captainsimon
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Reversing From A Gate

Tue Mar 13, 2007 1:57 am

It seems to me that waiting for ground tug for reversing aircraft from gates to the start up area on the apron wastes so much time and manpower and cost airlines millions a year.

I did once here that Boeing were developing a system where a 737 could reverse from an gate using its own power supplied by electric motors in the landing gear wheels.

This system would be a big advantage to the low cost airlines.

Is this development still going ahead?
 
mkorpal
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:00 am

It doesn't take that much time or effort to push back. The only advantage I could see is for very remote locations.
 
captainsimon
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:09 am

It did when I was at London Stansted this morning, Flying to Milan (LIME).
We were on time for our slot but was delayed for 15 mins waiting for a tug, this 15 minute delay meant that we lost our T/O slot. We were delayed for 40 minutes in total.
 
RDUDDJI
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:13 am

Yes, it would save money, but at with a risk to safety. Airplanes aren't made to "drive" in reverse. Some carriers already practice this (although usually only with clam shell reversers). It still usually requires a guideperson to keep the aircraft from hitting any obstructions. We used this practice when I worked at JI years ago (with our F100's). It's not without it's risks though. It sprays FOD towards the ramp crew and the terminal area. A small piece of crumbled concrete or something at that speed could critically injure someone or a piece of equipment. At JI the person guiding the aircraft back was required to wear safety goggles for that reason.
Sometimes we don't realize the good times when we're in them
 
KELPkid
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RE: Reversing From A Gate

Tue Mar 13, 2007 4:41 am

Many DC-9's are fully capable of a "powerback" (using reverse thrust to get out of a gate). NW airlines used to be a big proponent of this...wonder if they still do with fuel costs the way they are now  Wink
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
MDorBust
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RE: Reversing From A Gate

Tue Mar 13, 2007 5:09 am

AA used to powerback all of it's MD's at DFW.

It wears engines out faster and isn't fuel efficient. Not to mention, it's dangerous.

Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.
"I KICKED BURNING TERRORIST SO HARD IN BALLS THAT I TORE A TENDON" - Alex McIlveen
 
KELPkid
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RE: Reversing From A Gate

Tue Mar 13, 2007 5:28 am

Quoting MDorBust (Reply 5):
Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.

You sure about that? Everything I read on the Air Florida Potomac accident indicates that the fatal flaw was not turning on the engine inlet de-icinig, which allowed some important probes (EPR?) to ice over, thereby giving innacurate readings. The Aircraft Flight Manual recommended turning the probe de-icing on in any sort of freezing conditions...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
MDorBust
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RE: Reversing From A Gate

Tue Mar 13, 2007 6:18 am

Quoting KELPkid (Reply 6):
You sure about that?

Yup. Page 80 of the NTSB report mentions it in the findings of the investigation.

Quoting KELPkid (Reply 6):
...not turning on the engine inlet de-icinig

Not activating the de-icing was a major contributing factor to the crash. So was parking too close behing a DC-9. All three were contributing factors to the crash.
"I KICKED BURNING TERRORIST SO HARD IN BALLS THAT I TORE A TENDON" - Alex McIlveen
 
captainsimon
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RE: Reversing From A Gate

Tue Mar 13, 2007 6:49 am

I think we are going slightly off topic here, I asked about the Boeing programme of motors in the landing gear wheels in the 737 that was launched with the request of no frill carriers not DC9s.
 
JayDub
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RE: Reversing From A Gate

Tue Mar 13, 2007 6:57 am

Just about any aircraft with tail mounted engines can do a powerback. It's just not a good practice economically unless there is no other option.

Even if Boeing puts together a "reverse gear" on 737's, it likely wouldn't be used to back from a gate. Too much traffic, too much ground service equipment that could be hit. It would likely be used in a situation where an aircraft needed to back away from another aircraft on a taxiway.
"Travel is only glamorous in retrospect." - Paul Theroux
 
MDorBust
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RE: Reversing From A Gate

Tue Mar 13, 2007 7:05 am

Quoting Captainsimon (Reply 8):
...I asked about the Boeing programme of motors in the landing gear wheels in the 737 that was launched with the request of no frill carriers not DC9s.

Right, nevermind the discussion about self propelled pushback then.

Fine, you're into engineering. You should know why such a proposal is a no go from the start.

Have a nice day.
"I KICKED BURNING TERRORIST SO HARD IN BALLS THAT I TORE A TENDON" - Alex McIlveen
 
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Jetlagged
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RE: Reversing From A Gate

Tue Mar 13, 2007 7:52 am

Quoting MDorBust (Reply 10):
Fine, you're into engineering. You should know why such a proposal is a no go from the start.

Have a nice day.

Not so fast. As long as the electric motor doing the driving has something else to do, such as providing normal braking, it might just be feasible. It doesn't take much force to get an airliner rolling. Self reversing might not be practical on a busy ramp though.

Alternatively, what if each gate had a conveyor belt ...... perhaps let's not go there again  Smile
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
MDorBust
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RE: Reversing From A Gate

Tue Mar 13, 2007 9:10 am

Okay then, lets take a look at this.

Someone wants to create a drive motor system that can allow 737s to do self powered pushbacks, and they're going to offset the use of this device by combining it as a braking system. We'll just assume as given that it's even technologically feasible to build such a system into a 737s landing gear.. Alright, now they need to do integration work. They need to develop an in cockpit control system for the pushback sequence and route all the wires and cables to connect it, as well as redevelop the control logic for the 737 brake controls. They are also going to have to get all of this new equipment certified and approved by the various controlling agencies then refit it into the 737s. At some point, they will also have to retrain all of your pilots for it's use. Don't forget to refit the simulators while you are at it.

There won't ever be a cost benefit analysis that will find this program favorable.

We've pretty much seen agreement that you aren't going to see self powered pushbacks at a busy airports as you are going to at least need a wing team to avoid collisions, leaving us with the low density market where you could just do turn outs instead of pushbacks anyways.
"I KICKED BURNING TERRORIST SO HARD IN BALLS THAT I TORE A TENDON" - Alex McIlveen
 
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HAWK21M
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RE: Reversing From A Gate

Tue Mar 13, 2007 12:56 pm

Quoting Captainsimon (Thread starter):
did once here that Boeing were developing a system where a 737 could reverse from an gate using its own power supplied by electric motors in the landing gear wheels.

Never heard of this.

And remember during Powerbacking a B737 DO NOT USE THE BRAKES to stop.
 Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
KELPkid
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RE: Reversing From A Gate

Tue Mar 13, 2007 1:56 pm

Quoting HAWK21M (Reply 13):
And remember during Powerbacking a B737 DO NOT USE THE BRAKES to stop.

regds
MEL

Wow, had no idea a B737 could powerback  Smile

What happens if you tap the brakes, do you end up on the tail?
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
rwessel
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:13 pm

Quoting Jetlagged (Reply 11):
Not so fast. As long as the electric motor doing the driving has something else to do, such as providing normal braking, it might just be feasible. It doesn't take much force to get an airliner rolling. Self reversing might not be practical on a busy ramp though.

The system that's been proposed would add a modest sized (and heavily geared) electric motor to the nose gear only. The only link I could find on short notice:

http://seattlepi.nwsource.com/business/235015_air03.html
 
OPNLguy
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:33 pm

[threadcreep]

Quoting MDorBust (Reply 5):
Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.



Quoting KELPkid (Reply 6):
You sure about that? Everything I read on the Air Florida Potomac accident indicates that the fatal flaw was not turning on the engine inlet de-icing, which allowed some important probes (EPR?) to ice over, thereby giving innacurate readings. The Aircraft Flight Manual recommended turning the probe de-icing on in any sort of freezing conditions...



Quoting MDorBust (Reply 7):
Yup. Page 80 of the NTSB report mentions it in the findings of the investigation.



Quoting MDorBust (Reply 7):
Not activating the de-icing was a major contributing factor to the crash. So was parking too close behing a DC-9. All three were contributing factors to the crash.

As a former QH employee there at the time, I have to say that it's more than a little disingenuous to state "Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac" and infer that was a sole cause of the accident--there were many factors.

[/threadcreep]

Back to the subject, IMHO, installing some type of self-propelling mechanism on the aircraft itself would hardly be cost-effective. Sure, at some airports, there's wait for an available pushback tug/towbar, but more often than not, there isn't any wait, or only a minor one. Any self-propelling mechanism is going to add weight to the aircraft, and that means additional fuel burned, whenever the aircraft flies, including into airports where its use is not needed. It'd be far more cost-effective for an airline to acquire additional pushback tugs/towbars where they're needed so that delays (if any) awaiting them were minimal.

As far as the additional weight goes, let's assume a new-fangled self-propelling mechanism adds 200 bs. of weight to the aircraft. Doesn't sound like much, but whatever weight is added costs you about 2.5% of the weight in fuel consumption. (The exact percentage varies by stage length, but 2.5% is conservative). So:

200 lbs
x .025
= 5 lbs. of fuel wasted per flight
x 8 flts a day
40 lbs of fuel wasted per day, per aircraft
Divided by 6.7 lbs-to-gals
=5.97 gals, rounded up to 6.0 gallons
x $2.20 a gallon
=$ 13.20 a day wasted, per aircraft
x 365
= $4,818 wasted per year, per aircraft
x 100 aircraft fleet
= $481,800 wasted per year, feet-wide

That nearly $500,000 a year is a recurring cost, and over 10 years, that'd be nearly $5,000,000. Not included in any of that is the cost of acquiring/installing such a self-propelling mechanism, and the lost revenue from the aircraft downtime for installation.

Bottomline (literally), is that even at $481,800, or even half that, an airine could buy a shitload of additional pushback tugs/towbars for precisely the locations where they're needed.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
reins485
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RE: Reversing From A Gate

Tue Mar 13, 2007 2:54 pm

http://www.boeing.com/news/releases/2005/q3/nr_050801a.html

That is the press release talking about the 767 test. I think if Boeing wanted to it would not be very difficult to integrate it into the 787 program and with a few engineering modifications more airplanes could be integrated.

Quoting MDorBust (Reply 12):
There won't ever be a cost benefit analysis that will find this program favorable.

Well if it is used to taxi the airplane to the runway from the gate and less fuel is required then it would be as well as the fact that there would be less ware and tear on the engines. Plus, instead of starting an engine to a move a plane during a ground delay all they would have to do is kick the motor in gear, because the apu is most likely running anyways to keep people happy. Thus, as long as the apu is more efficient than an engine even if its not very large obviously that would mean less fuel that would have to be bought and burned just moving around an airport.

Quoting MDorBust (Reply 5):
ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.

Actually you just pulled that from a finding and not a conclusion of the report.
According to page 59 of the report "The Safety Board cannot conclusively determine whether the use of reverse
thrust affected the amount or character of the contaminant which subsequently adhered
to the aircraft. An American Airlines mechanic stated that he did examine the engines
following the use of reverse thrust and other personnel in the area stated that they did not
See any water or slush on the wings. However, heat developed from the engines and
reversers and the blowing snow and slush could have deposited a wet mixture, particularly
on the wing leading edge, which was not significant to observers, but which subsequently
froze and increased the leading edge area’s susceptibility to further accretions during the
continuing precipitation"
And there is no mention of the power back in the probable cause of the report causing the accident.
http://amelia.db.erau.edu/reports/ntsb/aar/AAR82-08.pdf
 
GQfluffy
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RE: Reversing From A Gate

Tue Mar 13, 2007 3:08 pm

Quoting Mkorpal (Reply 1):
The only advantage I could see is for very remote locations.

If a location is that remote, odds are the aircraft just turn out without hitting any buildings. Again, because this is a remote location, there probably won't be any ground equipment to worry about.

Quoting RDUDDJI (Reply 3):
Airplanes aren't made to "drive" in reverse.

True to an extent. Our (GQ) Metroliners could powerback rather easily, and the wasted fuel was marginal. The only trick was you had to make sure the a/c didn't get moving to quick, otherwise if the pilots touch the brakes, or they swap the props back to forward thrust too quickly, the Metro will sit on it's ass quicker then a blink of the eye.
This isn't where I parked my car...
 
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HAWK21M
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RE: Reversing From A Gate

Tue Mar 13, 2007 10:42 pm

Quoting KELPkid (Reply 14):
What happens if you tap the brakes, do you end up on the tail

Exactly.Remember the MLG has the Brakes  Smile
The procedure is to use Fwd trust to stop.
Not Advisable using Powerbacks on Wingmounted Engines though.


regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
MDorBust
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RE: Reversing From A Gate

Tue Mar 13, 2007 11:36 pm

Quoting OPNLguy (Reply 16):
and infer that was a sole cause of the accident--there were many factors.

Never meant to imply it as the sole cause of the incident. There is almost never an accident caused by a single point of failure.

Quoting Reins485 (Reply 17):
And there is no mention of the power back in the probable cause of the report causing the accident.

Section 3: Conclusions, subsection 3.1 Findings, Item 9.

As I said, page 80.

By the way, good cherry picking from the report there. Accidentally forget the significant portions of the entry?

Let's try the whole selection:

Quote:
Use of Reverse Thrust During Pushback.-The surface condition in the gate
area was slippery and the tug which was connected to the aircraft for the pushback after
the aircraft was deiced could not develop the traction needed to move the aircraft. After
it was apparent that the aircraft could not be moved with the tug, the flightcrew started
the engines and used reverse thrust to help pushback, contrary to advice from the tug
operator that the use of reverse thrust was prohibited by American Airlines' policy.
Witnesses estimated that the engines were operated for 30 to 90 seconds during which
time snow and slush were blown around the aircraft. The aircraft failed to move even
with the combined effort of reverse thrust and the tug, and the engines were shut down.

During its investigation, the Safety Board determined that Boeing Operations
Bulletins warning against the use of reverse thrust because of occurrences of takeoff
pitch control anomalies with the B-737 aircraft after ground operation in freezing
conditions, had been incorporated into Air Florida flightcrew's manuals.

The Safety Board cannot conclusively determine whether the use of reverse
thrust affected the amount or character of the contaminant which subsequently adhered
to the aircraft. An American Airlines mechanic stated that he did examine the engines
following the use of reverse thrust and other personnel in the area stated that they did not
See any water or slush on the wings. However, heat developed from the engines and
reversers and the blowing snow and slush could have deposited a wet mixture, particularly
on the wing leading edge, which was not significant to observers, but which subsequently
froze and increased the leading edge area's susceptibility to further accretions during the
continuing precipitation.

The Safety Board believes that the flightcrew was influenced by the prolonged
airport closure and by additional delays at pushback, leading them to use reverse thrust to
expedite operations. Regardless, the Safety Board concludes that the flightcrew's actions
in using reverse thrust contrary to advice and guidance provided indicates a lack of
Professional judgment consistent with their total performance. Whether the flightcrew
Was familiar with the guidance in the Operations Manual and consciously disregarded it
Cannot be determined.
"I KICKED BURNING TERRORIST SO HARD IN BALLS THAT I TORE A TENDON" - Alex McIlveen
 
kalvado
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RE: Reversing From A Gate

Wed Mar 14, 2007 12:11 am

Quoting OPNLguy (Reply 16):

200 lbs
x .025
= 5 lbs. of fuel wasted per flight
x 8 flts a day
40 lbs of fuel wasted per day, per aircraft
Divided by 6.7 lbs-to-gals
=5.97 gals, rounded up to 6.0 gallons
x $2.20 a gallon
=$ 13.20 a day wasted, per aircraft
x 365
= $4,818 wasted per year, per aircraft
x 100 aircraft fleet
= $481,800 wasted per year, feet-wide

That nearly $500,000 a year is a recurring cost, and over 10 years, that'd be nearly $5,000,000. Not included in any of that is the cost of acquiring/installing such a self-propelling mechanism, and the lost revenue from the aircraft downtime for installation.

Bottomline (literally), is that even at $481,800, or even half that, an airine could buy a shitload of additional pushback tugs/towbars for precisely the locations where they're needed.

Sounds like you suggest removing a single olive from the salad...  Yeah sure

back to numbers:
If you have 100 planes going to 100 outstations, you must have 100 tugs sitting there. Just a guess, a tug would cost about the same as a new car - 25-30 k$, so that's $2.5-3M of saved expenses right away, if tug lifetime is the same as a plane.
I'm not so sure what the bottom line would be with everything being put in equation - rampers hours, tug delays, MX for tugs and pushback motors.

Since 737 replacement is discussed daily, fitting something new on a new type of a plane does not sound unreasonable, and pilots need to be re-trained anyways.

So crazyness doesn't look obvious to me - maybe I'm missing something here?
 
DH106
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RE: Reversing From A Gate

Wed Mar 14, 2007 12:33 am

Quoting MDorBust (Reply 5):
Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.



Quoting MDorBust (Reply 7):
Quoting KELPkid (Reply 6):
You sure about that?

Yup. Page 80 of the NTSB report mentions it in the findings of the investigation



Quoting MDorBust (Reply 20):
The Safety Board cannot conclusively determine whether the use of reverse
thrust affected the amount or character of the contaminant which subsequently adhered
to the aircraft

The report mentions it but cannot "conclusively determine" that it contributed to the accident.
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
OPNLguy
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RE: Reversing From A Gate

Wed Mar 14, 2007 12:56 am

Quoting Kalvado (Reply 21):
Sounds like you suggest removing a single olive from the salad...

My airline doesn't serve salads (or meals), but the principle remains the same, namely what seems like a "minor" expense on a per-flight basis can often be huge one on an annual fleet-wide basis.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
captainsimon
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RE: Reversing From A Gate

Wed Mar 14, 2007 1:09 am

I heard in the grape vine that Ryanair are interested in this system as it would save money that they pay to ground handling companies and help keep flights ontime and keep fares down.
 
avconsultant
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RE: Reversing From A Gate

Wed Mar 14, 2007 5:11 am

Quoting Kalvado (Reply 21):
Just a guess, a tug would cost about the same as a new car - 25-30 k$, so that's $2.5-3M of saved expenses right away, if tug lifetime is the same as a plane.

The price of a new tugs push close to $100,000 with some tugs over million. Not including maintenance cost and registering the vehicle with airports, you're correct the +$400k for the aircraft system offests the tugs.
 
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Jetlagged
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RE: Reversing From A Gate

Wed Mar 14, 2007 5:27 am

Any system which drives through the aircraft wheels, especially the nosewheel, is going to be very low on traction, compared to a specialised pushback tractor. I should have thought such a sytem, if fitted, should drive through the main wheels, with the nosewheel being used for steering. The main wheel tyres would have more traction, being larger and carrying more of the aircraft weight. It would also be more stable directionally (main wheels pulling the aircraft back, rather than the nosewheel pushing it). It would only be necessary to drive one main wheel or axle. The nosewheel steering could easily counter the asymmetry.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
reins485
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RE: Reversing From A Gate

Wed Mar 14, 2007 9:58 am

Quoting MDorBust (Reply 5):
Ice ingestion during the powerback of an Air Florida 732 brought it into the Potomac.

This statement makes it look like you are saying this was the main and maybe the only cause, when it didn't even mention it in the probable cause.

Quoting MDorBust (Reply 20):

Never meant to imply it as the sole cause of the incident. There is almost never an accident caused by a single point of failure.

Well you need to be more careful about that and further more I know that several things have to go wrong but that was not listed as a probable cause, which is the NTSB taking the findings and determining which ones most likely caused the accident.

Quoting DH106 (Reply 22):
The report mentions it but cannot "conclusively determine" that it contributed to the accident.

That is my point if some thing in my field of study can't be conclusively determined then you really haven't proven it and thus they couldn't conclusively determine "the use of reverse thrust affected the amount or character of the contaminant which subsequently adhered to the aircraft." Then it is improper to cite that as a cause.

Quoting MDorBust (Reply 20):

By the way, good cherry picking from the report there. Accidentally forget the significant portions of the entry?

And I didn't want to fill up an entire page on someones computer with text in which only one line was important.

And I didn't mean to offend you, I just wanted to clarify what the probable cause of the accident actually was.
 
kalvado
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RE: Reversing From A Gate

Wed Mar 14, 2007 10:53 am

Quoting OPNLguy (Reply 23):
My airline doesn't serve salads (or meals), but the principle remains the same, namely what seems like a "minor" expense on a per-flight basis can often be huge one on an annual fleet-wide basis.

Agreed, but there is a very fine line between actually saving something, and showing savings in accounting.
In both cases we're talking about something like 1 cent per seat-flight; all expenses will be offset by 1 extra ticket per plane*month for WN, or 1 premium ticket per plane*year for AA salads - and you would never know what caused that small changes in ticket sales.
Not pissing off that single olive lover could actually help AA bottom line; and you probably could tell me how much 10 minutes of gate delay due to tag issues would cost.
While you're probably correct with spending side of the balance sheet (well, actually it's you who is the expert!), there may be some benefits as well..
 
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LHRBFSTrident
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RE: Reversing From A Gate

Wed Mar 14, 2007 1:10 pm

i saw something at JNB last week that I have never seen before - 'driverless' tugs pulling the a/c back to the taxiway from the stand.

Saw it in action on an SAA 738 and a Kulula.com MD-80 - it connected to the l/h main gear facing direction of travel (ie towards the a/c tail) and appeared to be operated by remote control (ground crew with a control box standing in the alley behind the a/c hopped onto the tug after it was clear of the a/c and had taxied away)

There appeared to be no wing walkers - so my guess is this system is more cost effective by reducing the number of personnel needed at pushback ('pullback' in this case?!)

is anyone familiar with this system - and/or familiar with its advantages/disadvantages?
 
speedracer1407
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RE: Reversing From A Gate

Wed Mar 14, 2007 2:46 pm

Quoting Kalvado (Reply 21):
If you have 100 planes going to 100 outstations, you must have 100 tugs sitting there.

Is that true though? Can't tugs be driven from gate to gate? All 100 planes don't leave at the same time, and while I know nothing about airport ground operations, I assume that one tug can keep itself busy pushing back planes from various gates at various times.

Some other thoughts:

-Although I know nothing about the longevity of tugs, it seems to me like an expensive piece of very heavy duty equipment like that should last for a VERY long time. In contrast, a pushback mechanism light enough to be feasibly installed on an aircraft might either require frequent maintenance or frequent replacement. Just an assumption, but I think it's a logical one.

-Would a pushback mechanism really be only a few hundred pounds? If nose-gear mounted devices didn't provide enough traction, it seems to me like designers couldn't just stick a torquey motor on a MLG wheel, even if the MLG were designed from scratch for an all-new airframe. Thus, the motor would need to be located near the wheel well with a transmission routing power (possibly through or beside the MLG oleo) to the wheels via long, heavy shafts. Seems like that'd weight a whole lot more than a couple hundred pounds.

Just some thoughts,

O
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
 
Mr AirNZ
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RE: Reversing From A Gate

Wed Mar 14, 2007 5:25 pm

When I was still working for Air NZ we would sometimes have ATR's reverse themselves out of a gate if for whatever reason their was not enough room to turn around.
 
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HAWK21M
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RE: Reversing From A Gate

Thu Mar 15, 2007 1:19 pm



Powerpush in Operation.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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LHRBFSTrident
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RE: Reversing From A Gate

Thu Mar 15, 2007 1:33 pm

yeah - that's the one MEL, thanks! - so officially it's called 'powerpush'?
 
Western727
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RE: Reversing From A Gate

Fri Mar 16, 2007 9:54 am

Quoting HAWK21M (Reply 32):
Powerpush in Operation.

Thanks, MEL. That is fascinating! Here's the description from the video you posted:

[paste]
Jetstar A320 pushing back using the PPS (power push system) at Melbourne International Airport. The aircraft is pushed back via the rear wheel with tug without a driver. The engineer controls the PPS tug with a remote while the pilot controls the nosewheel steering.
[end paste]

I wonder what the advantage of this system is as opposed to using a regular tug attached to the nose gear...? Why isn't it a widespread practice, unless it's still a very new method?
Jack @ AUS
 
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HAWK21M
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RE: Reversing From A Gate

Fri Mar 16, 2007 11:12 am

I may not win often, but I damn well never lose!!! ;)
 
Western727
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RE: Reversing From A Gate

Sat Mar 17, 2007 3:37 am

Quoting HAWK21M (Reply 35):
http://www.schopf-gse.com/products/tractors/powerpush.php

Much gratitude, MEL. I hope to see this more widespread in the near future, including the United States.
Jack @ AUS
 
Electech6299
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RE: Reversing From A Gate

Sat Mar 17, 2007 11:27 am

Quoting Speedracer1407 (Reply 30):
In contrast, a pushback mechanism light enough to be feasibly installed on an aircraft might either require frequent maintenance or frequent replacement. Just an assumption, but I think it's a logical one.

I have to agree with you... a mechanism like this installed on the nose gear would fall into the category of "underdesigned but functional". Just because a motor will function at it's desired loading doesn't mean that it will do so indefinitely. This is why most things (aviation leading the way) are de-rated from their "design" loading, even though the design loading is in fact derated from the ultimate capacity (usually by 50% or more). If there's an engineer that can design a motor, drive, and control system weighing only 200 lbs. that can be mounted to a nosewheel of an aircraft and effectively move 2.5 times the mass of a MTOW 767 from a dead stop, I really want to meet him!

And then there are the inevitable consequences of overdriving the mechanism when a ramper forgets to pull the chocks, and the pilot forgets to confirm.

Finally, the only ramper that can be replaced is the tug driver, and only if he is not doubling with signaling. If you need wing walkers, you need wing walkers-- it doesn't matter what the drive mechanism is. And you will always need the signalman. So I really don't see the savings on personnel.

Oh, wait a minute, I'm supposed to support the Mx, especially the whitecoats. Hell yeah, put them on! Job security, baby!
Send not to know for whom the bell tolls...it tolls for thee
 
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HAWK21M
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RE: Reversing From A Gate

Mon Mar 19, 2007 9:53 pm

Quoting MDorBust (Reply 5):
AA used to powerback all of it's MD's at DFW



Very neat Powerback.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Western727
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RE: Reversing From A Gate

Mon Mar 19, 2007 11:38 pm

Quoting HAWK21M (Reply 38):
Very neat Powerback.

Thanks, MEL, for making me drool at that classic DC-9-10!  cloudnine 

Living in MSP, I fondly remember all the 9 pushbacks I either watched or rode. I do have a tape of a 727 powerback from one of the G gates (the video you post is of the C concourse, btw), viewed from seat 4A. Starts with the 727 lurching forward a few feet towards the jetway and then powerbacking.

Immediately after reverse is terminated, the leading edge slats come right down as the 727 taxis forward and turns to the right for a flight to DEN in September 2002. Very cool.
Jack @ AUS
 
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HAWK21M
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RE: Reversing From A Gate

Sun Mar 25, 2007 9:58 pm

Quoting Western727 (Reply 39):
I do have a tape of a 727 powerback from one of the G gates (the video you post is of the C concourse, btw), viewed from seat 4A. Starts with the 727 lurching forward a few feet towards the jetway and then powerbacking.

Is it possible for it to be uploaded on maybe Youtube.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Western727
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RE: Reversing From A Gate

Mon Mar 26, 2007 8:15 am

Quoting HAWK21M (Reply 40):
Is it possible for it to be uploaded on maybe Youtube.

Certainly. I do need to get a new A/V cable for my camcorder (cannot find the one I had) to be able to import from the VHS videotape, before I can then transfer from the digital camcorder to my PC. I'll post the link once done, hopefully within a couple of days.
Jack @ AUS
 
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HAWK21M
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RE: Reversing From A Gate

Mon Mar 26, 2007 11:39 pm

Quoting Western727 (Reply 41):
I'll post the link once done, hopefully within a couple of days.

Thanks.Looking fwd to it.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Gib
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RE: Reversing From A Gate

Tue Mar 27, 2007 11:22 am

I'll never forget the time where this dude I worked with backed an AA MD-82 right into the mud. The right main sunk real good. Not a good day.
 
Western727
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RE: Reversing From A Gate

Thu Mar 29, 2007 12:30 am

Quoting HAWK21M (Reply 42):
Thanks.Looking fwd to it.

MEL and others: I apologize for I am not able to transfer the video to the PC yet, and I have to fly to AUS this afternoon, and I return on 2 April, so expect a posting no earlier than 3 April. I will let you know. Thanks for understanding.
Jack @ AUS
 
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HAWK21M
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RE: Reversing From A Gate

Thu Mar 29, 2007 1:46 am

Quoting Western727 (Reply 44):
I will let you know. Thanks for understanding.

No pressure.Take your time.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Starglider
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RE: Reversing From A Gate

Thu Mar 29, 2007 6:31 pm

Quoting Captainsimon (Thread starter):
did once here that Boeing were developing a system where a 737 could reverse from an gate using its own power supplied by electric motors in the landing gear wheels.

This system would be a big advantage to the low cost airlines.

Is this development still going ahead?

Honestly, i believe this idea will be shelved right next to the idea of wheel spin-up prior to landing, for the same reasons:

weight, maintenance costs and reliability.

Just my  twocents 


Starglider
 
DH106
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RE: Reversing From A Gate

Thu Mar 29, 2007 7:41 pm

Quoting Starglider (Reply 46):
Honestly, i believe this idea will be shelved right next to the idea of wheel spin-up prior to landing, for the same reasons:

I've often thought of a much simpler 'wheel spin up' system - smallish angled vanes or shapes on the wheels hubs that aerodynamically spin the wheels up in the same way an anemometer works (kinda cup shapes rotate round a shaft). When the gear extends into the slipstream, the wheels (as they're fairly massive) slowly start to spin up. If they were optimised & shaped correctly they could be optimised to approximately match the wheel rolling speed to the airspeed - or some value below it if needed Would obviously cause some extra drag when the gear was down and I guess there would be gear door clearance issues with some aircraft.
...I watched c-beams glitter in the dark near the Tanhauser Gate....
 
Starglider
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RE: Reversing From A Gate

Thu Mar 29, 2007 7:54 pm

Quoting DH106 (Reply 47):
I've often thought of a much simpler 'wheel spin up' system - smallish angled vanes or shapes on the wheels hubs that aerodynamically spin the wheels up in the same way an anemometer works (kinda cup shapes rotate round a shaft).



That idea has surfaced before as well and was shelved too for most of the same reasons. Mainly maintenance and reliability in this case. Ice accumulation (with danger of shedding ice striking other components), dirt, damaged, or warped vanes were considered a potential source for vibration.


Starglider

[Edited 2007-03-29 13:24:28]
 
Starglider
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RE: Reversing From A Gate

Fri Mar 30, 2007 8:57 am

Quoting MDorBust (Reply 7):
Not activating the de-icing was a major contributing factor to the crash. So was parking too close behing a DC-9. All three were contributing factors to the crash.

Asymmetric application of de-icing fluid/water mixture between left and right side of the aircraft due to a shift change during the de-icing / anti-icing process (????), and 50 minutes between treatment and take-off with exposure to moderate to heavy snowfall were also contributing factors in this accident. Also the lack of an outside visual or tactile inspection to make sure the aircraft was free of snow or ice contamination before dispatch was a contributing factor. To quote the AAR-82-8 report: "The Safety Board believes that an outside observation of the conditions may have influenced the crew's assessment of the wet/dry characteristics of the falling snow, an assessment which may have affected their later decisions."

National Geographic Channel's "Seconds From Disaster" is broadcasting this accident tonight on TV over here. I'll be watching. This accident always crosses my mind when the winter season starts, reminding me what is at stake during winter adverse weather operations. This accident and a few others in the early 90s resulted in improved procedures used today with better supervision.


Starglider

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