Delta Air Lines will begin shifting flights from Tokyo Narita to Tokyo Haneda airport in March, a move that will culminate in Delta's complete exit from Narita.

The carrier's transfer to Haneda, made possible by the recent opening of new flight slots, will complete Delta's long-standing dismantling of its Narita operation.

As part of the shift, Delta will cancel its Narita-Singapore flight in September and its Narita-Manila flight in March 2020, the carrier says, and will not move these flights to Haneda.

But it will replace the Manila service with a new flight to that city from Seoul Incheon, the hub it operates with joint-venture partner Korean Air.

Delta's customers will have access to Singapore via flights on Korean Air, Delta says.

It is making the changes thanks to the 9 August award by the US Department of Transportation of 12 new slots for flights from the USA to Haneda. The DOT divided those slots between American Airlines, Delta, Hawaiian Airlines and United Airlines.

Delta gained rights to serve Haneda from Atlanta, Detroit, Honolulu, Portland and Seattle.

Those routes will build on Delta's existing flights to Haneda from Los Angeles and Minneapolis, made possible by a 2016 DOT slot award.

Delta has been pulling back its Narita presence in recent years and shifting flights to Haneda, which is closer to downtown Tokyo. Delta says the shift makes its flights more appealing to Tokyo travellers.