US Airways Dividend Miles (Pre-FlightFund Merger) - ATL-DCA-ATL midweek via CLT: US $716, UA $210

Same flights, departing Apr 29 (Tue), returning May 02 (Fri), the routing is:

ATL-CLT-DCA and back.

The $210 fare on UA is also available via ORD (UA metal), PIT and PHL.

Why is US so outrageously expensive? $210 for ATL-DCA is not exactely cheap, given the 7+ days advance purchase and AirTran flying ATL-IAD... But $716?! http://www.flyertalk.com/forum/mad.gif That's more than you'll pay walk-up on Southwest, ATA and JetBlue to fly coast-to-coast!!!

Is it possible that the flights are already booked and there aren't many seats left? What class fare is that?