US chaos as planes grounded – what it means, why it occurred and the way UK flights affected

Last night the US experienced the biggest nationwide grounding of flights since the 9/11 attacks, which occurred ‘due to extraordinary circumstances’ and left thousands stranded at airports

The US Federal Aviation Administration has now ended the most extensive nationwide grounding of flights since the 11 September 2001 terrorist attacks. The FAA confirmed Friday’s disruption – which stretched beyond four hours – occurred “due to extraordinary circumstances” stemming from a communications problem impacting every air traffic control centre across the country.

Homeland Security Secretary Markwayne Mullin reassured the public there was no evidence of a cyber-attack and that everyone remained safe. Writing on X, Transportation Secretary Sean Duffy provided a “breakdown” of what happened: “At 3:36 p.m. ET, @FAANews experienced telecommunications issues at facilities & TRACONs across the country.

“The FAA issued a ground stop out of an abundance of caution while 3,500+ planes were in the air. Pilots and air traffic controllers followed established procedures to safely land the aircraft, bringing the number in the airspace down to under 400 as of 8pm ET.”

AI fears

The disruption began three days after a new AI-supported air traffic system called Strategic Management of Airspace or ‘SMART’ was rolled out.

The tool merges about 200 “data streams” – focused on flight paths, schedules, weather and other factors – onto a single platform to anticipate airspace constraints and other issues, the Washington Times reported.

Worst since 9/11

A nationwide ground stop has only been ordered once since all flights were banned from take-off for several days following the 11 September 2001 attacks.

A failure in the Notice to Air Missions (Notam) system in 2023 prompted a grounding that lasted an hour and 52 minutes, delaying about 9,500 flights and cancelling about 1,300.

“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, said.

What caused it?

Duffy revealed that an outdated air traffic control communications network had become overwhelmed with information. “So this is analogue telecom. Our switches, our routers actually got overloaded with data and they went down,” Duffy said.

He explained that both communications and radar systems had been impacted. The infrastructure requires a total rebuild, he noted, putting the estimated cost at $50bn.

“It’s going to continue to fail,” he said. Homeland Security Secretary Markwayne Mullin told the news conference that there was “zero evidence” it was a cyber-attack.

He also dismissed any connection to the worldwide Microsoft outage that commenced on Thursday. Mullin explained that introducing certain new technology into an ageing air traffic control system had caused it to crash. Both cabinet secretaries emphasised that the public was never in danger throughout the disruption.

Take time to get back to normal

Duffy warned the disruption would trigger knock-on effects lasting several days. “It’s going to take us some time to unwind what’s happened this afternoon,” he said.

Tens of thousands of travellers found themselves stuck at airports nationwide, with many “without any knowledge of where they’re going to sleep tonight”, Duffy said. Delta Air Lines and United Airlines announced they were getting back to normal operations.

American Airlines stated it was “focused on operating as many remaining flights as possible this evening”. JetBlue confirmed services would restart on Saturday morning.

British Airways, which has experienced some disruption to US-bound services, urged passengers to verify their flight status but to head to the airport as scheduled.

Trump’s ‘silence’

US President Donald Trump has been uncharacteristically quiet over the entire debacle.

Instead of addressing the American public directly, the Orange Manbaby turned to Fox News, leaving reporter Peter Doocy to relay his explanation for the historic disruption after speaking with the president by phone.

“He says it does not seem like this is a cyberattack or AI or anything like that,” Doocy told Laura Ingraham. “I asked him a couple different ways, and he said it doesn’t seem like that, and that that is the first thing that they always look for.”

“He said there’s nobody taking credit, which would be common if somebody did execute a huge cyberattack like this on critical infrastructure, but that he would let us know and the team would let us know if that is something that happened,” he continued.

UK flights knock-on

The groundings caused a ripple effect for UK flights too. AtGatwick, three flights scheduled to arrive from Orlando in Florida at 7.30am were cancelled.

The UK Civil Aviation Authority has warned of “follow-on disruption” to passengers.

Tim Johnson, consumer director at the UK Civil Aviation Authority, said: “While US flights have resumed, there may be some follow-on disruption as airlines work to re-book affected passengers and get all services back to normal.

“Anyone due to travel on flights between the UK and USA should check with their airline for the latest information before heading to the airport.

“We know that UK airlines are doing all they can to minimise inconvenience and to make sure their customers are properly looked after.”

British Airways also apologised for possible delays and cancellations and recommended passengers get to the airport as planned to arrive for the original departure time, unless informed otherwise.

A British Airways spokesperson said: “Our flights departing the United States may be delayed due to the ongoing air traffic control issue.”