studi... Guten tag
From the outset of the DFDR reads, the THS has taken some flack, this is not new. What is unique is the control Law between NORMAL, and DIRECT. Autotrim is not a protection, nor is it a Navaid, nor a required control for stabilized flight.
It is an accomodation to the size of the aircraft, and the economy of its operation. There is no feedback given the pilot, regardless his control inputs. Trim does nothing for recovery of controlled flight from upset or LOC. Whether his elevators are at five degrees deflection, or thirty, his only 'feel' is the instrument he may be using for PITCH ONLY. G does not count, or shouldn't.
In its operation, the HS changes the angle of incidence of the entire aircraft, if you define incidence as angle to airstream in level flight. The elevators change the PITCH, trim follows to make this the new "stable".
As its movement is slow, and measured, one wonders the need for it at all in upset, when inputs might needs be rapid, and opposing, as in roll control here, in the case of 447. It can throw off the scan, since one can lose track of the trim position, especially when in cockpit surroundings as 447....
These pilots had never experienced a STALL in their aircraft, especially not of the variety that led to their impact with the SEA. With full Nose UP trim, the a/c Was in dramatically high AoA. If I can interject here what I tried to say before, with an AoA of 40-50 degrees, full down deflection of the elevator puts them at roughly 70 degrees.....relative to airstream.
I do not focus too terribly much on the post STALL. THIS accident seems to have begun with PF' initial input of NU with Left Roll.