The US will cut 10% of flights across 40 major airports starting Friday, as the federal government shutdown stretches into its 36th day, becoming the longest in US history.

The move was announced by US Transportation Secretary Sean Duffy on 5 November, citing mounting pressure on air traffic control systems. The Federal Aviation Administration (FAA) faces a shortfall of 3,500 air traffic controllers, with many of the remaining staff working overtime, raising concerns about performance and, by extension, safety.

About as many as 13,000 air traffic controllers and 50,000 Transportation Security Administration (TSA) agents continue to work without pay, as per Reuters.

"We had a gut check of what is our job. Our job to make sure we make the hard decisions to continue to keep the airspace safe," said Duffy, who cited a confidential safety assessment highlighting potential dips in performance of air traffic controllers.

Following up, Bryan Bedford, the FAA Administrator, said, "When we see pressures building in these 40 markets, we just can't ignore it. We can take action today to prevent things from deteriorating so the system is extremely safe today, will be extremely safe tomorrow."

Although the FAA has said that 40 aviation markets across the US will be affected by the flight service cuts, it has not specified airports by name.

That said, Reuters reported that the cuts are likely to hit the 30 busiest airports in the US, including those serving New York City, Atlanta, Los Angeles, Dallas, and the capital, Washington DC.

The cuts are likely to reduce as many as 1,800 flights and 268,000 flight seats, as per aviation analytics firm Cirium.

The FAA categorises the ‘busiest’ airports in the US based on the number of annual enplanements.

With the cuts expected to hit some of the busiest airports, here is the full list of air transport hubs that are likely to be affected.