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Archive => Other Topics => Old Forum => Real-world aviation => Topic started by: EHM-1001 Robert on January 25, 2008, 10:12:02 pm

Title: Powerpush
Post by: EHM-1001 Robert on January 25, 2008, 10:12:02 pm
Hi mates,

I red it somewhere that there is not only Pushback, but also Powerpush. Here, a tractor pushes one of the main gears, while the crew is steering the aircraft. Although I cant imagine why is it better than pushback...

Any ideas ?
Title: Powerpush
Post by: EHM-1651 Christian on January 26, 2008, 08:22:23 am
You won't have to remove the pin or struts to the nose wheel steering on the nose landinggear, that way saving some time on pushback connecting and reconecting that system to the nose gear. That is the only advantage I can think of.
Title: Powerpush
Post by: EHM-1001 Robert on January 26, 2008, 09:09:29 am
I thought maybe because of noise restrictions. Also it may depend on where the aircraft nose is pointing. Although I still do not know an airport where it was used...
Title: Powerpush
Post by: EHM-1651 Christian on January 26, 2008, 09:32:06 am
The powerpush term is also used when aircraft perfrom pushback using their own enginepower, the DC-9's adn MD-80's were certifed for that aswell as ATR's.
Title: Powerpush
Post by: EHM-1001 Robert on January 26, 2008, 09:41:56 am
Well, by push I really meant a push forward :) So I seen a picture where the push tractor pushes the main gear strut from behind, and the stupid guys up in the cockpit were playing with the nosewheel to keep the baby in direction :P

I heard (maybe here) some powerful turboprops can make a pushback from the gate with "reversed thrust" setting of feathers. That could be strange though, I would like to see one ;D
Title: Powerpush
Post by: EHM-2155 Mariano on January 26, 2008, 09:26:04 pm
Yeah Rob, not only turboprops but some jets do that also. I have seen some videos in youtube, particularly one where it was snowy and the engine was just throwing snow all around...

Here's an example http://www.youtube.com/watch?v=DZSs_Fmyvx4
Title: Powerpush
Post by: EHM-1001 Robert on January 26, 2008, 09:52:39 pm
Wow. Thanks, that looks very interesting. Like the pilot would push it to reverse gear. And it at the end it will shoot out with spinning and smoking tyres ;D

Okay. I think the reason of that is the rear mounted engines. They are quite away from the terminals and cannot cause too much trouble for the building and the traffic in front of it.
Title: Powerpush
Post by: EHM-1883 Matt on January 27, 2008, 01:05:31 am
sometimes when flying in certain airports online (somewhere, can't remember) the controller tells me there's no pushback, you just go straight on to the taxiway infront of you. Maybe a powerpush is used there?
Title: Powerpush
Post by: EHM-1001 Robert on January 27, 2008, 09:48:17 am
That is a good question.

I think we need to divide it to two versions. I think the Powerpush is used to push you away fro the terminal area when your engines are pointing toward the terminal.

In the other case, parking spots make a kind of comb form: spots are next to each other in a row, but there is a line of taxiway behind and in front too... just an example is Vienna airport parking zone: LOWW. I think there you are far enough from the terminal, and so after you made en engine start you can turn onto the taxiway in front of you and go.
Title: Powerpush
Post by: EHM-2097 Andrei on January 27, 2008, 08:30:43 pm
A few more comments:

The powerpush unit (or PPU) is a remote controlled device, unlike the tractor used for pushback which is manned by the ground crew. From this comes the big difference, who is responsible for aircraft movement at this stage? I think the PPU technique may be in advantage because it does require less coordination between pilots and ground crew (as any coordination requirement introduces some risks too).

Then, after seing a picture of such a PPU, it's much smaller than a tractor. I suppose (in fact, rather speculate :) ) that it may be usable in confined places where there is no room for a tractor.

And, of course, it's about ease of mount/dismount too as Christian has pointed out.

One more thing (though I promised myself NEVER to argue on terminology), the fact of moving the aircraft backwards with its own power is called "powerback". Some virtual pilots on IVAO use to make fun of unsuspecting ATC like "this is an ATR, clear me to powerback not pushback, ha, ha".

In FS almost any aircraft is able to powerback ( except gliders, I presume :)  ) but in real life this technique is very restricted due to collateral risks. A B737 ditched into the Potomac after a failed take-off years ago, under heavy snow, due to engine power loss, and the investigation concluded that one cause were the pilots "helping" pushback by engaging reverse thrust. It was supposed the engines sucked in snow in the process.

So I think another reason for allowing this preferably to tail-engine aircraft is that in this configuration, engines are generally farther up from the ground.

Andrei
Title: Powerpush
Post by: EHM-1001 Robert on January 28, 2008, 06:56:11 pm
Powerback :D Very nice ;)