NADP1 saves 4kgs of fuel compared to the NADP2 profile, if Conf 1+F is flown. It costs an extra 5kgs if Flap 2 is used.

Getting to grips with Fuel Economy.

Altimeter setting
 

Can anyone relate on how and when to change altimeter settings to Standard when cleared to a FL by ATC while in NADP1?
Can't find any rules in Airbus manuals or my company manuals.
It makes sense not to change it until after the NADP1 due to the fact the altitude might change to the higher of the standard setting on 1013hpa, which would implement an earlier acceleration altitude then the NADP 1 stipulates. (and thus bust the procedure...)
I'd just like to know if there is a rule or procedure written in black and white on this....
Cheers!

Pall..

Whilst I cannot comment on the official Airbus rule as our company sop overrides theirs, what I can say is if you set STD prior to 3000', the aircraft will still accelerate at the altitude, not the flight level.

Airbus books assume us pilots change to STD at TA, so no dilemma there.

FD.

Thanks Cough, so you're saying even with STD set on the FCU, the fmgs will still climb to the NADP1 áltitude (not FL!) set in the MCDU perf.page before it will accelerate the a/c?

@ flightdetent: what do you imply with Airbus 'assumes' STD at TA?
- That... not until above TA the STD set in the FCU/Efis will actually take effect on anything programmed in the fmgs/MCDU?
- Or 'assumes' us pilots change the altimeter setting to STD when reaching TA even though we're giving a FL by ATC before TA? (which our company manual says: when given a FL by ATC change altimeter setting to STD...which almost always happens.)

Yes/No?
Any comments more?

The second option. Apologies for the late reply. The way I read FCOM the procedure is to set STD only when passing TA.

FD.