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