The Federal Aviation Administration grounded all flights nationwide Friday afternoon following a communication issue between air traffic control centers.
An FAA alert said the stoppage was “due to extraordinary circumstances and for reasons of safety.”
Ground stops were issued at Chicago O’Hare International Airport and Midway International Airport.
U.S. Transportation Secretary Sean Duffy said a communication issue affected all of the nation’s 22 air traffic control centers that route planes between airports.
Secretary of Homeland Security Markwayne Mullin said there was no sign yet that “this was a nefarious attack against us. It’s just a telecommunications outage.”
“Everybody’s safe. There’s no reason to be concerned about your loved ones if they’re flying,” Mullin said.
There is no timeline for restarting flights. Mullin said investigators will look at whether there is any link to the FAA’s nationwide rollout of a new artificial intelligence system to help identify problems and reroute planes. But that system operates out of one location near Washington, D.C., and just sends recommendations to the air traffic control centers.
The FAA’s first alert went out shortly before 3 p.m.
The FAA, in a separate statement, said the ground stop was issued “out of an abundance of caution. “Every flight has been accounted for and international flights will be handled on a case-by-case basis,” the FAA said.
The Chicago Department of Aviation said it had no comment and directed questions to the FAA, which did not immediately provide further details.
American Airlines, in a statement, said flights already in the air would continue to their destinations. “We expect disruption to our schedule for the rest of the day, depending on the length of the FAA’s nationwide ground stop,” the company said.
This is the first nationwide ground stop since January 2023, when a key FAA computer system malfunctioned. Before that, the last time had been after the Sept. 11, 2001 terrorist attacks.
The government has been working to overhaul the outdated technology that air traffic controllers rely on since Congress approved $12.5 billion for the project last year, according to the AP. Miles of old copper wires have been replaced with fiber optic lines and old radio systems are gradually being replaced at airports across the country.
But much work remains, the AP reported. Duffy has said that another $30 billion will be needed to complete the work, and the White House has begun lobbying Congress to approve it.
The FAA recently expanded its use of an AI tool that reroutes flights at O’Hare, though there is no indication that the system is related to the ground stop. The system, called Strategic Management of Airspace Routing Trajectories, or SMART, has been used in Washington, D.C., since September.
But the FAA this week said it is now being used at O’Hare to reduce delays. The system has been used to reroute 180 flights across the country, the FAA said. Duffy has said the AI tool would offer recommendations to human air traffic controllers, who would remain in control of rerouting flights.
This is a breaking news story. Check back for updates.
Contributing: Associated Press