Let's see what the manual (AOM) has to say...
AUTOMATIC FLIGHT - Autothrottle system
When the A/T is armed.
The EEC (FADEC) provides thrust equalization, controlled through the FMS.
So when the TO/GA button is pushed on T/O the T/L will go forward till one reaches the target position. But is is the thing you see. Now internally the ECC will make sure there will be no assymetric thrust, even if the T/L positions vary.
If you trigger the GO levers (only when the A/T system is armed) the ECC will direct the engines to there assigned target and the A/T servo will move in the right position, giving the pilots a clue of what is happening (at an A340 the T/L don't even move enymore).
Now for the fans:
For take off:
- push the TO/GA buttons at an IAS less then 50kts --> this will engage (when armed) the A/T in THR REF and advances the thrust levers to the limit as indicated. (flaps pos. must be out of up)
- at 65kts IAS, A/T servo disengages and HOLD mode is displayed
- if not engaged by 50kts IAS, it cannot be engaged until above 400ft AGL.
-Second push of the TO/GA button in flight cancels any T/O thrust derate. THR REF remains displayed and EICAS displays full rated thrust limit:TO
During the HOLD (de-cludge) phase, thrust can be manually adjusted.
OK so far for the take-off. Maybe will some other guy post the inflight situation.
Hope to be of some help.
