(BBC News) A nationwide US ground stop that caused thousands of flight cancellations was caused by an issue following a copper wire upgrade, Transport Secretary Sean Duffy said.
Duffy told a news conference that the government was trying to find out whether the problem was caused by “incompetence” on the part of the company doing the upgrades, or faulty equipment.
The US government does not believe it was as a result of a cyber-attack, although an investigation is still under way, Duffy said.
Friday’s suspension was the longest such incident since the September 11, 2001, attacks on the US, and the disruption is expected to last for days.
Maintenance was being carried out to switch from copper wire to fibre by a contractor called L3Harris, a technology provider company, Duffy said.
The US has “an incredibly old telecommunications system,” he added.
“It was such an old wire that it was being discontinued,” he said.
The transport secretary explained that a router that was being worked on had started flooding other air traffic control systems and created communication issues with planes which led the government to shut down the airspace for safety reasons.
Bryan Bedford, who heads the Federal Aviation Administration (FAA), told the same news conference: “We see zero evidence of anything nefarious, and zero evidence of anything AI related.”
No flights were allowed to take off from the continental US for more than four hours from 15:54 EST (19:54 GMT) on Friday.
More than 3,500 flights were cancelled and more than 2,000 delayed in the US on Saturday, according to tracking website Flight Aware, as knock-on disruption continues.
In some cases, passengers were left stuck inside planes on the Tarmac, unable to take off or to return to the gates. Some international flights were allowed to depart US airports, in an apparent effort to clear space.
Duffy warned that a similar issue could arise again unless the US Congress approved upgrades to air traffic control infrastructure.
US President Donald Trump has requested $30.1 billion for the upgrades.
Former TSA Administrator John Pistole told the BBC that “the fact that they were able to get it restarted in four-and-a-half hours is good news – it shows a resilience in the system – but what’s to say it’s not going to happen tomorrow?”
