like a screwed up cee gee, or loss of flaps or.......