US ground stop caused by aging equipment, no evidence of cyberattack, Transportation Sec. says

"What we have is an incredibly old air traffic control system," Duffy said, explaining that outdated analog telecommunications equipment began producing inconsistent data.

US Transportation Secretary Sean Duffy said Friday that the nationwide ground stop put in place earlier in the day was triggered by aging air traffic control equipment that became overloaded with data, causing disruptions to radar information and communications with aircraft.

"What we have is an incredibly old air traffic control system," Duffy said, explaining that outdated analog telecommunications equipment, including switches and routers, began producing inconsistent data.

More than 3,500 aircraft were airborne when the ground stop was imposed. Duffy said that, at the time of his latest update, fewer than 400 remained in the air as controllers worked to bring flights safely to their destinations.

Homeland Security Secretary Markwayne Mullin said investigators had found no evidence of a cyberattack, although the investigation was continuing.

"There is actually no cyberattack. We're still working through that process. Our teams are working," Mullin said.

Mullin said multiple federal agencies, including the Department of War, the Cybersecurity and Infrastructure Security Agency (CISA), the National Security Agency (NSA), and components of the Department of Homeland Security, are investigating the incident.

"There is nothing that indicates it yet," Mullin said. "There's no chatter. We haven't seen any footprints, as you would say, or identifications of people that got into the system."

He noted that cyberattacks are often accompanied by claims of responsibility, but no such claims have emerged.

Duffy calls for federal funding for air traffic upgrades

Duffy blamed years of insufficient modernization, saying previous administrations had spent approximately $15 billion over 25 years attempting to upgrade the system, with little progress.

He urged Congress to approve additional funding beyond the $12.5 billion already allocated under Trump's signature spending legislation.

"Let's not do a patchwork, a fix to a system that's critical for every single family," Duffy said. "It's not red. It's not blue. It's not Democrat. It's not Republican. It's American. Give us the money to fix it."