Southwest Plans Service to Dulles

Jenkins said United has plenty of experience competing with Southwest, particularly on the West Coast and now in Denver.

"The Dulles market can easily accommodate different models and different types of carriers," he said. "Dulles has been very successful for United's international operation."

United commented Tuesday on Southwest's entry at Dulles, saying, "We look forward to flying customers through our vast route network and our Star Alliance partners to the 800 or so destinations where they don't fly."

Meanwhile, Boyd noted that other changes are likely in the works for Southwest. He said he expects the airline to move to add seat assignments and in-flight entertainment in order to compete with carriers whose fares are equal to Southwest's and whose amenities are greater.

"Southwest isn't calling the shots any more," he said. "Now, as good as they are, they have to react to other airlines."