logged Fuel and Load always getting N - N or NEGATIVE VALUES on long haul flights

[garett_09]

Hello,

 

after entering the information from simbrief and using the correct aircraft in simbrief, when im flying a long haul flight like 14-15 hours, i am always getting this error in the FMS. I cant find anyway to fix it even by re-entering the values again, adjusting the CL, adjusting the fuel by small increments, changing the tropopause. 
 

this happens when the aircraft is fully loaded and is full of fuel. It doesnt happen on light flights like 5-8 hours. 
 

Using XBOX series X running 1.1.9 and still hasnt been fixed. 
 

plane: airbus a350-900 ULR as well as other a350 variants. 

[garett_09]

This is really getting frustrating. Im running v1.1.9

 

i can never do long haul flights with this plane. 

[Abdulaziz Al Dyri]

Happened to me on the A350 and A330 also. 

mainly happens with me after adding the step climbs but when i dont add them everything works fine 

[garett_09]

Well, i guess there is one way to replicate it. I have auto import step climbs and i think that is also the reason. I will try to turn it off then add the fuel and load ad add the step climbs after then i will report back here. 

[Abdulaziz Al Dyri]

5 hours ago, garett_09 said:

Well, i guess there is one way to replicate it. I have auto import step climbs and i think that is also the reason. I will try to turn it off then add the fuel and load ad add the step climbs after then i will report back here. 

used to happen even on the 330 so i dont think the auto import is the issue 

[garett_09]

The issue is on the plane itself im guessing. When im manually applying the step climbs and not placing in the FMS, it doesn’t give me a negative value or a crazy value. 
 

only happens when applying in the FMS

[aj_chugh]

I believe this is a known issue and they’re working on it. The issue has to do with the weather and the aircraft not reading the information correctly or accounting for it. Just fly the flight normally and it will fix itself as the flight progresses. Did a 12 hour flight on Xbox and had the exact same issue. I didn’t add any extra fuel and left everything as is and slept and woke up before TOD. The values fixed themselves and I had extra fuel left upon arrival. 

[garett_09]

On 12/26/2025 at 5:32 PM, aj_chugh said:

I believe this is a known issue and they’re working on it. The issue has to do with the weather and the aircraft not reading the information correctly or accounting for it. Just fly the flight normally and it will fix itself as the flight progresses. Did a 12 hour flight on Xbox and had the exact same issue. I didn’t add any extra fuel and left everything as is and slept and woke up before TOD. The values fixed themselves and I had extra fuel left upon arrival. 

I will try to do this and still fly the plane even if there are negative values. I always fly the plane on live weather and live time so i will see. 
 

 

[richboy2307]

Hey @garett_09@aj_chugh

Thank you for your report. That is unusual; based on the FROM/TO combinations I could identify from your screenshots, I haven't yet encountered similar issues.

Nevertheless, please send us the Simbrief OFP PDF for the route where you're experiencing this problem. It could assist us in better reproducing and diagnosing the cause. You can find your OFP in PDF format on Simbrief Dispatch:

This is OTHH-KLAX for example even with steps as computed by Simbrief, all automatically imported. So that is why we believe there has to be something specific in certain plans that may be causing it.

OFP: OTHHKLAX_PDF_1767977506[1].pdf
Thanks!

OTHHKLAX_PDF_1767977506[1].pdf

[garett_09]

Hello!

 

Thank you for the time to seeing this issue. Attaching the flight logs from Simbrief that happened today. I didnt get an N-N value but the fuel calculation is wrong. The block is only 116.8 but im getting a trip of 119.5t which is not correct thus getting DEST EFOB same as N-N. 

 

this is a legendary route for the airbus a350-900 ULR running 1.20 on xbox using latest SU4 update  

 

WSSSKJFK_PDF_1768071608.pdf

[garett_09]

Hello!

 

Also attaching here the step climbs @richboy2307