Fuel Planning Question

[DF9AA 0]

I try again - most probably they were to large. . .Flight planning chartFuel calculationFlight plan used during flight for flight followingand now the final results all the red figures are actual readings during flight. Really interesting are the FMC readings at the far right for ETA and fuel remaining - they are constantly changing during flight despite the fact that nothing really drastical changes. Reason for this is the calculation of the FMC for the last sector of flight between OM and touch-down - the fuel figure is MUCH too high - between 2500 and 3000 lbs of fuel for the last 2 minutes or so . . .As you can see the winds were OK ( only one sector with completely wrong winds !!) - using ASX.The final fuel burn was 282.3 L - calc was 283.4 L , which is not bad, but I had already better results. . .

[falk781 0]

What planning program is this?

[DF9AA 0]

Scott,my own, self-developed on excel-basisit's rather complicated but it does the job - for 737, 747 and MD11as one of the australian friends wrote : " for hard-core user only " . . .if interested, just write me a PM with e-mail adress.

[Johan_Dees 84]

My late friend Captain Tarmac, and those been on this board long enough know him, learned me that he always did a mental calculation od about 22000 lbs per hour, including everything, and worked always.(742 was 24000 lbs)So 3 hrs, should take 66000 lbs, to cover it all..

[phil747fan 14]

My late friend Captain Tarmac, and those been on this board long enough know him, learned me that he always did a mental calculation od about 22000 lbs per hour, including everything, and worked always.(742 was 24000 lbs)So 3 hrs, should take 66000 lbs, to cover it all..

Johan,you re right about the words from Mel but it was only for the cruise schedule not the entire flightplanning fuel.at least from what i remembered from him too. but i was really younger lol.have a good day. phil

[falk781 0]

It appears that the missing variable in my spreadsheet, and the PMDG manual is the correction factor multiplier relative to hours. The example in step 4 of 2-13 multiplies the correction factor by the adjustment value, but never multiplies it against the hours of flight travelled. I think this is why it doesn't matter on short runs, but long hauls it doesn't make it.I believe my interpolation is correct.I recalculated the route with the exact same figures and wind... let me lay it out here....Nautical Flight Miles - 5232Time Enroute - 10.85 HoursAverage Wind (based on ASX) 36 KT Tail Corrected Nautical Air Miles - 4841Basic Operating Weight - 394088Passengers - 65,700Cargo - 73,800ZFW - 533,288Minimum Landing Fuel - 24,000Alternate Fuel - 8,000 (based on ZFW + MLF)Contingency Fuel - 1 Hr = 18,000Planned Landing Weight - 583,288 Flight Plan Fuel - 200,600 (Interpolated between 4800 & 5200 miles @ FL 370) Planned Gross Takeoff Weight - 784,188Taxi Fuel Burnoff - 4,400Panned Taxi Out Weight - 788,288Final Fuel Correction = 10.83 @ 1000 lbs adjustment * 10.85= 108,500Fuel Required - 368,418ZFW - 533,288Reserves - 41,000

[phil747fan 14]

Scott,your calculation are good but not operationnally good ...your TOW must be 875 000 lbs not the number you foundZFW 533288 + 36 8418 fuel TIF + 41 000 res = 942 706 lbsi already told you watch the weights ...see you later.phil

[phil747fan 14]

Scott,im taking another angle to help you ...again 5100 nm.10h45 5100nm 117.5t trip fuel265T ldwroute res 4100 kgsfinal res 4200 kgs 00h30altn 200nm 5000 kgs 00H36taxy 800 kgsxtra 9100 kgszfw 242.6t (ldw-total res)total res 22.4t (rte res + altn+ final res)139.9t total trip fuel (trip fuel + final res)tow 382.5t (zfw + total trip fuel) 800 taxy140.7t total fuel (taxy+ total trip fuel)this is the maxi weights makeable for this specific flight but with real datas not pmdg charts .... as we are within 5% fuel burn with pmdg the xtra 9100 kgs is able to cover it easily. if you want to reduce your ldw weight and you can.for 1000 kgs remove 443 kgs of fuel.to find lbs just multiply by 2.242.again the 747 is very hard to dispatch and release and i think you should try lesser longer flight as i suggested you few posts before lets say a 3500 nm.you have to keep in mind the structural limitzfw 246143 kgs 542500 lbs (the manual says 535000 lbs the load manager says something else) oew 178806 kgs 394088 lbstow 397005 kgs 875000 lbs173474 kgs fuel 382236 lbs 285763 kgs ldw 630000 lbswish you a good flight.phil

[phil747fan 14]

It appears that the missing variable in my spreadsheet, and the PMDG manual is the correction factor multiplier relative to hours. The example in step 4 of 2-13 multiplies the correction factor by the adjustment value, but never multiplies it against the hours of flight travelled. I think this is why it doesn't matter on short runs, but long hauls it doesn't make it.I believe my interpolation is correct.I recalculated the route with the exact same figures and wind... let me lay it out here....Nautical Flight Miles - 5232Time Enroute - 10.85 HoursAverage Wind (based on ASX) 36 KT Tail Corrected Nautical Air Miles - 4841Basic Operating Weight - 394088Passengers - 65,700Cargo - 73,800ZFW - 533,288Minimum Landing Fuel - 24,000Alternate Fuel - 8,000 (based on ZFW + MLF)Contingency Fuel - 1 Hr = 18,000Planned Landing Weight - 583,288 Flight Plan Fuel - 200,600 (Interpolated between 4800 & 5200 miles @ FL 370) Planned Gross Takeoff Weight - 784,188Taxi Fuel Burnoff - 4,400Panned Taxi Out Weight - 788,288Final Fuel Correction = 10.83 @ 1000 lbs adjustment * 10.85= 108,500Fuel Required - 368,418ZFW - 533,288Reserves - 41,000

your problem is the reserve total .... why 41000 plus altn 8000 plus cont 18000 plus mini land fuel of 24000 all those numbers in lbs ... ?the 24000 lbs should include altn fuel 8000 plus hold reserve of 00h30 9600 lbs as we have only 176000 we add 6400 lbs XTRA and then we have 24000 lbs ...now you re contingency of 18000 lbs is a FAA rules 10% or you own deduction because you can shave it and take only 5% or 3% if you found an enroute altn airport (FAA dispatchers can head up here ...). but tell me about 41000 lbs dont find it in your fuel calculation.i must add that the chart in the manual is wrong on the fuel correction and you must not multiply by 1000 lbs for each 10000 lbs in ldw variation for each hour of flight. 454 lbs should be enough ... i wrote to some staff in omdg ops but never get an answer so i cant help more on this subject ...but your zfw with fuel needed is over the fuel capacity and of course the mtow ...wish you a good day and of course good calculations.phil

[DF9AA 0]

@ Peter Lloydin case you read this - neither e-mail nor PM will work !!

[falk781 0]

your problem is the reserve total .... why 41000 plus altn 8000 plus cont 18000 plus mini land fuel of 24000 all those numbers in lbs ... ?the 24000 lbs should include altn fuel 8000 plus hold reserve of 00h30 9600 lbs as we have only 176000 we add 6400 lbs XTRA and then we have 24000 lbs ...now you re contingency of 18000 lbs is a FAA rules 10% or you own deduction because you can shave it and take only 5% or 3% if you found an enroute altn airport (FAA dispatchers can head up here ...). but tell me about 41000 lbs dont find it in your fuel calculation.i must add that the chart in the manual is wrong on the fuel correction and you must not multiply by 1000 lbs for each 10000 lbs in ldw variation for each hour of flight. 454 lbs should be enough ... i wrote to some staff in omdg ops but never get an answer so i cant help more on this subject ...but your zfw with fuel needed is over the fuel capacity and of course the mtow ...wish you a good day and of course good calculations.phil

Ok, here goes.... Minimum Landing Fuel - 24,000 for internationalAlternate Fuel - 8000 for a weight of 557,588 to travel 100 NMContingency/Holding Fuel - 18000, but the manual says to report half of that.So - 24,000 + 8000 + (18,000 * .5) = 41,000 (Reserve)41,000 + 200,600 (Flight Plan Fuel) = 241,600 so farCorrection = 10.86 @ 1000 for 10.85 hours = 117,831Total Flight Plan Fuel is - 241,600 + 117,505 = 368,418 How is this over the 875,000..... I only jhave a total of 784,188 and a planned landing weight of 583,588??? I didn't have a chance to read the link, but I will....

[phil747fan 14]

Ok, here goes.... Minimum Landing Fuel - 24,000 for internationalAlternate Fuel - 8000 for a weight of 557,588 to travel 100 NMContingency/Holding Fuel - 18000, but the manual says to report half of that.So - 24,000 + 8000 + (18,000 * .5) = 41,000 (Reserve)41,000 + 200,600 (Flight Plan Fuel) = 241,600 so farCorrection = 10.86 @ 1000 for 10.85 hours = 117,831Total Flight Plan Fuel is - 241,600 + 117,505 = 368,418 How is this over the 875,000..... I only jhave a total of 784,188 and a planned landing weight of 583,588??? I didn't have a chance to read the link, but I will....

Scott,i understand some of your inputs and thanks for the clarification ...you cant have a TOW of 784 188 or tell me your calculation ... if you had a tow of 784418 your ldw should be 465987 with 41000 lbs reserve means a ZFW of 424897 ...a ldw of 583588 means you had the fuel need 200600 base plus correction 117831 =901693 lbs and this over the 875000 the -400 can do i included your reserve in the landing weight and a zfw of 542588 ... or maybe going cross the border in canada we dont have same calculations lol :( i can generate a 400er calculation to see how far the 747 can go but we re reaching the max for pax ops here ... i think 4000nm is the distance winning for max payload and pax after we re playing a little on the edge ... see you soon.phil

[falk781 0]

Scott,i understand some of your inputs and thanks for the clarification ...you cant have a TOW of 784 188 or tell me your calculation ... if you had a tow of 784418 your ldw should be 465987 with 41000 lbs reserve means a ZFW of 424897 ...a ldw of 583588 means you had the fuel need 200600 base plus correction 117831 =901693 lbs and this over the 875000 the -400 can do i included your reserve in the landing weight and a zfw of 542588 ... or maybe going cross the border in canada we dont have same calculations lol :( i can generate a 400er calculation to see how far the 747 can go but we re reaching the max for pax ops here ... i think 4000nm is the distance winning for max payload and pax after we re playing a little on the edge ... see you soon.phil

This is easily going to be the highest rated thread in this forum.... people's heads must be spinningI think I found the problem and you were right, I was wrong, butI'll confirm..... My Takeoff and Taxi Out calcs in the spreadsheet don't include the additional correction/adjustment...... I need to look closer at it.

[VHOJT 181]

41,000lbs of reserve fuel is way too much unless you have an alternate that is a long way away! 10-14 tonnes / 22-30k lbs is much more reasonable, depending on the flight plan.

[falk781 0]

41,000lbs of reserve fuel is way too much unless you have an alternate that is a long way away! 10-14 tonnes / 22-30k lbs is much more reasonable, depending on the flight plan.

Keep in mind that the reserve as populated in the FMC is a derived from the MLF + AF and 1/2 of the prescribed contingency. The MLF alone is 24,000 for international flight and 18000 for domestic. Alternate was only 8000.I'm still working on the calculation for the planner. I'll report back