SEATTLE >> A coalition of airlines including Alaska, JetBlue, United and Southwest has sued Washington state over its new sick leave law, saying it’s part of a mishmash of state and local measures that could increase costs and delays for travelers — and which are blocked by federal regulation of air travel and interstate commerce.

Airlines For America filed the lawsuit in U.S. District Court in Tacoma today. The organization said at least six other states — Arizona, California, Connecticut, Massachusetts, Oregon, and Vermont — and 30 cities have paid sick leave laws.

“Airlines cannot operate their nationwide systems properly if flight crews are subject to the employment laws of every state in which they are based, live, or pass through,” Airlines for America said in an emailed statement Wednesday.

The complaint put it this way: “A flight crew departing from SeaTac International Airport, landing in Portland International Airport, and continuing to San Diego International Airport is subject to three different paid sick leave laws in a single duty period, each with its own accrual, compensation, reporting, and leave requirements.”

The lawsuit seeks a ruling that federal regulation of air travel precludes Washington state’s sick leave law from applying to the airlines’ pilots or flight crews.

Airlines For America said it has not filed any similar complaints in other jurisdictions.

Voters approved Washington’s Paid Sick Leave Act in 2016 and it took effect Jan. 1. It requires employers to provide at least one hour of paid sick leave for every 40 hours worked and governs how workers can use that leave.

Washington’s Department of Labor and Industries, which is named as a defendant, declined to address the legal arguments raised by the complaint, but spokesman Tim Church noted that the department spent a year developing rules to implement the sick leave law based on what the voters passed.

“We know there’s a lot of passion and concern about the sick leave law, so we’re not surprised by this action today,” he said.

The airlines say many of their employees already have generous sick leave and other benefits, and they’re covered by collective bargaining agreements.

They also say that by restricting when employers can demand medical documentation for sick leave, Washington’s law will make it harder for them to crack down on fraud and abuse of sick leave policy. That, they insist, will lead to more employees calling in sick — and more flights being canceled or delayed due to a lack of adequate crew.

Airlines have faced prior lawsuits from jurisdictions accusing them of violating sick leave laws. New York City, for example, has sued Delta and JetBlue, saying workers were retaliated against for using sick leave as allowed by the law.

“Alaska and the other big airlines have tried time and time again to roll back gains for workers when the people of Washington have stepped up and tried to improve conditions for those workers,” said Sage Wilson, a spokesman for Working Washington, which supported the sick leave law.

He cited Alaska’s unsuccessful legal fight to avoid paying the nation’s first $15-an-hour minimum wage in SeaTac, the city that includes Seattle-Tacoma International Airport.

“It’s tough to have much sympathy for multibillion-dollar corporations who say keeping track of 6½ paid sick days per year is too hard,” Wilson said.