Fuel bug in A350

I was doing some fuel testing in solo and noticed a very bad fuel bug on the A350: at FL430 (and probably at other altitudes as well), the fuel flow decreases when you increase throttle from 88% to 90% (thrust, not speed, somewhere around there). I encountered an anonaly when doing fuel testing before when lower weight required more fuel, probably this same bug.

There has been a problem with the A350 since release where cruising above FL350 is never the most efficient altitude. I’m now wondering if this has to do with it.

Update: two screenshots showing the problem. Note higher thrust but lower fuel flow.

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Actually not just the A350 but other planes as well

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What other plane have you seen this on?
I know there is a problem on some planes with fuel increasing with altitude between 16000 and about fl320 but this is something else.

I noticed on the A330 and B772 as I flew it often for long haul. The funny thing j noticed is when I step climb from 360 to 380 the fuel flow increases but as I climb from 380 to 400 it decreases doesn’t make any sense. This goes the same for 772 and 330 as well.

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Did you read my post clearly? I’m talking about not setting speed AP, only changing engine thrust, and it takes more fuel to run engine at 88% than 90% thrust.

The fuel flow in IF at high altitudes are a bit all over the place. I actually really like the A330 though. I have fuel numbers at M.82, and it is actually optimal to go up to FL410 when near empty. You still end up a level lower than the real flight ususally, but at least you get a proper step climb.

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I personally don’t know much about it now, but I don’t think the A350’s travel speed is 90%. And then at some point it becomes inefficient again. In addition, FL430 is a very high FL. maybe all these factors are playing with it.

If you would like to test this out, I would give it a 787 etc. :)

this is about thrust not speed
it’s likely a data problem, so testing on 787 doesn’t help

This could be if we don’t have access to accurate fuel burn numbers at the specific altitudes (or someone botched it…)

I’ll have to check with the ones in the team poking around with this. And since it’s a Sunday, not much will happen today :)


Yeah I know there are inaccurate numbers/inaccurate physics. But lower fuel flow with higher thrust just sounds like a typo.

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On that we can agree :)
I’ll drop this to the team. In the mean time, as much details as you’re able to include in the original post would be helpful!

I attached screen shots.

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