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Fuel calculations not clear.

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Hi there,

 

So this will be a very easy question, but I've been using Simbrief for the past few months and now I'm using PFPX instead, because you have alot more options to make the flight plan realistic. (Simbrief still great though!)

The thing is when comparing the flights plans fuel consumption they are way off!

 

EHAM - KJFK (Simbrief) = 170,4LB

EHAM - KJFK (PFPX) = 101,2LB

 

And when I'm in the aircraft and loaded up with Simbrief fuel, it gives me 28,2LB left after landing...

I haven't checked with the PFXP fuel.

 

Which program is right....Because I'm clueless.

 

Thanks for reading,

 

iMove Quick

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Hi,

 

without knowing the exact planning details this is hard to give a proper answer to.

First of all the most obvious: Are you sure both programs planned with the same weights? Based on my experience SimBrief generally gives you a higher ZFW with the same number of passengers. This is because SimBrief (as far as I know) uses a fixed weight per pax (including their bag), while PFPX calculates with average values and different bag weights per distance (like real airlines mostly do, for instance a pax on an intercontinental flight will generally carry more baggage than one on a domestic flight).

 

So first of all make sure the ZFW's are the same.

 

Next is weather. Are you sure both programs are using up to date real world weather? Compare the average wind components (and estimated flight times) on your OFP to see if the weather data matches.

Seeing PFPX used so much less fuel on an eastbound transatlantic flight could mean it possibly did not have weather data available for the calculation since you are generally very likely to have a strong headwind on this route.

 

Finally the aircraft profile: Did you maybe make any changes to the aircraft profile in either planning program? Both SimBrief and PFPX have the option to customize the fuelburn values. While PFPX's options are generally more detailled you want to be sure the fuel bias is similar on both aircraft.

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39 minutes ago, Emanuel Hagen said:

Hi,

 

without knowing the exact planning details this is hard to give a proper answer to.

First of all the most obvious: Are you sure both programs planned with the same weights? Based on my experience SimBrief generally gives you a higher ZFW with the same number of passengers. This is because SimBrief (as far as I know) uses a fixed weight per pax (including their bag), while PFPX calculates with average values and different bag weights per distance (like real airlines mostly do, for instance a pax on an intercontinental flight will generally carry more baggage than one on a domestic flight).

 

So first of all make sure the ZFW's are the same.

 

Next is weather. Are you sure both programs are using up to date real world weather? Compare the average wind components (and estimated flight times) on your OFP to see if the weather data matches.

Seeing PFPX used so much less fuel on an eastbound transatlantic flight could mean it possibly did not have weather data available for the calculation since you are generally very likely to have a strong headwind on this route.

 

Finally the aircraft profile: Did you maybe make any changes to the aircraft profile in either planning program? Both SimBrief and PFPX have the option to customize the fuelburn values. While PFPX's options are generally more detailled you want to be sure the fuel bias is similar on both aircraft.

Thank you for the info! I will check on the fuel burn aswell as the zero fuel weights.

 

Maybe it helps to know that I downloaded a 777-300ER template.

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