I always use simbrief to prepare flights and determine fuel requirements, cruise, etc…
as of now simbrief does not have a profile of the a330neo–it’s probably too new. however, simbrief does have presets for the a359/x and a333; which one do you think is most similar to the a330neo?
I also use Simbrief to plan my flights and I’ve realised this issue as well. I select the A330-300 as the aircraft as this is the most common aircraft in comparison to the A330-900neo.
Make a custom A330-300 profile, set the MTOW to 251T, adjust MZFW/Structural weights, engine type, and rename it.
Do a flight with it using the standard fuel burn profile, and then adjust it after landing (keep note of the planned/actual numbers on your OFP) and then find the burn reduction during your cruise phase and then adjust your fuel bias accordingly,
Please note as of the time I’m positing this for the first time on Thursday 17th September 2021 at 05:37Z (06:37BST),I haven’t yet made a flight plan using this airframe!
I will of course update this comment if I change weights or fuel factors as necessary.