An equipment outage snarled air travel across the U.S. Northeast on Monday, significantly delaying passengers and diverting flights.

Flights at Newark Liberty International, John F. Kennedy International and LaGuardia airports began to stack up after a contractor apparently accidentally cut 600 feet of fiber communications line in New Jersey, Federal Aviation Administration chief Bryan Bedford said.

The cut fiber line was a backup data feed that was unavailable when a primary circuit failed, leading to a loss of radar data and radios, he said. The FAA was seeking to replace the circuit Monday.

Around 90 flights had been diverted because of the outage, he said early Monday afternoon, and delays compounded at Newark and Philadelphia-the hardest-hit airports-with spillover disruptions at the other New York City airports and Boston.

The disruptions occurred at an inopportune time for the United Nations General Assembly in New York, which began in early September and draws leaders from around the world. President Trump is expected to leave Washington on Monday for the assembly.

"Timing is absolutely horrible, and I'm very sorry for the delays and cancellations that the traveling public is experiencing, but their safety is the most important thing," Bedford said during a press conference focused on a new AI-powered tool aimed at reducing air-traffic disruptions. "We are going to do what is necessary to make sure the airspace is safe, and then we'll restart it."