Jump to content

Fuel required exceeds maximum fuel on board


Recommended Posts

Hi all,

 

I've been having this issue quite often lately. When computing a flight it tells me, that the required fuel would exceed the maximum fuel on board which is in turn limited by the MTOW. So far so good. But I don't understand why. Here's an example: I wanna fly in an A320 from EDDF to LFPG. My cruising altitude I set was FL300. Now I get the message that the required fuel exceeds the maximum fuel limited by MTOW. When I replan the flight and simply select optimum cruising altitude and everything else stays exactly the same I get FL240. And I can compute the flightplan, everything is fine. My problem is I don't understand the logic. When the flightplan is computed neither my actual TOW or the Fuel Onboard are nowhere near the limits. (TOW: 61153, MTOW:73000), Fuel on board 4452kg, maximum 18728kg. If I was very close to the MTOW it would be a different story and I'd understand why I'd get the message, as the climb to FL300 instead of FL240 probably requires a little more fuel. But this? 

Is there like some common misconception or setting in the aircraft profile that would be the culprit? Hopefully somebody has a solution.

Link to comment
Share on other sites

Version 2.04 and I am using the Airbus A320-214 CFM56-5B4 files, I dont know if its standard or not, can't remember. Its not a template, Author mentioned in the txt is Stephane De la Calle

Link to comment
Share on other sites

Tested here on 2.04 and Stephane's file, @65t TOW the computed plan returns FL300 without error.

 

Perhaps post a snaphot of your planning screen and also the general tab of the aircraft editor for the registration used.

 

What is the weather source?

Link to comment
Share on other sites

Weather source would be the standard PFPX one where you need to buy the subscription for 365 Days. I've also compared the winds etc. Theres like not much difference. Even if, the margins regarding how much space in the fuel tanks and how much gap there is to the MTOW are there, so I really don't get why I shouldn't be able to do the flight on level 300.

What I also noticed is, that for the A320 without sharklets, as seen in my Aircraft Editor screenshot I can only do LRC when planning the flight. I can't enter a Cost Index. May that have to do something with the problem? (Even if not, why can't I enter a Cost Index, which setting for an Aircrafts Performance file would it be?)

PFPX 1.jpg

PFPX 2.jpg

Link to comment
Share on other sites

Having configured here to match your settings FL300 without a fuel error is returned in v2.04

 

If your PC recently updated the .NET files then try reinstalling the 2015-2019 vcredist ( x86 & x64 ) available from Microsoft

 

The default performance file does not contain CI data hence only M0.78 or LRC is available, either check the forum download section or AirlinerPerformance

 

capture_001_02072021_191214.thumb.jpg.9af1e550c5dfc035fdd2868fa87b5faf.jpg

 

Link to comment
Share on other sites

  • 2 weeks later...

I don't know if you got it working again or not, but I have come across the same problem lately.... You are getting this error message because there is a route level restriction in PFPX. If you try to force a level above the restriction you get the error message. If you use optimum, then it uses FL240 which, for the route, must be the higher you can fly at. Why the message comes as "fuel exceeded..." is weird, but that is what it is.

Link to comment
Share on other sites

3 hours ago, Captain Nav said:

You are getting this error message because there is a route level restriction in PFPX

 

You have an example route where this occurs?

 

There is a known short trip cruise altitude issue that keeps levels low, workaround by using MAX cruise level and No Step on the planning screen. I haven't seen this lead to the 'maximum fuel exceeded' message though.

Link to comment
Share on other sites

I still had the problem one or two times out of like 20 flights I guess. Its weird as even when you do the maths even the maximum fuel load in those cases wouldn't exceed the MTOW. Very weird, but I have also found that it got something to do with the altitudes as it recently occured on routes where I have entered a set Flightlevel. If I then selected the optimum cruise level all was good.

Link to comment
Share on other sites

On 7/11/2021 at 2:28 PM, srcooke said:

 

You have an example route where this occurs?

 

There is a known short trip cruise altitude issue that keeps levels low, workaround by using MAX cruise level and No Step on the planning screen. I haven't seen this lead to the 'maximum fuel exceeded' message though.

Well, I am not 100% sure this is what's happening, but the chances are... it is.

I was working on a route from LFPG to LFBO.... It was giving me FL290 as max (Eurocontrol rule inserted in PFPX). If I was trying to force a higher level instead of optimum (FL350 for example), then it would give me the fuel error message. Once I removed the level restriction in the route restrictions (Altitude/FL restrictions) tab, then I could plan the flight up to FL350 with no error message and FL290 was not showing as max anymore.

It is working for me, I do think this is where the problem is....Why it comes as a fuel error message, I don't know, but I have fixed the problem. 

Take it or leave it!

Link to comment
Share on other sites

3 minutes ago, Captain Nav said:

It was giving me FL290 as max (Eurocontrol rule inserted in PFPX)

 

Are you using the RAD Restrictions and Directs update available from the download section of the forum.

 

I'm not seeing any level capping on that route with the updates.

Link to comment
Share on other sites

No, I am not using those updates, but it does not matter.... what I am trying to say is that IF there is a restriction in the RAD you have saved in PFPX (whatever version you may have), then it will "create" the fuel error message in PFPX v2.04 as we discussed above.

I have fixed the issue as far as I am concerned.

As I said, take it or leave it.

 

 

Link to comment
Share on other sites

The current filtering 'may' lead to an incorrect level capping which as you suggest can lead to the max fuel error when forcing a higher level via the Cruise Altitude/FL dialogue.  Where this occurs it can simply be overwritten in the MAX Alt/FL ROUTE section when planning ( capping can be seen in pale grey ).

 

Whilst it won't remove all level capping issues the RAD Restrictions and Directs updates contain many that are corrected.

 

As Captain Nav suggests, editing or deleting errant level capping entries can also be achieved by the user.

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

Hi,

 

I need help with this issue as well. Unfortunately I have no North American Altitude Database that I can edit altitude restrictions in . I only have Eurocontrol altitude restrictions so if it's an altitude restriction that is causing my problem, then I have no idea where it's coming from. I'm trying to at least plan for FL310  from CYVR to CYLW . I'm using a Prosim Flight model Boeing 738. I'm being limited to FL230 or lower..sometimes FL190 which is fine for a Q400 but not for a 738 in my opinion. If I remove all passengers and all cargo and have fuel load around 3000 KGs, then PFPX will allow a plan at FL330..which would be the limit as that's getting close to TOD. When sending this to TOPCAT it of course tells me I'm 22000KG's underload! Of course I realize I am..as no passengers, no cargo and low fuel....but yet PFPX restricts the flight. Inserting a couple pics..one of the error, which also includes the flightplan data..and another of my aircraft template information. Maybe someone can spot a problem with my data, I hope.

 

I did have a friend try the route in his PFPX with same flight model and he generated the route without an error, so I'm at a loss as to what my issue is. I'm using W10 Pro and I believe fully updated. I am using PFPX on a client. The client is also W10Pro. Would a re install of PFPX be recommended? Hate the thought of it..but will do if necessary.

 

Best Regards,

Ed B

PFPXerror.png

PFPX Template 738.png

Link to comment
Share on other sites

The routes are flown by 734 and 735's realworld at FL250, it is a short-trip.

 

A minimum level cruise segment is required ( 20% if I recall ) and trying to force it higher is resulting in your error.

Link to comment
Share on other sites

Hi Stephen,

 

If I understand correctly I'm limited by cruise segment. (20%) What I don't understand is that going the other way CYLW/CYVR) I can plan for FL310 with no fuel error. Is there a file I can edit to allow a higher altitude for the CYVR/CYLW route?

 

Best Regards,

 

Ed B

Link to comment
Share on other sites

In previous version the cruise length could be adjusted and was indeed set 20% by default.

 

I ran your original route with same weights and had  distance of 36nm from TOC to TOD at FL250 on a flightplan length of 185nm.

 

I certainly cannot achieve FL310 in the reverse direction at the same weight, using MAX FL and NO STEP returns FL260 with the same 20% level segment.

 

However you are using a different PFPX performance file to myself.

 

Link to comment
Share on other sites

Hi Stephen,

 

Regarding the performance file..yes..it's tuned to Prosim Avionics so probably different than yours. I reached TOC  at least 50 miles before TOD, still a fine line but greater than the 20%. I think even further but It was at 50 when I noticed.

 

Possibly weather related?  I'm thinking tail winds or headwinds. Tailwinds decreasing the distance to TOD there for limiting altitude going west and reverse for going easterly. Of course weight is a big factor as well. I may be heavier today. I'm almost always using Random. Today I cannot get over FL290 on the return trip  either.  I was most concerned that maybe I had my software setup wrong but it seems things are normal. I'll leave it at this point for now as I think by your results and comments my software is behaving as it should.

 

Thanks for your help Stephen.

Link to comment
Share on other sites

There is an issue with short trip cruise altitudes but this leads to an excessively low altitude return.

 

The workaround is to change from OPT level to MAX and NO STEP, this should still leave the level cruise segment.

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...