Originally Posted by
Lyman
takata
We are a committee. One is a writer, an editor, actually. A retired Pilot, an active PPL, and others, a designer, a mechanic, etc.
If this is illegal, then we say adieu.
If not, when you gather your thoughts, can you respond? You brought it up. The THS is dormant to help in the NU demand. Later, with a climb initiated, it activates and zooms the a/c.
With that collection of expertise, plus a copy of the report, you ought to have figured it out unaided.
C* control law is no mystery, it is a feedback control loop that moves the control surfaces to achieve the demanded movement (by g-load). Autotrim is no mystery either - THS follows elevator to unload it, slowly and with some hysteresis.
At the start of the incident, at cruise speed and alt, the elevator movement required to achieve the demanded climb was small, and the THS moved little or not at all to compensate because it didn't need to. The THS never zoomed the a/c - it started moving only after the zoom climb.
As airspeed bleeds off the control deflection required to achieve the demanded "climb" increases, and as the plane stalls the controls are trying to achieve the aerodynamically impossible - the elevator hits the stops and the THS follows. In the stall. In the stall, because that is what it is being asked to do. The basic control laws have no concept of "stall", just like previous generations of cables and hydraulics - and nor should they, it is far too complex a concept to attempt to build into such low level critical systems.