Re: Backing under own power

From:         rdd@cactus.org (Robert Dorsett)
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Date:         02 Jun 93 00:16:15 PDT
References:   1
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In article <airliners.1993.430@ohare.Chicago.COM> tdlowe01@ulkyvx.louisville.edu writes:
>Something I've always wondered.  Are jet aircraft able to back up under
>their own power?  I've often heard rumor that they can, but usually don't
>because of visibility problems, etc.  I know at UPS, we always use tugs to
>back our aircraft.

Airplanes with thrust reversers can generally push back under their own
power (not sure about planes with cascade reversers, though).  It requires 
a special ground control clearance, it can only be done in certain wind 
conditions (no appreciable tail-wind), and it may not always be feasible 
(airports where it's common often have blast-louvred and reinforced windows 
near the gates).  It may also not be desirable due to ground clutter or
personnel.

The reason it's done is to save time: if Southwest couldn't push back,
I'm sure its efficiency would go to hell in a handbasket. :-)  Beats having
to wait for a tug, wait for it to hook up, wait for it to disconnect, etc.

When is a tug better?  To save fuel, when you have the time.  A 747, for
instance, might start one engine for hydraulics, get a push-back, then
start the rest when backed out and waiting for the tug to disconnect.  A 
little bit of fuel on a lot of airplanes means big savings.

Tugs tend to be quite noisy, and can generally be easily heard from the
cabin.


---
Robert Dorsett
rdd@cactus.org
...cs.utexas.edu!cactus.org!rdd