Southwest, Delta and Boeing Capital : By now readers probably saw the news of a plan for Southwest Airlines to sublease the Boeing 717s from the AirTran fleet to Delta Air Lines. Most of the 88 planes are leased from Boeing Capital Corp by AirTran. This deal has been bandied about almost from the day Southwest agreed to buy AirTran. It's entirely in keeping with the Delta management (nee Northwest Airlines management), who like to acquire cheap, older aircraft to keep cap-ex costs down.