Hello airtren;
From BEA Final Report into TAROM A310 incident:-
2.3.2 Analysis of the Stall Protection Logic
Stall protection is organized around three angle of attack thresholds, that for Alphafloor, that for Alpha-trim and that for triggering the stall warning (see 1.16.1.4).
Alpha-floor protection could not play its role as, when angle of attack of 14.5° was reached, the throttle levers were already on maximum thrust.
Alpha-trim protection was triggered at a value for angle of attack of slightly less than 15° in conditions where the flight dynamics were close to the extreme. It should be noted that it also functioned after coming out of the stall by giving the opposite order
to the THS.
The stall warning did not sound and the stick shaker did not operate in the flight phase prior to the stall. When questioned, the aircraft manufacturer indicated that the cause for non-operation of these two warnings was the disturbance of the angle of attack sensors due to the dynamics of the aircraft’s movements, with the speed having dropped below 60 kt before the angle of attack reached 17.5°. The flight crew had, however, been warned of the approach of a stall by buffeting.
Back to AF447. Semantics can always be an issue. Neutralizing the elevator demand means just that, i.e. if continuous demand is made either NU/ND the THS will move in that direction until such time as the SS is placed in the neutral position. In Alt Law the Alpha protections are not available, and for this reason the elevator demand becomes a THS command as explained. At no time was the SS placed in the neutral position which would have enabled the autotrim function to maintain 1g, so effectively that function was over-ridden by the PF. Hence my reason for saying that 'autotrim' had nothing to do with it.
As an example, go back and have a look at the the initial zoom climb. The initial elevator NU commands were not aided by the THS moving because the allowable 'g' in Alt Law was exceeded ([+1.25/-0.75] where did I get that? Don't know - must have read it somewhere). During the climb the THS moved to maintain the pitch attitude when the SS movements were nominally around the neutral position, but when the 'g' went negative it moved back to 3°NU and only started tracking toward maximum with continued SS NU as the aircraft proceeded to leave the flight envelope.
The red overlaid lines on the Normal Acceleration and Elevator traces are to highlight the similarities, while the THS is also similar but initially with little movement.
As usual, you or others may disagree and I am open to other interpretations.