Originally Posted by
fastair
"Network carriers" such as AA and UA feed people into hubs, and connect them to other hubs or to final destinations. To provide enough traffic to fly with frequency from a hub to Podunk, that hub must have much feed from all over...that is what big planes going hub to hub do. The other options is a small flight every 1/2-1 hour, but that could increase costs
Actually, even though this sounds logical, I don't think so. The key is that UA doesn't seem to use intl configured planes to fly domestic routes unless it increases specific aircraft utilization. They would configure a domestic version 777 if they were only interested in capacity, because the intl planes actually carry fewer passengers. As stated, these flights are to increase aircraft utilization which would otherwise be parked at IAD waiting for the next day's international flight.
And actually UA frequently schedules two narrowbody flights at about the same time on high density routes (LAX-DEN, SFO-DEN, sometimes even LAX-IAD). Even though I don't have the figures, I have to think this is generally more economical unless the widebody is otherwise idle. It may be because it is more versatile and therefore on net cheaper to own the larger number of narrowbodies, even if the flight cost per passenger is a bit higher than the domestic widebodies.
Also, UA 946/947 LAX-IAD-LAX operates as a "hot spare" for the IAD Europe bank. If one of those Europe 767/777s goes out of service, UA can put the 777 that would have served UA947 on the Europe flight and either cancel the domestic flight or downgrade it to a 757. "Hot spare" is insurance for profitable international routes plus a little aircraft utilization. I'm not sure how the risk calculation comes out, but it costs UA a bundle if they have to cancel a Europe flight and send all those high fare F and C passengers to another carrier or reroute them on UA metal elsewhere and pay compensation.
Charles