Copper Wire Upgrade Triggered US Flight Ground Stop, Duffy Says

Washington, United States — A nationwide ground stop that canceled thousands of flights across the country was caused by a problem that emerged during a copper-to-fiber wire upgrade, US Transport Secretary Sean Duffy told a news conference, according to the BBC. Duffy said the government is still trying to determine whether the failure stemmed from "incompetence" on the part of the contractor performing the work or from faulty equipment.

What caused the ground stop?

Maintenance crews were switching air traffic control wiring from copper to fiber-optic cable, work being carried out by contractor L3Harris, Duffy said. He described the wire being replaced as part of "an incredibly old telecommunications system" in the United States. "It was such an old wire that it was being discontinued," Duffy said, according to the BBC.

Duffy said a router undergoing work during the upgrade began flooding other air traffic control systems with signals, disrupting communications with aircraft. Faced with that breakdown, the government shut down US airspace for safety reasons, he said.

Was it a cyberattack?

Duffy said the US government does not believe the failure was the result of a cyberattack, though an investigation remains under way. Federal Aviation Administration Administrator Bryan Bedford, speaking at the same news conference, went further: "We see zero evidence of anything nefarious, and zero evidence of anything AI related," he said, per the BBC report.

How many flights were affected and for how long?

No flights were permitted to take off from the continental United States for more than four hours beginning at 15:54 EST (19:54 GMT) on Friday, marking the longest such suspension since the September 11, 2001, attacks, according to the BBC. Some international flights were allowed to depart US airports in what the report described as an apparent effort to clear space, while other travelers were left stranded aboard aircraft on the tarmac, unable to either take off or return to the gate.

More than 3,500 flights were canceled and more than 2,000 delayed across the country on Saturday as the disruption continued, according to tracking website FlightAware, cited by the BBC. The ripple effects were expected to last for days.

Former Transportation Security Administration head John Pistole told the BBC that the roughly four-and-a-half-hour restart time pointed to resilience in the system, while also raising a lingering question. "The fact that they were able to get it restarted in four-and-a-half hours is good news — it shows a resilience in the system — but what's to say it's not going to happen tomorrow?" Pistole said.

What happens next for air traffic control funding?

Duffy warned that a similar failure could recur unless Congress approves funding to modernize air traffic control infrastructure. President Donald Trump has requested $30.1 billion for those upgrades, the BBC reported. Both chambers of Congress are currently controlled by the Republican Party, which could ease passage of the request, though no timeline for a vote was given in the available reporting.

Has a ground stop of this scale happened before?

According to the BBC, a nationwide ground stop of this kind has been ordered only once before — when all flights were grounded for several days following the September 11, 2001, attacks. Friday's suspension did not approach that duration, but officials and aviation veterans alike flagged it as a sign of strain in infrastructure that Duffy himself described as outdated.

The Department of Transportation has not released a timeline for completing its inquiry into whether contractor error or equipment failure triggered the router malfunction. The BBC's coverage, including original video from the news conference, is available in its full report on the ground stop, along with a related explainer on what travelers affected by the disruption should do next.

What should stranded travelers do now?

The BBC noted a related explainer addressing what passengers affected by the disruption should do next, published alongside its main report on the ground stop. Travelers facing cancellations or delays were directed to check directly with airlines for rebooking options as the knock-on disruption continued into the days following Friday's suspension.

For passengers still working through canceled or delayed itineraries, the scale of Saturday's figures — more than 3,500 cancellations and over 2,000 delays, per FlightAware — suggested the backlog would take time to clear even after air traffic control systems were restored. Some travelers described their experience to the BBC in video captured at affected airports, with one quoted simply saying, "We'll get home one day."

The Department of Transportation did not indicate in available reporting whether compensation or rebooking assistance beyond standard airline policy would be offered to those affected.