rj777
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Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 2:48 pm

Would it be more expensive to use thrust reversers or a tow tug to pushback an airplane?
Just something to throw around.
 
ben88
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 2:53 pm

There is no question it would be more expensive to use reverse thrust when you take engine wear and the risk of fod ingestion into account.
 
SkyGuy11
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 2:55 pm

Probabally more expensive to use thrust reversers. The engines operate at 60-70% of max when in reverse (correct me if I'm wrong) meaning fuel would burn faster. A tug could accomplish the same thing without the added burn. I would also think that the plane would be harder to control while reverse taxiing, there is no way for the pilot to see where he's (or she's!!!) going, and the jet blast could break some windows or at least knock some people over if it was directed toward the terminal. One more thing: if it was cheeper, the airlines would already be doing it!
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concorde1518
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 3:21 pm

AA said that one of the reasons that they are canning the 717's from TWA is because they can't be powered back by the thrust reverser. So, obviously, AA likes it as on option, so where would be a time that they would power back over a pushback?
 
hkg_clk
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 4:04 pm

I think some airports have actually banned this. There is a safety issue involved.
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D-AIGW
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 4:34 pm

At certain airports, the planes DO back out of their gates. However, it is not done in most airports due to a number of reasons.

The jet blast would create a huge windstorm in the vicinity and all hell would break loose. This can set almost anything into flight, and can cause damage to objects, injury or even death to people nearby. Also, ample fuel is required to back out. It isn't really worth backing out.

As a matter of fact, AA does it, I think it's because the airport is quite busy and the tugs aren't always available upon request, and the plane can't afford to wait for the tug or they're gonna lose the slot.
 
SESGDL
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 4:44 pm

Here @ MSP, DC-9's, Fokker 100's, 727's, and MD-80's are using thrust reversers to push all the time.
 
AUS_Spotter
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 5:50 pm

Every AA MD-80 or F100 flight I've been on from AUS or DFW have powered back from the gate. At MSP and CLE tugs have been used. From what I've seen AA always backs out of the gates at AUS with the MD-80's.

Jason
 
BestWestern
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 7:43 pm

The ATP has an excellent powerback system... probably the only saving feature in what was otherwise a terrible aircraft...

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717-200
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Thu Dec 27, 2001 11:43 pm

At ATL Air Tran powerbacks both 717's and DC9's
from most of their gates at concourse C.
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EA CO AS
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 1:40 am

Powerbacks have their downside, such as added fuel burn and possibility of FOD, but they also save the costs of owning and maintaining a fleet of tugs.

Some airports won't allow powerbacks since the aircraft has to use forward thrust to get off the flat spot on the tires created by sitting at the gate for awhile. Then the pilot engages the reversers and pushes back from the gate area. This initial forward thrust can wreak havoc on the AOA, depending on what's around (fences, other facilities, etc).

At PHX, Eastern used to do powerbacks off their gates with B-727-225s as well as B-757-225s. The 72s didn't hurt anything, but the initial forward thrust from the 75s would sometimes blow down the chain link fence lining the perimeter of the AOA.

So basically, whether or not powerbacks are used is ultimately a combination of the carrier's preference, along with the local airport management's directives.
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JA54123
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 1:57 am

I fly through DFW pretty often on AA and I have been on thier MD-80s, 727s, F-100s and even the AE ERJs when one time or another they have used the reversers to push back from the gate. It seems when at terminal B (I think) that they use the reverse thrust more often than when they are on the other side where the bulk of thier aircraft and gates are. I have never been on an aircraft with underwing engines where the reversers were used to back out of the gate. I guess the engines being low-slung are more dangerous to the ground crew working around the aircraft and are too much of a risk to do so.
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spinkid
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 2:38 am

I would say on most occassions the plane I am on uses it's thrusters to back up. This makes me believe it is cheaper or the airlines would always use a tug. The tugs are usually slower. they always seemed to be used when the plane is at a gate very close in and kind of precariously placed.

I would think it would cost more to employ an extra person to operate the tow. that more than anything would be more expensive.

 
lmml 14/32
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 3:02 am

Here in Europe I have never seen anything larger than an ATR or an ATP or Dornier 328 do a powerback. I cannot imagine a large jet maneouvering backwards in a confined space of some aprons like the Victor stands at LHR T4, for example. Re-727's I was under the impression that if a rear engined plane brakes while reversing there is the risk of it toppling backwards. From what I read here, this is not so.
 
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 3:59 am

Eastern was the first airline to use powerbacks, and when they did the initial test there was a lot of concern over whether or not a B-727 would end up on its' rear when braking. Boeing engineers said they simply weren't sure, but they thought it would be ok. Eastern went ahead and ran the test, which proved to be a rousing success. It wasn't very popular with the union, since they viewed it as being a way to eliminate the jobs of the highly-paid tug drivers. The union head (Charlie Bryan) actually went as far as to stand in back of the B-727 they used in the test, attempting to keep them from running the test. The captain applied forward thrust to get the plane off the flat spot, and the blast sent Bryan flying across the ramp. He barely had time to roll out of the way of the main gear as the plane thundered backwards. Of course, powerbacks then became an industry standard.

Eastern used the powerback procedure on all DC-9 series, B-727 series, and B-757 aircraft in their fleet. Only the widebody A-300, L-1011, and DC-10s in their fleet used standard tugs to push back.
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baec777
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 7:27 am

I prefer Tow Tugs for safeties of the plane, it can really slow the plane during push back or being towed from the hangar to the gate. I like them huge 1 with the nose wheel in the inner middle space of the tugs.

baec777
 
Goldenshield
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 7:37 am

When I worked ramp for AA, we were taught powerback procedure, however, we never actually did one, since we had ample tugs around.

The only aircraft that AA allows to powerback are the 727, md-80, and F-100 (if so equipped). We almost had to powerback a 757, however since we could not find a towbar that worked. After numerous calls, however we managed to find one that fit at UPS (there are 2 different towbar attachments that boeing made - one that could be attached by a 727 towbar, and one that was fit over like a clamp 737 style. AA had the 727 style, and DL, UA, HP, and OAS (another contractor at ONT) only had the clamp style.
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EI133
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 8:18 am

I once did a power back off a stand on an Aer lingus Fokker 50 but they are rare enough here in Dublin.
 
MD88Captain
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 8:19 am

I've used the feet flat on the floor power back technique since the Navy. It keeps you from trying to slow the aircraft with brakes and inadvertently putting the plane on its tail. Instead you ease out of reverse and apply forward thrust to slow and then stop the backward motion.

BTW. DAL forbids backing the aircraft with reverse even in a pinch. If some situation crys out for it you have to call to get premission.
 
blink182
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 9:55 am

I think thrust reversers are only used at busy airports and hubs.

For example, I have seen American use their thrust reversers at DFW all the time on MD-80s. In AUS however(i wasn't flying AA, but I was flying to Dallas though), they didn't.

I think thrust reversers are used mainly when there is a lack of tow tugs available.

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RayChuang
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 12:19 pm

I've never seen any plane at SFO, OAK or SJC use reverse thrust for pushback. I think there's two reasons for this besides the obvious problem of jet blast hazard: 1) it would dramatically increase air pollution at airports and 2) the airports I've mentioned have plentiful tugs for pushback operations.
 
DB777
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 1:08 pm

I used to approve power back ops on airport-controlled gates at MIA (excluding Eastern which at the time had leases on Concourses B and C and a few gates on Concourse D) on an individual airline basis as the gate control supervisor for the airport. We only permitted power back ops from the end gates of the concourses because of the hazards involved with the closer in gates. For a while in the early 90's, during AA's huge surge in growth due to the demise of Eastern, we allowed AA to do powerbacks off of some inner Concourse H gates before they moved to Concourse D and it caused a lot of complaints from Delta on the same concourse and from United and Air Canada at the opposite concourse on Concourse G, primarily because of jet blast and FOD flying all over.

It's one thing for power back ops on a concourse or section of an airport leased by only one airline where the airline can control their own people and secure the stuff that can fly all over and it's a totally different scenario where the gates are common-use and utilized by a variety of carriers (competitors) with different employees, service companies, caterers, fuelers, etc.

TWA had the end gates on Concourse G and we allowed them to perform power backs for a while. They wanted to do it as a cost-saving measure. Their mechanics union had a clause in their contract that only A&P mechanics could operate tugs pushing back aircraft and they could reduce the number of highly paid mechanics at the MIA station if they did power backs instead of pushbacks. The union filed a grievance and I guess they won because ultimately TWA went back to pushback ops.

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kjet12
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 1:55 pm

717-200: you said that the AirTran 717's use powerbacks at the gates, but Concorde1518 said that is why AA isn't keeping the 717!
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AA737-823
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 2:27 pm

I have seen pictures of AirTran powering back their planes.

AA does a lot of power back here at DFW. I think one reason people have neglected is the large cost of the tug. If you only buy thirty tugs, and only use them when you have to, you save much money over buying a tug for every gate for example.

I would think that powering back would be cheaper. Like this guy said about TWA.
1. Don't have to pay the guy to run the tug.
2. Don't have to buy the tug.
3. Dont' have to do the maintenance on the tug.
4. Don't have to put fuel in the tug.
5. Don't have to insure the tug.
6. Jet engine start while at gate give earlier indication of a problem.

But there are problems. FOD. And yes, you can quickly put a plane on it's butt by braking during reverse. Or so I have heard.

Randy
 
ejaymd11
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Dec 28, 2001 2:51 pm

Hey Concorde1518 one of the advantages of the
MD-90/95 was that they could power back under there own power, reducing turn around time, and equipment cost. So that can't be the reason that AA is canning there 717's.

Ejay MD-11
 
rj777
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Jan 04, 2002 1:36 am

OK Everybody,
The reason I asked was becuase when I came home to Eppley in Omaha, which is a small airport, I saw an AA MD-80 use thrust reversers to back out of the gate. Most aircraft at OMA use a tow tug.

Thanks,
RJ777
 
BestWestern
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Jan 04, 2002 1:39 am

Manx constantly power back their ATP's at DUB
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Notar520AC
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RE: Thrust Reversers VS. Tow Tugs For Pushback

Fri Jan 04, 2002 2:24 am

I think that would be a little dangerous, risking material ingestion, engine wear, controling the monster while it's moving backwards, and if the thrust was directed towards the terminal like most of you mentioned, it would be likely to shatter the windows from the jetblast and the sound waves. I believe only a few aircraft are capable of doing this, one being the MD-80 (correct me if I'm wrong). How does it manage to do this? Is it becase it has clamshell reversers and not he engine cowling that slides back, revealing the cascades?
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