Key facts
- Duffy said L3Harris, a longtime FAA contractor, was upgrading copper wire to fiber optic cable when the failure occurred.
- Duffy said the cause was either installer error by L3Harris or a faulty router, and that it is under investigation.
- FAA acting CTO Rebecca Guy said two points were pinging the network at a thousand connections every four to five seconds.
- FAA administrator Bryan Bedford said the agency sees zero evidence of anything nefarious or AI-related.
- Duffy said switchovers at bigger airports will happen late at night, and the timing of remote work will be reevaluated.
- The air traffic controllers union said it was not consulted on an FAA AI tool announced a day before the ground stop.
Transportation Secretary Sean Duffy said at a press conference on November 14, 2026, that a nationwide ground stop halting flights across the United States was caused by seemingly routine maintenance work. Duffy said copper wire at a remote location was being upgraded to fiber optic cable by L3Harris, a longtime contractor for the Federal Aviation Administration, and that a router then overloaded a critical communication system.
Duffy said the work was "pretty straightforward" and took place at a very remote location. He said the agency was working to determine whether the cause was incompetence, meaning user or installer error from L3Harris, or a faulty router installed by the contractor.
FAA acting CTO Rebecca Guy said the agency saw two places pinging its network at a high rate, a thousand connections every four to five seconds. Guy said the FAA disabled both right away, stabilized the network and is now performing a root cause analysis.
Duffy has repeatedly insisted at multiple press conferences that Congress needs to provide more funding for aviation equipment upgrades. Asked why the work was done at 3pm on a Friday afternoon rather than at midnight on a Saturday, he said switchovers at bigger airports will take place late at night while remote switchovers happen during the day. He said there will be a reevaluation of when the work is done.
The ground stop was only the third nationwide ground stop of the 21st century, according to the report. More than 8,200 flights were canceled on Friday evening, according to aviation data firm Cirium, and at least another 3,000 were canceled on Saturday as effects continued after the ground stop was lifted.
The ground stop came a day after the FAA announced the rollout of an AI tool for air traffic controllers. The air traffic controllers union said it was not consulted in designing the system. FAA administrator Bryan Bedford said the agency sees "zero evidence of anything nefarious and zero evidence of anything AI-related," and that it is working through what the defective piece of equipment was.