US Transportation Secretary Sean Duffy announced on Wednesday that 10% of flights at 40 major US airports will be cut starting Friday if a deal to end the federal government shutdown is not reached. The shutdown, now in its 36th day, has forced 13,000 air traffic controllers and 50,000 Transportation Security Administration agents to work without pay, causing staff shortages, flight delays, and long lines at airport security.

According to Duffy, this decision was made after careful consideration of their responsibilities. The affected airports have not been named, but it is expected that the 30 busiest airports, including those in New York City, Washington D. C. , Chicago, Atlanta, Los Angeles, and Dallas, will be impacted. This could result in a reduction of 1,800 flights and over 268,000 airline seats, as estimated by aviation analytics firm Cirium.

The purpose of this move is to ease the burden on air traffic controllers who have been working without pay. The Federal Aviation Administration (FAA) has also warned that if further air traffic issues arise, more flight restrictions may be added after Friday. Airlines for America, a trade group representing major US carriers, including Delta, United, American, and Southwest, stated that they are in communication with the government to understand the details of the reduction mandate and will try to minimize any negative impacts on passengers and shippers.

The FAA is scheduled to hold a call with airlines on Wednesday evening to explain the implementation of the cuts. This government shutdown has led to the closure of services, furloughs of federal employees, and left many low-income Americans without food assistance. Duffy had previously warned that if the shutdown continues for another week, it could lead to “mass chaos” and result in the closure of some national airspace.

Airlines have been urging an end to the shutdown, citing concerns about aviation safety. As a result of rising air traffic controller absences during the shutdown, an airline industry group estimated that over 3. 2 million passengers have been affected by flight delays or cancellations. While airlines have expressed that the shutdown has not significantly impacted their business, they have warned that bookings could decrease if it continues. On Tuesday, FAA Administrator Bryan Bedford reported that 20% to 40% of controllers at the agency’s 30 largest airports were not showing up for work. Additionally, Duffy stated that space launches will be limited to certain times of the day.