FAA lifts nationwide ground stop after 8,553 delayed flights

US regulators lifted a nationwide ground stop on Friday after a telecommunications failure grounded every departure in the country, delaying 8,553 flights and cancelling 6,816 more, according to the tracking site FlightAware.

The Federal Aviation Administration halted all departures at US airports after outages hit communication systems, radio frequencies and radar. The failures began in Chicago, according to The Air Current, an aviation news site. The FAA has not yet explained what caused what officials called a "telecommunications outage."

This is only the second nationwide ground stop of all departures since the 9/11 attacks. The previous one came in January 2023, when the FAA paused domestic departures for less than two hours.

Who said what?

Sean Duffy, President Donald Trump's transportation secretary, acknowledged that a technology failure led federal aviation officials to shut down the system and ground flights. Details remain scarce.

Duffy and Homeland Security Secretary Markwayne Mullin appeared to suggest the cause was older technology that became overwhelmed with data after the FAA introduced new technology.

Mullin, a former Oklahoma senator now leading the Department of Homeland Security, addressed the security question directly: "we've seen zero evidence that this was a cyber-attack."

Trump himself stayed uncharacteristically silent throughout the crisis. His two cabinet secretaries carried the public explanation.

How far did the disruption spread?

The outage did not stop at the US border. The FAA held US-bound flights at overseas airports out of concern that planes could not land once they reached American soil.

Guardian Australia reporter Ben Doherty, on a plane at Sydney airport waiting to fly to the US, reported that US-bound flights there were held on the tarmac, some for up to three hours. Authorities gradually cleared those departures for takeoff after the ground stop lifted.

The delays and cancellations rippled through the global aviation system. The full count of knock-on effects across international carriers will take longer to measure than the domestic totals FlightAware recorded on Friday.

What happens next?

The FAA has restored departures, but two questions remain open. First, what exactly failed inside the telecommunications system that connects radio, radar and data links across the national airspace. Second, why a technology upgrade left older systems vulnerable to being overwhelmed by data — a design problem, not a security breach, if the cabinet secretaries' account holds.

The January 2023 ground stop, which lasted under two hours, followed a corrupted pilot-notices database file. Friday's stoppage produced nearly nine thousand delays and almost seven thousand cancellations, a disruption an order of magnitude larger.

With no cyber-attack involved, per Homeland Security, the pressure now shifts to the FAA to explain how it introduced new technology without a fallback for the old systems carrying the national airspace.