Federal aviation officials said Saturday that an equipment issue during a contractor’s upgrade of an aging Federal Aviation Administration telecommunications line set off the nationwide ground stop that halted flights across the United States a day earlier, stranding tens of thousands of passengers and leaving airlines with a backlog of cancellations expected to last through the weekend.
Transportation Secretary Sean Duffy said at a briefing that L3Harris, a longtime FAA contractor, was performing routine maintenance at at least one remote FAA location, replacing copper wire with fiber. Routers at those facilities were manufactured in 2001, he said. The work is the kind of upgrade that has been underway in American institutions for decades.
“Virtually every single institution in America has gone from copper to fiber, from analog to digital,” Duffy said. “Just maybe the FAA is the last one to be doing this work because the investments haven’t been made, but this is not complicated.”
L3Harris did not immediately respond to a request for comment Saturday. The FAA is still investigating the exact error that started flooding other routers in the air traffic control system. Duffy said the inquiry is focused on whether the failure involved incompetence — user error or installer error by L3Harris — or a faulty router installed by the contractor.
Bryan Bedford, the FAA administrator, joined Duffy at the briefing and said there was no evidence that anything nefarious or AI-related caused the disruption. Homeland Security Secretary Markwayne Mullin also said there was no evidence the problem resulted from an attack.
The aviation system came back online and was slowly returning to normal Saturday morning, but delays and cancellations continued after Friday’s nationwide ground stop. Bedford said airline partners believe they can restore full schedule integrity by the close of business Sunday. Duffy told reporters Friday night that he expected operations to be back up as travel intensifies for Thanksgiving.
For about four hours Friday, thousands of flights at U.S. airports were grounded in one of the biggest disruptions of the nation’s air travel system since the terrorist attacks of Sept. 11, 2001. FlightAware recorded nearly 25,000 flights delayed and more than 9,000 canceled on Friday. The disruption carried into Saturday morning, with more than 4,000 cancellations recorded — 14% of flights departing the United States, based on data from Cirium, which tracks aviation analytics.
Duffy said Friday that air traffic control facilities experienced intermittent outages of radar and communications systems beginning earlier in the afternoon. He blamed old switches and old routers for the failures.
Flight boards at airports across the country remained filled with red cancellation marks Saturday morning. At Tampa International Airport in Florida, people in the main terminal area before security curled up in chairs to get some sleep. On Friday night, a flight board at Ronald Reagan Washington National Airport in Washington, D.C., showed dozens of flights delayed into the early morning hours or canceled.
Erin and Jake Britt spent half the day at the Washington airport Friday. Their plane to Fort Lauderdale, Florida, boarded at 3 p.m. By 5:30 p.m., passengers were getting off the plane — but they were still in Washington. The couple left the airport at 8 p.m.
Erin Britt said passengers were annoyed but reasonable overall, with some asking how the airline could not have been prepared. Her answer was that no one was prepared. Neither the pilot nor the flight attendants had more information than passengers, she said; they seemed just as much in the dark.
The Britts decided to cancel their weekend trip, but the night did not end there. They spent more than nine hours overnight waiting on the JetBlue customer service call line to seek reimbursement. Erin Britt said she set alarms at 20-minute intervals in case she fell asleep.
For travelers with events or plans over the weekend, the delays added another layer of stress. Joe Romano and Maddie Cabana had a cruise leaving Orlando, Florida, on Saturday afternoon. Romano described the situation as a big eye roll and said that because he already travels frequently for work, he constantly deals with flight delays. “Of course, it always happens to me,” he said.
Cabana called it inconvenient and frustrating as the pair considered checking their bags or going home. They held out hope that everything would work out. It eventually did: after their JetBlue flight was canceled, they quickly booked another flight on Southwest Airlines and made it early Saturday morning.
Others decided flying was no longer worth the trouble. Suze DiPietro’s husband drove about four hours from Ocean City, New Jersey, to pick her up in Washington. The couple had friends in the area and spent the night there. “My husband, my hero, is driving down from New Jersey to come get me,” DiPietro said.
Some travelers switched to Amtrak trains as they struggled to reach their destinations, though Amtrak’s system also had a brief outage Friday night.
Friday’s order was the second nationwide ground stop since the Sept. 11, 2001, attacks. The previous one of comparable scale came in 2023, when all U.S. airports were shut down because of an outage in the NOTAM system, which alerts pilots and airports to real-time hazards. That outage prompted fears of a cyberattack, but the FAA later determined that contract workers had inadvertently deleted critical files.
The FAA has recently begun rolling out an AI-enhanced software tool known as the SMART system as part of an ambitious overhaul of the nation’s air traffic control system. Air Space Intelligence, the company that makes the tool, quickly dismissed speculation that its product was connected to the flight disruptions. “The current ground stop is not based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC,” the company said on social media.