Fuel Calculation SimBrief and actual flight

[GMane]

Does anyone else have the recurring issue that the simbrief flight plan always seems to underestimate the amount of fuel needed for long-haul flights? I use the default profiles provided (which I assume are official from iniBuilds). The EFOB after loading the plan into the FMC is always borderline too low, and after the flight this is accurately computed. I have now taken to loading EXTRA 4t fuel for each flight. I wonder if this is a simbrief of aircraft issue?

[Beavertails76]

Starting flying long-haul with the A350 as well and noticed that too. Ended up simulating air-to-air refueling to be able to land properly lol. 

[yves3550]

I allways add 10% of fule so Im sure to have enough

[Stormfish]

Are you select default a350 simbrief profile? You should select exactly inibuilds a350 (-900, -1000) msfs profiles, not default. I don’t have problems with fuel in long hauls

Edited August 15 by Stormfish

[CS-TMT]

3 hours ago, Stormfish said:

Are you select default a350 simbrief profile? You should select exactly inibuilds a350 (-900, -1000) msfs profiles, not default. I don’t have problems with fuel in long hauls

I used to have that issue until v1.0.10 or something where on a short 1-2h flight I would need 1000-2000kg more than what SB planned (yes, with the inibuilds profile, which btw coincided with what the default profile calculated), but since 1.0.12 onwards I haven't had a problem. I had to set a fuel factor of P05 instead of the default P03, but since 1.0.12 or so it's on point with the inibuilds profile back to the default fuel factor of P03.

I have done four long flights (~9h out and 10h in on one of them and 12h30 out and 14h30 in on the other) and it matched the calculation of SB with the default P03 factor.

But yes, before 1.0.10 or .11 I also HD that problem regardless of being the inibuilds profile or the default one.

[Marcel1310]

Hi,

I experience the same issue. Bought the A350 2 days ago, but on two seperate flights I had this issue. Latest was RCTP -> EDDF, aircraft was almost topped off with 92.000kgs in line with SimBrief's calculation (should be sufficient indeed), EFOB displayed -36.000kgs! Not sure whats going on here, or what I might be doing wrong.

I verified the weights couple of times of course.

Thanks in advance if anyone can help.

 

Best regards,

Marcel

Edited August 15 by Marcel1310

[CS-TMT]

From the images it seems that your issue is with the flight plan. 9000+ nm is clearly wrong for RCTP-EDDF which should be around 5000nm or so. Check your route on the MCDU and see where the error is.

Also, now that you say about that, on my last flight VMMC-LPPT for the some odd reason there was something that I don't remember that triggered an EFOB of -8000 while still on the ground before departure or during climb. It was some mistake I did (distances were OK). I corrected whatever I did wrong and the EFOB went OK again.

Anyway, your issue is with the route, not with the aircraft. The route should be always crosschecked before departure between the OFP and the aircraft computer (GNSS, MCDU, FMS, whatever). Check points, distances between waypoints, tracks/ETEs and EFOB along the route and see where there's a mismatch.

[Marcel1310]

Hi,

You are right, thanks, checked the route and was something not right. I now have an EFOB of about 10.000kgs. However, I still keep receiving the 'Fuel weight data disagree' ECAM message (first image), so it does not seem related to the route issue.

Edited August 15 by Marcel1310

[Farlis]

On 6/19/2025 at 8:46 PM, GMane said:

Does anyone else have the recurring issue that the simbrief flight plan always seems to underestimate the amount of fuel needed for long-haul flights? I use the default profiles provided (which I assume are official from iniBuilds). The EFOB after loading the plan into the FMC is always borderline too low, and after the flight this is accurately computed. I have now taken to loading EXTRA 4t fuel for each flight. I wonder if this is a simbrief of aircraft issue?

My experience is that it OVERestimates the fuel burn.

I usually take up about 300kg more than the OFP states, which is good practice, but in the A350 that is not necessary because I end up with more than 1000kg than estimated at my destination.

At least it used to be this way, maybe the updated profiles calculate the fuel burn mor precicesly.

[CS-TMT]

Ending with 1000+ than estimated is not unusual. It depends on how much contingency fuel you take, which depends on the trip fuel most of the time. On a long flight, if all goes as planned and no deviations, holds and such are needed you will likely land with 2000-3000kg more fuel, which is the contingency fuel you didn't use. If you for unplanned reasons land with 2000-3000 LESS than planned, it's also alright, as long as there is a reason for that (route deviations, holding pattern on approach, etc). That's what contingency fuel is used for. Now if you say that you land with 1000+ fuel BEYOND the contingency fuel, that's indeed an over calculation (but as long as it is within MLW limits it's ok). In that case you can set a fuel factor of P02 or P01 (instead of the A350 default of P03).

Also keep in mind that some OFP layouts include the contingency fuel on the waypoints along the route while other formats will include only the MINIMUM fuel you should have at each waypoint and at destination (the minimum being without the contingency fuel, so to be totally safe you better have the specified fuel PLUS the contingency. Also, in real life for planning purposes you plan to land WITHOUT using the contingency fuel. The reason for that is that if you are MLW limited and plan your landing weight to be at the MLW and you don't burn your contingency fuel, you will be landing above your MLW. Trust me, I'm in the final process of my Flight Dispatcher course to get my Dispatcher licence 😅

[CS-TMT]

Look at this example of what I said in my previous reply.

This is a flight planned for the A350 between both factories LFBO Toulouse and EDHI Hamburg. I didn't change anything between examples, but one considers that you will not use the contingency fuel (the LIDO OFP format), so it considers that you will take-off with 13,6tons of fuel and land with 4,7t. In this case, if you use the contingency fuel or part of it, you will land at destination with less fuel than those planned 4,7t, but as long as you land with at least 4,2t you are good to go, as those 4,2t are the fuel for alternate plus final reserve of 30min holding at 1500AGL at the alternate.

The other example, using the Easyjet OFP format considers the MINIMUM fuel that you shall have from take-off to landing. In this case the MINIMUM take-off fueel on board is 13,1t (instead of 13,7) and MINIMUM landing fuel is 4,2t. If you won't use the contingency fuel, you will end up landing with more than those shown 4,2t.

Note that even in the Easyjet OFP it says that the planned FOD is 4,7t even though the landing fuel is around 4200kg.

Note that this 0,5t (or more precisely 445kg) of fuel that you will eventually land with on the Easyjet OFP is this low because the flight itself is quite short. On a 10+h flight it's perfectly plausible that you land with 2-3t more than shown (if using the Easyjet format for example (I don't know if there are other formats that show the minimum fuel at destination).

Contingency fuel quantity is dependant on the trip fuel (either 5% or 3% of TRIP or 5min cruise consumption, whichever is more, or 20min at cruise consumption, whichever is less).

I don't know what OFP format you are using, but that may be the reason why you are landing with more fuel than "planned".

 

LIDO OFP:

 

Easyjet OFP:

Edited August 16 by CS-TMT