Fuel Burn
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Fuel Burn
Years ago I worked at Glasgow Airport as a ground engineer turning round Vanguards and later Tridents.A normal fuel figure for a 140 Vanguard was 6120kg or for weather 7200kg. Trident 1 was 9000kg and T3 was 13540kg - all these from memory. I am interested to know what the fuel figure for GLA - LHR is these days with more fuel efficient equipment.
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Fuel Needs?
An interesting question, although it looks like you forgot to mention the Intended Route. Ahem, sir, that does make a huge difference! As only a a wild-assed guess, if you are thinking long-haul or x-ponding with today's twins, I'd WAG it in the 60% range. As you should know, it varies a LOT, always dependent upon the aircraft type, the load and the route.
After rereading your question, I'm not sure that I understand your objective. Can you restate your basic question? In extremely simple terms, yes, today's aircraft load less fuel than in your experience. Most burn two engines, not four and are more efficient. Gross loads vary a lot as does the weather. Please restate you question, including what you Really want to know, and I'm sure that someone will provide a few answers. Good luck, sir. Yup, got to be a bit more specific.
After rereading your question, I'm not sure that I understand your objective. Can you restate your basic question? In extremely simple terms, yes, today's aircraft load less fuel than in your experience. Most burn two engines, not four and are more efficient. Gross loads vary a lot as does the weather. Please restate you question, including what you Really want to know, and I'm sure that someone will provide a few answers. Good luck, sir. Yup, got to be a bit more specific.
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Fuel required depends not just on aircraft type, its load factor, diversion alternate, holding fuel taken due expected delays (statistical delays can help assess this)...
For 737 series the calculation can be roughly made as:
For 737 series the calculation can be roughly made as:
- trip burn 2.5t/(first hour of flight, GLA-LHR is around that so thus valid assumption)
- final reserve 1.2t (30 mins)
- diversion fuel 1.2t (many available choices within 30 mins like LTN, LGW, STN, BHX, EMA, BRS, ...)
- contingency 5% trip /w minimum 200kg
- taxi out fuel 100-200kg depending operator
- holding fuel (as required)
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Dave Reid UK - I meant departure fuel. The figures for Trident were the standard shuttle fuel. This was the figure that the aircraft was loaded to unless informed otherwise by load control. I was just curious as to how much more fuel efficient modern short haul aircraft are. Since 1981 I worked long haul 747 and Tristar so have no comparison to make.
It's a fair question, the answer will show how much Aviation as a whole has improved.
Can anyone answer his simple question without sprouting too many complicated formulas?
Ok I'll give it a try.....
As a typical 737 and A320 burns around 2,500kg/hr I imagine that for a 1 hour flight they would carry around 2 hours to 2 1/2 hours endurance? So around 5,000kg to 6,000kg would be my guess as an average departure fuel. At the same time carrying 160 to 180 odd pax and freight.
Aviation has improved a hell of a lot, not just in Aircraft performance either.
Can anyone answer his simple question without sprouting too many complicated formulas?
Ok I'll give it a try.....
As a typical 737 and A320 burns around 2,500kg/hr I imagine that for a 1 hour flight they would carry around 2 hours to 2 1/2 hours endurance? So around 5,000kg to 6,000kg would be my guess as an average departure fuel. At the same time carrying 160 to 180 odd pax and freight.
Aviation has improved a hell of a lot, not just in Aircraft performance either.
Last edited by ACMS; 4th Dec 2014 at 21:43.
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Very difficult to come up with a figure, and your examples are 'standard' fuel loads which I guess have long since disappeared in the days of shrieking accountants. At a guess, a 737-7 (Vanguard pax load) would PROBABLY load around 6-6.2 for a CAVOK LHR (given expected 21st Century delays), but that is conjecture. Perhaps a nice Nigel AB driver could cast a figure? Whether 6.2 for CAVOK would result in a 'coffee no biscuits chat' with one of the suits I have no idea since, of course, we have the 'no diversion fuel needed at LHR' modern age
I happen to have a flight plan for a similar trip on my iPad, 366 nautical mile ground distance with an 737 NG. Total flight plan fuel was 4259 with a final reserve of 787 kg, alternate fuel 992 kg and a burn of 2280 including taxi. Obviously we were not full as we were picking up most of the pax at an intermediate point and continuing on. But it is not unusual to have a planned remaining fuel quite a lot less than 2000kg. Equally last week I had a flight where I told the fueler to fill her up. We managed 20600kg saving three and a half thousand dollars by tankering fuel according to the data on the flight plan.
It would be interesting to know what the actual fuel burn and trip time would have been on the guardsvan. I have seen elsewhere that scheduled time for the flight even increased from the sixties to the present day. The total fuel loaded of around 6000kg on the turboprop seems remarkably similar, although the trident 3 looks eye wateringly high.
However the devil is in the detail. These days we rarely have a standard fuel. The last time I can remember was nearly ten years ago with a milk run route where we would load wings full fly an hour and then fly back without needing to fuel.
These days we take as close to flight plan fuel as conditions allow. Final reserve has been reduced from 1200kg to at times less than 800kg and single engine taxi, avoiding use of the APU, continuous descents etc. while individually quite small all add up to a meaningful amount.
The difference an individual captain can make, adds up easily into the mid ten of thousands per year just on fuel alone. Airlines seem very enthusiastic about buying new fuel efficient aircraft and quite rightly so. However saving on pilot's salaries is much easier to measure than the additional cost if you have demotivated pilots.
However the devil is in the detail. These days we rarely have a standard fuel. The last time I can remember was nearly ten years ago with a milk run route where we would load wings full fly an hour and then fly back without needing to fuel.
These days we take as close to flight plan fuel as conditions allow. Final reserve has been reduced from 1200kg to at times less than 800kg and single engine taxi, avoiding use of the APU, continuous descents etc. while individually quite small all add up to a meaningful amount.
The difference an individual captain can make, adds up easily into the mid ten of thousands per year just on fuel alone. Airlines seem very enthusiastic about buying new fuel efficient aircraft and quite rightly so. However saving on pilot's salaries is much easier to measure than the additional cost if you have demotivated pilots.
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Amusing, But...
An amusing questtion, if intended as such, but... It is nearly impossible to respond with a a lot more detail. Most modern aircraft burn less fuel today than they did 30+ years ago, but details and computations do matter. Are you asking about flat gallons per trip - to where? Gallons/pounds/liters per seat or seat mile? Most numbers are far better today, and obviously the major carriers compute these details down to the 0.1% level 0 because it matters. And you question was???
No Fly Zone I will try and be diplomatic here. The original poster quite clearly stated that he block fueled the regular Glasgow London flight in kilos. I apreciate you may do things differently in the USA but his question seems pretty clear. A BA shuttle pilot as BOAC has said could provide a snapshot comparison.
lederhosen: Vanguard cruise fuel burn was ~ 2400kgs/hr for a TAS of 360kts.
Very similar to a B737-200 with same 130 pax. and TAS of 405kts!!
In response to the introduction of BCAL 1-11s on the domestic routes BEA simply climbed the Vanguards at 290kts and descended at 300kts to achieve block times within 5 mins of those achieved by the jets.
As an indication of efficiency improvements:
1977 B707-300 cruise M.79 189 pax initial fuel burn 5440kgs/hr (12,000lbs/hr)
2007 A320-200 cruise M.78 180 pax initial fuel burn 2200kgs/hr
Very similar to a B737-200 with same 130 pax. and TAS of 405kts!!
In response to the introduction of BCAL 1-11s on the domestic routes BEA simply climbed the Vanguards at 290kts and descended at 300kts to achieve block times within 5 mins of those achieved by the jets.
As an indication of efficiency improvements:
1977 B707-300 cruise M.79 189 pax initial fuel burn 5440kgs/hr (12,000lbs/hr)
2007 A320-200 cruise M.78 180 pax initial fuel burn 2200kgs/hr
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Thank you for your posts - I finally got the simple answer I needed. Perhaps I was a little naive in thinking that it was a simple question. Our American friend that did not read the question really made a meal of it - I suspect he is a Microsoft pilot or is very new at the game.
Meiklour - I was still at Glasgow when they took the Vanguards of the route - it was not until we got the T3 with 140 seats that we had the same capacity - the fuel load for the T3 was double that of the Vanguard for a journey time only a few minutes shorter. The Spey was very good at turning fuel into noise! BAC 1-11 with no acoustics was something else,I sat on top of one at max power for a leak check - only once.
Meiklour - I was still at Glasgow when they took the Vanguards of the route - it was not until we got the T3 with 140 seats that we had the same capacity - the fuel load for the T3 was double that of the Vanguard for a journey time only a few minutes shorter. The Spey was very good at turning fuel into noise! BAC 1-11 with no acoustics was something else,I sat on top of one at max power for a leak check - only once.
Right here we go. Hopefully this is exactly what you want. These are from real flights GLA-LHR, figures in tonnes.
Boeing 767, approx 190 pax.
Taxi fuel 0.4
Trip fuel 4.6
Alternate fuel 1.9
Contingency fuel 0.5
Final reserve fuel 2.2
Total 9.6 tonnes.
Airbus A320, approx 150 pax.
Taxi fuel 0.2
Trip fuel 2.8
Alternate fuel 1.1
Contingency fuel 0.2
Final reserve fuel 1.1
Total 5.4 tonnes
Hope that helps.
As BOAC mentioned, 6 tonnes for a CAVOK day at LHR would be rather on the high side....
Boeing 767, approx 190 pax.
Taxi fuel 0.4
Trip fuel 4.6
Alternate fuel 1.9
Contingency fuel 0.5
Final reserve fuel 2.2
Total 9.6 tonnes.
Airbus A320, approx 150 pax.
Taxi fuel 0.2
Trip fuel 2.8
Alternate fuel 1.1
Contingency fuel 0.2
Final reserve fuel 1.1
Total 5.4 tonnes
Hope that helps.
As BOAC mentioned, 6 tonnes for a CAVOK day at LHR would be rather on the high side....
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looks like for 150 pax on the A320 compared to 140 on a T3 there is a huge difference. 5700Kg as compared to 13540 Kg.
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Doug E - would you not be 'padding out' for, say, the 'rush hour' at LHR? I think I would - but then I'm not fussed about biscuits...
It is also worth remembering that in BC's 'day' there was far less pressure on fuel costs and also no option to dispense with alternates, so maybe the Vanguard 'standard' figure is not really 'excessive' PLUS that the figure would have been for all pax/cargo loads and time of day and would be designed to avoid the need for an expensive top-up of a few 100kg, and thus be 'generous'. As for the ground-hogger, well, construct an a/c like a brick-bulit khazi and.........
BC - out of interest, what was the BEA Vanguard seating?
It is also worth remembering that in BC's 'day' there was far less pressure on fuel costs and also no option to dispense with alternates, so maybe the Vanguard 'standard' figure is not really 'excessive' PLUS that the figure would have been for all pax/cargo loads and time of day and would be designed to avoid the need for an expensive top-up of a few 100kg, and thus be 'generous'. As for the ground-hogger, well, construct an a/c like a brick-bulit khazi and.........
BC - out of interest, what was the BEA Vanguard seating?
Last edited by BOAC; 10th Dec 2014 at 08:00.