Originally Posted by exerda
Unless your fare rules specifically allow it, or you get a sympathetic agent, I doubt it. The normal "standby co-terminals" are IAD/DCA, ORD/MDW (soon to cease to be relevant), and JFK/LGA (which share so few destinations as to be nearly irrelevant).
I much prefer DCA to IAD, but I believe fares are generally higher out of DCA and there isn't that much service on UA metal. So of how much practical significance could there be to the IAD/DCA "standby co-terminals"? If one is scheduled WAS-BOS, can they standby for a UA/US codeshare from DCA? I suppose a DCA-ORD for IAD-ORD substitution would be the most likely option. Other destinations for which one might standby from DCA rather than go as scheduled from IAD? And I suppose none of these standby provisions or anything else make it possible to switch an IAD destination to a DCA one, right?