LAX From United States of America, joined Dec 2000, 2290 posts, RR: 3 Posted (12 years 6 months 2 weeks 1 day 13 hours ago) and read 2689 times:
Especially during a severely long wait to takeoff, why is it not feasable to tow an aircraft to the active runway via a tow tug.....rather than wasting fuel by having the craft taxi on its engine power?
One problem (possibly)........Is it considered dangerous (or against some regulation) for a jetliner to start up its engines with another plane immediately behind it (such as in a queue for takeoff)?
Along the same lines ...... Don't some airlines frequently tow their planes back to the gate after the plane has landed (to conserve fuel)?
IFlyADesk From United States of America, joined Mar 2001, 309 posts, RR: 0 Reply 1, posted (12 years 6 months 2 weeks 1 day 12 hours ago) and read 2654 times:
UA actually did this during the beginning of their ORD-HKG non-stops, for the purpose of conserving fuel during the winter wind season. Taxi fuels on larger jets can easily reach the 2000-3000LB range, especially when taxi/takeoff delays can be encountered.
Another obvious solution is to taxi with not all the engines started. However, the risk is that an engine wont start prior to reaching the runway. In that case the aircraft must taxi all the way back to the gate for maintenance to figure out why. That really messes up ground traffic, gate availability, and adds additional delays to that flight.
Taxi fuel is always included in 'today's' flight plans.
AA7771stClass From United States of America, joined Jun 1999, 293 posts, RR: 6 Reply 2, posted (12 years 6 months 2 weeks 1 day 12 hours ago) and read 2635 times:
Another problem includes the tug itself. The airlines can't drag a fully laden 747-400 to the runway without burning out the tug. They would have to buy the special kind I read about in Car and Driver (anyone see that article!?!).
IFlyADesk From United States of America, joined Mar 2001, 309 posts, RR: 0 Reply 3, posted (12 years 6 months 2 weeks 1 day 12 hours ago) and read 2627 times:
I remember that story in C/D! There are super tugs that are capable of towing fully-loaded 747s for distances, ie. from the gate to the hangar. You can see them at NRT, they are referred-to as Godzillas.
But you bring-up another good point, the wear and tear on the ground equipment. GSE can be expensive to repair, especially for an airline that has hundreds of them. Another fact to consider is what if the tug craps-out halfway to the runway, on a taxiway where the aircraft cannot be turned around? That would REALLY piss-off the ground controller...
RayChuang From United States of America, joined Jun 2000, 7865 posts, RR: 5 Reply 4, posted (12 years 6 months 2 weeks 1 day 10 hours ago) and read 2604 times:
While towing a fully-loaded plane out to the end of the runway from the terminal will likely save fuel, this may result in airplane tugs running up a lot more miles (and a lot more wear and tear).
Besides, it's not necessary to have all the jet engines running to taxi the plane around on the ground. I've seen several instances of planes taxiing with only two engines running (747's) or only one engine running (most twin-engine jets) to save fuel as they taxi out to the end of the runway.
Trintocan From United Kingdom, joined Apr 2000, 3211 posts, RR: 4 Reply 6, posted (12 years 6 months 2 weeks 1 day 10 hours ago) and read 2586 times:
The problem is, fuel may be saved by tugging to the runway but unless a large enough area is available for planes to warm up there will be more congestion. Additionally any warm-ups on the runway itself will cause delays by slowing the plane turnover rate on the runway.
B727-200 From Australia, joined Nov 1999, 1051 posts, RR: 3 Reply 8, posted (12 years 6 months 2 weeks 1 day 8 hours ago) and read 2548 times:
I suppose there would be a number of issues with regards to this, some of which I am not too technically across.
Apart from the things already mentioned above, there is the presurisation of the aircraft and removing the lock-pin. As part of the warm up, I am sure there are a number of items such as hydrolic pressures and fuel flows to stabalise.
Also, if the aircraft has pooped an APU, how do they start it out there?
PhilB From Ireland, joined May 1999, 2915 posts, RR: 14 Reply 9, posted (12 years 6 months 2 weeks 1 day 8 hours ago) and read 2542 times:
This idea has been mooted a few times and widely discussed at various Airport Management/Airport Environment and Ground Handling Conferences.
There are a number of factors, some of which have been touched on already.
TUGS: It is not beyond engineering to come up with tugs to handle any fully loaded aircraft inc AN124, B747 or even A380 and still save money overall on the operation.
OPERATION: Tugs may be operated by the airline at hubs or home base but elsewhere, many airlines use tugs from ground handlers. At present tugs are limited to the ramp which is considered a "free operation" area compared to taxiways and holding points which are considered aircraft manoeuvering areas in which vehicles are allowed only under very strict arrangements. The problem comes with regard to the operation within this area where the question of who is in charge of the aircraft (Captain or tug driver) blame/insurance in the case of an accident or incident and also communication arrangements arise.
All of these problems are able to be sorted but it will be a long processs
SPACE: There would need to be a large area close to the runway to unhook the tug plus a freeway back to the ramp to enable the tugs to return promptly to the ramp.
SAFETY: When tugs unhook on the ramp, they are normally well clear of other aircraft running engines. This could not be so were aircraft all to start engines in what would be a more crowded area (unless you were to replicate ramp spacing at the holding point).
So that is where the situation lies at present. It will, no doubt, continue to be looked at and one day, when the price of fuel rises so much it becomes cost effective to overcome the problems, the idea maight take off.
Srbmod From United States of America, joined Mar 2001, 17284 posts, RR: 51 Reply 10, posted (12 years 6 months 2 weeks 20 hours ago) and read 2516 times:
The supertugs rocks!!!! Delta has a number of them, and ASA has a mini-supertug. The only problem is the cost. The supertugs cost as much as a Ferrari, and like an earlier post stated, what if you have an airstart to conduct. And imagine the traffic jam of pushbacks on the ramps during a push. I consider myself to be a pushback master, and I've had times where I had to push a plane out with planes on both sides of the aircraft once I got it on to the ramp. I love the feel of jetblast, except when it's been raining. And there's nothing worse than when a Delta plane is pulling into a gate directly across the concourse from you and blowing dust and other matter into your eyes, especially from a L1011 or a 757 powering up for those last few feet into the gate. At many airports, the ground control crews have enough to worry about without having to worry about pushbacks coming at them from all directions. What they need to do is put a fuel station near each runway during heavy delays so that planes can top off if they've burned up alot of fuel. I've seen planes sit out on the taxiways for 2 hours and then have to return to the gate to refuel. I watched a Swissair MD-11 sit in the same spot in line for an hour before it even moved a foot. I joked that they've probably already had meal service and watched most of the movie by then.
PhilB From Ireland, joined May 1999, 2915 posts, RR: 14 Reply 11, posted (12 years 6 months 2 weeks 18 hours ago) and read 2479 times:
Your joke, someone else's truth. In really bad situations and IF it is known that a take off slot is far enough ahead with absolutely no chance of an earlier departure, airlines have been known to serve meals on the ground - especially on late evening flights where serving a meal after a delayed departure would mean the pax not eating until well after 10.30pm, if the flight was due off at, say 7.30pm or 8 pm - as can happen if there are active thunderstorms blanketing the mid and north eastern USA for instance.
CAETravlr From United States of America, joined Oct 2000, 907 posts, RR: 1 Reply 12, posted (12 years 6 months 2 weeks 18 hours ago) and read 2461 times:
One more cost that they might incur, though it still might not deplete the fuel savings value, is the number of extra ramp personell that you have to have working at a time, if some of them are busy pulling a plane to the runway, instead of coming immediately back in and working the next plane. How much would labor costs go up in this situation?
A woman drove me to drink and I didn't have the decency to thank her. - W.C. Fields
Red Panda From Hong Kong, joined Jun 2000, 1521 posts, RR: 0 Reply 14, posted (12 years 6 months 2 weeks 18 hours ago) and read 2443 times:
it's not economic to do that. Tho it can save fuel, but airlines would have to buy more cars and to hire more drivers to drive the taxi cars. If a/cs can taxi by themselves, why use others to do the job?
Say if you can walk, would you still want a wheelchair and get someone to push you? I don't think so.
PhilB From Ireland, joined May 1999, 2915 posts, RR: 14 Reply 15, posted (12 years 6 months 2 weeks 17 hours ago) and read 2436 times:
When I was typing my first post on the topic, I was called away, so only posted part of the full picture.
Two more problem areas arise.
1 The obvious one of the extra tugs needed. Tugs only travel short distances on the ramp. Some holding points would entail round trips of 3 or 4 miles, which takes time. Depending on the airport, it has been calculated that, to cater for peaks, up to 75% more tugs may be needed, but these may be idle for up to 18 hours per day.
2. Many environmentally sensitive airports now ban the use of the APU on the gate (and some for starting).
They provide hook ups for pre-conditioned air, electrics and pressurised air for starts.
Whilst the pressurised air could be deleted at the gate, the runway end start point would need all three, the gate the other two. Also, how would airconditioning and systems electrics be provided during the tow where APUs are banned?
There have been some innovative airport designs toted around in recent years. On has gates at either ends of parallel runways with arrivals one end, departures the other with a central service module for check in, customs, shopping etc., connected by a tram or subway. The gates would change us as the runways changed with the wind and there would be only the minimum safe distance from the gates to the runways.
Aircraft would be towed "dead" between arrival and departure gates.
A much more radical design has aircraft parked at remote stands close to the runway with no gates as such but the aircraft serviced by giant mobile lounges from a central service area. Does that seems similar to something they have been using in Virginia somewhere for over quarter of a century?
RayChuang From United States of America, joined Jun 2000, 7865 posts, RR: 5 Reply 16, posted (12 years 6 months 2 weeks 14 hours ago) and read 2411 times:
Using mobile lounges is probably a good idea, but can you imagine how many trips you're going to need to service a 747-400 or A380? And I'm not going to imagine driving these mobile lounges in inclement weather, either.
Soku39 From United States of America, joined Nov 2000, 1797 posts, RR: 9 Reply 17, posted (12 years 6 months 2 weeks 12 hours ago) and read 2397 times:
Ya I heard about how BA tows 747s but only because they need most or all of the fuel on board. That must really tear up those normal tugs. I have also seen when ground vehicles get behind jet engines its not a pretty site. It seems to me to get back to the terminal would take an extremely long time (w/ existing taxiway systems) if they are to avoid other aircrafts jets. You know unless the tug driver feels like going off-roading.
OO-AOG From Switzerland, joined exactly 13 years ago today! , 1426 posts, RR: 4 Reply 21, posted (12 years 6 months 2 weeks 2 hours ago) and read 2357 times:
As a previous push-backer, I can tell you that this is just impossible. With nowadays hub and spoke fashion, you' r already short of push back tugs when all planes depart together. You have to speed between 2 gates and always take the first one ready to depart. I remember one day when I was on duty at the cargo terminal and had 3 departures within 10 minutes of each others (Air Hong-Kong 747 - China Eastern MD11 and Royal Jordanian 707)...nightmare.
Don't forget that a tug cost a lot (not speaking of the driver itself) so I don't see an airline buying 20 extra tugs just to save the taxi fuel. Can't imagine the additional traffic jams at holding point!. Takes at least 5 min to disconnect towbar and start engines...
This procedure should be allowed only for very long haul flights were each lbs of fuel needs to be saved.