Flights resume in U.S. after hours-long nationwide ground stop halts travel - Toronto Star

All commercial flights were grounded for more than four hours, throwing the air travel system in the U.S. into chaos.

Planes line up at departure gates and are placed on hold at Philadelphia International Airport on Friday.

PHILADELPHIA — Plane departures across the U.S. were allowed to resume Friday night after the Federal Aviation Administration lifted a nationwide ground stop due to “extraordinary circumstances” caused by communications problems at regional air traffic control centres.

All commercial flights were grounded for more than four hours, throwing the nation’s air travel system into chaos in one of the most significant disruptions since January 2023, when a key FAA computer system malfunctioned, and the second since the aftermath of the Sept. 11, 2001, attacks.

The initial FAA notice at just before 4 p.m. announcing the ground stop said it was being imposed “due to extraordinary circumstances and for reasons of safety.” An estimated 3,500 planes already in the air were ordered to land at the nearest available airport.

There was widespread confusion over the cause of the outage. Homeland Security Secretary Markwayne Mullin initially said there were no indications it was the result of a “nefarious attack,” but did not immediately rule out a cyberattack, or a malfunction in the AI system that had been integrated into key FAA systems earlier this week. 

The U.S. Secretary of Homeland Security Markwayne Mullin said there are no indications of an attack against the nation, after the Federal Aviation Administration grounded all flights nationwide Friday afternoon due to communications problems. (Nov. 13, 2026)

“There’s nothing completely certain right now,” Mullin said, adding there are no “footprints” showing an attack and that it appears to be “mechanically driven,” adding that officials were still looking for the cause.

U.S. Secretary of Transportation Sean Duffy speaks as U.S. Secretary of Homeland Security Markwayne Mullin listens during a press conference at the White House on Friday night.

In a press conference shortly after the ground stop was lifted just before 8:20 p.m., Mullin and U.S. Transportation Secretary Sean Duffy blamed the outage on an antiquated air traffic control system. Mullin said the introduction of new technology overwhelmed it. The system needs funding for a complete overhaul, he said, estimating a $50 billion price tag and blaming Congress for not providing the money.

“I don’t want to rule out that we didn’t have nefarious activity here,” said Duffy.

“This is what the leadership of President Trump looks like, by the organization and the team he’s put together. We are built to handle crisis like this,” said Mullin.

“It was an old legacy equipment,” said Duffy. “It failed, and listen, it’s going to continue to fail. But my number one job is America’s safety.” 

Duffy did say the outage was caused by an overload of the time delay multiplexing, or TDM copper-wire system, which underpins the American air traffic control system and carries both radar signals and voice information from air traffic control to pilots. Duffy did not say why the system overloaded.

“We’re still working on the details of what went wrong today,” said Duffy. “I’ll be happy to give you more information when we have it.”

Across America airplanes were stranded on tarmacs, airports ground to a halt, and travellers scrambled to rent cars and trains, book hotels, and rebook travel without any clarity on when the system might resume. CNN reported some airports neared saturation points on tarmacs and runways, with too many planes and not enough space. According to flight trackers, some international flights to Europe, Asia, and Hawaii were being allowed to leave from airports on both coasts.

Passengers make calls in front a flight departure board as planes are placed on hold at Philadelphia International Airport on Friday.

This ground stop extended widely, and the chaos spread. The New York Times reported that the FAA asked its European counterpart to suspend flights from 42 European nations. Some 11,000 flights carrying more than 1.5 million passengers were scheduled to take off from airports in the U.S. after 4 p.m. EST, raising the likelihood of more cancellations and flight diversions.

The American air traffic control system operates on antiquated computer systems. The government has been working to overhaul the outdated technology that air traffic controllers rely on since Congress approved $12.5 billion for the project last year. Miles of old copper wires have been replaced with fibre optic lines and old radio systems are gradually being replaced at airports across the country. Earlier this year, the FAA fledged to eliminate floppy discs from the air control system by 2028. 

The Federal Aviation Administration grounded all flights nationwide Friday afternoon due to communications problems at regional air traffic control centers. This is the first nationwide ground stop since January 2023 when a key FAA computer system malfunctioned. (Nov. 13, 2026)

Duffy has said that another $30 billion will be needed to complete the work, and the White House has begun lobbying Congress to approve it. In the press conference Friday night, he repeatedly asked for $50 billion.

The problem appeared similar to a regional air traffic control communication outage in September that snarled hundreds of flights across the Northeast, aviation safety expert Steve Arroyo said, except this time on a nationwide scale. 

Three days before Friday’s ground stop, the FAA said an AI tool called SMART AI was being integrated into the air traffic control system. In September, the National Air Traffic Controllers Association, which represents some 15,000 members nationwide, told Flying magazine it was not consulted or involved in the “design, testing, or implementation of SMART and therefore cannot speak to its effect on the air traffic control workforce.”

Air Space Intelligence, the company responsible for the SMART AI tool, wrote on X, “The current ground stop is not based on or a result of the SMART system, any product of ASI or our integration with FAA and (Air Traffic Control).”

Both administration officials denied AI caused the outage, but Mullin said, “What it appears to be right now is ... (the) FAA was going in and putting patches into the system, they were putting new equipment and new technology, and that new equipment, new technology was overwhelming the older system.” Mullin did not specify what technology he was referring to.

Air Canada announced it was cancelling Canadian flights to and from the United States, and said that flights to international destinations that were scheduled to pass through American airspace might be affected. Some flights destined for American destinations were expected to be rerouted to Canadian airports.

“Canada has offered its full assistance to the Federal Aviation Administration (FAA) as it manages the situation, including accommodation of US-bound aircraft as required,” wrote Minister of Transportation Steven MacKinnon in a statement posted on X. “We remain ready to provide support to our American colleagues as the situation evolves.”

Canadian airline systems were not affected although flights to and from the U.S. out of Toronto’s Pearson airport were suspended before also resuming Friday night.

“NAV Canada is aware of the FAA ground stop and is monitoring the situation,” said the air navigation service provider in a statement. “Our systems are operating normally, and there is currently no impact to NAV Canada operations. Safety remains our top priority. NAV Canada continues to support the safe movement of air traffic within our airspace, including any aircraft that may be diverted.”

“Questions regarding the ground stop, including its scope and operational implications, should be directed to the FAA.”

Bruce Arthur is a columnist for the Star. Follow him on Twitter: @bruce_arthur.