The US Transportation Department plans to begin flight cuts at 4% on Friday at 40 high-volume airports in response to safety concerns about air traffic control staffing issues as a government shutdown hits its 36th day, four sources told Reuters.
The Federal Aviation Administration told airlines on a call the planned cuts would start at 4% Friday, rise to 5% Saturday and 6% Sunday before hitting 10% next week.
The FAA plans to exempt international flights from the cuts but told airlines it was making drastic cuts in general aviation flights at those major airports.
USDOT and FAA did not immediately comment.
US Transportation Secretary Sean Duffy confirmed on Wednesday that he would order a 10% reduction in scheduled air traffic at 40 major airports starting Friday unless a deal to end the federal government shutdown is reached.
The shutdown, now in its 36th day, has forced 13,000 air traffic controllers and 50,000 Transportation Security Administration officers to work without pay. This has worsened staff shortages, caused widespread flight delays, and extended lines at airport security screening.
"We had a gut check of what is our job," Duffy told reporters, explaining why he made the decision.
Reuters earlier reported the plan.
More flight restrictions possible
The move is aimed at taking pressure off air traffic controllers. The US Federal Aviation Administration also warned that it could add more flight restrictions after Friday if further air traffic issues emerge.
Duffy had warned on Tuesday 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, a drastic move that could upend American aviation.
Airlines have repeatedly urged an end to the shutdown, citing aviation safety risks.
Shares of major airlines, including United Airlines and American Airlines, were down about 1% in extended trading.
An airline industry group estimated that over 3.2 million passengers have been affected by flight delays or cancellations due to rising air traffic controller absences since the shutdown began on October 1. Airlines have been raising concerns with lawmakers about the impact on operations.
Airlines said the shutdown has not significantly affected their business, but have warned bookings could drop if it drags on. More than 2,100 flights were delayed on Wednesday.
On Tuesday, FAA Administrator Bryan Bedford said that 20% to 40% of controllers at the agency's 30 largest airports were failing to show up for work.
The federal government has mostly closed as Republicans and Democrats are locked in a standoff in Congress over a funding bill. Democrats have insisted they would not approve a plan that does not extend health insurance subsidies, while Republicans have rejected that.