Thanks for all the information provided here.^

It did work, but unfortunately, I could not find a seat on UA.

On March 25, I went to NRT early and asked AA to endorse the ticket to UA. The AA agent was very helpful and did not ask any questions. I then took the bus to Terminal One South where the Start Alliance terminal is located. UA ticket office was also very customer friendly. Unfortunately when I got there 2 pm, UA (according to the UA agent) had upgraded the remaining passengers on the waitlist, and I was not able to get on that flight (NRT-IAD UA 804).

The UA agent was hoping to find me a flight via the west coast or ORD back to IAD. No luck, all flights to IAD/DCA from West Coast and ORD that day were all sold out in Y. I had AA Business (D fare) from NRTto LAX, and LAX to IAD on Y fare. I was also unable to swap AA D fare to UA C fare on the earlier NRT-ORD flight.

Perhaps it was just fate, I ended up taking the bus to Terminal 2 to get on the AA flight to LAX... it ended up as one of the better flights I have ever experienced. Please see the following thread for detail:

http://www.flyertalk.com/forum/showt...ferrerid=19989