I searched for flights for the route DCA-DFW, one-way. One option is DCA-MCI-DFW with U.S. Airways operating the DCA-MCI leg. I checked AA’s codeshare partners via their website and U.S. is not one of them (I know they are planning to merge though) and the flight has a U.S. Airways logo on the reservation screen. So what’s going on here? Are bags checked through etc.? Is check-in at U.S. or AA counters?
AA.com has been selling tickets on carriers that they don’t codeshare with for about 2 years.
It’s a somewhat unique proposition. Basically they try to offer the tickets in situations where it’s unlikely they would get any of the sale if they did not (or they think the sale would be done by an Online Travel Agency like Orbitz, Expedia, Travelocity, etc.). In this case they get revenue for the MCI-DFW segment and avoid having to pay an Online Travel Agency comission that they would have paid if the same ticket would have been bought elsewhere.
In certain circumstances AA.com will even sell a ticket on United or Delta. For example, search for a ticket from CMX (an airport only served by United) to LAX or RHI to DFW.