Greetings,
Airbus always resisted to incorporate ANTI ICE function into the vertical profile of ALL Airbuses
, and the IDLE + DELTA is NOT for ANTI ICE
it is the extra bit of reduction the FMS will use to keep you within the descent brakets, it is here to accomodate for wind, temperature, differences between forcast entered values and the real world
.
We all know that the FCOM is the worst document, and that Airbus is very badly documented, however HWL and THALES have published Pilots Guides, just try to get one and you will see
A lot Airline have complained about it because it is not a all economic, during several conferences ( where I was)
