A coalition of airlines sues Washington state over its new sick leave law they say could increase costs and flight delays for travelers. The group, Airlines for America, includes Alaska Airlines, JetBlue, United Airlines, Southwest Airlines and others.

The lawsuit was filed in response to Washington’s voter-approved Paid Sick Leave Act, which took effect Jan. 1. The law requires employers to provide at least one hour of paid sick leave for every 40 hours worked; it also controls how workers can use leave.

The Washington, D.C.-based group says local measures are blocked by federal regulation of air travel and interstate commerce.

“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,” a representative for Airlines for America said in a statement.

The lawsuit seeks a ruling saying federal regulation precludes the law from applying to airline pilots or crews. The concern is if more employees call in sick, it could lead to flight delays.