US aviation shutdown traced to L3Harris router, officials say

Flights across the United States were grounded for nearly five hours on Friday after a router installed by government contractor L3Harris during a routine wiring upgrade overwhelmed the communications system linking air traffic control centers, government officials said on Saturday. More than 20,000 flights have been disrupted since the ground stop began, and the Federal Aviation Administration is still trying to establish the root cause.

Transportation Secretary Sean Duffy said the trouble began during maintenance to move FAA telecom lines from copper wire to fiber at, according to officials who spoke to Reuters, remote sites in Arkansas and Texas. The new routers began flooding other routers with more than 1,000 connection attempts every four to five seconds. Communications at 17 of the FAA's 22 en route centers, the regional hubs that hand aircraft between controllers, became unstable. Because the agency could not identify the cause, it stopped departures nationwide.

"This was an FAA system that didn't meet the moment," Duffy said.

He said investigators had not established whether the fault lay with L3Harris's installers, with the way the equipment was used, or with a faulty router. "We're working to determine whether we had incompetence, meaning was it user error or installer error from L3Harris, or did they install a faulty router? We haven't determined what the fault was," he said, adding: "We need L3Harris or whoever provided that router to us to do a better job."

The FAA said communications did not go down and no center went dark. Data became unstable instead. The routers being replaced are about 25 years old and were due to be swapped out in 2006, Duffy said.

L3Harris said it took the issue seriously and was "supporting the FAA in its investigation to understand the conditions that led to the Nov 13 ground stop of our nation's air travel." The company said it had completed more than 70 percent of the planned conversion of airspace communications from legacy copper wires to fiber optics.

The FAA spends about $1 billion a year maintaining the copper network. Congress has given it $12.5 billion to upgrade its aging air traffic control and telecom systems, and Duffy has asked for $50 billion more for air traffic control and airports.

The agency's equipment has failed in smaller ways before. A 2023 ground stop that lasted 90 minutes and disrupted 11,000 flights followed a contractor's accidental deletion of files, and was the first nationwide stop since the hijacked-plane attacks of Sept 11, 2001. In September, a circuit failure at a Philadelphia air traffic facility and a construction crew's severed fiber cable in New Jersey delayed or canceled thousands of flights in the Northeast. Last week the FAA said it would retire floppy disks used for weather and other critical information at more than 400 facilities by the end of 2028.

Friday's stoppage hit as weekend travel was building. Duffy said the agency would reconsider the timing of work at smaller facilities to prevent a repeat.