On a Friday afternoon, a quiet failure inside the machinery that keeps American skies orderly brought the country's air traffic to a halt for four hours, the longest nationwide pause since the attacks of September 11, 2001. The fault lay not in the planes or the pilots but in the aging switches and routers that carry the data controllers depend on, which began to produce contradictory information under strain. As the system slowly reopened, the human cost gathered in airport halls, where tens of thousands of travelers waited for a departure that could not yet be promised. The episode leaves a
US Lifts Nationwide Ground Stop After Air Traffic Communications Failure Strands Thousands
Tens of thousands of passengers were stranded at airports nationwide, with some facing overnight stays and thousands of flights canceled or delayed.
"It's going to be slow," the transportation secretary said of the restart
Mark
Why does this one stand out from other flight disruptions?
Mimi
Scale and length. It was the longest nationwide shutdown since September 11, 2001. The only other nationwide ground stop since then, in January 2023, lasted about 90 minutes. This one was four hours.
Mark
And the cause?
Mimi
Duffy says switches and routers were overloaded with data and gave inconsistent readings, so the system was shut down. He says radar and communications were never fully lost.
Luke
That's his account, though. The investigation isn't finished, and nothing independent has confirmed the overload explanation yet.
Mark
What about a cyberattack?
Mimi
Mullin said there's zero evidence so far, and that it looks mechanical. But investigators haven't ruled out an attack or a rogue AI system, and the NSA is helping.
Luke
Worth stressing that "zero evidence so far" is not the same as ruled out. And the L3Harris link comes from two airline officials. The company didn't respond, so it's unconfirmed.
Mark
What does it mean for travelers?
Mimi
Over 6,600 cancellations and 8,600 delays, per FlightRadar24, with 1,500 more canceled for Sunday. Some people spent the night in airports. Airlines don't owe compensation since the failure wasn't theirs.
Luke
Also note the funding numbers differ: $30.1 billion requested earlier in the day, $50 billion called for by Duffy afterward. Whether Congress moves on either is unknown.
Le Pouls
- A four-hour nationwide ground stop froze US air travel, the longest such shutdown since September 11, 2001.
- Overloaded switches and routers sent inconsistent data to air traffic controllers, forcing officials to halt flights.
- Over 6,600 flights were canceled and 8,600 delayed, leaving tens of thousands of passengers stranded across the country.
- Investigators from the FAA, NSA and DHS are probing the cause, with no evidence of a cyberattack so far but no possibility yet ruled out.
- Congress now faces a decision on $30.1 billion to $50 billion in modernization funding as airlines work to restore schedules.
On a Friday afternoon, a quiet failure inside the machinery that keeps American skies orderly brought the country's air traffic to a halt for four hours, the longest nationwide pause since the attacks of September 11, 2001. The fault lay not in the planes or the pilots but in the aging switches and routers that carry the data controllers depend on, which began to produce contradictory information under strain. As the system slowly reopened, the human cost gathered in airport halls, where tens of thousands of travelers waited for a departure that could not yet be promised. The episode leaves a larger question hanging over the country: whether a system built for an earlier era will be given the means to be rebuilt before the next silence arrives.
On Friday evening, at 8:15 Eastern Time, American airspace reopened. Transportation Secretary Sean Duffy announced that the Federal Aviation Administration had lifted a nationwide ground stop, the longest such shutdown since the September 11 attacks. He warned that the restart would be gradual: "It's going to be slow."
The trouble began at 3:36 p.m., when instability in the radar and communications systems at air traffic control centers set off the shutdown. Duffy said overloaded switches and routers had begun producing inconsistent data. He insisted controllers never fully lost radar or communications, and that thousands of planes had landed safely. The problem, he said, was fixed and flying was safe.
The damage was wide. More than 6,600 flights were canceled and 8,600 delayed, with more cancellations already set for Sunday. Passengers filled departure halls from Boston to Seattle. Edward Kargbo, 50, of West Chester, Pennsylvania, was rebooked on a 6 a.m. Saturday flight to Lomé and resigned himself to a night in the terminal: "I'm stranded." In Newark, Louise Maher, whose British Airways flight to London was disrupted, said, "I might cry at some point but not yet."
Airlines will not have to compensate travelers, since the failures lay in the FAA's systems. Still, shares of American, United and Delta fell one to two percent after hours, and JetBlue slipped about three percent.
The cause is still under investigation. Homeland Security Secretary Markwayne Mullin said there was "zero evidence" of a cyberattack or rogue AI, though neither had been ruled out. Two airline officials said the outage appeared to involve a telecommunications network overseen by L3Harris Technologies, which carries radio frequencies controllers use to talk with pilots. L3Harris did not respond to a request for comment.
The failure struck a system already strained by aging equipment and a shortage of several thousand controllers. Duffy blamed Congress for not funding a new system and called for $50 billion to modernize it: "Give us the money to fix it." The question now is how quickly airlines recover, what investigators find, and whether lawmakers act on the funding request.
On Friday evening, at 8:15 Eastern Time, US airspace reopened. Transportation Secretary Sean Duffy announced that the Federal Aviation Administration had lifted a nationwide ground stop, the longest nationwide shutdown of American air travel since the September 11, 2001, attacks. He cautioned that the restart would be gradual. "It's going to be slow," he told reporters at the White House.
The trouble began at 3:36 p.m., when air traffic control centers experienced instability in their radar and communications systems. Duffy said the switches and routers had become overloaded with data and began producing inconsistent information, and that this was why the system was shut down. He said controllers never completely lost radar or communications, and that thousands of planes were landed safely. The immediate problem, he said, had been fixed and flying was safe.
The damage on the ground was large. According to FlightRadar24, more than 6,600 flights were canceled and 8,600 delayed, and another 1,500 were already canceled for Sunday. Aviation analysts said the four-hour grounding could disrupt airline schedules for days. Duffy said tens of thousands of passengers were stranded at airports across the country. He added that he and Homeland Security Secretary Markwayne Mullin had met with President Donald Trump in the Oval Office to discuss the outage.
Passengers filled departure halls and airline desks from Boston to Seattle and from New York to Los Angeles, with aircraft parked at gates. Edward Kargbo, 50, of West Chester, Pennsylvania, had a 9 p.m. Ethiopian Airlines flight to Lomé, Togo. He was rebooked on a 6 a.m. Saturday departure and planned to wait at the airport. "I have to squat the night here," he said. "I'm stranded." At Newark, Louise Maher, 47, was caught up when her British Airways flight to London was disrupted. "I might cry at some point but not yet," she said.
US airlines will not have to compensate stranded passengers, because the carriers were not responsible for the FAA system failures. Markets still registered the hit: in after-hours trading, shares of American, United and Delta fell between 1 and 2 percent, and JetBlue dropped about 3 percent. American said it was prioritizing flights to smaller cities outside its major hubs, along with international destinations, to position aircraft and crews for a faster recovery.
The cause remains under investigation. Mullin said there was "zero evidence" so far of a cyberattack or a rogue AI system, though investigators had not ruled out either. "It appears this was mechanically driven, however, we're still looking," he said. The National Security Agency is working with the Department of Homeland Security on the inquiry. Two airline officials said the outage appeared to involve a telecommunications network overseen by L3Harris Technologies, which carries critical radio frequencies controllers use to speak with pilots. L3Harris did not respond to a request for comment.
The failure lands on a system already strained by aging technology, equipment and communications problems, and by a shortage of several thousand controllers. Duffy blamed Congress for not funding a new system and called for $50 billion to modernize it. "What we have is an incredibly old air traffic control system," he said. "Give us the money to fix it." Earlier Friday, before the outage, the White House and the Department of Transportation had urged Congress to approve $30.1 billion for airport and air traffic control upgrades.
The only other nationwide ground stop since 2001 came in January 2023, when the FAA halted domestic departures for about 90 minutes. Now the questions are how quickly airlines recover, what the investigation finds, and whether Congress acts on the funding request.
Citations marquantes
It appears this was mechanically driven, however, we're still looking.— Homeland Security Secretary Markwayne Mullin
I have to squat the night here. I'm stranded.— Edward Kargbo, 50, stranded passenger
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