I have been trying to solve this issue for sometime but can’t find the solution. When planning for a flight on sim brief, I get to choose the new a320n profile. The simbrief will calculate the amount of fuel I need for the flight; however when flying the actual flight I end up using much lower fuel than estimated by simbrief. The other day I took a flight from LEMD to LFBO, simbrief estimated 14000 lbs for the flight however after the end of flight there were 10700 lbs left. After a flight of 1 hr 20 minutes ended up using only 3300 LBS; that is too low!
Would appreciate any thoughts
Yeah. In general the fuel consumption is still off. We are working on it.
Did you use time compression?
We are working on a new simBrief profile by the way. The current one is a bit off too.
EDIT: and it should be already there for download. See here:
https://github.com/flybywiresim/a32nx/blob/master/README.md
2 Likes
I fuelled a320s irl and the new neos used barely anything for short haul flights maybe used 2-3 tons if that
How off is the fuel consumption. I took a flight from ebbr to lfpg, according to simbrief I needed 9700 lbs for the trip. I ended up with 7500 lbs of fuel at lfpg; consuming only 2200 lbs for the whole trip; does not make sense.
Is this what u r experiencing.
Appreciate your thoughts
Did you use the new simbrief profile?
You have to keep in mind, that simbrief does not only calculate the fuel needed on the trip, but alternate fuel, extra fuel, reserve fuel, etc.
As said, the Neo is pretty frugal. For such a short trip 1t of fuel is pretty realistic.
I used two different profiles for A320nx; the one from FBW and the new profile by simbrief. Both profiles yield around the same fuel required for any trip. I think the problem is the FBW plane itself and not the profiles. The fuel consumption of the plane is not realistic. There is a mod to fix the fuel consumption; do u advise to that mod.
Maybe there’s a misunderstanding (I don’t use simBrief regulary). SimBrief is not the problem, that’s correct. But simBrief didn’t calculate 9700 lbs as needed fuel for the trip itself, did it? If so, simBrief would actually be the problem. SimBrief calculates also reserve fuel, alternate fuel, extra fuel, taxi fuel, etc. As any decent planning tool would do. This is your 9700 lbs of fuel. You shouldn’t arrive empty at your destination. Actually using 2200 lbs on such a short trip isn’t that far off though.
9700 lbs of fuel covers the whole trip from Ebbr to lfpg including Altn and reserve. The designated fuel for trip only is around 3000 lbs. The plane cruised at fl 190 and fuel remaining at gate in LFPG was 7700 lbs. So consumption of only 2000 lbs.
Heya!! Dunno if htis is any help, but I discovered the Simbrief fuel consumption seemed based on the normal engines and not the LEAP engines, which are 30% more efficient. Therre is a setting on the Aircraft page in Simbrief where you can set a fuel factor M30 - ie minus 30% I have been using that for months and my predicted landing weights have been very accurate
I found this accurate until yesterday… and now today, I find my fuel is about 30% short… I landed at Bali on fumes (400kg) , and why I am poking around the forum on this. I did the FBW update yesterday and note the little LEAP icon does not appear on the FBW install app
I checked weights and wind in the FP, even the Cost Index… all seemed spot on. Something here has changed
edit: checking the FBW team post above, there is an updated simbrief profile for the A320 with new weights. Perhaps the fuel consumption was update and I no longer need the reduced fuel factor. will fly and see… I don’t think the passengers need to know… lol
2 Likes
Thank you…can you update us with your findings.
so far it’s looking good. No long flights yet
ok… 1hr flight yesterday and it still appeared to be using more fuel than calculated.
via simbrief, with the new plane specs as previously discussed in the A32NX Dev ver 3c61594
today, Seattle to Denver. Wind info also entered into MCDU CLB CRZ DES profiles, all altitudes. Had the 60kn tailwind allowed for in the Simbrief FP.
BLOCK FUEL 6.5t
TOW less the estimated Landing Weight 65.6 - 61.6 = 4t fuel estimated
the actual fuel used was 4.9t
I cross checked the sim weights versus the simbrief/MCDU weights and all seemed to correlate. I flew very close to the planned profile, and even optimized the descent for fuel conservation. I was assigned a slightly longer approach, but not 30 minutes longer. The Cost Index was also correct in the FP and the MCDU. Finally I Departed 20 minutes behind schedule… and arrived 20 minutes behind schedule.
I am no expert… so very open to the idea of having missed something, but I can’t see it, and found my previous efforts to be accurate.
I reckon I am going to do another flight, and if I get similar results, allow for extra 23% fuel consumption or P23 Fuel Factor in simbrief
actual weight in pics… due to slide limitations, there was a 0.1t TOW rounding difference… ie no impact
at the gate after landing and sitting while.
Very nicely done. One important note on that is:
CI is not calculated correctly in the A32NX for now. You can change the CI in the MCDU, but it has very low impact on the planes behaviour (very low). It’s pretty difficult to calculate CI and it’s impact on the speeds in the flightphases, since this is a non linear calculation. And we don’t have enough Airbus info on that yet (for the NEO!!). Maybe this is a reason for the consumption difference.
And one question: you said trip wind from simBrief was 60kts tail? Was it kind of the same in the sim during the actual flight?
mmm interesting note on the CI modelling. That could indeed be the root cause of minor variances. The big diff I think boils down to the LEAP fuel efficiency not being accounted for properly… it can’t be sheer chance the difference is 20- 30% or the same as the actual fuel efficiency improvements
Another Flight just then, Melbourne to Brisbane… a little less precise to the FP. If I were to add a Fuel Factor of P23% in Simbrief my flight was within 300lbs of estimates, and that would eb the long slow final approach.
Therfore… all future flight plans I will use P23 fuel factor, until the next change.
Winds, yes… the winds aloft ARE accurate in FS with live weather. The predicted 60kn tail wind was present in the simulated flight. Since I started manual fuel planning originally, I have noted the real v simulated winds are quite accurate. Another example, with pics below from today’s flight. They were 100% accurate until the end of the flight where I started getting heavy gusts up to 110kn (see screencap below). - previously btw, I flew through a cyclone, remember that one that hit Greece in the Med last year? Welp it was in the sim too. Technical issues aside… this sim blows my mind sometimes, and how connected our world is.
One thing I have noted… Australia is hella windy at altitude. The tropo line btw shoots off the chart on the cusp of a cold front
and the cyclone, cause why not… with real weather satellite at the time. (DA62)
Again, nice findings. You always have to tweak the fuel factor a bit, I guess.
This youtube guy made an own simBrief profile which I tried some time ago. It seemed to be pretty accurate then. Maybe you want to try it (link to the profile is in the description below):
1 Like
ok, my final comment. Just did Melbourne to Christchurch, a decent length, WITH the P23 fuel factor. Checked FOB against the FP at various waypoints and it matched within 200kg. The entire flight was within 100kg fuel use versus estimates.
In 787,it told me not enough fuel for flying from RCTP-EHAM even i set 90% fuel before take off ! Not so in real life for sure!
