Flight delays continued at U.S. airports Sunday amid air traffic controller shortages as the government shutdown entered its second month, with Newark airport in New Jersey experiencing delays of two to three hours.

New York City’s Emergency Management office said on X that Newark delays often ripple out to the region’s other airports.

Travelers flying to, from or through New York “should expect schedule changes, gate holds, and missed connections. Anyone flying today should check flight status before heading to the airport and expect longer waits,” the social media post added.

George Bush Intercontinental Airport in Houston, Dallas Fort Worth International Airport and Chicago O’Hare were also seeing dozens of delays and one or two cancellations, along with major airports in San Francisco, Los Angeles, Denver and Miami, according to FlightAware.

U.S. Transportation Secretary Sean Duffy has been warning that travelers will start to see more flight disruptions the longer controllers go without a paycheck.

“We work overtime to make sure the system is safe. And we will slow traffic down, you’ll see delays, we’ll have flights canceled to make sure the system is safe,” Duffy said Sunday on CBS’S “Face the Nation with Margaret Brennan.”

He also said he does not plan to fire air traffic controllers who don’t show up for work.

“Again when they’re making decisions to feed their families, I’m not going to fire air traffic controllers,” Duffy said. “They need support, they need money, they need a paycheck. They don’t need to be fired.”

Earlier in October, Duffy had warned air traffic controllers who had called in sick instead of working without a paycheck during the shutdown risked being fired. Even a small number of controllers not showing up for work is causing problems because the FAA has a critical shortage of them.

The Federal Aviation Administration said Friday on X that nearly 13,000 air traffic controllers have been working without pay for weeks.

Staffing shortages can occur both in regional control centers that manage multiple airports and in individual airport towers, but they don’t always lead to flight disruptions. According to aviation analytics firm Cirium, flight data showed strong on-time performance at most major U.S. airports for the month of October despite isolated staffing problems throughout the month.

Before the shutdown, the FAA was already dealing with a long-standing shortage of about 3,000 air traffic controllers.