On a Friday afternoon, the United States paused its skies: the Federal Aviation Administration halted every departing flight after a telecommunications failure reached all 22 of its air traffic control centres, and for more than four hours thousands of journeys hung in suspense. Officials insist no attack lay behind the silence, yet the question of what did fail, and whether a newly installed artificial intelligence system or an ordinary software update is responsible, remains open. It is a reminder, in a century of ever-deeper dependence on invisible networks, of how much of the sky's order r
US Flights Resume After FAA Lifts Four-Hour Nationwide Ground Stop Caused by Communication Outage
Over 4,000 flights were cancelled and more than 10,000 delayed, disrupting travellers and airline crews; no casualties were reported.
"This is not another 9/11."
Mark
Four hours with every departure stopped. How unusual is that?
Mimi
Very. The last nationwide ground stop was January 2023, and before that you have to go back to September 11, 2001.
Mark
And all 22 route centres were affected, not just one region.
Mimi
Right, which is why the FAA chose the blunt option. Pilot Kyle Bailey said grounding planes was the safest move until they understood what was happening.
Luke
Worth being clear on what we actually know. The cause hasn't been determined. Everything about software updates comes from one unnamed official cited by Bloomberg.
Mark
What about the AI system? The SMART expansion was announced November 10.
Mimi
The timing is close, and Secretary Mullin said it can't be ruled out. But the company, Air Space Intelligence, says its products had nothing to do with it.
Luke
So timing is all we have. Proximity isn't evidence, and the denial is also the company's own statement, not an investigation's finding.
Mark
And the numbers, over 10,000 delays and 4,000 cancellations?
Luke
Those are FlightAware figures relayed through CBS News, and the in-air count of 4,042 is Flightradar24's. Useful, but third-party tallies, not FAA totals.
Mimi
The no-threat assurance comes from Mullin and an FBI view reported secondhand. That's reassuring, but the investigation is still open.
Mark
So what do we watch?
Mimi
Duckworth's demand for answers, and whether Congress grants the extra $30.1bn on top of the $12.5bn already approved.
Le Pouls
- A single telecommunications fault froze departures across the entire United States, leaving thousands of aircraft and travellers in limbo for more than four hours.
- Over 10,000 flights were delayed and 4,000 cancelled, scattering airline crews and aircraft out of position across the network.
- Investigators are weighing whether a software update, possibly tied to a freshly expanded AI air traffic tool, triggered the collapse, while the company involved denies any link.
- Lawmakers are demanding a full investigation and debating a further $30.1bn overhaul of an ageing control system, with the true cause still undetermined.
On a Friday afternoon, the United States paused its skies: the Federal Aviation Administration halted every departing flight after a telecommunications failure reached all 22 of its air traffic control centres, and for more than four hours thousands of journeys hung in suspense. Officials insist no attack lay behind the silence, yet the question of what did fail, and whether a newly installed artificial intelligence system or an ordinary software update is responsible, remains open. It is a reminder, in a century of ever-deeper dependence on invisible networks, of how much of the sky's order rests on wires that few people ever think about until they fall silent.
At 3:54pm Eastern on Friday, the Federal Aviation Administration ordered every departing flight in the United States to remain on the ground. The agency described a "temporary telecommunications outage" striking its air traffic control system, and said the halt was a precaution. International flights would be handled case by case.
The stop lasted more than four hours. By the time the FAA lifted it at 8:15pm, the outage had reached all 22 of the centres that guide aircraft across the country. Thousands of flights had been airborne when the order came, and by the end of the day more than 10,000 had been delayed and over 4,000 cancelled. Airlines now face the slow work of returning aircraft and crews to where they belong.
Homeland Security Secretary Markwayne Mullin told reporters there was no sign of a threat. "Everybody's safe. The flights are accounted for," he said. Investigators reportedly do not believe a cyberattack or criminal act was responsible, and are examining whether a software update could have caused the failure.
The question of artificial intelligence hung over the White House briefing. The FAA had awarded a contract in June to build an AI-assisted traffic system, and days before the stop it announced plans to expand it across all its centres. Mullin said officials had not ruled out a connection. The company rejected any link, insisting the stop was not a result of its product.
The disruption spread beyond aviation. Amtrak's website and app showed errors as customers struggled to reach agents, and the railway apologised. A former FAA safety representative said grounding flights was the right call, while warning that no one could honestly claim to know the cause so early. Senator Tammy Duckworth demanded a thorough investigation, noting that the safety of the skies depends on redundancy.
The outage struck a system already strained by equipment failures and controller shortages. Congress had approved $12.5bn for modernisation last year, and now officials are asking for $30.1bn more. The last nationwide stop came in January 2023, and before that only after the attacks of September 11, 2001. For now, the cause remains unknown.
At 3:54pm Eastern on Friday, the Federal Aviation Administration ordered every departing flight in the United States to stay on the ground. The agency said a "temporary telecommunications outage" had hit its air traffic control system and that it was halting flights as a precaution. International flights, it added, would be handled case by case.
The order lasted more than four hours. At 8:15pm Eastern, the FAA announced it had lifted the ground stop. By then the outage had reached all 22 of the air route traffic control centres that guide aircraft across the country. According to Flightradar24, 4,042 flights were in the air heading to US airports when the order came down. FlightAware figures, reported by CBS News, put the toll at more than 10,000 delayed flights and over 4,000 cancelled. Airlines now face the work of getting aircraft and crews back where they need to be.
Homeland Security Secretary Markwayne Mullin told reporters there was no sign the shutdown was caused by a threat to the country. "Everybody's safe. The flights are accounted for," he said. "This is not another 9/11." Bloomberg, citing an official familiar with the matter, reported that the FBI does not believe a cyberattack or criminal activity was behind the failure. That official said investigators are looking at whether a software update could have caused it, though no cause has been determined.
The question of a possible link to artificial intelligence came up at the White House news conference. The FAA awarded Air Space Intelligence an $875m contract in June to build and deploy SMART, an AI-assisted air traffic management system. On November 10, just days before the stop, the agency announced it would expand SMART across its 22 centres. Asked whether the rollout could be to blame, Mullin said officials have not ruled it out. "You just can't rule out anything at this point. We are going through that process," he said. The company rejected any connection, saying on X that the ground stop was not based on or a result of SMART or any ASI product or its integration with the FAA and air traffic control.
President Donald Trump had not spoken publicly about the disruption since the FAA's announcement, and a reporter asked Mullin why. Mullin said the president was "fully engaged," had been briefed throughout, and had spoken with officials multiple times. "I don't run the president's comms," he said. He also defended Trump by saying the president has been pushing to overhaul the country's ageing air traffic control infrastructure.
The effects spread beyond the airports. Amtrak said its website and app were showing error messages and that customers were struggling to reach a representative because of higher-than-normal call volumes tied to the airline disruption. The company apologised and suggested customers try again later.
Kyle Bailey, a pilot and former FAA safety team representative, told Al Jazeera that grounding flights was the safest response while officials worked out what was happening. He cautioned that anyone claiming to know the cause so early was not being honest. "It is very alarming what we saw," he said, adding that the FAA's priority is protecting everyone in the US flight system.
Democratic Senator Tammy Duckworth, ranking member of the Aviation Subcommittee, called for a "thorough and complete investigation," noting that the safety of the skies is built on redundancies. She said she will demand answers from the FAA.
The outage lands on a system already under strain from equipment failures, communications problems and controller shortages. Congress approved $12.5bn for the overhaul last year, and on Friday the Department of Transportation and the White House asked lawmakers for another $30.1bn. This was the first nationwide ground stop since January 2023, when a key FAA computer system malfunctioned; before that, the last was after the September 11, 2001 attacks. The cause of Friday's outage remains undetermined.
Citations marquantes
You just can't rule out anything at this point. We are going through that process.— Homeland Security Secretary Markwayne Mullin, on whether the AI rollout could be to blame
The safety of our skies is built on redundancies. Whatever led to the nationwide ground stop will warrant a thorough and complete investigation.— Senator Tammy Duckworth, on X
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