Duffy points to an L3Harris copper-to-fiber switch as the origin of the US flight halt

US Transportation Secretary Sean Duffy said at a press conference on Saturday, November 14, that Friday's nationwide flight halt began when L3Harris, a contractor for the Federal Aviation Administration (FAA), was carrying out routine maintenance at at least one remote facility to replace copper lines with fiber, according to NPR and NBC News. A router at that facility overloaded other parts of the system, according to CNBC.

Duffy said there were more than 1,000 connection attempts every four to five seconds and that the routers at those facilities were manufactured in 2001, according to NBC News and NPR. "What we're working to determine was whether we had incompetence, meaning was it user error, installator error from L3Harris, or did they install a faulty router?" he said, according to NPR. L3Harris did not immediately respond to NPR.

FAA Administrator Bryan Bedford said there is no evidence of a malicious cause or of a problem related to artificial intelligence, according to CNBC and NPR. Bedford added that the AI system the FAA has been rolling out for months is not connected to the systems that failed, according to NBC News.

According to Bedford, 12,000 of the flights affected on Friday could not recover, and the FAA expects between 4,000 and 5,000 cancellations out of the roughly 41,000 flights scheduled on Saturday, according to NBC News. Airlines expect to restore their full schedules by the close of Sunday, Bedford said, according to NPR. FlightAware counted more than 4,200 cancelled flights in the United States as of 12:00 Eastern time, according to NBC News.

The FAA has not published a technical report on the cause. Duffy said the investigation remains open and the specific fault has not yet been determined.