Can someone explain that to me why the trim automatically adjusted the HS to a high nose up prior to a pilot nose-down command but, did not adjust the HS to a more nose-down position after the pilots pushed the column full forward.
In the first case, the autopilot was engaged - in the second case the autopilot was NOT engaged. Auto trim is a function of the autopilot.
Re-read pages 4-5 and note carefully when the A/P was engaged in LOC-G/S mode, and when it was in CWS mode, and when it was disengaged.
"The
autopilot tracked the glideslope accurately, gradually increasing the pitch of the aircraft to minimise glideslope deviation
and adjusting the stabiliser angle to keep the aircraft in trim......
"The autopilot mode changed from localiser and glideslope to Control Wheel Steer (CWS) pitch and CWS roll6. The aircraft pitch attitude which had been steadily increasing under the influence of pitch trim, reached 12o nose-up. The automatic pitch trim stopped at 4.9o (7.9 units) of stabiliser trim.....
"Four seconds after the thrust levers reached the fully forward position, with airspeed increasing and N1 on both engines increasing through 81%, the TOGA mode became active.
The autopilot disengaged, the pitch attitude started to increase again and the stick-shaker reactivated....