Originally Posted by
MA700C
HKG to IAD with a transfer in NRT using a "C" ticket. When checking in at HKG they apologized and said all segments were over booked. Instead they moved me to a new itinerary that add a transfer in ORD but moved me to "F" for all segments.

There is (and was) an IAD->SFO->HKG flight that returns the same way, with a plane change (each way) at SFO using different plane types. The domestic leg IAD-SFO-IAD uses a smaller domestic aircraft, while SFO-HKG-SFO is on a 744.
There is (and it is relatively new) an IAD->NRT->SIN->NRT->IAD flight. This one swaps planes at NRT, but they are both international 772s, so the plane swap is just a minor annoyance.
I don't recall there ever being an HKG->NRT->IAD flight without an intermediate stop. Until about a year ago, there were no non-stop UA flights between IAD and Asia/Pacific. I just rechecked the current UA timetable and there is no IAD-NRT-HKG flight (oh, how I wish there were ! This is one of my real wish-list routes) listed there.
In a different thread about Asia/Pacific Route Wishlist, restoration of the former NRT-HKG-NRT route, which was discontinued a while back, is a hot topic and the number 1 desire expressed in that other thread. There is one code-share (not on UA metal) between NRT and HKG in the current UA timetable, but the timing of that flight doesn't really permit onward connections with UA at HKG (e.g. to SGN or SIN).
So I am guessing there is more to the routing than the thumbnail above provides, right ?

If you have some secret sauce on a good routing between IAD and HKG, please do share that. :-)