Southwest Airlines lost three of its slot pairs at Ronald Reagan Washington National airport in October, following the lifting of restrictions at Newark Liberty International airport.
The Dallas-based carrier returned the slots to United Airlines, which assumed control of them through its 2010 merger with Continental Airlines. Continental had traded the pairs with AirTran Airways in exchange for slots at the then newly slot-restricted Newark airport in 2009. Southwest acquired AirTran in 2010.
The trade was nullified with the US Federal Aviation Administration’s decision in April to lift slot restrictions at Newark from 30 October. This eliminated the collateral that Southwest provided United under the terms of the deal.
"While it was not ideal for Southwest Airlines, it was an agreement that we agreed to in the lease," says a spokesman for the airline.
Southwest now has 42 slot pairs at Washington National, putting them just ahead of United with 41 pairs and well behind Delta Air Lines with 54 pairs, FlightGlobal schedules data shows. American Airlines has the largest slot portfolio at the airport operating up to 251 daily flights.
The airline paid more than $200 million for 54 slots - 27 pairs - at Washington National divested by American Airlines in the first quarter of 2014, which allowed itt o more than double its size at the close-in Washington DC airport.
Southwest remains one of the largest carriers in the Washington DC region, despite the reductions at Washington National. It is scheduled to operate more than 31% of all seats from Baltimore/Washington, Washington Dulles and Washington National airports compared to 21.6% on United and 21.4% on American Airlines in the first quarter, schedules show.
The carrier is second only to American in the number of flights flown from the three airports.
Southwest dropped a single frequency to Chicago Midway, Houston Hobby and Milwaukee from Washington National when it returned the slots on 30 October, schedules show. United added single frequencies to Chicago O’Hare, Houston Intercontinental and Newark three days later.
Chicago-based United declines to comment on the slots.
Southwest is taking advantage of the changes at Newark to expand its operations at the New York City area airport. It added a Saturday-only seasonal flight to San Juan this month and plans to add a new daily flight between Newark and Fort Lauderdale in March.
AirTran used the Continental slot pairs at Washington National to add flights to its Atlanta base and launch service to Orlando in November 2009, schedules show.