A310 Fuel Usage, actual compared to predicted

[Woolies]

Hi,

I know this has been raised before but I do feel that the fuel usage of the A310 is not very accurate and the FOB at arrival is quite a bit under at destination compared to the prediction from Simbrief.

As an example, I ran a flight from EGHH to LCPH using a Simbrief plan generated with the inibuilds provided airframe profile from this forum, freshly loaded for this flight. The Simbrief plan is attached as a PDF as are a few selected images from the flight of loadings from EFB, INIT, lined up for take off and on arrival to show the fuel on board.

A brief summary of the actuals from the flight and the EFOB from simbrief, all weights in KG:

at take off my FOB was 21.4 ... EFOB 21.2

at TOC the FOB was 19.0 ... EFOB 19.0

at TOD the FOB was 5.2 ... EFOB 5.6

on arrival the FOB was 3.7 ... EFOB 5.0

Climb usage is usually ok, cruise sees it burn a bit more than expected and descent sees it burn a lot more than expected. During descent I find an average of 2400KG/H which seems high considering the average in cruise is about 4000KG/H?

To confirm a few things:

- all weights at in KG

- I never paused the game in flight, which has been mentioned before

- Simbrief was calculated at M80 however the flight was run at M .78 by the AP on PROF and NAV all the way at the cruise of FL370 as imported from Simbrief

- I set a cost index of 40 as that is what is indicated in the tutorial videos but there is no helpful documentation on this in the manual provided with the A310

- the only manual flying was take off to about 1500ft before engaging AP and landing from 500ft after disconnecting the AP the rest was on NAV and PROF

- I compared winds during flight to those from Simbrief plan and all were in the same ball park and not hugely different

It would be interesting to get some feedback on this as the A310 is a great aircraft to fly but I always seem to be way short of EFOB in the range of 10-20% depending on the flight.

Cheers

Matt

EGHHLCPH_PDF_1674908937.pdf

[DegXI_FS]

Yep, for some reason it doesn't match the fuel flow some times or its higher for what Simbrief give you. Since I realized I added a "P10" in the fuel factor and now when i reach my destination I have enough fuel.

[OliveBeast20441]

Hello, Matt,

I am not a developer, but a user who has seen the same issue with the A310's fuel consumption. I understand from my forum thread that INIBuild is basing the range of this aircraft as 3500nm, which is what they state on the aircraft page in the MSFS2020 aircraft menu.

That being said, I have adjusted the A310's SimBrief profile of fuel consumption (found at the very bottom of the aircraft's profile page) to P15 (see attached photo). This has given me the correct fuel to load for each long-range flight. I have flown with this profile over the Atlantic ocean several times and always landed with my reserves intact.

In so far as the cost index, setting it to 40 may result in a cruise setting lower than 0.80M. You might try using 70 or 80, as the higher you go with cost index, the faster you will fly (and consume more fuel). Airbus has a really great article on this subject (https://ansperformance.eu/library/airbus-cost-index.pdf) which may help you decide on what CI to use.

Hope this helps,

Mark

[OliveBeast20441]

Sorry, forgot to include the photo:

 

[Woolies]

Hi Mark,

Many thanks for your comments.

I totally understand all you are saying but was hoping to get a comment from iniBuilds as when this has been raised previously I think they have indicated that the Simbrief profile is correct and there is no issue with fuel burn rate. Yep adding a P10 to P20 or just extra fuel will help for sure with having some fuel reserves.

My concern is that the fuel burn in decent seems way too high in my flights, as per my example where it chomped thru over 1T of fuel on the way down as it seems to struggle to maintain its decent speed without heavily stepping on the gas all the time. Whether this is accurate or not is really the question.

Cheers

Matt

[JoshF]

Hi folks, thanks for getting in touch. This kind of thing is quite nuanced to balance as we're dealing with a myriad of variables here; Simbrief's data and calculations, our data and calculations; winds in the sim maybe not matching the predicted as closely as expected; cost indexes; procedural approaches adding more burn; the A310's notoriously problematic VNAV (IRL). The data we have provided for the profile is the same as that in our manual, which is what we use for our calculations in the sim. Having just performed a flight, I landed with 800 kg less than planned on Simbrief; however this is including what appeared to be several wind shifts at cruise in the sim, and following the full procedural approach to the ILS, which is not factored into Simbrief's calculations.