Atlanta passengers could experience flight delays lasting up to three hours due to furlough days doled out to thousands of air traffic controllers, which kicked in Sunday.

Congress recently required the FAA to reduce its budget by $637 million. The agency decided to give one furlough day every other week to its 47,000 employees. That includes 15,000 air traffic controllers, which could, in effect, delay when airplanes take off and land.

Industry officials say as many as one out of every three passengers across America could experience delays.

Sunday, those delays had yet to be seen at Atlanta’s Hartsfield-Jackson International Airport, according to Channel 2 Action News. But several passengers at the airport said the furloughs made them nervous.

Lee Moak, the president of the Air Line Pilots Association, said Sunday is usually a light air travel day and by Monday, the effects of the furloughs could start to “snowball.”

Two airline trade associations and the Air Line Pilots Association said they have filed a lawsuit for the U.S. Court of Appeals to stop the furloughs.

The earliest a hearing could take place is sometime next week, according to Nick Calio, head of Airlines for America, which represents major carriers.

—The Associated Press and Channel 2 Action News contributed to this report.