Alaska Airlines has reached an agreement to buy Hawaiian Airlines, the company announced Sunday.

Alaska Air Group, Inc

The boards of both companies have agreed to the deal, which is expected to close in 12-18 months, the airlines said in a statement. The deal still has to be approved by U.S. regulators and Hawaii Holdings, Inc. Shareholders’ approval is required.

Regulatory approval is not guaranteed. Earlier this year, a federal judge ruled JetBlue and American Airlines They want to end their partnership, saying the alliance weakened competition and hurt consumers. The judiciary is also trying to prevent it JetBlue’s proposed acquisition of Spirit Airlines.

Reached Alaska Air Group Agreement in 2016 Buy Virgin America. Alaska Airlines later Virgin America dropped the name and symbol.

Under the terms of the new agreement between Alaska Airlines and Hawaiian Airlines, the combined organization will operate in Seattle under the leadership of Alaska Airlines CEO Ben Minicusi.

“This combination is an exciting next step in our partnership to provide our guests with a better travel experience and expand options for West Coast and Hawaii travelers,” Minicucci said in a statement.

The airlines said the move would protect both brands and open up more travel space for passengers. The combined company will serve 138 destinations, including non-stop service to 29 top international destinations in the Americas, Asia, Australia and the South Pacific, the statement said.

Earlier this year, travel website The Points Guy Alaska Airlines ranks first The third largest airline in the United States, after Delta Air Lines and United Airlines. Hawaiian Airlines ranked sixth.