About 2 weeks ago, I went to the airport to catch the outbound segment of an MCI-PHL-BWI-PHL-MCI roundtrip. Upon reaching the airport, I learned that the PHL segment was delayed to the point where I would miss my BWI connection, meaning that I would either have to spend the night in Philly, stay in KC, or rent a car at PHL and drive to DC.

However, I noticed that the MCI-DCA nonstop was ontime (leaving within the hour). I suggested that they book me on that flight since it appeared to have plenty of seats available (Wed. evening flight).

I've commuted probably 75-80 times back and forth between Missouri and the DC area in the past four years, and I know that in the past, when a flight has been canceled or delayed, the airline will offer to fly you to one of the "coterminal" airports in leiu of waiting for the next day's flight.

However, this time, the agent said that new policies prohibit this practice on discounted coach tickets. (I was traveling on a deeply discounted ticket to BWI, which was about $40 lower than the cheapest ticket to DCA.) In my case, I was clearly taking advantage of the lower cost of flying to BWI, so in a way I sort of see their point. Sort of. US cited the higher cost per seat of delivering pax to DCA, in conjunction with my rock-bottom BWI fare, and said "Sorry, no can do."

The agent went on to explain to me that US was taking a "no exceptions" rule to allowing people to fly to different coterminal airports, unless they pay full-fare to switch the ticket. (I even asked the question would they allow the reverse - a DCA flight is canceled, I'm willing to go to BWI, what would they do? Same answer: pay full-fare or it's not allowed. So this rule isn't strictly tied to the fact the BWI fares are, in general, less expensive than DCA fares.)

So, what were my choices here? Delay reaching DC by a day, or fly to Philly and hope I can find a one-way rental car to get there late that night. However, I came up with a third option: AA had a flight leaving MCI within the hour that would make a connection in Chicago to get me to BWI that night. I suggested rebooking me on to this flight to the US agent, and she immediately called up AA (two gates over), booked me seats on those flights, printed me a paper ticket, and sent me on my way to AA to get on their flight.

At this point, I'm thinking "Wouldn't US have saved themselves money by putting me on their own MCI-DCA flight with empty seats?"

Anyway...I don't have checked luggage, I'm now happy to get to BWI that night, I'm even salivating about the double AA miles I'll now receive...so off I go to AA. I head for the counter to check-in and maybe even upgrade the flights.

And guess what happens: the AA agent says "It looks like your BWI flight out of Chicago is delayed due to late equipment arrival. Would you like to go to IAD or DCA instead? It'll probably save you an hour or two." To make the rest of the story short, I flew MCI-ORD-DCA on AA and arrived at about the same time I was originally supposed to get to BWI. In first class, no less.

So apparently US is enforcing their coterminal rules more strictly than some other airlines (namely AA, in this case). Or perhaps the rules around the paper ticket that US gave me for AA were less strict than my restricted coach fare. Either way, it seemed like AA took an extra step to get me to my end destination as soon as possible, whereas US did not. Yes, US "protected" that $40 of revenue that I saved by booking BWI instead of DCA to begin with, but they really made me rethink booking future flights on them at all. Of course I'll still take the nonstop when it's the best option, but if I'm connecting, I'm probably headed for TW/AA from now on.