The Federal Aviation Administration lifted a nationwide FAA ground stop at 8:15 p.m. Eastern Time on Friday, November 13, ending a roughly four-hour shutdown of US aviation that officials described as the longest since the September 11, 2001 attacks. The order, issued in the afternoon, was the second nationwide grounding since the attacks and the first since January 2023. By 11:30 p.m., nearly 10,000 flights had been cancelled, according to Flightradar24, with shares of American, United, Delta and JetBlue lower in after-hours trading.
The order came from the Air Traffic Control System Command Center, an FAA facility in Northern Virginia responsible for monitoring traffic and mitigating risks, which sent the ground stop order to all 22 regional air traffic control centres in the country. According to SiliconANGLE, the memo explained that the move was due to extraordinary circumstances and for reasons of safety. That language is the trigger airlines and controllers watch for when the agency needs to halt departures broadly, and it is what turned a technical fault into a national event.
FAA ground stop: What broke, and what officials say happened
Transportation Secretary Sean Duffy said the FAA issued a nationwide ground stop for all US airports following a communication issue impacting all Air Route Traffic Control Centers, and that FAA technicians were investigating the issue. He said the trouble began at 3:36 p.m., when air traffic control centres experienced instability in radar and communications systems.
Duffy described the mechanism in detail. Our switches, our routers actually got overloaded with data and they started to give us inconsistencies in the data from those routers and because of that we shut the system down, he said, adding that at no stage did they completely lose radar or communications and that they were able to safely land thousands of planes. Engadget reported that the equipment that had already been replaced was not affected, only the older kit.
According to CBS News, the problem affected a private communications network that connects components of the US air traffic control system, and sources said an update caused the network to reboot, which in turn led it to crash. Reuters reported that the network appeared to be one overseen by L3Harris Technologies, according to two airline officials, and that it handles critical radio frequencies used by air traffic controllers to communicate with pilots. L3Harris did not respond to a request for comment, so the attribution remains an account from two airline officials rather than a confirmed finding.
The disruption numbers
The ground stop began at 3:54 p.m. EST, and US airspace reopened at 8:15 p.m. Eastern Time. As of 5:50 p.m. Eastern, 496 flights had been diverted back to the airport from which they originally took off, while 104 were sent to a different airport, according to Cirium, an aviation analytics company. At least 600 flights had been diverted overall. Airports that absorbed diverted flights included Chicago O’Hare International Airport, Denver International Airport, Dallas Fort Worth International Airport and Ronald Reagan Washington National Airport.
More than 13,000 flights were reportedly delayed or cancelled, and some 11,000 flights carrying more than 1.5 million passengers were scheduled to take off from US airports after 4 p.m. Eastern. Some aircraft at major airports waited more than five hours for a gate, Flightradar24 said. Cancellations ran to more than 2,200 each at Delta Air Lines and American Airlines, and 1,800 at United Airlines.
Eurocontrol, the organisation that helps European Union member states coordinate air traffic, suspended flights to the US at the request of the FAA. Inbound international flights were handled on a case by case basis, FAA officials said, and American Airlines stated that flights already airborne would proceed to their destinations. Reuters reported that the four-hour grounding could disrupt airline schedules for days, and that American Airlines said it was prioritising flights to international destinations and to smaller cities outside its major hubs to position aircraft and crews for a faster recovery.
Security questions and the AI system
Homeland Security Secretary Markwayne Mullin told reporters at the White House there was no indication yet that this was a nefarious attack, saying it was just a telecommunications outage as of right now. Later he said there was zero evidence so far that the outage resulted from a cyberattack or a rogue AI system, though investigators had not ruled out either possibility. Mullin said it appears this was mechanically driven, however we’re still looking, and that the National Security Agency was working with his department on the investigation. He also clarified that the incident was not related to the lengthy outage that took out Microsoft’s services for over 24 hours.
The AI angle matters because the FAA last week announced it was expanding its use of an artificial intelligence system called SMART, which analyses weather patterns, flight paths and related data to generate air traffic scheduling recommendations and is designed to reduce delays and fuel consumption. Mullin said investigators would look at whether there is any link to the nationwide rollout of that system, but noted it operates out of one location near Washington, D.C. and just sends recommendations to the air traffic control centres. That detail weakens, though does not eliminate, any suggestion that SMART played a role in the outage.
A precedent that points to old hardware
Duffy called the US air traffic control system incredibly old and said the country still uses TDM telecom, a legacy analog telecommunications technology, to transmit information between facilities. He said the immediate problem had been fixed and that flying was safe, but warned that a broader overhaul of the aging air traffic control system was needed to prevent similar failures. Aviation safety expert Steve Arroyo, a former United Airlines pilot, said the problem appeared similar to a regional air traffic control communication outage in September that snarled hundreds of flights across the Northeast, except this time on a nationwide scale. Arroyo said if you do not have that ability, whether it’s because the old wires that they have are just run down or for whatever reason, you’ve got to stop airplanes on the ground and not put them in the air where you are going to risk not being able to communicate with them.
The only other nationwide ground stop since the September 11 attacks came in January 2023, when the FAA halted domestic departures for about 90 minutes after a key FAA computer system malfunctioned, grounding 9,500 flights. Duffy noted the FAA has issued ground stops only three times this century, and this was the second longest after the September 11 attacks.
The funding fight behind the failure
Duffy blamed Congress for not funding a new system and called for 50 billion dollars to modernise it, telling reporters the system was going to continue to fail and asking how many times this had to happen for Congress to give the money to fix it. Reuters reported that the White House and Department of Transportation had earlier on Friday urged Congress to approve 30.1 billion dollars to upgrade the nation’s aging airports and air traffic control infrastructure. Congress approved 12.5 billion dollars for the overhaul last year, with miles of old copper wires replaced by fibre optic lines and old radio systems gradually being replaced at airports across the country. Reuters also framed the failure as the latest and most dramatic sign of strain on a US air traffic control system beset by aging technology, equipment and communications problems and a shortage of several thousand controllers.
What it means for passengers and airlines
The practical consequence is that the end of the ground stop did not end the disruption. Duffy warned that departures would resume gradually and it would take time for airlines to restore normal operations, calling it going to be slow. Reuters reported that tens of thousands of passengers were stranded at airports around the country, with passengers crowding departure halls and airline desks from Boston to Seattle and New York to Los Angeles as aircraft remained parked at gates. Thousands faced being stranded overnight, and some travellers said they were deciding whether to book a hotel room or drive instead.
One consequence may soften the passenger backlash. US airlines will not be required to provide compensation to stranded passengers because the carriers were not responsible for the FAA system failures, according to Reuters. Investors were already pricing in a financial hit: shares of American, United and Delta fell between 1 and 2 percent in after-hours trading, while JetBlue Airways dropped about 3 percent. The FAA ground stop therefore carried a visible cost to carriers without triggering the usual compensation obligations, and the longer term argument rests on whether Congress funds the modernisation Duffy says would prevent a repeat.