Southwest Airlines to order larger Boeing aircraft

Southwest Airlines Co. is getting new, larger planes that could pave the way for the all-domestic airline to offer international flights.

Chief Executive Officer Gary Kelly said Wednesday that Southwest will change an existing order with Boeing Co. and get 20 new 737-800 jets beginning in March 2012.

Those jets have 175 seats, 38 more than the largest planes in Southwest’s current fleet, which means potentially more revenue per flight.

The airline, the busiest at McCarran International Airport, plans to add international service when it completes the purchase of AirTran Airways, which flies to Mexico and the Caribbean. It could still use AirTran’s planes for those flights.