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View Full Version : Virgin Atlantic towing a/c to the hold.


Mike Mercury
24th Apr 2007, 21:57
When is someone actually going to beard old woolypully properly and point out the inanity of towing aircraft to the holding point? I can already see the traffic jams, the lack of tugs, the starting problems, the queues, the roar of hundreds of diesels. For goodness sake, I understand his need for publicity, but this is becoming monotonous, not to mention ridiculous. The next thing you know, it will become politically fashionable, Gordo will subsidise it to look green, and we'll be even later on each sector.

Clear land 27R after the tug vacating to the left.......

(I'm not even going to mention his 'deal' with Boeing regarding 'green' fuel, I'm sure Boeing will take ever so much notice of a tiddler airline and change their engine policies overnight...NOT!

redflyer
24th Apr 2007, 22:10
On the virgin web site it doesn't say anything about towing aircraft to the holding point. It mentions a "starting grid".

I would asume that "starting grids" aren't that common at many airports in the world.

If a starting grid was created I imagine it would be some where between the stands and the holding point, but seeing as they don't yet exist, who knows.:}

22/04
24th Apr 2007, 22:12
As I understand it this is being taken seriously. I'm sure I have seen studies on flight deck controlled vehicles attached to the nosewheel. How about disconnecting these at the hold, starting engines. The "tug" homes to a supermarket trolley style park, where it is recharged using green renewable or nuclear electricity. From there it can be dispatched back to terminal via a distinct route and drawn to the next departure.

On arrival as the aircraft vacates, tug emerges form another supermarket trolley park, connects, and then engines are shut down and tug moves aricraft to stand.

Is it feasible and how much would it save?

Gonzo
24th Apr 2007, 22:14
VIR tried it once at LHR.

Not trying again.

DISCOKID
24th Apr 2007, 22:16
a british company has already invented such a remote controlled motor .... Delta has taken a stake in the company and will soon be conducting trials
more here...
http://business.timesonline.co.uk/tol/business/industry_sectors/engineering/article1652587.ece

Re-Heat
24th Apr 2007, 22:23
Burning fuel for half an hour or five minutes? Makes sense, and is actively being persued by quite a few.

Certainly is not a foolish fashion statement.

Love_joy
24th Apr 2007, 22:26
True - but at least he is thinking about the issue.

Just wait till the greenies insist on eco friendly steam-powered catapult launches from Heathrow. Actually... that doesnt sound like such a bad idea :E

slice
24th Apr 2007, 22:39
Virginblue in Oz use remote controlled (by ramp personnel) tug devices that attach to the right main gear and disconnect after pushback. Are these used in Europe? I understand that these were introduced to reduce the number of people required for pushback and not as any kind of 'green' device though.

rookie#1
24th Apr 2007, 22:47
Seen one in use at MRS.

Human Factor
24th Apr 2007, 22:58
Are these used in Europe?

Powerpush. Used to use them in BRU years ago.

Navy_Adversary
24th Apr 2007, 23:09
Just you pilots remember, when the tug driver gets up enough speed and gives you the thumbs up, foot off the clutch and awf you go, but make sure you are in 2nd gear.:D

mocoman
24th Apr 2007, 23:18
VIR tried it once at LHR.


I'm hoping that it was an unmitigated disaster...
:ugh:

fireflybob
24th Apr 2007, 23:28
This assumes we believe in Global Warming! Much as I respect and admire Branson I am not so sure this proposal is "joined up" thinking. Sounds more like a good publicity stunt to me - have you seen the latest TV adverts for Virgin trains?

Mark1234
25th Apr 2007, 02:55
What none of these proposals, or Zero emission vehicles, or every other low emission concept seems to consider is that the power has to come from somewhere.. which is, for the greater part of the world, fossil fuels.

Which do you think has more of an impact - burning oil to produce electricity to warm up power lines, to charge batteries to move a truck to push an aeroplane.... with all the attendant losses and inefficiencies all the way down the chain..

Or just burn the oil in the plane/car in the first place? :D

Perhaps 'they' should concentrate on replacing power generation infrastructure with solar and wind, to reduce environmental impact that way. But then the enviro weenies will complain about the noise, and spoiling the landscape. :ugh:

Sorry, bordering on a rant, but I'm sure I'm not the only one that thinks there's a real lack of grown up thinking around this sort of thing!

apaddyinuk
25th Apr 2007, 03:21
Well although in theory the system could work.... With Virgin having its main base at LHR where exactly does he suggest they place these "Starting grids"??? Ramp space is at a premium and the taxi ways are generally congested enough as it is!!!!

Grand for somewhere like Dallas or Houston but lets be realistic!

Dan Winterland
25th Apr 2007, 03:35
But at JFK? Doesn't bear thinking about!

beerdrinker
25th Apr 2007, 05:50
It is just another example of Beardey's publicity seeking ego-mania.

There is no way a squadron of tugs could tow the huge nember of arriving and departing aircfaft at places like LAX, LHR, JFK etc etc.

As for bio-fuel, the USAF have been testing it in a B52 and the South Africans are way ahead of Beardey in research into it's use for aviation.

Five Green
25th Apr 2007, 06:01
I think that it comes down to the taxi times and not the airport config/space.

At airports like LHR or JFK where there can be considerable taxi delays being towed out could save ALOT of fuel industry wide.

As a 400 driver we sometines burn over two tonnes of fuel taxiing in NY LHR and CDG. That is more than twice the taxi fuel at most airports. Not to mention when the weather gets bad and departure seperation increases. It makes sense to be towed out , delay starting until within 15 min of take off.

On the down side there would be a little more work for GND control. If you had a problem on start, getting back to the bay would be an issue. Weighing the occasional probleem against the savings still makes this a good idea.

As for the size or availability of starting grids, the a/c could be started right on the taxi ways in departure sequence. The tug could then be disconnected and driven back via a parallel service road or use a parallel taxi way. It would even pay airlines to build service roads.

I am all for sensible calculations of actual carbon footprint. I am certain that a tug would burn far less than any aircraft.

Our airline would save 2 tonnes per flight per day, BA and Virgin would save millions. It is a good idea. Might be a little more hassle for us at the pointy end, the controllers and the ground personel, but the savings and goodwill are worth it in todays economic and enviromental climate.

FG

aviosaurus
25th Apr 2007, 06:08
Is there any INDEPENT analasis available comparing the real polution produced by an aircraft taxiing and the tug that might possibly replace it for a part of the journey?
I spend much of my time breathing the fumes of both, and I would suggest that your average aircraft engine is much better maintained than the equivalent in the tug.

Few Cloudy
25th Apr 2007, 06:37
I have quite a few unrealised inventions in my mental cupboard - sure I would be rich if I had done something about them - sure you have had the same things...
One of them was an electrical drive to L/R Main Wheels, powered by the APU which would allow a/c to move independently of Tractor and of Engines.
There - now I have given it away and someone else will be rich instead.
FC.

HEATHROW DIRECTOR
25th Apr 2007, 06:50
<<On the down side there would be a little more work for GND control. If you had a problem on start, getting back to the bay would be an issue. Weighing the occasional probleem against the savings still makes this a good idea.>>

With the greatest respect, some people on here really want to spend a couple of hours in the Tower at Heathrow or similar airport from where they might just get a different view. Slow towing aircraft can provide real headaches and there is no doubt that, overall, things would slow down. I'm sure Gonzo would confirm all this.

ETOPS
25th Apr 2007, 07:36
Few Cloudy
Already invented wheeltug (http://www.wheeltug.gi)
And ordered by DAL delta-and-wheeltug (http://www.chorusmotors.gi/press/pr_070329.shtml)

Re-Heat
25th Apr 2007, 08:02
Which do you think has more of an impact - burning oil to produce electricity to warm up power lines, to charge batteries to move a truck to push an aeroplane.... with all the attendant losses and inefficiencies all the way down the chain..

Or just burn the oil in the plane/car in the first place?
Well Mark, the power station is the most efficient form of power generation, emitting less energy as wasteful heat, and more as power than any other method. Power lines are not heated up due to high voltage of the power cables, and even including the moderate power loss through transmission it still far trumps generation at the point of usage.

Now are you prepared to backup your false statement with science, or are you content with accepting that you are just wrong?

Five Green
25th Apr 2007, 08:10
Heathrow Director.

Having operated in and out of Heathrow for many years I appreciate what the extra work load may mean. However for some reason the media has singled out aviation as the worst transportation polluter. Having just watched the BBC doc "Should we give up flying ?" it can be safely said that we as an industry must look for improvements, whatever the logistical implications.

Probably because to examine their own driving habits would be too difficult.

That said, the nose wheel tugs where meant to be "high speed' tugs. They are at least capable of sufficient speeds and when holding on the taxiway is expected they could be used. Their speeds could also be used to meter traffic in the sense that once all the traffic is moving it does not need to be doing 20+ knots to keep the departure flow rate the same.

As for better maintained, a badly maintained tug will still pollute far less than 4 Trents. Oh and you could service the tug too !!

For us long haul guys it means having a little extra fuel en-route on the days we would have cut into contingency before we even get off the ground.

We are talking about the savings of millions of litres per day industry wide. Surely we can sort soomething out.

brain fade
25th Apr 2007, 08:43
What about the energy involved in manufacturing all the extra tugs?

Must be significant.

NWT
25th Apr 2007, 09:03
This could be a good plan if it is organised properly.....however there are lots of improvements that could be done around the airport to help the pollution/green issue; Many of the stands at LHR the fixed ground power does not work...check out the lovely new stands for the 380 (301-307) none of the power works on these stands and has been like that for weeks, the jettys are regularly failing, meaning buses for the passengers etc.....now a 747 APU running for a 3 hour t/round......towing to the runway would be good, but lets sort the basics out first....(cost theBAA money so they wont bother)

Digitalis
25th Apr 2007, 09:04
Despite the cynicism of some - and the flat-earther-stylee climate-change denial of others! - this issue is one that has to be tackled, and someone has to be first to do it. There is no denying that any airline that acquires a mantle of environmental awareness will have an advantage in a marketplace that is sensitive to such matters, however, and Branson is a past master of exploiting such things.

The tug-to-the-runway approach is a coarse first step in a process which will eventually see aircraft making their way to the runway with their main engines shut down. Whether that's by the 'shopping trolly' system mentioned earlier, or auxiliary electric axle motors on board, or some other system is irrelevent as yet - the fact is that the experiment and development phases must begin somewhere. I'm sure most of us can see many of the disadvantages in using old, dirty, and scarce tugs to drag aircraft to somewhere near the pre-departure hold, but this is surely to establish simply how much fuel can be saved and what problems actually transpire, as opposed to what might be anticipated. From the data and experiences learned, decisions can be made as to what the next step should be.

dixi188
25th Apr 2007, 09:15
Is this a way to help Heathrow to reduce the pollution around the airport so that it can expand and build the third parallel runway and T6?

Just a spotter
25th Apr 2007, 11:03
Simple, socially responsible, eco friendly solution .... get a whole lot of young lads with ASBO's into a chain gang and have them lug the aircraft around the field!

Unhappy ASBO chaps, happy hippies ... :}

win/win

JAS

smith
25th Apr 2007, 11:14
what about an underground cable, like the cable cars in San Francisco? The aircraft could latch on to the continuously moving cable and detatch at the appropriate point. Just a far fetched thought.

green granite
25th Apr 2007, 19:09
Conveyor belts come to mind. :rolleyes::E

WideBodiedEng
25th Apr 2007, 20:12
"Slow towing aircraft can provide real headaches and there is no doubt that, overall, things would slow down."
If all aircraft were towed, the departures would still be same as now. It would just take a little longer to get there.
If 3/min go to the hold at 20 mph under their own steam, or at 10mph by tractor, they'll still be released at the same rate.
It would work.
However I'm sceptical of this whole global warming thing. 30 years ago we were going to freeze. Its a natural cycle. The Leftie Greenies need some way to have a dig at the west and of course the "great Satan"!!!
Anyone seen C4's The Great Global Warming Swindle"? see http://video.google.com/videoplay?docid=2332531355859226455
Yes it has an agenda as well but it gave me food for thought esp the ex Greenpeace founder!
Can anyone get the stats for the amount of motor fuel used in ,say, the UK vs the amount of aviation fuel?

A and C
25th Apr 2007, 23:14
Twenty years back Dan-Air (remember them?) started taxing the B727 to the hold with the #2 engine shut down, it was then started just before take off as a fuel saving measure.

The number of # 2 engine failures dramaticly increased mostly due to the engine thermal stress that resulted when a cold engine was set to take off power.

All this nonsence will stop when the first few big fan's go bang!.

Few Cloudy
26th Apr 2007, 06:44
Thanks ETOPS for the links.

I am not convinced that the nosewheel is the best location for a wheel drive -such a drive should be near the CG to avoid slippage in wet / poor conditions.

I imagine that the complexity of the Main Wheel brake system (and the relative simplicity of the nosewheel) is what has led to this configuration.

Anyway, as long as the system is being developed, now surely would be the time for Virgin to assess it?

FC.

Dan Winterland
26th Apr 2007, 07:22
Too late, it's already invented. Delta are going to test the system.

ETOPS
26th Apr 2007, 08:00
Dan - here's your cup of tea, time to wake up now:zzz:

Check my post 24hrs ago...........:D

Taildragger67
26th Apr 2007, 08:58
Read the papers, people. Whether it's misguided or not, aviation is in the cross-hairs at the moment and has to be seen to be at least thinking about doing something.

Anyone who's sat in the evening departure queue at Kennedy in the last year or two cannot but have thought about how much juice is being spewed into the atmosphere. Some posters on this thread have called for independent evidence - well, that's what a trial is for. It may well be that, taking into account the cost of buying and running all the extra tugs needed, the impact on arriving a/c of having to perhaps taxy around departing a/c under tow, etc. might stop it in its tracks. Then again, it might be that a tonne or two can be saved per 747, per departure on average and over the life of the a/c, that's a saving that any rational carrier couldn't sneeze at. Management is also under a duty to shareholders to constantly look at ways of cutting costs.

Starting grids? Little different from de-icing grids at some airports or the little circular holding bays that some airports used to have near the runway ends. Kennedy already has engine starting points off the taxiways - so not a totally alien concept - so it's just a matter of moving these out on the field (ok, a bit of construction will be involved).

Engine probs due to cold starts? OK, so f'rinstance at Kennedy, rather than have all 4, or both, running for an hour or more in the queue, start them up (or the ones which weren't started straight after push-back) out on the field with 20 or 30 mins to go (I don't think anyone's suggesting going straight from the start point onto the departure runway).

Aviation needs to be seen to be doing something. It is in the interests of all those in the industry to look for ways to cut emissions (and costs). Being seen to be pro-active is better than being seen as having to be dragged along. This issue will not go away.

Five Green
26th Apr 2007, 11:21
Brain Fade :

There is certainly an issue with extra manufacturing impact of more tugs. However I think that once an airline has obtained the extra tugs needed they will eventually re-coup that impact with the savings. We are talking about a huge amount of fuel globally. Additionally once airlines get organised they should be able to do this with less increase in tugs than is suggested, as a tug's utilization rate is not that high (ie they sit for some time after each aircraft they push/pull in.) Obviously depends on airport and airline and airline flight frequency. Perhaps pooling the tugs would be a way to go.

I think initially it would work well to tow out but not so for towing in (unless waiting for a gate and then the tug should be sent out) We burn 1.5 tons parked on a taxiway with one shut down, while waiting aprox 40 mins for a gate.

As far as engine wear goes, might not need 20 mins as sometimes our taxi times are very short and we launch in under 10 mins from last engine start.

Like the cable idea !!

Cheers

FG

harrogate
27th Apr 2007, 07:41
It's all about a series of uphill runways, running in all directions.

Planes stop quicker when landing, then they can free-wheel from the top of the runway downhill to the terminal, which would be located half way down the taxiway that's parallel to the runway. Then, when departing, they can freewheel down the rest of the hill to the bottom of the runway.

OK, so they have to take off uphill, but seeing as they're going up anyway...

Alpine Flyer
27th Apr 2007, 09:00
Even if you assume that a tug has only 1/10th of the fuel efficiency of an average SUV there is no way it could burn a couple hundred kgs for 3-5kms of push to the runway.

We use single-engine-taxi in and out whenever there is a longer taxi time and there is no evidence of increased engine stress if the required warm-up times before departure are adhered to.

Towing to the runway and no-diesel ground power won't save the planet single-handedly but it sure makes sense to cut emissions and noise wherever possible.

It would, of course, save a lot more if we just got startup and pushback clearances in time to avoid endless holdings before take-off. It is pretty inconceivable that we're unable to predict at least a little better when to release A/C from the gate in order to have not more than 2-3 waiting at the holding point.

It would save even more if we'd invented a better way of sequencing A/C so as not to have dozens of them in holdings (left of the channel) or flying useless mileage along huge waypoint-based traffic patterns (right of the channel) at inefficient speeds and altitudes.

AEA claims that we could save app. 10% of all fuel burned in aviation by just having a single Eurocontrol ATC and that is probably not far off the mark.

All these better potential savings are no excuse for not doing the small stuff and sometimes taking public tranport ourselves :)

Bernoulli
28th Apr 2007, 15:06
Starting grid eh!! Someone blows a whistle and we all sprint to the jets. First one to get rolling wins:} That'll spice up the day:)

eman_resu
29th Apr 2007, 05:37
I'm glad you didn't say starting pistol... However that would also act as a bird scarrer, thus two birds with one.. Never mind..

Apart from the thermal stress alluded to earlier, is there any other problems associated with only using 1 or 2 engines for the taxi run, bearing in mind the almost 30 minute changeover some of the airlines are now managing...

Would the engine have chance to cool down that far before being restarted anyway?