Quote from CONF_iture (my clarification in square brackets):
"Two different things related to the thrust system happened earlier :
(1) During the take off run, the system bizarrely requested to set the thrust levers to the CLB position.
(2) At 1000 AGL [roughly top of climb]
when it was time to set the thrust levers to the CLB position, the N1 command did not follow the request and remained to the previous setting. Asseline had to retard the levers behind the CLB position, only then the N1 command was elaborated but not without delay."
Before I read the captain's memoir, I may be able to explain (1), and I've some observations on (2).
(1) In the early months of A320 airline operation, we had quite a lot of minor glitches on the FMGS. The PERF page includes separate figures for thrust-reduction and acceleration altitudes, the defaults of which are either 1000 ft or 1500 ft above the departure aerodrome, but each can be amended manually before T/O. Basle (LFSB/BSL) is 883 ft amsl, so the default settings may have been 1900/1900.
AFAIK, the only function of the THR RED function is to provide an aide-memoire for the crew to reduce to climb thrust (if both donks are still running), which it does by a flashing "CLB" in amber on both pilots' thrust FMA.
The glitch was that the THR RED figure would be lost just after take-off thrust was commanded on T/O, leading to an immediate flashing CLB prompt. This was distracting, but had no effect on engine performance.
(2) After T/O the L/G was retracted in the normal way. After climbing only 1100 ft, the short cruise was conducted at 2000 ft QNH, i.e., roughly 2000ft amsl, maintaining the T/O Flap setting of 1+F (Slats 18 deg, Flaps 10), so ALT* (altitude-capture mode) would have been triggered well below it, pre-empting the acceleration phase for the FDs, which seem to have been in use. "Alt Star" was called by the copilot at 12:41:47, about 17 seconds after airborne, and his call may have been some seconds after the mode change.
At ALT*, the thrust would have needed to be reduced immediately and substantially below CLB thrust, to avoid exceeding the flap limiting speed. (With Habsheim so close, an IAS of about 185 kt would have been reasonable.) In fact, the CVR recorded sounds of thrust reduction starting 5 sec after reaching 2000 ft. At that point, the A/THR was still engaged, and would have changed to SPD (speed) mode because of ALT*. So the thrust reduction would have been achieved by resetting the speed to a figure at or below the current IAS, and/or by retarding the thrust levers well behind the CLB gate, thereby introducing an
upper thrust limit less than CLB. (Partially retarding the thrust levers to the desired N1 would in either case have been desirable before changing to manual thrust.)
A/THR was in fact disengaged about 8 sec after start of thrust reduction, and happened to coincide with a L/G CRC warning. The latter would have been caused by a combination of N1 < 75% and radio height < 1000ft, (as the captain intimated, although my 1988 FCOM states < 750 ft). There were some low hills to their left at this point.
So, prior to reading Capt Asseline's account, I see no evidence of anomalies of engine performance in the T/O, climb or cruise phases. I agree with CONF_iture, however, that it would be good to see the DFDR for the whole flight.