The disruption affected some of the country's busiest airports, including those serving New York, Philadelphia and Boston, as the US Northeast prepared to receive world leaders and senior officials arriving for the annual United Nations General Assembly in New York.
More than 5,600 US flights were delayed or cancelled, according to FlightAware, including about 1,200 flights at the three major New York-area airports. More than 100 flights were also diverted to other airports as air traffic restrictions spread across the region.
The FAA initially halted incoming flights at Philadelphia International Airport, Newark Liberty International Airport and Teterboro Airport after communications problems developed at the Philadelphia Terminal Radar Approach Control, known as Philadelphia TRACON.
The disruption subsequently spread to other airports, including John F. Kennedy International Airport, LaGuardia Airport and Boston Logan International Airport, as traffic was diverted and airports struggled to absorb additional flights.
Failed primary circuit, damaged backup
The immediate problem began when a primary telecommunications circuit serving Philadelphia TRACON failed.
According to FAA Administrator Bryan Bedford, controllers attempted to switch to a backup system but discovered that the backup fibre-optic line had also been damaged.
The cable had been severed in New Jersey by a construction crew working near an Amtrak rail line. Verizon confirmed that the damaged fibre belonged to the company and said construction contractors had dug up and cut the cable. The company said its facilities had been functioning normally up to the point of the damage and that it was working with partners to restore connectivity.
“When it went to flip into the backup, we discovered that the backup fiber had a break, and that fiber break is probably 13 hours to repair. It's massive, I'm told. Meanwhile, we've got the new circuit ready to install now,” Bedford said.
The FAA said it would not fully restore incoming traffic at affected airports until officials were satisfied that the airspace could be operated safely.
Some flights resume
As repair efforts continued, restrictions were gradually eased at some airports.
Incoming flights resumed at LaGuardia and Philadelphia on a limited basis, while Newark and Teterboro continued to face restrictions for part of the day. Boston also experienced a ground stop because of additional traffic created by diverted flights from the Philadelphia outage.
Reagan Washington National Airport also temporarily halted flights because of traffic-volume problems resulting from the wider disruption.
Despite the gradual resumption of operations, officials warned that delays could continue for hours as airlines and airports worked through the backlog created by the outage.
Major airline hubs affected
The disruption hit important airline hubs.
Newark Liberty is a major hub for United Airlines, while Philadelphia International is a major hub for American Airlines. Disruptions at the two airports therefore had the potential to affect flight schedules well beyond the immediate New York and Philadelphia regions.
The knock-on effects were also felt at airports outside the Northeast as diverted aircraft and passengers added pressure to other parts of the US aviation network.
Renewed concerns over ageing air traffic system
Monday's incident has renewed attention on the condition of the US air traffic control infrastructure, which has faced years of complaints over ageing technology, staffing shortages, congestion and communications failures.
The Philadelphia facility had already experienced significant communications problems in 2025. The FAA said a telecommunications outage last year affected communications and radar displays at Philadelphia TRACON. The same facility was also linked to significant disruptions affecting Newark in May 2025.
Congress approved $12.5 billion last year for improvements to the country's air traffic control system and efforts to increase controller hiring.
Transportation Secretary Sean Duffy said the latest disruption demonstrated that more investment was required.
“This is unacceptable in America,” Duffy said, while calling on Congress to approve an additional $17.5 billion to complete the planned overhaul.
The latest incident comes as the United States undertakes a broader effort to modernise its air traffic control infrastructure and replace systems that officials have described as outdated.
UN General Assembly adds to timing pressure
The disruption occurred at a particularly sensitive moment for New York, with world leaders and senior government officials travelling to the city for the UN General Assembly.
The annual gathering brings delegations from around the world to the United Nations headquarters and significantly increases demand on the region's transportation infrastructure.
Although the flight restrictions were caused by an aviation communications failure rather than the UN gathering, the timing meant that thousands of passengers and international delegations were dealing with an already congested travel environment.
The FAA continued working to restore its primary communications link while technicians worked separately to repair the severed backup fibre cable.
For passengers, however, the immediate consequence was a day of widespread delays, cancellations and diversions — with the disruption exposing how a failure at one critical air traffic control facility can quickly ripple across one of the world's busiest aviation networks.