Hi HN39,
Thanks for recapping the information from the post-1988 FCTM.
My English-language FCOM from 1988 is in agreement that the first stage of what it calls Landing Mode involves two things passing 50R (50 ft on the radio altimeter): memorising of the pitch attitude; and freezing of the THS setting.
The BEA report indicates that this first stage would have been engaged as a result of the ramp of height to 32R at t -21 (TGEN 313), as the a/c passed over the copse ("bosquet") before the airfield boundary.
As you know, the second stage of what is now called Flare Mode, which begins crossing 30R, introduces a slow bias of pitch that modifies the zero-stick pitch progressively from what it was at 50R to minus-2 degrees - this during a period of 8 seconds. That sub-mode would probably have been engaged by the recorded height of 24R at t -20.
The BEA states that, because the rad-alt height in the following 2 seconds was over 50 ft, flare mode was disengaged back to Normal Law for that period.
AFAIK, there is nothing in the recorded data to suggest otherwise.
By t -17, however, the height had once again fallen below 50R, which would have re-engaged the first stage of Flare Mode, freezing the THS at its current setting of U04 (4 deg nose-up trim). The second stage of Flare Mode would never have engaged, because TOGA thrust had been selected by t -4 (see Tome 4), at which point the height had not crossed 30R. (A second later, the AoA exceeded 14.5 deg, and Alpha-Prot Law would have engaged.)
In summary, the only adverse effect of the regime of the first stage of Flare Mode between t -17 and t -5 would have been the freezing of the THS at 4 deg nose-up trim. After levelling off at t -13, the PF had to pull back slightly and increasingly on the sidestick as the a/c decelerated. However, in my experience, pilots of a/c with conventional flight controls flying deliberate approaches to the stall do not continue pitch-trimming below Vref. At level-off, the IAS was already below the Vref for Flaps 3.
Bon soir, roulishollandais,
Does the above interpretation address any of your concerns?