Date: 01 Mar 97 18:42:14 From: M.J.Jennings@amtp.cam.ac.uk (Michael Jennings) Organization: University of Cambridge DAMTP References: 1 2 3 4 Followups: 1
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In article <airliners.1997.536@ohare.Chicago.COM>, Terry Schell <email@example.com> 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 >747's? >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. firstname.lastname@example.org "`I need every aluminum can you can find! And duct tape!"