Southwest Airlines Co., which acquired most of the flying rights sold by American Airlines Group Inc. at Washington’s Reagan National Airport, said it secured one pair of the slots for free.

Southwest, the largest low-fare carrier, doesn’t plan to use that pair, which would allow one Sunday round trip at flight-constrained Reagan, Whitney Eichinger, a spokeswoman for the Dallas-based carrier, said in an e-mail today.

“It’s only Sunday, and that is something that is very difficult for our schedule,” Eichinger said. “We do operate Saturday only in certain markets, but not Sunday only.”

Southwest’s acknowledgment accounts for the final pair of slots at Reagan that American agreed to divest to settle a federal antitrust lawsuit that sought to block its merger with US Airways Group Inc. The slots are prized by airlines because of flight limits at Reagan, which is used by business fliers who often pay higher fares.

American declined to comment, said Casey Norton, a spokesman who works for public relations firm Weber Shandwick.

American agreed to give up 52 slot pairs at Reagan and 17 pairs at New York’s LaGuardia. A slot allows for one takeoff or landing, and a pair is needed for a round trip. Reagan and LaGuardia are two of four major U.S. airports where the U.S. limits access to control congestion.

Southwest agreed to purchase a bundle of Reagan slots that included rights for 27 daily round trips and the unwanted Sunday pair, which “we did not pay for,” Eichinger said. JetBlue Airways Corp. is buying rights for 20 pairs and Virgin America Inc. for four. Terms of the sales, which must be approved by the U.S. Justice Department, haven’t been disclosed.

LaGuardia Sales

Virgin America, the U.S. low-cost carrier partly owned by U.K. billionaire Richard Branson, and Southwest also acquired slots sold by Fort Worth, Texas-based American at LaGuardia. Federal regulators required that the flying rights go to carriers that would offer lower fares and boost competition.

Under the lawsuit settlement, US Airways and former American parent AMR Corp. also agreed to give up two airport gates each at Boston Logan, Los Angeles International, Chicago O’Hare, Dallas Love Field and Miami International.

AMR and US Airways combined on Dec. 9 to create the world’s largest airline, based on passenger traffic.

Editors: John Lear and James Callan.

To contact the reporter on this story: Mary Schlangenstein in Dallas at To contact the editor responsible for this story: Ed Dufner at

Photo Credit: Southwest Airlines jets wait on the tarmac at Denver International Airport in Denver January 22, 2014. Rick Wilking / Reuters