They went bankrupt.  No biggie, all the airlines except AA went Chapter 11 after 9-11.  Time is just catching up to them.  That and they blame TSA for turning so many people off to flying, as AA has a pile of routes on the Amtrak system they think they've been losing passengers to the train.

http://money.cnn.com/2011/11/29/news/companies/american_airlines_bankruptcy/index.htm?hpt=hp_t2