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A321 Fuel flow


iforrage

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Well, first, yes, I've searched through the forum for answers, but all I found was arguments about why something wasn't modelled this way or that way.  I'm not here to argue why anything was done the way it was done.  I love this product, and that's saying a lot because I enjoy Boeings more than the Busses, but if I have to fly one, then this has to be it.

My problem is that, I had enough range, and still almost didn't make it.

There surely has to be something wrong somewhere. 

On a flight from Kahului, HI (PHOG) to LAX, I used BOTH PFPX and AS Fuel Planner, checking and cross checking to make sure everything was good.  According to both, it was.

The load was 149 PAX, 5900 lbs cargo (baggage) - ZFW 124433 to be exact.  The flight plan was 2192 NM.  95 NM to the alternate.  Using Class II operations for fuel planning in PFPX, I was given right around 40000 lbs of fuel for release.  FAR reserve of 3950, Hold fuel of 4000 (45 mins each).  Plugged all these numbers along with my average tail wind (28) into AS fuel planner, and it came within 200 lbs of what PFPX gave me.  Of course, I loaded the top number.  According to the fuel summary, we'd land in Los Angeles with a hearty 10500 lbs of fuel remaining.

Now for the problem.  With tailwinds exceeding my assumptions (so, faster travel time, less consumption, yes?), and 2 step climbs to maintain Optimum Cruise altitude - at M .78, I ended up landing at LAX with ONLY 1500 LBS of fuel remaining!!

If I've made a mistake, then please tell me where to look, but to me, it seems there may be a problem with a fuel flow scalar somewhere.

Thanks for your time,

-Jesse

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Jesse,

Thanks such much for taking the time to write to us about this.

If you like, you may provide all the PFPX data (in as much detail as possible) for the flight in question and we can take a look at this.

Since the Aerosoft Airbus only uses KGs, I'm wondering if the 5900 lbs actually became 5900 Kgs, which would be a significantly higher weight and thus would hyave produced a significant increase in fuel used. If this was the case, then it's all settled.

If not, t hen it would be very helpful if  you could provide the saved flight flies from before departure and after landing. This would allow us to check everything.

Thanks again for your time!

 

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I'm  tagging onto this thread that I've been having problems planning a flight from LAX to PHNL. What loads work and how much fuel does it take? Been noticing a little discrepancy between pfpx, the as planner and the actual in flight levels.

Thanks

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2 hours ago, reddishknight said:

Been noticing a little discrepancy between pfpx, the as planner and the actual in flight levels.

Forgive me, but I didn't understand your question, but I can provide you with a general comment regarding all fuel/flight planners.

There are many different variables to planning a flight and determining the amount of fuel that will be required.  So many factors that real world there is professional training and certifications for doing this work.  In our world (commercial flight simulation) we have many of the same variables, and these varibales can change from one user to the next based on the settings of all the software they use (Flight Simulator settings, Flight Planner settings, Weather Engines and Weather Engine settings, etc.)  Then there are the user input variables..

What this all means is that fuel calculations are going to vary from person to person and flight to flight.

Additionally, different software is going to produce different results as the programmed constants they use are often different. This includes everything from fuel planning to which flight level is optimum for your flight.  Where flight levels are concerned, the optimum level depends on a host of different factors.  Winds, aircraft weight, engine specifications, temperature, etc. . Here we add yet another set of variables, which is what source your software is pulling the data from (this often differs from software to software).  Note please that the Airbus only takes a few user inputs for determining the optimum flight level, so if you're flight planner is giving you something different then it is likely to be more accurate.

Another word about fuel planners is that it's best to pick one and stick with it.  Each of the weather variables is important for fuel planning, so I recommend selecting a planner that takes as many of these variables into account as possible PROVIDING you are using a weather engine what injects these variables into your simulation.  If you're using a weather engine that doesn't inject these variables (or not using a weather engine at all) then you'll need to discount them in the fuel planner or use a fuel planner which doesn't use them.

To wrap this up, remember that where flight and fuel planning are concerned one must be aware and make the most use of the input variables.  There is a very old saying when it comes to computing anything... "Garbage In = Garage Out". 

I hope I've answered your question and the additional information is helpful to you.

 

Best wishes, and Happy Aerosoft Airbus Flights!

 

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First, I must apologize about what I said my total load was, I was looking at the A320 settings in AS Fuel Planner while I was typing.  Luckily I had not made any other A321 flights, so that data was still there, load was 33461, with a ZFW of 136461.  Even though my ZFW was higher than stated above, I was still well within limits, and still had right around the same amount of release and "supposed" reserve fuel.  I don't believe it's a mix up with conversion from LBS to KG, as I checked in sim for the total load after I had loaded the loadsheet, just to verify I wasn't too heavy.  That is the number I plugged in to PFPX.  Luckily, I also recorded the flight with AS flight recorder!

I had added the aircraft to PFPX using the performance files for the Airbus X found in the AS downloads section.

Here is the release from that flight, as well as the as recorder file, and loadsheet:

 

AAL254 PHOG-KLAX (28 Nov 2015) #1.pdf

85677290-5673-4b8b-bf81-5b1c845a2dab.fdr

LoadSheetA321.txt

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For what it's worth, I've heard reports from some of the pilots at my VA that the A318 is a a bit on the thirsty side, though I haven't got round to verifying this myself yet. I can ask for more data/incidences to be logged going forward if it would be of interest?

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  • Deputy Sheriffs

Seeing how most people here try to fly the bus as realistic as possible I would suggest the following.

In real life we make a time and fuel check every 30 minutes on our flightplans. I sort of assume that most of you (VA) pilots also adhere to these RW regulations.

These OFP logs (scan or photographed) would certainly help us in "discovering" any possible "fuel leak".

For those who have this problem I would ask to supply us with these written out OFP's or just time-fuel checks. Other files do not help that much because weight/FL/wind are variable parameters that have a big influence that would make searching for a "bug" that more time intensive/diffecult.

Thanks!

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13 hours ago, The Dude said:

Seeing how most people here try to fly the bus as realistic as possible I would suggest the following.

In real life we make a time and fuel check every 30 minutes on our flightplans. I sort of assume that most of you (VA) pilots also adhere to these RW regulations.

These OFP logs (scan or photographed) would certainly help us in "discovering" any possible "fuel leak".

For those who have this problem I would ask to supply us with these written out OFP's or just time-fuel checks. Other files do not help that much because weight/FL/wind are variable parameters that have a big influence that would make searching for a "bug" that more time intensive/diffecult.

Thanks!

Wow.  15 years of simming, and I've actually never heard of this.  Could you please elaborate, and let me know exactly what I should be recording?  Thanks!

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1 hour ago, iforrage said:

Wow.  15 years of simming, and I've actually never heard of this.  Could you please elaborate, and let me know exactly what I should be recording?  Thanks!

Here's an example OFP. It's in British Airways CIRRUS format (generated via Simbrief), though most other layouts will have the same or similar information.

The idea is that you use the OFP to track the flight's progress independently of the FMS, so you effectively have an extra check on position, fuel state, progress etc.

In the ETA column you calculate the estimated times at each waypoint. You do this by recording the takeoff time at the start, and the adding the TIM figure (just beneath the ETA field) to each waypoint (working through the whole FP at a convenient moment after TOC). So here we estimated GITEP at 0033, 0033 + 15 = 48, 48 + 13 = 0102 and so on. No need to write the hour unless it changes.

RTA is for revised estimates if they've drifted significantly.

ATA is obviously actual time over and should be recorded from the clock as you pass the waypoint.

The far right column is the fuel column. The REQ figure (70.3 at GITEP) is the fuel burn from that position to destination (in other words -- it reads zero over destination). Above this you enter the actual fuel figure (from the totaliser), so 90.7 tonnes over GITEP (not an Airbus, as you can see!)

The actual remaining of 90.7 minus the required fuel to destination of 70.3 gives 20.4 -- this is the amount of fuel we expect to have remaining when we arrive over our destination. Compared to the TOT RES (Total Reserve) figure at the top of 16.5 tonnes (which is the final reserve plus the diversion) tells us we've got 3.9 tonnes to play with (which sounds like (and is!) a lot in the Airbus, but in the 747 is just about enough for a G/A and reposition). If you do these calculations for each waypoint, you build up a picture of the overall trend in terms of time and fuel -- so by the time we got over EDENI, the estimated fuel over destination had dropped to 20.3. This tells us that at some point in that segment we've burned a hundred kilos or so more than the flight plan was expecting. We can also compare that number to the number computed by the FMS to check that its calculations are making sense.

Obviously if the estimated fuel over destination was going down rapidly with no obvious explanation, this could be an indication of a fuel leak or some other issue which is causing the aircraft to burn more fuel than predicted by the flight planning software.

In terms of other information recorded on the plan, the numbers underneath the calculated fuel over destination are the fuel temperature, and the numbers on the far right are the pitch attitude and N1 (not mandatory, but useful if your ASI goes south...)

Hope that makes sense and helps explain!

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One other thing I have a habit of doing as well as the aforementioned by Skelsey (something I and others do in the real world just for extra safe measures) is write a new column on the right labelled FOD (Fuel Over Destination), during the fuel checks (every 30 minutes as mentioned) I will also write in what the computers compute I should have at the destination, any major changes will be evident in order to view the difference quickly.

 

But back to the Original issue, I know that with the A319/320 the PFPX fuel planner is good within 200kgs (0.2T) over a 3 hour flight, I will put a flight together today to check the FF and PFPX Data for the A321 and post the results back here.

One last thing, check that the units of weight match (LBS, KGS ect....)

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  • 2 months later...

Hello again.  Sorry it's been so long, but I haven't had much time for flying since last post.  170 people lost their lives today, as the Airbus Industrie A321 they were flying in crashed in a field just east of Dover (Delaware) Air Force Base.  Preliminary reports indicate the aircraft fell from 15000 feet after running out of fuel.  It appears the Captain declared an emergency, and was trying to land the now paperweight at Dover, when the crash occured.  American Airlines Flight 2053 was en route to Philadelphia from Tampa.

 

So, here it is.  I did the flight log thing that was suggested.  I also have screenshots of some other interesting behavior.  For the purpose of this "test" flight, I converted PFPX and AS Fuel Planner to use the Bus' default of KG instead of LBS, for consistency.  As you can see, the PFPX log is still below what I get from ASFP, but not much, and I added to the fuel figures to make it match what ASFP was giving me for the flight.  I know nothing's going to match perfect, but at least the fuel planner that came with the aircraft should be correct, and that is the issue.  I still suspect fuel flow as the major contributing factor, though.  I did take note of the fuel flow at one point, and it is notated on the OFP.  At that point I had a tailwind of around 110, although it was more at a 45 from the left, but still a tail wind.  It seems kind of high to me, 2700 Kg/HR, but even if that is correct, this was only 2 hrs flight time, and I should have only burned 5400, then.  I did notice, it's a hog on climb, though.  From takeoff to TOC, it ate through 3500 Kg.  I also included at the end of the OFP, the fuel summary, with notation of what I got (and used) from the AS Planner.  The PFPX aircraft profile was the A321 NEO available in the AS downloads section.  Although, I'm thinking the sharklets are just visual eye candy, and that the flight model does not realize the actual flight dynamics.  (Or does it?)

 

Oh, I also noticed the left engine FF is about 60Kg more than the right engine.  Is that right?

 

As for the screens of the planner.  Note the "Item Result" Column for Final Reserve when switched between Kgs and Lbs.  For some reason it's adding to what you enter when in Lbs mode.
 

Thanks again for your time!

LoadSheetA321.txt

TPA_PHL.pdf

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Iforrage I have the same issue as you but with the A318 and the total opposite as you with the A321 where I tend to land with 2-3 tons extra fuel flying flights 4 to 4.5hrs, I think there is an issue flying mid-haul and long haul flights with the busses, iv only made a complaint about the a318 as I tend to always run out of fuel which is a far greater and annoying problem. Have a look at this post.

Also I would really appreciate it if someone could repeat my EINN-KJFK flight and let me know how they did with fuel burn so that I can try to figure out what variables may be causing fuel burn issues beyond the norm. I'm so tempted to fly all the busses across the pond with zero wind and 32 pax to see if there is a pattern with the predicted landing fuel from the fuel planner and the actual landing fuel on the upper ECAM. 

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On 2/8/2016 at 9:57 PM, iforrage said:

Hello again.  Sorry it's been so long, but I haven't had much time for flying since last post.  170 people lost their lives today, as the Airbus Industrie A321 they were flying in crashed in a field just east of Dover (Delaware) Air Force Base.  Preliminary reports indicate the aircraft fell from 15000 feet after running out of fuel.  It appears the Captain declared an emergency, and was trying to land the now paperweight at Dover, when the crash occured.  American Airlines Flight 2053 was en route to Philadelphia from Tampa.

 

 

Not in good taste. And even it was only in the virtual world, the blame lies solely with the Captain for not following procedures.

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6 hours ago, flyingfish55 said:

the blame lies solely with the Captain for not following procedures.

 

Well, that's what we're trying to figure out here, so thanks for adding nothing to the subject matter of this post. :)

 

-Jesse

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10 hours ago, flyingfish55 said:

Not in good taste. And even it was only in the virtual world, the blame lies solely with the Captain for not following procedures.

 

I believe the correct procedure is to find out if this has happened to anyone else in a similar situation so it can be fixed and not kept quiet to prevent the entire virtual human population from extinction attempting to fly long distant holidays on an Airbus that I love flying in my free time.

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Well, I discovered this problem with the A320, as well.  I've only used the CFM models to this point, but I will give the IAE model a shot today and see what happens.  I also have not tried flying the A318/A319's yet.  I'm pretty sure i didn't have these issues before the last update, though.

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On 8.02.2016 at 10:57 PM, iforrage said:

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It's just a double conversion. I will look into fixing it!

 

But as you can see the amount of loaded fuel is not affected by this - only the value in the box is taken into account.The Item result value is only for information.

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  • 3 weeks later...
On 2/15/2016 at 8:41 AM, iforrage said:

Well, I discovered this problem with the A320, as well.  I've only used the CFM models to this point, but I will give the IAE model a shot today and see what happens.  I also have not tried flying the A318/A319's yet.  I'm pretty sure i didn't have these issues before the last update, though.

 

And, yes, it happens with the A319 now, too.  Any way to go back to the version before the last update? (if I didn't save those installation files?)

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  • 2 weeks later...
  • 2 weeks later...

Thanks for linking your topic to mine, maybe we can get some answers together.  The only thing I can add for now, is that I noticed in the [turbineenginedata] section of the cfg, the values for rated_N2_rpm are way high, almost double the real world values for each engine type.  I've been going through and changing them, but I don't know if this has any effect on fuel flow.  I'll report back after I do another flight with the adjusted settings.

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I thought you had disappeared, I will have a look at that file but I'm unable to fly my sim at the moment as I don't have my controls with me, please do let me know how your flight goes ;-)

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I'm just comparing the A319 IAE [TURBINEENGINEDATA] with the A319 CFM and there isn't a huge difference in data bearing in mind my A319 IAE fuel consumption matches that of the fuel planner... Hmm :-/

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So here are all the Aircraft.cfg starting with the A321-A319IAE on the top row and the button row A321-A318CFM.

Just to let you know I don't have this issue with the IAE engines, out of the CFMs I only fly the A318 and Iv noticed the high fuel burn with it. Comparing the engine data of the CFM engines this issue should be noticeable on the A318 to A320 CFMs as they have the same data. I know in real life the IAE engines are more fuel efficient but comparing the A319 IAE and CFM TSFC the A319 IAE should burn more fuel right? If this is the case then could this be a hidden weight issue with the CFM aircrafts :-S

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