United Airlines will cancel 35 roundtrip flights a day from its schedule at Newark Liberty International Airport in New Jersey after thousands of passengers faced hourslong delays this week, CEO Scott Kirby said Friday, blaming the disruptions on air traffic controller staffing shortages and the Federal Aviation Administration’s technology problems.

The flight cuts amount to about 10% of United’s daily schedule at its Newark hub.

More than 300 flights in and out of Newark were delayed as of Friday afternoon, adding to more than 1,400 other delays and cancellations earlier this week, according to flight-tracking site FlightAware.

“It’s disappointing to make further cuts to an already reduced schedule at Newark, but since there is no way to resolve the near-term structural FAA staffing issues, we feel like there is no other choice in order to protect our customers,” Kirby said in a note to customers on Friday.

The schedule cuts will begin this weekend.

Kirby said that 20% of air traffic controllers for Newark “walked off the job” in recent days after several technology failures.

“Keep in mind, this particular air traffic control facility has been chronically understaffed for years and without these controllers, it’s now clear – and the FAA tells us – that Newark airport cannot handle the number of planes that are scheduled to operate there in the weeks and months ahead,” he said.

The FAA said in an advisory that staffing issues were delaying operations at Newark on Friday.

Kirby said the airline is now urging the agency to more tightly control capacity at the airport by establishing flight restrictions like those in place at other highly congested facilities like New York’s LaGuardia Airport and Ronald Reagan Washington National Airport.

Last year, the FAA moved air traffic controllers responsible for airspace around Newark to Philadelphia instead of a facility in New York in an effort to help alleviate congestion.

The FAA and the Transportation Department didn’t immediately respond to requests for comment on Kirby’s statement. But Transportation Secretary Sean Duffy wrote on X that he visited the Philadelphia facility that “to talk with our hard working air traffic controllers as we work to fix these equipment outages caused by outdated technology. It’s unacceptable.” He called for an “all-new air traffic control system.”

The air traffic controllers’ union declined to comment.

Kirby said he spoke with Secretary Duffy on Friday and praised the Trump administration for vowing to invest and fix aging air traffic control infrastructure in the U.S.