A320 (FMGS) idle factor
Does anyone ever bother to alter idle factor (during FMGS initialization from the default factory setting of 0%) ?
I am talking about the Idle factor only, NOT perf factor.
I find that the FM descent point is usually earlier (far too conservative) than intended (something like 3 x + 20 or well more) when the aircraft is capable of descending later/ steeper (3x +10).
Often you will get a message "too steep path ahead" yet the aircraft is fully capable of descending at this so called "steep path".
When you fly a managed descent (even with all the descent winds), it will often fly slower then the managed ECON descent speed as the aircraft has to slow down (raise the nose / reduce VS) to maintain profile. Once again this is because the FMGS calculated a shallower descent profile than what the aircraft will actually fly.
Will modification of the idle factor resolve this error and the FMGS now reflect more what the aircraft is capable of achieveing ? (more accurate descent points and no more steep path messages)
Are there any hazards / risks when modifying the idle factor away from the default factory setting ?
The FCOM says modification of the idle factor is to adjust FM descent predictions. Will it do anything else ?
Unfortunately, no where does it say in the FCOM / Airbus SOP's (or I couldn't find it) that a pilot is to even check or allowed to modify the IDLE factor during FMGS initialisation ?
However the FCOM explains what modification of the idle factor does (as I stated) but doesn't say if / when you can do it.
Are pilots allowed to adjust the idle factor or would this be a deliberate breach of the FCOM / SOP's ?