Over 2,000 US flights cancelled: What caused FAA communication outage

A communications failure in the US air traffic control network brought flight departures across the country to a halt on Friday (November 13), exposing vulnerabilities in the Federal Aviation Administration’s (FAA) ageing infrastructure.

Although the agency lifted the nationwide ground stop after about five hours, airlines were still dealing with cancellations and delays on Saturday (November 14), as they worked to restore normal operations.

More than 2,000 flights were cancelled across the US on Saturday, according to the Associated Press (AP), with airlines struggling to reposition aircraft and crew members displaced by the shutdown. The disruption could take several days to clear, even though the FAA has allowed departures to resume.

What caused FAA outage?

The failure involved switches and routers that carry information across the air traffic control network. US Transportation Secretary Sean Duffy said the equipment became overloaded with data and began transmitting inconsistent information to air traffic control centres.

Duffy said the problems began at 3.36 pm Eastern Time on Friday, when the agency experienced instability in radar and communications systems at its air traffic control centres. The FAA suspended departures nationwide as a safety precaution.

“Our switches, our routers actually got overloaded with data, and they started to give us inconsistencies in the data from those routers, and because of that we shut the system down,” Duffy said at a White House briefing.

Also read: FAA grounds all US flights in second nationwide stop since 9/11

The failure did not mean that all radar and communications capabilities were lost. Homeland Security Secretary Markwayne Mullin said more than 3,000 aircraft already in the air were safely landed.

CBS News, citing multiple sources, reported that an update to the private communications network connecting the air traffic control system had caused it to reboot, triggering a communications outage. The network is operated by L3Harris. Mullin said new security patches appeared to have overwhelmed the older routers, although officials were still investigating the precise cause.

The administration also clarified that the FAA’s new AI-powered system, designed to help predict problems in the airspace, was not involved in the failure. The problem was with the older infrastructure.

Will flight disruptions continue?

The lifting of the ground stop did not immediately restore airline schedules. During the shutdown, aircraft were diverted to other airports or left waiting on the ground, leaving planes and crew members away from where airlines needed them.

Airlines have since been working to reposition aircraft, bring crews back into place and accommodate passengers whose journeys were cancelled or delayed. CNBC reported that carriers were deploying spare aircraft and making schedule adjustments to recover from the disruption.

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Duffy said the FAA had rebooted the affected system after reviewing the failure, but acknowledged that further outages could occur.

“We didn’t think we would have this kind of outage. We did,” he said, adding that the system had been restarted but that “you will have more of these”.

The FAA said it had tested its systems before allowing departures to resume and confirmed that operations were stable. Officials expect the system to be operating normally in time for the Thanksgiving travel rush later this month.