The slot trade is subject to regulatory approval, and a similar deal in 2009 fell apart after the Transportation Department imposed restrictions that the airlines said were too onerous.
Analysts expect it will go through this time because there's more competition from discount carriers at those airports. Southwest Airlines Co.'s acquisition of AirTran gives it access to Reagan National for the first time, and JetBlue has begun flying there as well. Southwest also flies out of LaGuardia now.
"It appears highly likely the proposal will be approved within weeks or even days," wrote airline analyst Hunter Keay of Wolfe Trahan & Co. in a client note.
"In what are critically important cities for each airline, Delta's increased LaGuardia presence should alleviate strain on its JFK operation," which would likely become more internationally focused, Keay wrote.
Meanwhile, US Airways would retain its profitable Boston-to-Washington shuttle while adding at least 15 destinations from Washington. US Airways said previously that it had expected to earn $75 million a year from the deal.
"It would certainly be earnings positive for both companies in the sense that LaGuardia tends to be a money loser for US Airways and Reagan National is one of their most profitable operations," Keay said.
US Airways president Scott Kirby said at a recent transportation conference in New York that employees often asked him why the airline wanted to reduce flying in the "biggest air-travel market in the world. How can you give up slots in a place like LaGuardia?" Kirby said.
"We don't make money here, and don't have a path to being profitable in LaGuardia. So we're willing to stop flying places that lose money."
