U.S. Transportation Secretary Sean Duffy holds a press conference on the impact of the government shutdown on air travel, at LaGuardia Airport in the Queens borough of New York City, U.S., October 28, 2025. REUTERS/Shannon Stapleton

By David Shepardson

WASHINGTON (Reuters) -U.S. Transportation Secretary Sean Duffy warned on Tuesday that if the federal government shutdown continues another week it could lead to "mass chaos" and could force him to close some of the national airspace to air traffic, a drastic move that could upend American aviation.

"If you bring us to a week from today, Democrats, you will see mass chaos, you will see mass flight delays. You'll see mass cancellations, and you may see us close certain parts of the airspace, because we just cannot manage it," Duffy said at a press conference Tuesday. "We will restrict the airspace when we feel it's unsafe."

U.S. aviation has already faced tens of thousands of flight delays over the last month. The comments represented the Trump administration's most dire warnings of impending impacts from rising air traffic controller absences.

U.S. carriers' shares slumped on the news, with Delta, United Airlines and American Airlines all falling more than 5%.

As the shutdown entered its 35th day, the Federal Aviation Administration delayed a new round of flights on Tuesday. Airlines said this week 3.2 million passengers have been hit by delays or canceled flights due to a spike in air traffic controller absences.

On Tuesday, there were more than 2,300 flight delays as the FAA imposed delays in Phoenix and expects to delay flights in Houston after seeing staffing issues in Denver, Detroit and elsewhere.

FAA Administrator Bryan Bedford told Fox Business' "Varney & Co" on Tuesday that at the agency's largest 30 airports "anywhere from 20 to 40% of our controllers aren't coming to work."

Democrats blame Republicans for not negotiating with them to reopen the government. The shutdown has exacerbated staffing shortages, forcing 13,000 air traffic controllers and 50,000 Transportation Security Administration officers to work without pay, leading many of them to call in sick or absent.

In 2019, widespread disruptions in air travel pressured lawmakers into ending a 35-day government shutdown during President Donald Trump's first term in office.

On Friday, the FAA said nearly half of the 30 busiest U.S. airports faced shortages of air traffic controllers on the single worst day since the shutdown began.

In New York on Friday, 80% of air traffic controllers were absent, the agency said.

(Reporting by David Shepardson; Editing by David Gregorio and Aurora Ellis)