Hello ini,

I wanted to ask if the Tristar's enroute fuel burn performance has been vetted against real life performance charts. I don't doubt you have. However, I use not only SimBrief but also PFPX extensively. What I am seeing after keeping my navlog completely from start to finish on 9-hour flights is that,

1. The ini Tristar burns ~14% less fuel than the SimBrief profile

2. The ini Tristar burns ~ 9% less fuel than the PFPX profile

Now, I'm not saying which of the three are right and I'm happy to adjust both SimBrief and PFPX accordingly. I've tried to source any cruise tables from the Tristar -500 to verify. Unfortunately, I can't find anything online.

You are definitely not alone. The Simbrief profiles overpredict the required fuel burn relative to the iniBuilds Tristar and actually in this case, it is the Simbrief profile that needs correcting. For example, I once dispatched between EGLL and TBPB with around 30.7 tonnes of payload, and the Simbrief dispatch release said that I needed over 90 tonnes of fuel for a flight of just around 9hrs long. That's almost 10 tonnes of fuel burn per hour when the actual Tristar only burns around 7.5-8 tonnes per hour on average. So that's an overprediction of around 10-15% per flight by Simbrief. My own conservative estimates suggest that from now on, every flight will need a fuel factor bias of around M10 to M15.

EGLLTBPB_PDF_1776325525.9d4b1b23.pdf

Edited April 19Apr 19 by vgtu-154m

Correct. So what I did on my 9 hour flight was take the fuel over time from the fist waypoint after ToC and the last waypoint before ToD and compared SB vs actual. It came out to around 14%. I corrected all my SB profiles to M13 of the fuel factor. But since the PFPX models is also around 9% over, I thought maybe I'd ask.

Hi, I will pass this along to the team, thank you.

A closer investigation after a series of 20-30 flights have now revealed the following:

i) For stage lengths and flight times between 500 to 2000 nmi (2-6hrs), it is recommended to use a fuel bias of M10 in the Simbrief profile.
ii) For stage lengths between 2000 and 4000 nmi (6-9hrs), it is recommended to use a fuel bias of M12-M13 in the Simbrief profile.
iii) For stage lengths above 4000 nmi (>9hrs), the fuel bias of M14-M15 brings Simbrief profiles in line with the Tristar we have in the Sim.