FAA lifts US ground stop after nearly 8,000 flights cancelled

The US Federal Aviation Administration lifted a nationwide ground stop on Friday after more than four hours, triggered by a failure in an analogue air traffic control communications system. Flight-tracking firm FlightAware recorded more than 8,500 delayed flights and nearly 8,000 cancellations, in the longest such stoppage since the 11 September 2001 attacks.

Homeland Security Secretary Markwayne Mullin said there was no indication of an attack and that everybody was safe.

How many flights were affected?

The FAA’s first announcement, issued at 15:54 EST (20:54 GMT) on Friday, said all flights departing within the United States would be grounded until further notice. More than 3,500 aircraft were already in the air at that point; some were diverted to other airports and others continued to their destinations.

Hours later, some departures were allowed from San Francisco International airport. The FAA said it reopened US airspace at 20:15 EST.

Which international flights were disrupted?

Eurocontrol suspended all US-bound air traffic from its 42 member states “on request of the FAA due to technical issues”, according to the agency’s website. Those member states include dozens of EU nations, the UK, Ukraine, Turkey, Israel and Morocco.

Sydney, Australia’s largest international airport, grounded all US-bound flights until further notice, and Air Canada cancelled flights between the US and Canada.

When will normal service resume?

Transportation Secretary Sean Duffy told a news conference on Friday night that the outage would have a ripple effect for several days. “It’s going to take us some time to unwind what’s happened this afternoon,” Duffy said.

Tens of thousands of people were stranded at airports around the country, Duffy said, many of them “without any knowledge of where they’re going to sleep tonight”.

Delta Air Lines and United Airlines said they were resuming operations. American Airlines said it was “focused on operating as many remaining flights as possible this evening”, and JetBlue said it would restart flights on Saturday morning.

What caused the ground stop?

Duffy said a legacy air traffic control communications system became overloaded, affecting both communications and radar. “So this is analogue telecom. Our switches, our routers actually got overloaded with data and they went down,” he said.

The system needs a complete overhaul, Duffy said, estimating the cost at $50 billion. “It’s going to continue to fail,” he said.

Mullin said there was “zero evidence” of a cyber-attack and ruled out any link to the global Microsoft outage that began on Thursday. He said the introduction of new technology into an old air traffic control system had overwhelmed it. Both cabinet secretaries said the public was never in danger during the stoppage.

When was the last nationwide ground stop?

Friday’s stoppage was only the second of its kind since the immediate aftermath of the al-Qaeda hijackings of 11 September 2001. “This looks like the worst since 9/11, but clearly not on that scale,” Dr Guy Gratton, an associate professor of aviation at Cranfield University, told BBC Verify.

Gratton noted a 2023 grounding caused by a failure in the Notice to Air Missions (Notam) system, which lasted 1 hour and 52 minutes, delayed about 9,500 flights and cancelled about 1,300. Friday’s incident lasted longer.

Frequently asked questions

How many flights were cancelled during the US ground stop?

FlightAware recorded nearly 8,000 cancelled flights and more than 8,500 delays on Friday, when the FAA grounded all departures within the United States for more than four hours.

What caused the FAA ground stop?

Transportation Secretary Sean Duffy said a legacy analogue air traffic control communications system became overloaded, knocking out communications and radar. Homeland Security Secretary Markwayne Mullin said there was zero evidence of a cyber-attack.

When was the last nationwide US ground stop?

Friday’s stoppage was the second nationwide grounding since the aftermath of the 11 September 2001 attacks. The previous one, in 2023, followed a failure in the Notam system and lasted 1 hour and 52 minutes.

Are US flights operating again?

The FAA reopened US airspace at 20:15 EST on Friday. Delta Air Lines and United Airlines said they were resuming operations, American Airlines was operating remaining flights that evening, and JetBlue planned to restart on Saturday morning.

With reporting from BBC News.

Stock image, not from the events described. Globe World — Jo%E3o%20Silas / Wikimedia Commons (CC0 1.0)