The Federal Aviation Administration held every departing flight in the United States on the ground for four hours and 20 minutes on Friday, after the radar feeds and radio frequencies that controllers depend on began failing across the agency's en route centers. It was the longest nationwide ground stop in 25 years, according to the Associated Press, and the first of any length since a corrupted database file took down the pilot-alert system in January 2023.
The order went out at 3:54 p.m. Eastern time and was lifted at about 8:15 p.m. Roughly 3,500 aircraft were already airborne when it took effect and were allowed to continue to their destinations, Transportation Secretary Sean Duffy said. By the agency's own accounting, at least 10,000 flights and more than two million passengers were affected.
The disruption did not end with the order. Airlines canceled more than 2,000 flights on Saturday as they moved crews and aircraft back into position — a count the tracking service FlightAware later put above 2,500, with hundreds more delayed. Duffy said larger aircraft would be prioritized through the weekend, and that he expected schedules to recover before the Thanksgiving travel rush.
What failed
The FAA's own statement on Friday afternoon said only that it was acting because of "communication issues impacting multiple Air Route Traffic Control Centers," that technicians were investigating, and that the information was preliminary.
Duffy filled in the picture that evening. The agency's network switches and routers, he said, were overloaded with data and began returning inconsistent information, at which point the FAA shut the system down rather than keep flying on it. "What went down was old — old legacy equipment," he said, describing a system still carrying traffic over analog telecommunications.
The failure spread rather than arriving all at once. According to The Air Current, the FAA's command center in Washington was told at about 3:30 p.m. that controllers had lost radio frequencies and radar; the problem started at the Chicago center and was confirmed minutes later by Boston, New York, Washington and Minneapolis. A ground stop for eastbound traffic went out at 3:44 p.m. and was widened nationwide as more facilities reported trouble. One airline dispatcher was told 10 of the agency's 22 en route centers were affected "and growing."
Aircraft that had already landed filled the gates faster than airports could clear them, worst of all at Chicago O'Hare, and carriers began diverting arrivals to smaller cities. United Airlines opened its emergency operations center. In Canada, Nav Canada imposed traffic restrictions at Toronto Pearson, Montréal-Trudeau, Calgary and Vancouver.
Not a cyberattack, officials say
Homeland Security Secretary Markwayne Mullin said at a White House briefing that the outage "does not appear" to be a cyberattack and that investigators had found no evidence of improper access, while declining to close the question. He said it was unrelated to the recent Microsoft outages, and that the National Security Agency, the Defense Department, the Cybersecurity and Infrastructure Security Agency and the Federal Emergency Management Agency were all helping examine what happened.
Attention briefly turned to new technology rather than old. Mullin said investigators were checking whether the outage had anything to do with SMART, an artificial-intelligence scheduling system that Duffy said had been switched on at all 22 en route centers on November 10. Air Space Intelligence, the company that built it, said the ground stop was neither based on nor caused by its system, and Duffy said the equipment recently converted from analog to digital had not failed.
The bill arrives in Congress
The outage landed in the middle of an argument about money. Congress appropriated $12.5 billion in 2025 to begin modernizing air traffic control, and Duffy has said repeatedly that the sum is not enough. On Friday he asked lawmakers for an emergency bill giving the Transportation Department another $50 billion and a mandate for what he called a complete overhaul, describing the situation as an emergency.
The practical consequences reached beyond airports. Several college football teams had their travel disrupted, pushing kickoff times on Saturday, and one American Airlines flight sat for hours at Charlotte.
Reporting from the Federal Aviation Administration, ABC News, Nextgov/FCW, The Air Current, the Associated Press and Al Jazeera.
