In AIRBUS, The «Flare mode» brings automatically the thrust to idle provided the autothrust is under the dependance of the FMGS, in this case irrespective of the pilot action moving back the levers or not, the thrust will go to idle. On the other hand if the approach is done in SPEED mode AND WITHOUT THE AUTOPILOT USED IN PARALLEL, it is mandatory to move manually the levers to idle, otherwise the autothrust will increase the power after landing just to maintain the approach selected speed, in this case it is important to move the levers to idle during flare.
Please refer to the following website:
You will read:
Remember that "RETARD" is a reminder, not an order: however, with the A/THR engaged in a manual landing if you do not retard the thrust levers to idle the system will add thrust to keep the the aircraft on target speed, which will result in you continuing to fly gently a couple of feet above the runway! In an autoland the system will automatically reduce the thrust to idle
Similarly, please refer to:
You may read:
The pilots must program the FMS (or tune the appropriate radio aids), configure the aircraft for landing and engage the autopilot and autothrust systems in the normal fashion. The Autoland system then provide inputs to the aircraft flight controls and adjusts the engine power settings in order to maintain the required approach profile and land the aircraft safely without pilot intervention. Some systems require the pilot to reduce thrust to idle when performing autoland. The Airbus requires the pilot to move the thrust levers to the idle positon when the autocallout calls "RETARD" at 10' RA. HOWEVER, the autothrust has already reduced the thrust to idle before this point - the retard call is to remind the pilot to match the thrust levers to the demanded thrust requirement. In all cases, the pilot must select reverse thrust settings. The autopilots will be disengaged after landing to taxi clear of the runway
As a summary if on approach the AP/FD is in approach mode, the autothrust
is in thrust mode and automatic idle occurs even if the pilot doesn’t move the lever to idle. On the other hand if the autopilot is not used, and the autothrust is in « speed mode », manual reduction to idle is necessary.
In all cases, at landing the « retard » aural annunciation is done.
Important note: on Airbus, a single radio altimeter failure will change the autothrust redundancy, at worst case an automatic disconnection will not prevent to reengage the autothrust, this will not prevent correct functioning of the autothrust, that is the idle is automatic if the autothrust is coupled to the autopilot; the idle should be manually forced if the autothrust is in SPEED mode and is not coupled to the autopilot.
Anyway bringing back the levers to idle is mandatory if reversers will be used
Thank you for ymb1 about RA. RAs are not voted