The Federal Aviation Administration grounded all departing flights across the U.S. Friday due to telecommunications problems and for “extraordinary circumstances” and “reasons of safety,” snarling thousands of air travelers nationwide.
Homeland Security Secretary Markwayne Mullin said there was no indication of a threat to the U.S. and that all flights were grounded “out of an abundance of caution.
He said the cause is related to “a telecommunications outage throughout FAA.”
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More than 10,000 flights in the U.S. were delayed by early Friday evening, with about 1,840 cancellations, according to FlightAware, a global flight tracking platform.
Asked about a possible cyberattack, Mr. Mullin said, “As of right now, that’s not known.”
He said President Trump was briefed on the outage and “took the lead in this immediately.”
SEE ALSO: FAA expanded AI air traffic tool to all centers days before nationwide ground stop
The FAA issued the ground stop advisory to airports and pilots.
“By order of the [FAA] Command Center all airports are ground stopped,” it said. “All traffic should remain ground stopped until further notice. Inbound international flights will be managed on a case-by-case basis.”
Transportation Secretary Sean Duffy said it involves a “communications issue.”
“The FAA issued a nationwide ground stop for all U.S. airports following a communication issue impacting all Air Route Traffic Control Centers,” he wrote on social media just after 4 p.m. EST. “FAA technicians are investigating the issue. We will provide immediate updates as we have them.”
Planes already in the air were allowed to continue to their destinations, but aircraft on the ground could not depart.
The problem began at the FAA’s Kansas City air traffic control center before spreading to others, including Chicago, according to reports and pilots who described it to passengers. The FAA has not confirmed where the outage began or how it spread.
John Cox, a 56-year aviation veteran and aviation safety expert, said he suspected that if the problem was spreading, the FAA did not want a lot of airplanes in the air, becoming the driver behind the ground stop.
Planes in the air were allowed to continue to their destinations, and the FAA said every flight was accounted for. Mr. Cox said that “tells me it’s not a security issue.”
“I think they’re being conservative,” he added.
Friday’s grounding marks the third time the FAA has halted flights nationally since Sept. 11, 2001. The last nationwide ground stop came in January 2023, when the FAA paused all domestic departures for less than two hours.
The FAA’s National Airspace System Status at approximately 4:30 p.m. Eastern time showed that O’Hare and Midway airports in Chicago were experiencing equipment outages.
In Washington, Reagan National, Dulles and BWI said all flights were delayed. Reagan and Dulles said the terminals remained open and urged travelers to check with their airlines.
Mr. Mullin said all airline passengers are safe.
“We’re getting a ton of calls saying, ’Is this a terrorist attack?’ Everybody’s safe. There is no reason to be concerned about your loved ones if they’re flying. I just want to make sure everyone is at ease about that,” he said. “There should be no fear to the public.”
Mr. Mullin said the outage is not affecting other countries that he is aware of, adding there are two areas in the U.S. where the communications “are not affected” but did not elaborate.
The FAA expanded its AI-supported SMART tool, which merges roughly 200 data streams to predict airspace constraints, to all 22 control centers three days before ordering a nationwide ground stop.
“We’re taking a look” at that system also, Mr. Mullin said.
Air Space Intelligence, the technology company behind the SMART system, refuted speculation that the stop was related to their tool.
“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 ATC,” the company said.
Mr. Mullin also dismissed speculation that the crisis was linked to the recent Microsoft outage.
“I don’t see a reason to connect those two at all,” he said at the White House. “Those are separate issues. There was no prior indication, no indication as of yet that this was a nefarious attack against us.”

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