The US Department of Transportation (DOT) is ready to order a 10% reduction in scheduled air traffic at 40 major airports starting Friday, November 7, if the federal government shutdown continues after that date, Reuters reported.

“As we start to implement this drawdown in service, it will be restricted to these 40 high-volume traffic markets,” the Federal Aviation Administration (FAA) Administrator Bryan Bedford said. “We’re going to ask the airlines to work with us collaboratively to reduce their schedules.”

The FAA said capacity reductions at the airports would start at 4% on Friday, rising to 5% Saturday and 6% Sunday, before reaching 10% next week, Reuters reported. The FAA also plans to exempt international flights from the cuts.

The regulator is aiming to alleviate pressure on air traffic controllers, who are considered essential employees and must work during the shutdown, but are not being paid. Bedford said that 20% to 40% of controllers at the agency’s 30 largest airports were not showing up for work. As the shutdown has now lasted for over 30 days, every government employee has missed at least one paycheck.

Meanwhile, Transportation Secretary Sean Duffy said, “We are going to proactively make decisions that keep the airspace safe.”

The 40 impacted airports are: Anchorage Ted Stevens, Atlanta Hartsfield Jackson, Boston, Baltimore International, Charlotte International, Cincinnati International, Dallas Love Field, Washington National, Denver International, Dallas/Fort Worth, Detroit Metropolitan, New York Newark, Fort Lauderdale International, Honolulu, Houston Hobby, Washington Dulles, Houston Intercontinental, Indianapolis International, New York JFK, Las Vegas Harry Reid, Los Angeles International, New York La Guardia, Orlando International, Chicago Midway, Memphis International, Miami International, Minneapolis St. Paul International, Oakland International, Ontario International, Chicago O'Hare, Portland International, Philadelphia International, Phoenix Sky Harbor, San Diego International, Louisville International, Seattle Tacoma International, San Francisco, Salt Lake City, Teterboro, and Tampa International.

Duffy had warned on November 4 that if the federal government shutdown continued another week, it could lead to "mass chaos" and force him to close some of the national airspace to air traffic.

On Friday, October 31, New York City airports were disrupted because of reduced staffing at multiple air traffic control centres.

In a statement posted on social media, United Airlines acknowledged that reductions will start on Friday, and that it will continue to make rolling updates to its schedule, so it can provide several days' advance notice. Its long-haul international and hub-to-hub flights will not be impacted, instead focusing on schedule reductions to regional and domestic mainline flights.

Similarly, American Airlines indicated that most of its customers would see minimal disruption. Southwest Airlines, meanwhile, said it was evaluating how the cuts would impact its schedule and would communicate with customers as soon as possible - while also urging lawmakers to resolve the shutdown immediately.

The shutdown is already the longest in the history of the United States as the country's two parties are unable to agree on a new budget, largely over healthcare funding.