FAA Ground Stop Canceled More Than 6,600 Flights Nationwide

The FAA's nationwide ground stop on Friday canceled more than 6,600 flights across the US before the airspace reopened late Friday night, according to FlightAware data as of 9:45 p.m. Eastern time. Officials blamed decades-old hardware, not a cyberattack, and used the outage to ask Congress for $50 billion to modernize the system.

Transportation Secretary Sean Duffy said at a press conference that the FAA experienced "inconsistency" in its data systems that communicate with airplanes, prompting the ground stop around 3 p.m. Eastern. About 3,000 flights were in the air at the time, and all of them landed safely using alternative systems, Duffy said.

Was the public ever in danger?

Homeland Security Secretary Markwayne Mullin said late Friday that the "public was never in danger" during the closure and that "all your loved ones are safe." He stressed the event was a communications issue, not a safety threat, and told Americans not to assume it was "another 9/11."

Mullin said he'd seen "zero evidence" of a cyberattack or a problem with artificial intelligence — which he dubbed "SI," for the Trump administration's preferred term, "superintelligence." The FAA itself had described the stop as due to "extraordinary circumstances and for reasons of safety."

What caused the outage?

Duffy and Mullin pointed at the age of the nation's air-traffic control system. They called on Congress to fund a $50 billion modernization — up from the $30 billion previously pitched in September.

"I have already replaced some of those switches with President Trump, and our new IP switches did not go down," Duffy said. "It's the old hardware that went down."

The IP switches are new voice communication systems replacing the decades-old analog voice switches that much of the national airspace system still relies on. Mullin also said there was "no indication" the stop was related to Microsoft, which had faced massive service outages this week.

Duffy said officials were still "working on the details" of what caused the failure and how to prevent it. Asked whether the traveling public should feel safe, he couldn't guarantee it wouldn't happen again.

Was a new AI tool involved?

Suspects included SMART, a new FAA AI tool for air traffic control that started deploying this week. ASI, the company that builds SMART, said Friday's issues weren't "based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC." Duffy confirmed SMART was not at fault. Earlier in the day, when asked if the AI system might be related, Mullin had said: "That's what we're looking at."

How bad were the cancellations?

• More than 6,600 flights canceled in, out of, or within the US as of 9:45 p.m. Eastern, per FlightAware.
• Chicago O'Hare led with 395 cancellations.
• Atlanta's Hartsfield-Jackson, the world's busiest airport, saw more than 350.
• New York, Boston, Texas, and Denver airports each logged more than 200.

Many planes diverted or turned around. Delta Flight 958, a Boeing 767 from Los Angeles to New York's JFK, turned back nearly four hours in and landed in Cincinnati at 4:11 p.m. Another Delta flight from Atlanta to JFK diverted to Baltimore. A Volaris flight from Puebla, Mexico, to Los Angeles landed in Tijuana, just south of the US border. Delta and Volaris didn't immediately respond to requests for comment.

Why could the chaos last for days?

Mark Stephens, a retired Delta pilot, told Business Insider that pilots in the air "continue via the flight plan, and then start using backup methods," using digital tools to reach controllers and dispatch. Unless told to divert, the plan is to "stay the course and do what you're trained: aviation, navigate, communicate."

He warned the disruption would snowball. "Long delays will turn into a crew rest nightmare," Stephens said. "Tomorrow is going to be a very difficult reset as pilots and flight attendants will be all over the country, and planes will be stuck in cities without crews." He added that "major hubs don't have space for all these planes."

Passengers had little recourse for meals or hotels because the events weren't the airlines' fault. Some tried Amtrak instead — its website and app began generating errors. "We're currently experiencing higher-than-normal call volumes due to ongoing airline issues," the operator posted on X. One passenger at Springfield-Branson Airport in Missouri said every remaining flight was canceled and airline systems were too overloaded to rebook him.

The last nationwide ground stop came in January 2023 and lasted about 90 minutes; before that, the only precedent was September 11, 2001. Airlines now face a weekend-long scramble to reposition aircraft and crews — while the case for that $50 billion modernization just got harder for Congress to ignore.