Airlines across the United States were ordered to hold all departures on Friday afternoon after a communications failure hit the Federal Aviation Administration's air traffic control network, producing a nationwide ground stop that lasted more than four hours and left tens of thousands of passengers stuck or rebooked.
The FAA announced the order at 3:54 p.m. Eastern, saying it was needed "due to extraordinary circumstances and for reasons of safety." It was lifted at about 8:15 p.m. According to the Associated Press, as relayed by ABC7 Chicago, this was the first time since January 2023 that the agency had halted flights nationwide, and before that the last was after the September 11 attacks. The 2023 stop, caused by a failure in the Notice to Air Missions system, ended after about an hour and a half.
At the moment the order was issued, Flightradar24 counted 4,042 flights in the air and bound for US airports. Those flights continued to land. Departures stayed frozen, with the FAA saying a small number of flights would be allowed to leave on a case-by-case basis.
Duffy first described the problem in a social media post as a communication issue affecting all Air Route Traffic Control Centers, which manage aircraft at higher altitudes between airports, and said FAA technicians were investigating. He offered no further detail at that point.
After the stop was lifted, he spoke at a White House briefing and gave a fuller account. Switches in the system had become overloaded with data, he said, causing instability in communications with planes and in radar data at the agency's 22 regional centers. "What we have is an incredibly old air traffic control system," Duffy told reporters, adding that officials had not expected an outage of this kind.
Mullin, speaking earlier outside the White House, called it a telecommunications outage across the FAA. He said two areas of the country were still able to communicate normally but did not identify them.
Mullin said repeatedly that nothing so far suggested a hostile act and that all flights were accounted for. "This isn't another 9/11," he said. CNN reported, citing law enforcement sources, that preliminary indications did not point to a cyberattack.
Officials did stop short of closing off other explanations. Asked whether the ground stop was connected to the global Microsoft outage on Thursday, Mullin said nothing had been ruled out, and the same went for a planned rollout of a new artificial intelligence tool for air traffic controllers. A contractor working on that tool told ABC News it was not behind the stoppage. The anxiety was heightened by a string of hoax bomb threats earlier this month that disrupted dozens of flights in Europe, as the Times of Israel noted.
For now, Duffy's description of overloaded equipment is the only cause on the public record.
FlightAware's tracking showed more than 10,000 US flights delayed and about 2,500 cancelled by 6 p.m. Eastern, with the totals still climbing. ABC News later reported that nearly 5,000 flights had been cancelled in all. At Chicago O'Hare more than 700 flights were cancelled, and some travellers abandoned their trips, rented cars or went home, ABC7 Chicago reported. Canadian airports saw cancellations too, according to the CBC.
United Airlines said it was resuming operations once the stop lifted, and major carriers issued travel waivers. Friday's disruption followed nearly 7,000 delays on Thursday, per NPR. The FAA said flights were resuming gradually and that delays would linger into the weekend. A record number of Thanksgiving travellers is forecast for later this month.
Duffy used the briefing to push for money. "This is an emergency," he said, calling on Congress for $50 billion to fund what he described as a complete overhaul of the air traffic control system. Mullin cited the same estimate.
President Trump has previously asked Congress for $30 billion, the CBC reported, while Reuters reported that lawmakers approved $12.5 billion over five years last year. Duffy pointed to earlier outages at Newark and warned that failures like Friday's would keep happening if the system is not replaced. He and Mullin also criticized Congress for putting off the upgrade, The Hill reported. How the $50 billion figure was calculated has not been made public, and Congress has not signalled whether it will act.
Travellers with bookings this weekend should check with their airline for rebooking options before heading to the airport.
