American, Southwest cooperating in airline collusion probe

North Texas-based American Airlines and Southwest Airlines are being investigated by the U.S. Department of Justice in a probe of whether airlines colluded to keep airfares high when making capacity plans. The Justice Department sent “civil investigation demand” letters to several U.S. airlines this week asking the carriers to provide all documents pertaining to how they decide how many available seats and flights they will operate and whether they are talking to each other about capacity. Josh…