Transportation Secretary Sean Duffy said on Saturday that Friday's nationwide ground stop — the longest shutdown of U.S. airspace in 25 years — began when contractor L3Harris was performing routine maintenance to replace aging copper telecommunications lines with fiber at a remote Federal Aviation Administration facility, and investigators are now trying to determine whether the failure came from installer error or a faulty router.
"What we're working to determine was whether we had incompetence, meaning was it user error, installer error from L3Harris, or did they install a faulty router?" Duffy said at a news conference at the Transportation Department on Saturday morning. "We haven't determined what the fault was."
Duffy said a router being replaced as part of the switch from copper to fiber began flooding other routers across the air traffic control system, and that the routers in the affected facilities were manufactured in 2001. L3Harris, the FAA's longtime telecommunications contractor, did not immediately respond to NPR's request for comment.
FAA Administrator Bryan Bedford, who joined Duffy at the briefing, said there was "zero evidence of anything nefarious, and zero evidence of anything AI-related" behind the outage. Homeland Security Secretary Markwayne Mullin had said on Friday that there was no evidence the failure was caused by an attack.
Bedford said airlines should reach full schedule integrity by the close of business on Sunday, projecting that 4,000 to 5,000 of the roughly 41,000 flights scheduled for Saturday would be canceled as carriers repositioned planes and crews. "We will still have delays and cancellations today, but that will set us up for a full recovery tomorrow," he said, adding: "I do think the worst is behind us."
The ground stop, issued just before 4 p.m. ET on Friday after radar communications at air traffic control centers became unstable, lasted more than four hours before airspace reopened just after 8 p.m. More than 9,100 flights were canceled on Friday and more than 24,500 were delayed, according to FlightAware, and more than 4,000 flights were canceled by Saturday afternoon. Bedford said that of the 50,000 flights scheduled for Friday, about 12,000 were lost outright.
Duffy has blamed the failure on the FAA's aging infrastructure, saying "old switches, old routers" were overloaded with data on a network that still runs on "1980s little copper lines." The administration is seeking $50 billion in emergency funding from Congress to modernize the air traffic control system.
The FAA recently switched on SMART, an AI-enhanced traffic planning tool, at all of its air route traffic control centers, but Duffy and Bedford both stressed that the outage was an equipment issue, not a cyberattack and not connected to artificial intelligence. The FAA has promised a root cause analysis once its investigation is complete.
