flyby519
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Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 1:19 pm

I remember reading a press release:

http://news.bbc.co.uk/2/hi/business/6203636.stm

And wondered if there has been any progress made with this initiative to tow aircraft from the gate to the runways to reduce fuel burn/emissions. The article states that this was going to occur in the 1Q 2007 at LHR and LGW airports. Anyone have info?
 
BHXFAOTIPYYC
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 1:24 pm

Why not just set up a giant rubber band and ping airliners off the runways?

Really though, didn't someone with a lot more knowledge than I say on this forum that engines need time to warm up? What if you get to the threshold and one won't go? Get towed back?

Many emissions would be saved if Branson could shut up for 5 minutes though....
Breakfast in BHX, lunch in FAO, dinner in TIP, baggage in YYC.
 
bx737
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 1:30 pm

What is the story with the motos that were to be attached to the nosewheel of aircraft to enable them get out to the runway without turning on their main engines.

Quoting BHXFAOTIPYYC (Reply 1):
Many emissions would be saved if Branson could shut up for 5 minutes though....

 rotfl 
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 1:53 pm

Quoting BHXFAOTIPYYC (Reply 1):
Really though, didn't someone with a lot more knowledge than I say on this forum that engines need time to warm up?

We were just discussing this in my Flight Technique Anaylsis class the other day. I believe American Airlines was/is also considering this idea. And I would have to answer yes to BHX's question. IIRC someone had said that some airlines used to start up only #1 and #3 on three engine aircraft, then #2 when ready for takeoff. But then they got some unusual readings on the #2 on takeoff because it was not able warm up first. Anyone with more info on this, please let us know.
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 2:19 pm

Quoting BHXFAOTIPYYC (Reply 1):

Really though, didn't someone with a lot more knowledge than I say on this forum that engines need time to warm up? What if you get to the threshold and one won't go? Get towed back?

Why not start the engines up while taxiing (i.e. while being towed)? Time it so that all are running right before you get to the runway (perhaps the last taxiway turn-off), thus giving the aircraft a chance to get towed back without causing disruption to traffic flow. Reading the article, it sounds like that is basically what's being proposed.

The tow thingies are really expensive, aren't they? They also take a large amount of energy to manufacture. Plus they use a fair amount of fuel (though much less than the turbofans). It might save fuel, but would this really save money?
 
MD88Captain
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 2:40 pm

It is a great idea. Don't worry about the warm-up time on the engines - the pilots always make sure their warm. No one wants one to come apart and then explain why it warmed up for 3 minutes instead of the required 5. That mistake will cost you a job (or a few months off).

Towing can save many thousands of gallons of fuel. Tones of $. Tons of emissions. It will provide the ability if needed to fly a little farther or have a little more continegcy gas when you get there. Factor in 1+ hr taxi times (JFK) and the plus side gets big.

Downside. Extra tugs, training, turf wars (think FAA/ATC), and paying tug drivers.
 
Queso
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 2:40 pm

Quoting Analog (Reply 4):
Plus they use a fair amount of fuel (though much less than the turbofans). It might save fuel, but would this really save money?

Not to mention they also have to taxi at least a couple of miles back to the ramp/gate area. Those things are not geared for long trips at an efficient criusing speed. You're also having to pay more people for their time to do this "new" job. Pay for significantly increased tire wear on the tugs, more oil changes, more filter changes, etc. It's a false economy.

Why not take it a step further? A huge amount of fuel is expended just getting the aircraft up to speed. Build a SuperTug that could take the aircraft up to 160kts or so and then release as the aircraft rotates.  Yeah sure
 
flyby519
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:02 pm

Apparently the geared machines that attach to the nosewheel of the aircraft to drive it without engine power were too heavy and the added weight had to be carried during the entire flight as well. As far as tugs pulling a/c to the runway, this is an excellent idea. Yes aircraft need about 5 mins to warm up their engines, but when you have a 767/777/747 at a congested airport the taxi time is often well over 1hr. How much fuel does a jumbo burn per hour during taxi? I think the savings would be huge.

[Edited 2007-10-10 08:03:00]
 
N1120A
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:18 pm

Quoting BHXFAOTIPYYC (Reply 1):

Really though, didn't someone with a lot more knowledge than I say on this forum that engines need time to warm up? What if you get to the threshold and one won't go? Get towed back?

Sure. Not to mention that by being towed back, you are saving stress on the one engine that is functioning.

Quoting Analog (Reply 4):

The tow thingies are really expensive, aren't they? They also take a large amount of energy to manufacture.

That is completely overshadowed by the fuel and wear savings on the engines.

Quoting Analog (Reply 4):
It might save fuel, but would this really save money?

In the long, and even short run, absolutely. You save on fuel, engine wear, wear on the nose gear, etc. You also save money on diversions and can carry greater weights because you have more fuel on board.

Quoting MD88Captain (Reply 5):
turf wars (think FAA/ATC)

The use of super tugs is, in many ways, faster than using aircraft power.
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
 
StarGoldLHR
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:24 pm

Hmm

for the ultra revolutionary...

How about an airport which replaces tugs altogether..

you could have a system of underground cables and a "grip" that the aircraft uses to grab the cable and pull the plane round the airport...

no need for extra taxi ways to move the tug out of the way.. or staff or training or even those dirty smelly non-environmentally friendly tugs in the first place ?

Am i thinking out of the box here ?

Startup the aircraft whilst on the way to the runway.
So far in 2008 45 flights and Gold already. JFK, IAD, LGA, SIN, HKG, NRT, AKL, PPT, LAX still to book ! Home Airport LCY
 
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azncsa4qf744er
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:29 pm

Didn't UA tried this method years ago when they started ORD HKG flight? Then Boeing came in and said if they continued it would void out the warrenty due to nose gear can only be towed for short period of time?
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:43 pm

Quoting StarGoldLHR (Reply 9):
How about an airport which replaces tugs altogether..

you could have a system of underground cables and a "grip" that the aircraft uses to grab the cable and pull the plane round the airport...

no need for extra taxi ways to move the tug out of the way.. or staff or training or even those dirty smelly non-environmentally friendly tugs in the first place ?

Am i thinking out of the box here ?

 rotfl  Yes. But I like your thinking!
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:47 pm

Quoting N1120A (Reply 8):
In the long, and even short run, absolutely. You save on fuel, engine wear, wear on the nose gear, etc. You also save money on diversions and can carry greater weights because you have more fuel on board.

If the cost savings are huge and obvious, why aren't airlines doing this already? If it's against the rules, why haven't they been fighting tooth and nail to change the rules.

The fact that they have not makes me a little bit suspicious of claims that the short term savings are huge

Quoting AznCSA4QF744ER (Reply 10):
Didn't UA tried this method years ago when they started ORD HKG flight? Then Boeing came in and said if they continued it would void out the warrenty due to nose gear can only be towed for short period of time?

Maybe that's why? Although if fuel savings were huge, then Boeing would see a benefit in marketing new aircraft (and mods to old aircraft) that allow this.

Quoting StarGoldLHR (Reply 9):

you could have a system of underground cables and a "grip" that the aircraft uses to grab the cable and pull the plane round the airport...

Sounds complicated (how to handle intersections, etc.) and unreliable (think snow, ice, salt).
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:58 pm

Quoting Analog (Reply 12):
Sounds complicated (how to handle intersections, etc.) and unreliable (think snow, ice, salt).

So does flying. (at least pre-1900s)  Big grin
 
pnwtraveler
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 3:59 pm

If there are long queues at runways pilots often shut down one engine and restart 5 minutes before departure. One engine is often not sufficient for taxi if a plane is quite loaded. You have to rev the engine so high that it kicks up all sorts of stuff off the sides of the taxiway and the jet blast becomes much more of an issue around ramp attendants etc.

I cannot see aircraft clogging up taxiways in busy airports while they wait for tractors to hook up and then tow. You would need parking areas near the runways and there just isn't space for that. Maybe quite small airports could get away with it. The same for departures. There isn't sufficient space around most airports for all these tugs and tractors to be hooking up and unhooking. As it is in some airports you have to wait for ground personel when it is busy. Imagine how many more gate staff would be needed if some of them are pulling aircraft across the airport to take off.

I can't see any of this being very practical.

Some airlines have made other adjustments in order to save fuel that I think is much more reasonable. Not reversing engines as often on landings makes a lot of sense. Many AC aircraft are now doing this. Bringing up the landing gear more quickly. Using flaps later and lowering landing gear later also helps. All of this is conditional though on traffic on traffic contraints at the time
 
babybus
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 4:00 pm

I think it's a really good idea. The aircraft always ends up waiting at least 5 mins in the large taxi area near the runway anyway and it could start up then.

Very early morning arrivals at LHR get tugged to the gate once clear of the runway, so why not the other way round?
and with that..cabin crew, seats for landing please.
 
StarGoldLHR
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:14 pm

Quoting Analog (Reply 12):
Sounds complicated (how to handle intersections, etc.) and unreliable (think snow, ice, salt).

How do you go round corners and do intersections using a converyor belt..same idea... inertia & rollers... plane already has movement and wheels... even 400 tons at 5mph isnt going to just stop like that.

Computers could control the grip and release... control towers control the computer.. all of a sudden all ground control movements are managed by computer.
As for the snow and ice...

Cable railways seem to manage ok.. effectively you have a small hole in the ground with a revolving cable.. no other moving parts. A grip capable of holding 400 tons won't just slip on a bit of ice...sand on rails solved this problem with steam trains... but computer controls have replaced this

[Edited 2007-10-10 10:17:58]
So far in 2008 45 flights and Gold already. JFK, IAD, LGA, SIN, HKG, NRT, AKL, PPT, LAX still to book ! Home Airport LCY
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:21 pm

Quoting StarGoldLHR (Reply 16):

Cable railways seem to manage ok.. effectively you have a small hole in the ground with a revolving cable.. no other moving parts. A grip capable of holding 400 tons won't just slip on a bit of ice...sand on rails solved this problem with steam trains... but computer controls have replaced this

Cable railways don't have to make arbitrary turns at taxiway intersections. Each section would have to be individually controlled and reversible.

Have any cable railways been built in the last 50 years?
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:22 pm

Quoting StarGoldLHR (Reply 16):

Cable railways seem to manage ok.. effectively you have a small hole in the ground with a revolving cable.. no other moving parts. A grip capable of holding 400 tons won't just slip on a bit of ice...sand on rails solved this problem with steam trains... but computer controls have replaced this

Cable railways don't have to make arbitrary turns at taxiway intersections. Each section would have to be individually controlled and reversible.

Have any cable railways been built in the last 50 years?
 
Candid76
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:44 pm

If congested airports weren't so congested there would be no need for any of this malarkey. But building new airports or greatly expanding existing ones is environmentally unfriendly so we have massive congestion and wasted emissions as aircraft hold for ages to depart and also circle for ages waiting for a slot to land, especially in bad weather. In my book this is no more environmentally unfriendly. Of course in the UK, the whole LHR/LGW situation would be far less of a problem if flights were more evenly spread through other airports (putting my MAN hat on as usual) but that's another argument.

I don't think it will work at LHR due to the likelihood of exacerbating ground congestion. I'd also be concerned about all these tugs driving around on taxiways (once they have unhooked the aircraft they'll have to drive back). On the one hand Virgin want to concentrate their whole operation at over congested airports but on the other want to be seen as "green" -you can't have your cake and eat it. Commercial priorities will always triumph over environmental ones.
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:49 pm

Quoting Candid76 (Reply 19):
I'd also be concerned about all these tugs driving around on taxiways (once they have unhooked the aircraft they'll have to drive back).

Tugs need less space than aircraft. There's probably a good way to get them back to the terminal (like towing arriving aircraft from a parallel runway) so that they don't add that much to the ground traffic.
 
Candid76
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:56 pm

Quoting Analog (Reply 20):
Tugs need less space than aircraft. There's probably a good way to get them back to the terminal (like towing arriving aircraft from a parallel runway) so that they don't add that much to the ground traffic.

To reach the parallel (and only) other runway at LHR the tug would have to drive across practically the whole complex, I'm sure that your theory would work OK at some US hubs. Personally I wouldn't want tugs all over the taxiway system, especially in LVPs, and I can't think of many worse laid out airports than LHR.
 
Analog
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 5:59 pm

Quoting Candid76 (Reply 21):

To reach the parallel (and only) other runway at LHR the tug would have to drive across practically the whole complex, I'm sure that your theory would work OK at some US hubs. Personally I wouldn't want tugs all over the taxiway system, especially in LVPs, and I can't think of many worse laid out airports than LHR.

Is there room between taxiways? Either that or could the tugs go the long way around the taxiways on a dedicated road?
 
N1120A
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 6:45 pm

Quoting AznCSA4QF744ER (Reply 10):
Didn't UA tried this method years ago when they started ORD HKG flight? Then Boeing came in and said if they continued it would void out the warrenty due to nose gear can only be towed for short period of time?

That is because United was using the conventional tug + tow bar setup, which puts a lot of stress on the nose gear. Supertugs lift the nose gear off the ground and cradle it safely so that there is very little stress on the gear.

Quoting Analog (Reply 12):

If the cost savings are huge and obvious, why aren't airlines doing this already?

One, because fuel has only recently become a major issue. Two, because Supertugs are relatively uncommon in the US, outside of Continental's major facilities.

Quoting Analog (Reply 12):
If it's against the rules, why haven't they been fighting tooth and nail to change the rules.

It isn't against the rules really.
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
 
flexo
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 6:57 pm

Quoting Analog (Reply 22):
Is there room between taxiways? Either that or could the tugs go the long way around the taxiways on a dedicated road?

The tugs wouldn't even have to go back as they could just wait at the other end of the runway for a landing aircraft to pull it back to the terminal (at least when running in mixed mode).

The best way to avoid having to pay extra drivers for the tugs would be to use fully automated tugs that can be steered by the pilot once they are connected to the front wheel. Of course that would require an extra system aboard the aircraft and extra training for the pilot but if the savings justify it on the long run - why not!
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 9:56 pm

Quoting Flexo (Reply 24):
The best way to avoid having to pay extra drivers for the tugs would be to use fully automated tugs that can be steered by the pilot once they are connected to the front wheel. Of course that would require an extra system aboard the aircraft and extra training for the pilot but if the savings justify it on the long run - why not!

Now that's creative! It kind of mixes some ideas together. Brings up many more issues, but those can always be fixed with research and development. ie: How does the tug initially attach to the aircraft? And detach? Pilots have to learn how to 'drive' using the tugs, as you said. And MORE controls have to be put into the cockpit, oh my! As much as I like the idea, I don't think it would really be worth it.
 
StarGoldLHR
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:09 pm

Quoting Flexo (Reply 24):
The best way to avoid having to pay extra drivers for the tugs would be to use fully automated tugs that can be steered by the pilot once they are connected to the front wheel. Of course that would require an extra system aboard the aircraft and extra training for the pilot but if the savings justify it on the long run - why not!

Rather than Pilot controled.. it should be controled by the Tower.. far safer and simpler.. just give the pilot an "emergency stop".


re-cable ways... San Francisco just replaced it's entire railway.. and it goes up and down insane hills and round corners..seems they figured it 100 years ago. Why not a plane ?

I think in reality an easier option would be a computer controled,.. electric powered.. guided tug.
The kind where there's a painted line on the road and a sensor on the tug to guide it.

Let the control tower give it a "route map" and let it go.

At the end of the runway, have it detach and run highspeed to the other end of the runway and out of the way... added benefit would be camera's to check for debris on the runway... it can sit and wait for another plane or go elsewhere.

Whilst the tug scans the runway, the plane runs up it's engines.

This will work for "less busy" runways, but it's a reasonable start until you get the technology right.
So far in 2008 45 flights and Gold already. JFK, IAD, LGA, SIN, HKG, NRT, AKL, PPT, LAX still to book ! Home Airport LCY
 
flipdewaf
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:10 pm

Quoting StarGoldLHR (Reply 9):
Hmm

for the ultra revolutionary...

How about an airport which replaces tugs altogether..

you could have a system of underground cables and a "grip" that the aircraft uses to grab the cable and pull the plane round the airport...

no need for extra taxi ways to move the tug out of the way.. or staff or training or even those dirty smelly non-environmentally friendly tugs in the first place ?

Am i thinking out of the box here ?

It would be like a scalectrix! it the automated tug system was incorporated aswell it could be easily controlled by a computer although there would have to be huge infrastructure changes.

Fred
Image
 
StarGoldLHR
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:24 pm

Quoting Flipdewaf (Reply 27):
It would be like a scalectrix! it the automated tug system was incorporated aswell it could be easily controlled by a computer although there would have to be huge infrastructure changes.

How cool would that be.. the people in the control tower each holding a Scalectrix "joystick".. then press the trigger to race down the runway !  Smile
These systems work in factories.. Amazon.com uses something like this, even Boeing's production line is a plane constantly moving round the factory.
The technology is there.
So far in 2008 45 flights and Gold already. JFK, IAD, LGA, SIN, HKG, NRT, AKL, PPT, LAX still to book ! Home Airport LCY
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:36 pm

Quoting StarGoldLHR (Reply 26):
At the end of the runway, have it detach and run highspeed to the other end of the runway and out of the way... added benefit would be camera's to check for debris on the runway... it can sit and wait for another plane or go elsewhere.

Whilst the tug scans the runway, the plane runs up it's engines.

Alright, I think we should all get together, make a little mock up and present it to the airlines and airports. Lets start making some money off this!  Silly
 
SABE
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:39 pm

I see I'm not the only one with fond memories of Scalectrix!!  Smile

Back to the topic, does anyone have rough estimates of the fuel cost of one B747 taxiing for one hour? And the cost of one supertug? Then we can start to figure out if this makes sense or not, economically speaking.
TUS-DFW-EZE... can't wait to visit home again!
 
AgnusBymaster
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:47 pm

Problems are that the engines need time to warm up prior to takeoff, so this could cause delays depending on how long the takeoff line is. And then, if there is a warning light engine on start up or something, they have tow the plane all the way back to the gate. Also would increase taxi times and requiring increased block times.
 
pilotboi
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 10:56 pm

Here's a better idea: http://www.wheeltug.gi/

Delta is the launch customer Big grin
 
Flighty
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 11:05 pm

I like the idea, but an idling 747 only burns something like 200 gph, ballpark estimate, or $500 per hour. It's nice to save $500 day after day, but only if it's PERFECTLY seamless. Otherwise forget it - the "solution" will cost money too.

Besides, it is quite practical to taxi around on 50% engine count, even on a 747, until 5-7 mins before takeoff. The best solution to this problem is shut off half your engines while taxiing. Airlines already do that.
 
vv701
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RE: Towing A/C To Runway: Virgin Atlantic

Wed Oct 10, 2007 11:59 pm

Good to read so many innovative and thought through replies. But can we go back to the original question:

Quoting Flyby519 (Thread starter):
And wondered if there has been any progress made with this initiative to tow aircraft from the gate to the runways to reduce fuel burn/emissions. The article states that this was going to occur in the 1Q 2007 at LHR and LGW airports. Anyone have info?

Has it happened? If not, why not? Or was this a case of more Branson hot air?

Elsewhere others have raised the issue of warming up the engines before departure. I get the feeling that in this primarilly Anglo-American discusion we may be running into one of those instances where usual practice is different on the two sides of the Atlantic and therefore clouds the issues a little.

Here in the UK each departing aircraft is assigned its own unique departure slot at each of our four major international airports, LGW, LHR, MAN and STN. Provided it reaches the holding area at the end of the runway on time an aircraft will be granted use of its slot. So it will be given departure priority over another aircraft that has arrived in the holding area before it but is operating in a later departure slot. Hence there are always at least two and very often three queues of aircraft in the departures holding area at busy times and taxiways are designed to allow for this. So there are opportunities for an aircraft to be temporarilly parked after reaching the holding area so its engines warm up without necessarily blocking the progress of other aircraft. However gate departure time would need to be brought forward so that the aircraft had warmed engines when its allocated slot becomes available.

If an aircraft misses its assigned slot in the UK I am under the impression it has to wait until a new slot can be assigned. I would welcome clarification from someone with greater knowledge as to how this works in practice if, indeed, I am correct in the first place.

(I believe - again please correct me if I am wrong - that in the USA there is no actual allocation of a specific departure slot and, at busy times, aircraft depart in the order that they enter the departure queue.)
 
birdbrainz
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RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 1:32 am

Quoting AznCSA4QF744ER (Reply 10):
Didn't UA tried this method years ago when they started ORD HKG flight? Then Boeing came in and said if they continued it would void out the warrenty due to nose gear can only be towed for short period of time?

exactly.

Quoting Babybus (Reply 15):
I think it's a really good idea. The aircraft always ends up waiting at least 5 mins in the large taxi area near the runway anyway and it could start up then.

engine start, then get things stabilized, read checklists, get clearances. Too much stuff to do in not enough time.

Quoting Babybus (Reply 15):
Very early morning arrivals at LHR get tugged to the gate once clear of the runway, so why not the other way round?

The plane is A LOT lighter. No checklists to read, etc.

Quoting N1120A (Reply 23):
That is because United was using the conventional tug + tow bar setup, which puts a lot of stress on the nose gear. Supertugs lift the nose gear off the ground and cradle it safely so that there is very little stress on the gear.

Where's the difference? The aircraft is still being pulled by the nose gear. The big difference is that by holding the nose gear more securely, the *empty* aircraft can be accelerated, decelerated, and moved more quickly and safely.

Quoting Flighty (Reply 33):
I like the idea, but an idling 747 only burns something like 200 gph, ballpark estimate, or $500 per hour. It's nice to save $500 day after day, but only if it's PERFECTLY seamless. Otherwise forget it - the "solution" will cost money too.

Yes. Taxi fuel is only about 1500 lb (~240 gal), compared with 300,000+ lb of fuel for a long flight. do the math. Btw, that fuel is burned before the flight, so don't start about having to burn fuel to carry an extra 1500 lb of fuel.

Also, thing about the cost of one collapsed gear or cost of added inspections? Not worth it.

If it were such a great idea, why aren't more airlines doing it?
A good landing is one you can walk away from. A great landing is if the aircraft can be flown again.
 
N1120A
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RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 2:00 am

Quoting Birdbrainz (Reply 35):


Where's the difference? The aircraft is still being pulled by the nose gear. The big difference is that by holding the nose gear more securely, the *empty* aircraft can be accelerated, decelerated, and moved more quickly and safely.

The difference is that the hinges and joints between the gear and the aircraft are not being stressed to the same degree as with a tow bar.
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
 
usairways787
Posts: 226
Joined: Wed Jun 22, 2005 12:42 pm

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 3:38 am

Quoting Queso (Reply 6):

Haha they already have those. Catapults
 
Boeingluvr
Posts: 347
Joined: Mon Jun 18, 2007 1:56 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 3:46 am

Quoting Bx737 (Reply 2):
What is the story with the motos that were to be attached to the nosewheel of aircraft to enable them get out to the runway without turning on their main engines.



Quoting Flyby519 (Reply 7):
Apparently the geared machines that attach to the nosewheel of the aircraft to drive it without engine power were too heavy and the added weight had to be carried during the entire flight as well. As far as tugs pulling a/c to the runway, this is an excellent idea. Yes aircraft need about 5 mins to warm up their engines, but when you have a 767/777/747 at a congested airport the taxi time is often well over 1hr. How much fuel does a jumbo burn per hour during taxi? I think the savings would be huge.

How recent is this info? What's the source?? I know AC retro fitted a B767 with one and the tests were very succesful for taxi. This was a couple of years ago tho, maybe three actually. Perhaps something's changed since then.
 
tribird1011
Posts: 214
Joined: Mon Mar 14, 2005 10:08 pm

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 6:36 am

Quoting N1120A (Reply 36):
The difference is that the hinges and joints between the gear and the aircraft are not being stressed to the same degree as with a tow bar.

That's not entirely true. Quite honestly, the only difference that i see is that with a supertug (towbarless tug) is that the nose wheel does not touch the ground, and that's pretty much it.

whether you are towing the airplane with tug and bar or with a towbarless, the nosewheel still turns in relation to the airplane, and you have to be carefull with regards to turning angles.

Now, if there is a towbarless that is capable of towing an airplane, and maintain the nosewheel straight in relation to the airplane, then what you say becomes true, but AFAIK, towing with a towbarless still turns the nosewheel, so in that sense, it makes no difference if towing is accomplished with a towbarless, or tug and towbar.
 
pilotboi
Posts: 711
Joined: Thu Sep 06, 2007 8:16 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 6:39 am

Quoting Boeingluvr (Reply 38):
How recent is this info? What's the source?? I know AC retro fitted a B767 with one and the tests were very succesful for taxi. This was a couple of years ago tho, maybe three actually. Perhaps something's changed since then.

Maybe I wrote it in invisible font the first time. I'll try again: http://www.wheeltug.gi/

Delta has signed an agreement (in March 2007) to use this on the 738s. Certification is to be completed by 2009 (it's like trying to certify a freaking aircraft!) and there has been recent news (within the past month)...so there's definatly something going on.
 
Boeingluvr
Posts: 347
Joined: Mon Jun 18, 2007 1:56 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 6:57 am

Sorry didn't see that link anywhere!
 
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usair330
Posts: 705
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RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 7:22 am

It wont happen. APU has to be on so the fuel will still be waisted. Secondly, I don't know about all airlines but at WN we require a 2 man crew. (1 to drive obviously and the other to disconnect headset and remove the towbar.)

Anything is possible but this wont happen for a Loooooong time.
 
georgebush
Posts: 488
Joined: Tue Jul 11, 2006 8:15 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 8:35 am

Quoting Tribird1011 (Reply 39):
That's not entirely true. Quite honestly, the only difference that i see is that with a supertug (towbarless tug) is that the nose wheel does not touch the ground, and that's pretty much it.

Thats right, the only thing your doing is saving the stress on a 20$ pin from the tow bar.

Quoting Usair330 (Reply 42):
don't know about all airlines but at WN we require a 2 man crew. (1 to drive obviously and the other to disconnect headset and remove the towbar.)

Anything is possible but this wont happen for a Loooooong time.

Actually, many airlines have a 3 and 4 man procedure especially for heavies when you consider your wing walkers. Which if every plane at LHR was being towed around the ramp, thats a hell of a lot of extra people walking around.

Towing planes isnt exactly safe... I have seen an MD-88 break out of the tow bar on push back because the tug driver hit the breaks too hard. It broke the headset cable, so we had no communication with the flight deck, and that bird rolled right into the grass before the captain saw us waving frantically and the tug which he thought was connected to his airplane.

Your vantage point from a tug is wayyy worse than from in the flight deck. It gets almost impossible to tell how close your wings are to an obstacle from the seat of a tug.
Al Gore invented global warming.
 
StarGoldLHR
Posts: 1346
Joined: Mon Feb 16, 2004 1:29 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 9:00 am

http://www.wheeltug.gi/

It looks like a rubber band with a 12v motor attached  Smile

Are they going to carry this thing around with them inflight ? What happens if the rubber band breaks.. the whole thing would explode over the wheel on a landing !!!

It'd be far better leaving it behind on the ground and picking up a new one on arrival.
So far in 2008 45 flights and Gold already. JFK, IAD, LGA, SIN, HKG, NRT, AKL, PPT, LAX still to book ! Home Airport LCY
 
cumulus
Posts: 1003
Joined: Wed Aug 23, 2006 4:39 pm

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 11:29 am

Quoting BHXFAOTIPYYC (Reply 1):
Many emissions would be saved if Branson could shut up for 5 minutes though....

Stupid comment...............
What Goes Up Must Come Down, Hopefully In One Piece!
 
flipdewaf
Posts: 2988
Joined: Thu Jul 20, 2006 6:28 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 1:39 pm

Maybe this little cart thing on the Nose gear could be used on the main gear too and on landing have it connected so as the motors are used to generate electricity as the aircraft is slowed? just a thought.

Fred
Image
 
Leezyjet
Posts: 3544
Joined: Sun Oct 14, 2001 7:26 am

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 2:25 pm

Quoting Babybus (Reply 15):
Very early morning arrivals at LHR get tugged to the gate once clear of the runway, so why not the other way round?

Only in ONE cul-de-sac in T4, and even then they taxi to the end of the cul-de-sac and then shut down, so they only get tugged in for the last few hundred m or so.

Just watched the video on that website, no Health and Safety in operation at Air Canada during that test !!. Towing with passenger doors wide open, and not even with the safety strap in place and also the cargo bay doors open !!!. Nice little accident waiting to happen.

IIRC the Cargo bay door forms a structural part of the a/c and should always be closed when the a/c is moving. Our engineers will not even allow our a/c to move 6" without the cargo bay doors being closed !!.

Quoting Birdbrainz (Reply 35):
If it were such a great idea, why aren't more airlines doing it?

Because things in aviation move very slowly whilst everyone argues over who is going to pay for the staff/equipment etc. Most airlines use handling agents rather than their own staff at a majority of stations, so the handling agents won't want to buy the extra equipment and pay out for staff if they are not going to see much of a return on the investment. It is the airlines that foot the bill for the fuel, but the handling agents would be the ones making the major investments in the staff and equipment to allow this idea to work.

The idea itself is a very good one and will work in principle, but procedures will need to be looked into in order for it to become common pratice, by looking at starting area's, warm up times, at what point it would become more cost effective over using the engines over what distances/times/ a/c weights etc.

At airports such as JFK where taxi times are in excess of 2 hours on some days, it would probably be a great benefit to the surrounding communities and the environment, whilst at other airports there would be no point if taxi times are short and traffic light. Maybe if the airport authorities were the ones to buy the equipment and pay the staff and recoup the cost via landing fees, it would work, but I guess an awful lot more research will have to be done before it becomes the "norm".

 Smile
"She Rolls, 45 knots, 90, 135, nose comes up to 20 degrees, she's airborne - She flies, Concorde Flies"
 
dubliftment
Posts: 25
Joined: Tue Sep 11, 2007 5:24 pm

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 3:01 pm

Quoting AznCSA4QF744ER (Reply 10):
you could have a system of underground cables and a "grip" that the aircraft uses to grab the cable and pull the plane round the airport...

This idea is downright fascinating and I think a fine chance of the future, especially for new airports. Such underground motors, making the a/c sort of run on invisible rails, could use "green" electricity (sun, wind). It could also simplify the work of ATC Ground Control and minimize collisions on airports. Only thing, it would be very challenging to build such machinery into existing airports.
 
WPIAeroGuy
Posts: 319
Joined: Tue Aug 21, 2007 11:52 pm

RE: Towing A/C To Runway: Virgin Atlantic

Thu Oct 11, 2007 3:15 pm

How about, at airports with parallel runways, have with a relativitly steep uphill grade and then one with a steep downhill. Aircraft from the gate can just roll downhill to the end of the runway. Of course they would have to fight the uphill slope on the takeoff, however that would be madeup on the landing as the grade would slow them down, then when you stop you'll be on the high end and can roll back to the gate.
-WPIAeroGuy

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