US links flight stoppage to telecoms upgrade as cancellations continue

The Federal Aviation Administration (FAA) lifted the ground stop at 8.15pm Eastern time on Friday 13 November, more than four hours after departures were halted. The BBC reported that it was the longest nationwide stop since the 11 September 2001 attacks.

The FAA had ordered departing aircraft to remain on the ground for safety reasons, while incoming international flights were handled case by case. More than 3,500 aircraft were already in the air, the BBC reported; some diverted and others continued to their destinations. A limited number of departures were permitted during the stop.

The BBC, citing flight-tracking service FlightAware, reported more than 8,500 flights delayed and nearly 8,000 cancelled on Friday. Those are daily figures, not a count of flights disrupted solely by the ground stop. Air Canada cancelled flights between Canada and the US, while European air traffic agency Eurocontrol suspended US-bound traffic from its member states at the FAA’s request.

Transport Secretary Sean Duffy said switches and routers in an old air traffic control communications system had been overloaded with data, causing instability in radar and communications. Homeland Security Secretary Markwayne Mullin said it appeared that new equipment and technology had overwhelmed the older system, but the cause was not yet certain. He said there was no indication of a cyberattack, though officials were still investigating.

A previous nationwide stop in 2023, caused by a failure in the system used to publish air safety notices, lasted one hour and 52 minutes, aviation expert Guy Gratton told the BBC. He said Friday’s disruption appeared to be the worst since 9/11, but was not on the same scale.

Duffy said the disruption could have a ripple effect for days as airlines worked to return to capacity. Delta and United said they were resuming operations, while JetBlue said it would resume flights on Saturday morning.

Update

US Transport Secretary Sean Duffy said a telecommunications upgrade triggered the air traffic control problems behind Friday’s nationwide halt to departures. Airlines were still dealing with widespread disruption on Saturday, even as aviation systems returned to full operation.

Duffy said contractor L3Harris was replacing old copper wire with fibre-optic cable when a router being worked on began flooding other air traffic control systems with data, causing communication problems.

The precise fault remains under investigation. Duffy said officials were examining whether contractor error or a faulty router was responsible. CBS News reported that government sources had received conflicting information about the cause; L3Harris did not immediately respond to the broadcaster’s request for comment.

Federal Aviation Administration (FAA) chief Bryan Bedford said there was no evidence of malicious activity or involvement by artificial intelligence. Duffy said the investigation into a possible cyberattack was continuing.

The FAA ordered the nationwide ground stop on Friday, 13 November, after communications and radar systems became unstable. It was lifted at 8.15pm Eastern Time, more than four hours later. Some limited departures to Europe and Hawaii were permitted during the stop.

By about 12.52pm Eastern Time on Saturday, tracking site FlightAware listed 4,444 cancellations and 4,219 delays for flights within, into or out of the US that day. Those totals include disruption from all causes, not just the ground stop.

Duffy said all FAA systems were back to full operation. Bedford said he expected airlines to return to normal schedules by the end of Sunday.