US administration officials said Friday that outdated air traffic control equipment became overwhelmed by the installation of new technology, triggering communication disruptions and intermittent radar failures that forced the Federal Aviation Administration (FAA) to impose its longest nationwide flight suspension in 25 years.
The nationwide ground stop was lifted Friday night after approximately five hours, during which most aircraft across the United States were prohibited from taking off.
The disruption affected thousands of flights and potentially more than one million passengers across the country. Homeland Security Secretary Markwayne Mullin told reporters at the White House that passenger safety had not been compromised, noting that more than 3,000 aircraft had landed safely. However, Transportation Secretary Sean Duffy acknowledged that he could not guarantee a similar incident would not happen again.
Mullin explained that the FAA had been introducing new equipment and advanced technology, but the upgrades appeared to have overwhelmed the country's ageing air traffic control infrastructure. He added that there was no immediate evidence suggesting a cyberattack had caused the disruption.
Although a limited number of domestic flights resumed operations Friday evening following the lifting of the restrictions, airlines were expected to need several days to return to normal schedules. Many aircraft and flight crews had been left in locations different from their planned destinations. Officials nevertheless expressed confidence that the aviation system would recover before the busy Thanksgiving holiday travel period.
The incident marked the first nationwide flight suspension since January 2023, when a malfunction in a major FAA computer system disrupted aviation operations. It was also only the second such nationwide stoppage since the September 11, 2001, terrorist attacks.
Officials Find No Immediate Evidence of Cyberattack
When asked whether authorities could completely rule out a cyberattack or an incident involving uncontrolled artificial intelligence, Mullin said it was too early to make a definitive conclusion.
He explained that investigators had found no evidence or digital traces indicating malicious interference. Initial findings suggested a technical or mechanical problem, although officials were continuing to investigate the exact cause.
According to aviation analytics company Cirium, at least 827 flights had been diverted during the disruption. By 7:05 p.m. Eastern time, 670 aircraft had been redirected to their original departure airports, while another 157 were sent to alternative airports.
Major diversion destinations included Washington Dulles International Airport, Los Angeles International Airport, Cincinnati/Northern Kentucky International Airport and Nashville International Airport.
Approximately 11,000 flights carrying more than 1.5 million passengers had been scheduled to depart US airports after 4 p.m. Eastern time.
Transportation Secretary Duffy said around 3,500 aircraft were in the air when the ground stop began. However, that number had fallen to fewer than 400 by the time he provided an update.
He warned that restoring normal air traffic operations would take time because of the scale of the disruption.
Passengers Face Uncertainty at Airports
Travellers at Chicago O'Hare International Airport experienced considerable confusion as flight information screens displayed widespread delays and cancellations.
Many passengers contacted friends and relatives while considering whether to spend the night in Chicago or find alternative ways to reach their destinations.
Among those affected was 27-year-old Amber McQuilkin, a software engineer from Seattle, who feared missing a planned trip to New York to attend the League of Legends world finals. Her friends had already arrived in the city, but she remained stranded at the airport.
McQuilkin said passengers were receiving very little information about the situation. Although she briefly considered abandoning her flight and driving to New York, she eventually realised that such a journey would be extremely exhausting.
Another affected passenger, Austin Curtis, was travelling with his wife from South Bend, Indiana, to Denver to attend a friend's baby shower. Their journey was interrupted during a stopover in Chicago.
The couple had already boarded their connecting flight at O'Hare when airline personnel instructed passengers to leave the aircraft.
Curtis noticed luggage being unloaded from their plane and other aircraft, leading him to believe the delay could be substantial. The couple had not decided whether to book a hotel or remain at the airport. Since arrangements had already been made for their two young children at home, they were considering spending the entire weekend in Chicago.
Sports Teams and Cargo Flights Also Affected
The aviation disruption created major problems for professional and college sports teams travelling to scheduled competitions.
NBA, NHL and college football teams faced difficulties reaching their destinations, while NFL teams were concerned about whether the situation would be resolved before their weekend matches.
Transportation Secretary Duffy said college football teams scheduled to play on Saturday would receive priority assistance in arranging flights.
He encouraged university football programmes to contact the FAA directly to coordinate departure schedules and ensure players could reach their destinations before kickoff.
Cargo transportation was also affected, creating additional concerns for businesses and international supply chains.
FedEx, the world's largest cargo airline, said it was prepared to implement contingency arrangements to minimise possible disruptions to its delivery operations.
According to Airlines for America, the aviation industry's trade association, US airlines transport approximately 61,000 tons (55,340 metric tonnes) of goods every day to and from more than 220 countries. These shipments include everything from letters and documents to commercial packages.
Despite the nationwide flight restrictions, SpaceX proceeded with its latest Starship rocket test launch from Texas on Friday afternoon.
Previous Technical Failures Raise Concerns Over Ageing Equipment
The latest disruption has drawn comparisons with previous technical problems involving the US air traffic control system.
In September, a communications failure at a regional air traffic control facility disrupted hundreds of flights across the northeastern United States. That incident was reportedly caused by construction workers accidentally cutting a fibre-optic cable.
Ageing aviation infrastructure was also blamed for brief radar outages last year that affected operations at Newark Airport.
Aviation safety expert Steve Arroyo said Friday's incident was particularly serious because the communication problems occurred on a nationwide scale, making it difficult for air traffic controllers to maintain reliable contact with pilots.
Arroyo, a former United Airlines pilot, explained that when controllers cannot communicate reliably with aircraft, the safest option is to keep planes on the ground rather than risk sending them into the air without dependable communication systems.
He noted that Friday's incident differed from the nationwide aviation shutdown following the September 11 attacks in 2001. During that emergency, aircraft were not necessarily ordered to land immediately, and pilots were generally still able to communicate with airport ground controllers.
The latest incident has once again raised questions about the reliability of America's ageing aviation infrastructure and the challenges of introducing modern technology into systems that are already under considerable pressure.