Buying a V class refundable BNA-BWI ticket. Can I stand-by for DCA? Nothing in the fare rules says otherwise. It says something about BWI-WAS being coterminals and considered the same point. If yes, since its refundable would I be charged the $25?

I tried this several years back and was declined even though routing rules mention something about DCA-BWI and PHF-ORF considered to be the 'same airport' or words to those effect...too many beers to look up the exact lingo right now :D

It's worth asking -- maybe you will get lucky -- but my understanding is that, despite the ambiguous way in which the fare rules are written up, you can only actually stand by for a flight to a co-terminal if the exact same fare is available to the alternate airport, and since most of the cheap fares into BWI are BWI-specific (i.e., not available for DCA, which tends to be a much more expensive destination), you might be asked to pay fare difference in addition to the stand-by fee if you wanted to stand by for a flight going there. I don't present this as a definitive answer, but this is more or less what I was told when I called the CP line recently to see if I could go to DCA and stand by for a the return leg of a trip that was ticketed as being to/from BWI.

(I did once succeed in getting rerouted onto a flight to DCA with a ticket to BWI, but that was because the flight on the first leg of my BWI-bound itinerary kept getting delayed, meaning that I would miss my connection ... so they were willing to put me onto a direct flight to National. That worked out nicely!)

The above responses to your post are 100% correct; I've tried to fly standby to NYC co-terminals a few times and have sometimes been successful. Even if standby to a co-terminal is allowed (same fare code req'd for both flights), only a few US agents I've dealt with know that rule, so just keep asking different agents until one tells you you can do it (if the rules allow you to) and maybe try to get that agent to note it in your record, if s/he can't print a new boarding pass for you.

The above responses to your post are 100% correct; I've tried to fly standby to NYC co-terminals a few times and have sometimes been successful. Even if standby to a co-terminal is allowed (same fare code req'd for both flights), only a few US agents I've dealt with know that rule, so just keep asking different agents until one tells you you can do it (if the rules allow you to) and maybe try to get that agent to note it in your record, if s/he can't print a new boarding pass for you.

Thank you - do you know where in the fare rules it states where co-terminals are illegal should they be?

Sorry but I don't understand about "illegal" co-terminals; in the fare rules there is usually a section captioned, "Co-Terminals", which should usually include a blurb stating, "The following cities are considered the same point" and should include "BWI-DCA" if the fare rules for your ticket include them as co-terminals. Also I would recommend checking the top of the fare rules that show the point to which your ticket is valid; it would need to be WAS-Washington-All Airports.

If you buy the ticket as a UA ticket you might have more luck; UA fare rules usually, at least for NYC, include JFK-LGA as co-terminals and specifically include some language allowing standby between the two, which I have done without a problem on UA; UA fare rules might include BWI-DCA and have specific standby language for those two airports as well.

About a year ago a friend was to fly BWI-PHX but was quite sick and had to change her flight. To make a long story short after me calling HP and doing a whole song and dance and going through about 2 supervisors I was able to get the ticket changed from BWI to DCA without some fee or another but in normal circumstances they are/were not considered co-terminals.

I was flying to SJC, connecting in PHX. I wanted to get on the SFO flight instead. I went around asking a few different places in PHX if it was possible, and on the third try found someone who didn't even charge the $25. If they say no or want some huge fee, just say "Thanks anyway and have a good day." This would work less well someplace where you can't keep asking different people.

I did this a couple years ago on HP. Ticketed LAS-PHX-BWI and while in PHX I went to the DCA gate and they switched me no problem as seats were available. However, this was long before the merger and $25 charge to switch same-day flights.

Sorry but I don't understand about "illegal" co-terminals; in the fare rules there is usually a section captioned, "Co-Terminals", which should usually include a blurb stating, "The following cities are considered the same point" and should include "BWI-DCA" if the fare rules for your ticket include them as co-terminals. Also I would recommend checking the top of the fare rules that show the point to which your ticket is valid; it would need to be WAS-Washington-All Airports.

If you buy the ticket as a UA ticket you might have more luck; UA fare rules usually, at least for NYC, include JFK-LGA as co-terminals and specifically include some language allowing standby between the two, which I have done without a problem on UA; UA fare rules might include BWI-DCA and have specific standby language for those two airports as well.
Does UA require their coterminal standby to have the exact same fare basis available? I've always assumed US has that rule to keep people from buying cheap BWI tickets to travel to much more convenient DCA.

Does UA require their coterminal standby to have the exact same fare basis available? I've always assumed US has that rule to keep people from buying cheap BWI tickets to travel to much more convenient DCA.

Not sure- when I flew standby to LGA with a UA JFK ticket there were no questions asked. Is US the only carrier that offers cheap tickets to a less-desirable airport near a more desirable one?