WASHINGTON — The nationwide ground stop that halted departing flights across the United States for more than four hours on Friday began when a router flooded the air traffic control network with connection attempts during contractor L3Harris’s copper-to-fiber replacement work at a remote legacy FAA site, Transportation Secretary Sean Duffy and FAA Administrator Bryan Bedford said at a briefing Saturday at U.S. Department of Transportation headquarters.
“As we switched from copper to fiber, it started flooding other routers and our air traffic control system. So specifically, we had over 1,000 connection attempts every 4 to 5 seconds,” Duffy said. The routers at the site were manufactured in 2001, officials said. Bedford said the problem equipment was isolated within about 45 minutes, no systems “went dark” or were fully lost, and the ground stop was ordered as a precaution after the system detected instability.
Duffy said investigators have not determined whether the failure was installer error by L3Harris or a faulty router. “We haven’t determined what the fault was. Was it the router? Or were they not doing great work for us at L3Harris?” he said. “This was an FAA system that didn’t meet the moment. Our contractor didn’t meet the moment, or the equipment didn’t meet the moment and caused the outages.”
Rebecca Guy, the FAA’s acting chief technology officer, said the problem function has been disabled on the roughly 60 routers of the same type nationwide, with further testing planned alongside L3Harris, according to accounts of the briefing.
Bedford said the failure was not a cyberattack. “I think we’ve all concluded that it’s not a cyber issue,” he said, adding there is “zero evidence of anything nefarious and zero evidence of anything AI related.” Bedford said the White House situation room and the national-security apparatus were activated, and the FBI was in FAA facilities, while the cause was still unknown. Duffy said the SMART system “had zero impact.” Bedford said a full root-cause analysis will be shared when it is complete.
“This morning, the system remains stable,” Bedford said, and Duffy said, “We are back at full operations.” Bedford opened the briefing with an apology: “First of all, I’d like to start with an apology, sincere apology to the American traveling public.” In his own post Saturday morning, Duffy said operations were slowly returning to normal, that it is safe to fly, and that delays and cancellations would continue as carriers reschedule flights and reposition aircraft and crews.
Bedford said officials anticipated heavy Saturday cancellations as airlines recover. “We do anticipate somewhere between four and five thousand of the 41,000 flights that are scheduled today likely will cancel,” he said. “But that will set us up for a full recovery tomorrow, and based on everything that we’re hearing from our airline partners, they believe that they’ll be able to have full schedule integrity by the close of business on Sunday. So I do think the worst is behind us.” FlightAware data reported Saturday put the day’s cancellation count above 4,400 by 1 p.m. ET.
The FAA itself has published no statement on the cause. Its only statement, issued Friday and described as preliminary, said: “The FAA issued a nationwide ground stop for all U.S. airports following communication issues impacting multiple Air Route Traffic Control Centers. FAA technicians are investigating the issue. We will provide updates.” L3Harris has not commented; the company did not respond to requests for comment from NPR and other outlets.
Duffy demanded $50 billion in emergency funding for the aviation system on Friday night, before the briefing. In a Saturday post, he blamed the failure on a system “operating on DECADES-OLD, analog equipment” and pointed to a $12.5 billion down payment toward modernizing it.
The ground stop began at 3:36 p.m. ET Friday and was lifted at about 8:19 p.m. ET. The FAA said Saturday morning that operations had returned to normal.
Read JNN’s original coverage: FAA grounds all departing flights nationwide over air traffic control communications failure
This story is based on Saturday’s U.S. Department of Transportation briefing as reported by NPR, the Associated Press and other outlets, and on Secretary Duffy’s public posts. The FAA has not issued a written statement on the cause.
