The master lease agreements that apply to airlines at Hartsfield-Jackson Atlanta International Airport do not expire until September 2010, but talks between the sides have already heated up.

Atlanta-based Delta Air Lines Inc., the world's biggest carrier, and discount carrier AirTran Airways, a unit of Orlando, Fla.-based AirTran Holdings Inc., say that if their costs are too high they may be forced to move some connecting flights to other airports.

Airlines threaten to move flights from Atlanta