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View Full Version : How much fuel is burned each day above LHR?

Uncle Fred
27th May 2012, 20:38
Here is a think piece. I know that the idea of a new runway for Heathrow is, and always will be, a contentious issue.

As I was taking up the hold the other day at OCK I was trying to guess at how much fuel is burned on a running 24 hour period by all aircraft when three holding fixes are in use?

In a 777 I figure that I am burning about 100 pounds a minute. As we all know some times one merely touches the holding fix and does a 360 to exit whilst sometimes one is in for a good 10 minutes or longer.

Since the Hounslow International is primarily a bigger aircraft aerodrome, I guess that between 50 and 100 lbs a minute is a pretty accurate figure.

As we also know we often have someone above and below us and so our little slice of the world has at least two or three more airplanes that are also burning at this rate.

If we take 250,000 lbs of fuel and divide it by 100 we, of course, get 2500. If we divide that by 60 we get around 41 total hours of holding per 24 hour period--enough fuel to send a large aircraft a long way--every day of the year.

Of course we could also add a few thousand pounds in for holding in long lines for takeoff.

Not sure if this is even an accurate stab at the issue, but I just wonder if those who oppose an expansion of Heathrow on environmental grounds know just how much fuel is being burned overhead.

Please do not misunderstand. There is a lot more to this issue than just the fuel burned in holding and since I am not expert on all the factors I cannot cast my vote my way or another. But I was rather just curious as to how much fuel is burned.

Of course this would open the question up of other airports in the world that use vectors for the spacing instead of a spin in the holding pattern. It seems to be a staggeringly complex issue to squeeze efficiencies out of limited airspace so I do not envy those who have to give it a crack.

I would say however, that since Frankfurt poured new concrete the days of 35 mile finals are growing rarer so perhaps there is something to a works project.

UniFoxOs
28th May 2012, 07:37
Please do not misunderstand. There is a lot more to this issue than just the fuel burned in holding and since I am not expert on all the factors I cannot cast my vote my way or another

Yes, I reckon there is a touch of the Parkinson's law about this. Add an extra runway to cope with the existing traffic, then there's no waiting in holds or runway queues, punters and airlines like this and the airlines put on more services until delays get just as bad and you have gone from 2 runways-worth of holding traffic to 3 runways-worth with all the attendant hassle and fuel consumption.

But I don't know the answer either.

Cheers
UFO

ExSp33db1rd
28th May 2012, 08:33
But I don't know the answer either.

Too many people in the World - and getting worse ?

UniFoxOs
28th May 2012, 10:53
Too many people in the World - and getting worse ?

True, enough - or anyway too many wanting to fly.

There's no glamour to it like when we were young (1960s), though, and it is now possible to do so much online, I have to wonder where all the pax come from - it's not attractive to me anymore but there seem to be plenty wanting to do it.

Cheers
UFO

Vercingetorix
28th May 2012, 11:37
Uncle Fred
Interesting calculation to which should be added unnecessary fuel burned while taxying and waiting at the hold on the ground.
'tis a lot but not sure that the present system could be much improved.:{

Uncle Fred
29th May 2012, 02:36
Yes, I reckon there is a touch of the Parkinson's law about this. Add an extra runway to cope with the existing traffic, then there's no waiting in holds or runway queues, punters and airlines like this and the airlines put on more services until delays get just as bad and you have gone from 2 runways-worth of holding traffic to 3 runways-worth with all the attendant hassle and fuel consumption.

I heard an economist speak a few weeks ago on something similar as it relates to automobile traffic and the number of lanes a highway should have and, if needed, high occupancy vehicle (HOV) lanes. He made a lot of counterintuitive points but they all served to tease out the fact that such problems and solutions are an admixture of the mathematics/statistics and policy. Were it just the first, one could range in on size of aircraft, passenger loads, arrival rates and those variables. Introduce the second consideration however, and you are going to allow the math to roam more freely and with a lot less certainty.

Since he was speaking only to inform about the issues at hand and not to advocate a single solution, it became clear just how important the policy factor is. Does LHR, or any major airport, wish to pour more concrete to attract even more flights? Does it wish to pour concrete only to alleviate existing bottlenecks? Or, which is certainly sometimes the case, does it wish to pour concrete as transportation funds were allocated in a different economic condition and so the project must go ahead in expectation of better times?

Sort of an interesting cauldron of decision making.

Loose rivets
29th May 2012, 04:59
As a wonder boy, (remember him?) I wonder what the total fuel used in say, the US, would look like as a cube standing in the middle of the country.

When calculating aviation fuel, one should also include fuel to haul everything - from passenger travel to the airport, the delivery of concrete, the energy used to bake the Portland etc., etc. The usage is staggering, yet there's supposed to be centuries of reserves.

The US claims to have oil under the ground, some 300% of the total Arab reserves. I think this might be true, but tonight, I just want to visualize it when translated into a contiguous blob?

Mechta
29th May 2012, 11:21
The airport operator's ideal is presumably whatever gives the maximum number of SLFs through the airport shops in the course of a day. Whether this is achieved by an A380 in every slot, or a smaller aircraft with a shorter separation distance, someone will know. There is probably also a statistic for which destination gives the highest revenue to the airport per SLF (shop spend, fuel upload + countless other sources of revenue, no doubt), as the poorer passengers might not spend so much.

With regard to wasting fuel, it has always struck me as madness that at a busy airport, as one airliner lands, using its brakes and reverse thrust to dissipate its kinetic energy, the next one takes off, burning fuel to get itself enough kinetic energy to reach rotation speed. Hopefully airports of the future will have some sort of ground based accelerator/decelerator system so the energy can be captured and reused (probably not at aircraft carrier rates of acceleration/deceleration, as the grannies won't like that...).

29th May 2012, 14:32
Hopefully airports of the future will have some sort of ground based accelerator/decelerator system

What, you mean something like a conveyor belt?

It does seem strange in this day and age that we hold before take-off at all. Surely its within the wit of man to devise a system where you taxi direct to the runway and take-off at your allotted time. Perhaps we could borrow some workflow technology from the car industry? Not only would this save fuel but it would allow pax to spend more time in the terminal with all the attendant benefits to the airport's owners.

Another idea - perhaps engine makers could look at something like the stop-start technology becoming more commonplace on cars, or a 'super-idle' mode?

Doctor Cruces
29th May 2012, 15:55
Could solve the holding for take off fuel burn by towing everything to the holding point (queue) and not actually firing up the engines until you are close enough to the front of the queue to be able to move onto the runway once your engines are all turning, burning and all tha after start checks etc are completed. I would guess the APU running for aircon, power etc would use significantly less.

hellsbrink
29th May 2012, 16:43
Branson tried that, Dr. C, and quietly abandoned the idea.

Oh, how much diesel does a tug use towing an aircraft? And how many tugs would that mean at a place like Heathrow?

ExXB
29th May 2012, 17:04
Tugs are not designed to tow a fully laden aircraft. Aircraft landing gear (tow bar attachment points) the same.

etc. etc. as the Bearded one discovered (and his people knew before he suggested it)

Future 737NG pic(?)
29th May 2012, 17:27
Forget tugs to and from active runways.

The technology already exists for motors on the main landing gear (the weight of which will be reduced as soon as sufficient numbers are being produced on a commercial scale). VIDEO: L-3 and Lufthansa get moving with e-taxi demonstrator (http://www.flightglobal.com/news/articles/video-l-3-and-lufthansa-get-moving-with-e-taxi-demonstrator-365815/)

Continuous use of "TEAM", no ban for early morning arrivals, a 3rd runway and the use of a connected Northolt for domestic/near Europe short haul ops are the only short- to mid-term solutions to reduce wasting fuel for holding.

Am not advocating this as the right option long-term though.

Uncle Fred
30th May 2012, 05:14
All the technology for tugs to the runway or motorized wheels...but a few heading changes instead of direct routings or a level off that lasts a couple of minutes too long and all that is used. I realize that fuel saved is fuel saved so it does not really negate what is saved on the way out, but it seems the real areas to save fuel overshadow the taxi out or in. JMHO.

anotherthing
30th May 2012, 15:02
Uncle Fred

Unfortunately a 3rd runway at Heathrow would not just be utilised to cope with existing traffic.

It has been stated that an extra 150,000 (roughly) odd movements per year could be achieved with a 3rd runway.

Of course that is a pie in the sky figure, because the LTMA cannot cope with an extra 150,000 movements... stick as much concrete down as you wish, but airspace is finite.

There is a huge project at the moment re-designing the LTMA, but as you can imagine, it is a big undertaking with so many airports so close together... every SID interacts with at least 1 other, usually much more interaction occurs. Grab a chart of the LTMA and draw on the SIDS for every airport on it... you will soon see the enormity of the task.

ZOOKER
30th May 2012, 21:31
Years ago, NATS/CAA used to publish such a chart, at 1:250,000, (and for the MTMA as well). I have copies of both somewhere.
The only way you will ever eliminate holding is by "massive flow-control". -Spreading the load.
An ATC system is like a drainage basin, it is a 'process-response system'. Holding is the equivalent of 'flooding'.
In a NATS environmental brochure published a few years ago, one of their 'CO2 Gurus' said he wanted ti eliminate holding completely.
It could be done, but would involve technology and a considerable change in the way airlines and airports operate.

Loose rivets
31st May 2012, 07:28
Reversing without the comfort of knowing you can use the engines to stop??!!

Not bleeeeedin' likely.

I suppose they could fit a bouncy castle that pops out under the tail should it start to sit on its haunches.

Mariner9
31st May 2012, 11:19
I wonder what the total fuel used in say, the US, would look like as a cube standing in the middle of the country.

Daily world crude oil production would occupy an 800 x 800 x 800 foot cube, 80% of which would be made into fuel. The USA would consume around 21% of the cube, and the UK a (relatively) trifling 2%.

Vercingetorix
31st May 2012, 12:28
Mariner9
The USA with a population of approx 330 million consumes 21% against the UK with a population of approx 60 million taking up 2% of your cube.
Nice to know that we are not profligate and are doing our bit for the planet!:cool:

Ancient Observer
31st May 2012, 12:53
Is the hot air burn in pprune more or less dangerous for the planet than the fuel burn over lhr/jfk/hkg?

Having an whole airport named after you is pretty cool. JFK sounds so much better than LHR.

What should we call heathrow?

Mrs M Thatcher airport??

(ducks for incoming)

MagnusP
31st May 2012, 14:18
What size of cube would hold all the electrons used in the distribution of PPRuNe hot air each year?

I blame quantum. And the French, of course.