US Airways and American Airlines have completed their merger.
The deal means the combined airline will overtake Delta as the biggest carrier in the world.
The new airline will have over 1,000 aircraft flying 6,700 daily flights to 330 destinations across 54 countries. It will employ 24,500 flight attendants and 12,500 pilots.
US Airways will leave Star Alliance to join oneworld from March 31 next year following completion of its merger with founding member American Airlines.
Regional affiliates operating under the US Airways Express brand will also transition to oneworld at the same time.
The airlines claim the merger – which will see the combined airline retaining the American Airlines name – will save them $1bn a year within 12 months.
Over the next 24 months, the merged company will bring all aircraft into line, which chief executive Doug Parker described as "not easy".
He told ABC News: "We have consultants on board who’ve done this with other carriers.
"It’s not easy, but…both airlines have been through a merger in the semi-recent past."
