Fuel Burn

[bcgallacher]

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.

[DaveReidUK]

Is that fuel burned or fuel carried?

[OntimeexceptACARS]

From dispatcher days a narrowbody Airbus or B734 around 2-3t fuel burn. Higher for a B752.

[No Fly Zone]

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. :confused:

[Skyjob]

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:
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)

[bcgallacher]

No Fly Zone - read my post again it clearly states GLA - LHR.

[bcgallacher]

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.

[ACMS]

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.

[BOAC]

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:)

[lederhosen]

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.

[ACMS]

Yep BOAC I stand by my generalized answer.

That is basically all he wanted to know without every possible scenario thrown in.

[lederhosen]

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.

[No Fly Zone]

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???:)

[lederhosen]

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.

[Meikleour]

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

[bcgallacher]

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.

[Doug E Style]

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....

[bcgallacher]

Doug - Ta much - 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.

[C_Star]

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.


On the other hand...13540 kg of Jet A1 back then must have been much cheaper than the 5700 kg nowadays... :}

[BOAC]

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?

[lederhosen]

The nearest I get is Stansted, but was there not some guideline about 30 minutes holding fuel required for Heathrow? At the end of the day it is total fuel burn that impacts the bottom line so alternate, final reserve and convenience fuel only matter in terms of the additional cost of carrying it.

Overall some interesting points have come out.
1. The sixties turboprop did the trip with more or less the same time and fuel as a comparable A319/737G
2. The Trident seems to have burned at least twice as much as the Vanguard doing the same job, although I remember it as a much more pleasant experience

I saw recently an estimate that 40% of total airline costs are now made up of fuel, obviously varying quite widely dependent on circumstances. Hopefully a sustained reduction in fuel prices together with modern technology and practices can reduce this and contribute to the survival of our employers.

[BOAC]

It is unusual to see minimum contingency fuel planned - CAA guidleines are that such 'anticipated' dely fuel should be in the trip fuel, not contingency.

I'd be impressed if you got 35 minutes holding out of ".3-.5T":confused:

leder - the expression the CAA came up with was 'expect 20 minutes delay for a 'no-delay' approach':) (Aged CAA PINK)

[lederhosen]

Doug I also do not quite understand how your contingency fuel is equal to 35 minutes holding. We have a set percentage contingency amount and then an amount called extra, which is 99% blank unless ops have a special requirement and used by the captain for circumstances like expected holding or weather.

The rest of the figures make absolute sense and thank you for posting them. Incidentally the 737 like for like, being a bit lighter, uses a bit less fuel than the Airbus family. The purchase price and residual value allegedly balance things out, although not always the maintenance costs according to companies that operate both side by side.

BOAC thanks for the clarification.

[BOAC]

We are sliding away from BC's thread here, but.....that's for people other than myself (an ordinary line pilot) to bother themselves with but as long as I have a sensible amount of fuel for the flight, given the prevailing conditions, I don't really care which column that fuel is in. - well, think about it - it can be an 'aid' for those who find themselves 'under pressure' ( erm - no names...) through loading 'extra' when if expressed as an increased trip fuel (and, of course justified) it can sometimes ring less bells.

Although 'somewhat aged' (like me) this was the CAA advice in 2000 with the relevant bit highlighted, when it was 'common practice' to increase contingency for this purpose, which is not, of course, what it is for:

SPECIAL OBJECTIVE CHECK ON AIR OPERATORS' FUEL PLANNING POLICIES - SUMMER 2000

1 Introduction

1.1 A Special Objective Check (SaC) on UK air operators' fuel planning policies was carried out in the Summer of 2000. The sac also asked questions which reflected concerns raised in letters to the Confidential Human Factors Incident Reporting Programme (CHIRP).
4.3.3 AIC 36/1998 recommends that adequate reserves of fuel should be carried when intending to land in the UK at certain airfields where delays should be expected at times when the associated terminal areas will be busy. This AIC had been re-issued because it again became apparent that too many aeroplanes continued to arrive in the vicinity of their planned destination with little more than Alternate and Final Reserve Fuel remaining. Concern remains that this message has still not been acted upon to the extent envisaged: in late September 2000 one controller dealt with three fuel shortage PAN calls in one shift.

4.3.4 Recommendation 2 Operators should review their fuel policies to ensure that adequate provision is made either through their computer programs or by adjustments made by aircraft commanders or dispatchers (acting in accordance with guidance or instructions specified in operations manuals) for the Trip Fuel to include, where appropriate, fuel for use in holding prior to commencing the approach when there is reason to believe that this will occur. An example of such circumstances can be found in AIC 36/1998 (Pink 170).

leder - again 'out of date', but from an AIC (PINK 82/2003) at a time (again) when certain 'foreign' airlines were pushing fuel carriage somewhat:

3.1 'No delay expected' means in these circumstances:
'Do not anticipate being required to remain in a holding pattern longer than 20 minutes before commencing an approach'.
3.2 Where a delay greater than 20 minutes is expected, the controller will pass an EAT. When delays are expected to be less than 20 minutes, controllers will, when requested, give a general indication of the expected delay.
4 Traffic situations in the terminal areas can change very quickly even though 'No delay expected' will often mean precisely that,
crews should expect that on occasions some holding will be required before they are fitted into the final approach pattern.
5 It is important, therefore, that operators and crews should take a realistic view of the amount of fuel required, to satisfy the
minimum fuel overhead destination requirements.


I suspect both publications may have been 'massaged away' by pressure from operators, and please don't all shout "it's all out of date" because I need convincing that life has changed so much!