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Excessive Fuel use

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Hello everyone,

Thanks for all the reports. We can see that there is something wrong with the fuel predictions in some cases and we are looking into this.

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Further the to fuel prediction issues, I also am seeing drastic shortfalls in range. On flights btw Orly and Reunion I'm running dry around 1200nm short of the destination (both directions). This weekend went as far as performing the flights with max fuel and zero pax/cargo, same result (ff approx 5.5k). I've also had the fuel planner throw some very odd values at me (ie 42k lbs for Honlolulu > Tokyo).

 

Oddly, the fuel prediction stayed consistent on the Reunion run at around -1.4k (lbs) the whole flight, even after I became an imitation of Transat 236, lol.

 

Will post log of next attempt. Still enjoying the plane!

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I have the same problem. Flew from EBBR - CYYZ. Had to divert to EGCC due to -0.6 EFOB at destination, I took 2tons of extra to my block fuel... Then when I departed from EGCC - CYYZ and took also 2tons extra to my block fuel it showed me 1.2tons at CYYZ which is below FINRES significally. I just quited the sim because I couldn't cross the Atlantic. Please fix the issue. Simbrief gives the actual block fuel for every addon correctly for me. (PMDG, QW 787) etc. It's not a reason to blame SimBriefs fuel flow.

 

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2 hours ago, Mathijs Kok said:

Please let us know what weather tool is used.

I used Active Sky for P3D V4. And simulator version 4.5.

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Thanks, we do not know exactly what causes it but the rather weird weather we see inserted certainly plays a role.  Being looked at today again.

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I can confirm there are still issues with 1.0.0.4 with respect to fuel. EHAM-EGLL took 46,000 lbs EFOB before take off was 33.7. After takeoff and on SID it snaps to 25,300 on arrival. Just about to start descent and have 39,500 lbs.....Latest Activesky. If someone wants to watch my screen on screen share id be happy to help...

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We have now spend some time with the logfiles and the videos and one thing is pretty obvious. In many occasions the predictions are whacked out of shape because of very weird weather. In one occasion the temperature at FL370 was +20 Celsius for a while (and -30 before and after) and in two others we seen an 80 knots tailwind  disappear in two seconds only to appear a few seconds later again.  If the fuel predictions are done in those moments it is obvious they will be wrong (or rather correct for the incorrect conditions).

 

It's not easy to decide on how to fix this.  Filtering out this obvious incorrect weather is a massive task and prone with problems. As other aircraft developers have to deal with the same issues I will talk to PMDG and see how they handle it.

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Mathijs,

 

I have noticed something. I was using the LBS/POUNDS version, then i switched to the KGS/TONNE version and just took off for YYZ- from LHR... Since switching to KGS, my predictions are still slightly off but my EFOB at YYZ is not negative. planned as 10.5 at the threshold and after take off its now 5.1 (not unreasonable). Could the issue be a simple LBS to KG or KG to LBS issue? Just trying to help

 

Jody

 

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vor 3 Stunden , Mathijs Kok sagte:

We have now spend some time with the logfiles and the videos and one thing is pretty obvious. In many occasions the predictions are whacked out of shape because of very weird weather. In one occasion the temperature at FL370 was +20 Celsius for a while (and -30 before and after) and in two others we seen an 80 knots tailwind  disappear in two seconds only to appear a few seconds later again.  If the fuel predictions are done in those moments it is obvious they will be wrong (or rather correct for the incorrect conditions).

 

It's not easy to decide on how to fix this.  Filtering out this obvious incorrect weather is a massive task and prone with problems. As other aircraft developers have to deal with the same issues I will talk to PMDG and see how they handle it.

 

Not going to make any comparisons here and only wanting to help:

I made 100+ flights using ActiveSky with the Airbus of the other (more expensive) developer that also imports the winds from ActiveSky and never ever had an issue with the EFOB predictions there. So I doubt that this can simply be put down to weird weather by ActiveSky.

 

Also if it was caused by fluctuations in the ActiveSky weather the EFOB values should also be fluctuating. But that is not what I see. The EFOB goes constantly down in the first half of the flight and goes constantly back up again in the second half of the flight.

 

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Well, in what was send to us the weather was as I explained, how that affects what is seen we have to look at.  Fact is we can recreate the issue with AS and not without.  What exactly is in play remains to be seen. But weather most definitely is  a factor and when weather is not changing the issue will not happen. 

 

By now I talked to some other aircraft devs and have some idea how they filter out these weird weather events.

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1 hour ago, RALF9636 said:

 

...The EFOB goes constantly down in the first half of the flight and goes constantly back up again in the second half of the flight.

 

 

Not to pile on a dead horse, but I've seen this behavior as well (using KGS) with the MCDU fuel remaining at destination.  Generally speaking, though, the actual fuel burn is consistent and within a few percent of SimBrief from what I've experienced.

 

For instance, on a CYYZ-CYVR flight (with 1.0.0.2 IIRC), my block fuel (from SimBrief with a 1.10 fuel factor) was 33400 kgs.  The screenshot was captured 1:16 into the flight (3:15 to go) with a SimBrief EFOB prediction of 21.7k-23.2k kgs. As you can see, the ECAM FOB is slightly high but nearly dead on, while the MCDU is way off.  It finally started to correct around Calgary.  A quick sanity check by summing the upper ECAM engine fuel flows divided into the FOB shows there is plenty of fuel remaining (almost 5 hours!)

 

2019-12-13_21-30-35-560.thumb.jpg.3e1423053bf258e3048f83b161b5ef01.jpg

 

Upon arrival at the gate at 20:59 (3.5 hours later), the ECAM reported FOB was 7950 - compared to a SimBrief prediction of 5.3k-6.7k kgs.

 

 

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I just accidentally found this issue. It might be related. The trip fuel calculation apparently depends on the block fuel entered (and not just because of the different fuel weight). I just entered different block fuel values here pre-flight and the trip fuel shows unplausible values, it even becomes negative.

 

29.jpg.c39896c5805defccf9867a1fc1512851.jpg

 

5.jpg.5d4c826889605f9b0231d111b20098bf.jpg

 

50.jpg.6ed84aa73ea6347137862a8da998ea8e.jpg

 

 

Additionally I also have the issue with the invalid GWCG value, reported here (and I cannot always solve it with "instant load"):

 

 

Maybe related as well.

 

 

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Well went out for supper with friends. Came home to a paused SIM at the T/D showing a predicted EFOB of 5.1. This is great.....UNTIL, I unpaused the sim and the fuel jumped automatically up to 52,000KGS after unpausing. Now showing an EFOB of 51,500 KGS? Damn, I give up. Almost time to put it in the hangar for a while....

 

Jody

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Fuel Used 1.6 ??? 

REM 51.6?

Just after unpausing at the T/D the fuel jumped back up. It was showing 5.1 as mentioned above

 

HMMM.PNG

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i have that too. Not in that big numbers but still not nice.

 

KBOS to LEMD, realtime/realweather with the time you see in cockpit on the clock. Ive used Simbrief with the provided AS A330 profile. 294 pax, 5.2 tons cargo. Simbrief gave me 43 tons, AS fuelplanner gave me around 32 tons so i took Simbrief values. Did windrequests in fmc.

 

On the ground after refueling, efob of 5.6 at LEMD

 

2019-12-20_1-32-18-326.thumb.png.aebc97ceef2952160a00a3aa99412cd7.png

 

 

7 mins in the air ive got this

 

2019-12-20_2-2-57-528.thumb.png.aa7913a49b2b444d9fcdd80383248d37.png

 

1h later in cruise, already -0.6 efob. You can see i have pretty strong tailwind even, 82 knots. But it still gows lower and lower in calculated efob.

 

2019-12-20_2-46-32-728.thumb.png.77a738f25ec2b23f4328097f83499269.png

 

 

latest a330 version, experimental

p3d v4.5 hf2

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We are still checking this out. We are now almost 100% sure weather is involved. Again yesterday evening I got a video where the IAS jumped 70 knots in a second because the wind was there one second and simply gone the next.  It appeared again three seconds later.

 

In another video we got the temperature at FL320 was +20 degrees C.

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Dear Aerosoft,

 

I can confirm (Active Sky used for weather input).

 

Hovewer, I have noticed another strange thing - maybe this is somehow related. Notice a very strange difference of UTC times between DUDNI waypoint and my destination CYYC (they are 80nm apart, see the ND). 

 

Best, Jan

utc.png

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didn't know about this topic, and today tried EDDF-KBOS. Around 159t ZFW and 51t of fuel regarding simbrief... After an hour flying -0.9 EFOB, engines around 6t/h (both, so 3t/h one) (during flight) and around 7t/h (both) during climbing. Thought I won't arrive and disconnected.

 

Maybe you can allow "in case of emergency" to refuel during flight. Now I know - add 5-10% more what Simbrief keeps saying, but as people keep saying - This will be my 1st plane where Simbrief can't calculate the fuel.

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vor 4 Stunden , F1le sagte:

didn't know about this topic, and today tried EDDF-KBOS. Around 159t ZFW and 51t of fuel regarding simbrief... After an hour flying -0.9 EFOB, engines around 6t/h (both, so 3t/h one) (during flight) and around 7t/h (both) during climbing. Thought I won't arrive and disconnected.

 

Maybe you can allow "in case of emergency" to refuel during flight. Now I know - add 5-10% more what Simbrief keeps saying, but as people keep saying - This will be my 1st plane where Simbrief can't calculate the fuel.

 

But the fuel consumption itself seems to be correct. It is just the EFOB values that are miscalculated somehow.

 

So you should be fine to continue the flight with the fuel calculated by simbrief.

 

Did you compare the actual FOB with the predictions calculated by simbrief for each waypoint? For me it always is quite spot on. And the EFOB values somehow recover to the end of the flight.

 

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For me this problem has absolutely nothing to do with ActiveSky.

 

This time I did not launch ActiveSky at all to test this. I used the "Cold Fronts" weather theme of P3D.

 

Exactly the same issue shortly after takeoff.

 

As you can see from the screenshot:

actual FOB = 15.8

EFOB at next waypoint (which is 9 nm away) = 10.1 !

 

 

A330.thumb.jpg.c2008186a9b8d5ab0ee3b3a119622530.jpg

 

Data.zip

 

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9 hours ago, RALF9636 said:

 

But the fuel consumption itself seems to be correct. It is just the EFOB values that are miscalculated somehow.

 

So you should be fine to continue the flight with the fuel calculated by simbrief.

 

Did you compare the actual FOB with the predictions calculated by simbrief for each waypoint? For me it always is quite spot on. And the EFOB values somehow recover to the end of the flight.

 

 

Well I agree, No I haven't calculated FOB with predictions for each waypoints, but thanks for a hint, so I'll try during next flight. Yes, EFOB recovers, many times during PMDG long flight (6-8h) after a start had 1.5 EFOB, and after 4h flight 5.0 EFOB (increasing each hour), but when I calculated here in A330  6t/h and having 42t on board it's 8h of flying (even more as last 1h during descending is almost zero fuel burn)  , so left with 6-7h of flying, but EFOB was going each hour more negative, so scared a bit and gave up, but I should have arrived.

 

Anyway need to test it.

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Can everyone check the predicted UTC times for waypoints? Mine was also completely off (not just estimated EFOB). I had a discontinuity after last waypoint, and also a complete nonsense UTC prediction after this discontinuity (like 8 hours on 80nm distance). Cannot this be a cause? (I have no idea how EFOB predictions are actually calculated).

 

 

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