| Cheap Flights: Austin to/from Washington, D.C $105-$115 r/t â American Airlines American Airlines has round-trip flights from Austin (AUS) to Washington, D.C. (IAD/DCA) for $105-$115 with a connection. Flights January, February, April, and May. Departures on Tuesday, Thursday, and Sunday. Extended Weekends available. Note: Carry-on bag is allowed for free on American Airlines. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate. We donât charge a subscription fee. All of our deal notifications are available for FREE via Instagram, Facebook, Twitter, our Webpage, and our E-mail list. If you are paying someone a subscription fee for our content, you are being ripped off. Read More Cheap Flights: Austin to/from Washington, D.C $105-$115 r/t â American Airlines . | 