Re: Boeing cancels 747-500X/600X?

Date:         01 Mar 97 18:42:14 
From: (Michael Jennings)
Organization: University of Cambridge DAMTP
References:   1 2 3 4
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In article <airliners.1997.536@ohare.Chicago.COM>,
Terry Schell <> wrote:
>Of course, if these super-jumbo's require more flight separation,
>longer/wider runways, longer turnaround times and more gate space...
>they may not serve to reduce congestion at Nartia at all.
>Furthermore, the 3XX will probably only hold 20% more passengers
>than a 747-400... which implies a relatively minor impact on congestion
>even if all of the 747 switched to the new super-jumbo's and even
>without considering the moderating factors mentioned above.

	I can buy the flight separation argument, although I haven't seen
figures suggesting that the A3XX will require more than the 747-400.
(Can someone shed more light on this?). Turnaround times depend to some
extent on the efficiency of your ground operations. More gate space is
normally much more politically easy to build than more runway capacity.
Ditto (although perhaps to a lesser extent than gate space).

>Compare that
>to the effect on congestion if all of the smaller planes switched to
>I guess what I am saying is that I don't buy the "reducing congestion"
>argument for the next generation super-jumbo.  If there were intense
>congestion problems we would be seeing pressure to replace the smaller
>planes with bigger ones... but the current trend in most markets is
>the opposite.  We could reduce the flight cycles in most markets by
>100% even with currently avail. planes, but we are not doing it.

	Again, this argument doesn't really hold at Narita. 747s are
used for most movements there, and this is largely due to congestion.
(Congestion is an important reason for 747s being used on Japanese domestic
routes also). At the most capacity constrained airports elsewhere, there
certainly is pressure to use larger aircraft. The average sized aircraft
being used at Heathrow (especially by BA) has increased significantly
in recent years. Plans for terminal five are based upon a very significant
increase in the number of passengers without a significant increase in
aircraft movements.  (There is a way to go there before a super-jumbo will
make a huge difference, but the trend is definitely the opposite to the
'smaller aircraft' trend where there is capacity to spare).
	I'm not disagreeing with you to a great extent. The number of airports
at which you see this effect is very small, and the number at which it is
sufficiently advanced that a super-jumbo would make a difference
is even smaller. I don't believe that this factor provides a large
enough market to build a super-jumbo at present. (In fact, even with other
factors as well, I don't presently believe that there is a market sufficient
to support such an aircraft). I am only arguing that it provides a market
for some aircraft. 'Some' might not be very many.

Michael Jennings
Department of Applied Mathematics and Theoretical Physics
The University of Cambridge.

	"`I need every aluminum can you can find! And duct tape!"