The US Federal Aviation Administration stopped departures across American airspace on Friday 13 November, after a fault in the communications and radar feeds used by air traffic control. The stop was lifted at 8:15pm Eastern Time, 01:15 GMT on Saturday. France 24 writes that it was only the second nationwide ground stop of this kind in US airspace since the attacks of 11 September 2001. Transportation Secretary Sean Duffy tied the incident to the replacement of an old copper line with fibre, and said the precise fault is not yet settled.

In Saturday’s Department of Transportation statement, Duffy sets out what he believes happened. At at least one remote FAA site, the contractor L3Harris was doing routine maintenance, moving lines from copper to fibre, from analog to digital. The copper line was so old it was about to be discontinued. L3Harris owns the network the FAA uses and has worked for the agency for more than 20 years. Duffy says it is not yet clear whether this was an installation error or a faulty router. The router being replaced began flooding other routers in the system: more than 1,000 connection attempts every four to five seconds. Communication with aircraft suffered, and so did some radar feeds. “Your safety is paramount,” he said: the airspace was shut, aircraft were brought down, the problem was isolated, and the sky was reopened. Controllers and pilots grounded more than 3,500 flights. After the stop was lifted, more than 8,000 operations resumed that same night. On Saturday the airspace was open, with delays and cancellations still expected.

France 24 reports Saturday’s briefing by FAA chief Bryan Bedford. He apologised to travellers. He said 12,000 flights were cancelled on Friday and that, of 41,000 scheduled for Saturday, between 4,000 and 5,000 were likely to be cancelled. He expected a full schedule by the close of business on Sunday. FlightAware had logged more than 6,200 cancelled flights by Saturday evening. ABC News, counting earlier on Saturday morning, gave different FlightAware figures: 12,506 cancellations on Friday and Saturday combined, of which 9,132 were on Friday, plus 7,030 delays on Friday, and on Saturday morning 3,374 cancellations and 1,008 delays. Those are two different moments, not one total.

Bedford said, according to CNBC, that there was “zero evidence” the problem was something nefarious or related to artificial intelligence. ABC quotes Homeland Security Secretary Markwayne Mullin: there was no indication of a cyberattack, and the check continues. France 24 notes that some lawmakers asked for investigations, including into whether the system is secure against cyber crime. That is a question they raised, not a finding that the stop was an attack. The same report says Saturday’s news conference started late because of the audio.

Duffy asked Congress for $50 billion to modernise air traffic control. ABC quotes him on Friday night at the White House: “This is an emergency,” there “will be more of these” unless the system is rebuilt, and flying stays “less safe” without the money. France 24 carries the replies on X. Illinois governor JB Pritzker, a Democrat: “Cut the crap. Trump and Republicans have controlled Congress and could have funded the system.” New York governor Kathy Hochul asked Duffy to resign or be fired by Trump: “We’re fortunate no lives were lost.” Republican senator Eric Schmitt wrote that air traffic control and airport infrastructure need to be rebuilt. France 24 noted on Saturday evening that President Donald Trump had not yet made a public statement about the stop.

At LaGuardia, Lisa Beraid, 48, who works for an insurance company, told AFP on Saturday morning that she was tired and frustrated. Pat Curlett, 62, a Ford worker, said he was stuck for about 36 hours. Steven Rathe, 77, on a four-leg trip to Albuquerque, said they were lucky it had not lasted longer. Tim Johnson, consumer director at the UK Civil Aviation Authority, warned that disruption can continue after flights resume, as airlines rebook passengers.

CNBC reports that L3Harris said it has completed more than 70 percent of the switch from copper to fibre. The photograph shows Dulles airport as seen from the Udvar-Hazy Center, not the remote site of the work and not Friday’s queues. The image is by Ad Meskens and is published on Wikimedia Commons under the CC BY-SA 3.0 licence.

Source consulted: Copper wires to blame for US flight disruption, says Trump administration.