Thrust Idle on A320?
Any guys or girls who can give me some info on the following:
During descent, the A320 can have various modes for the A/THR, Mach, Speed, THR IDLE..
Most of the time, when THR IDLE is displayed on FMA, the "IDLE" message is also flashing on the E/WD and N1 pointers move to around 35%, but on some occasions, it is not, and the thrust set by the A/THR is far from idle. In fact, it can be anything I have seen up to 50-52% N1. Nothing to do with a geometric profile, and on top of it, my last observation was during a tailwind descent. After a while (last observed when passing FL210), the engine did throttle back to "real" idle, and the FMA annunciatiors did not change a bit. Note: no anti-ice operation.
I have looked in FCOMs, but it only mentions that when FMA is showing THR IDLE, the engines are commanded at idle power. It happens only on rare occasions, I have asked a couple of trainers and no one seems to come with an answer, although they have seen it before.
Any thoughts?
Thanks
Flex