U.S. halts flight departures nationwide on air traffic communications outage

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U.S. regulators ordered aircraft departures to halt nationwide on Friday after telecommunications outages at air traffic control centers disrupted radar and radio frequencies used by controllers and pilots.

The ground stop was issued at 3:44 p.m. Eastern time, with the FAA telling airlines that all flights currently airborne could continue to their destinations, both international and domestic. The nationwide stop is still in effect with multiple ATC frequencies still not working, an airline source said, but the FAA has begun releasing some international flights to Europe on a case by case basis.

“FAA technicians are investigating the issue. We will provide immediate updates as we have them,” Transportation Secretary Sean Duffy said on X.

Secretary of Homeland Security Markwayne Mullin said in a 5 p.m. White House press briefing that the agency had no current indications of outages being tied to a cyberattack or potential terror threat, adding that the nationwide ground stop was “just a telecommunications outage.” He did not rule out the possibility of a cyberattack, however.

“There should be no fear to the public at all,” Mullin said, adding it’s “too early to tell” how long the outage or ground stop will last.

The unprecedented ATC outages quickly snarled air traffic during the typically busy Friday afternoon rush, both on the ground and in the air. With stranded planes far outpacing available airport gates, especially in major airline hubs like Chicago’s O’Hare International Airport, airlines began diverting aircraft to smaller cities.

The FAA’s Washington, D.C. command center was notified around 3:30 pm local time that multiple air centers around the country had lost communication, radio frequencies and radar, TAC has learned. The outages began with the Chicago air traffic route control center, with Boston, Washington, New York and Minneapolis verifying they had problems as well in rapid succession.

At that point the FAA decided to issue a ground stop for all aircraft flying to the east of the national air system. As that call was being made, more air traffic facilities began experiencing communications and frequency malfunctions and U.S. authorities extended the ground stop nationwide.

Mullin said that as part of the government’s investigation to understand the outage it was “looking at” any possible relationship to the FAA’s expansion of its SMART AI system that provides scheduling recommendations to air traffic controllers based on weather patterns, flight paths, arrival/departure statistics and other data. Duffy said earlier in the week that that the new system was activated at all 22 ARTCCs on Nov. 10.

But the company that designed SMART, Air Space Intelligence, asserted on X that “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.”

A spokeswoman for United Airlines tells TAC that it has activated its Emergency Operations Center in response to the ground stop. A dispatcher at one U.S. carrier told TAC earlier that the FAA command center had communicated that the outage was affecting 10 enroute centers “and growing.”

Nav Canada said in a post on X that as a result of the FAA’s ground stop, it is implementing traffic management measures at Toronto Pearson, Montréal-Trudeau, Calgary and Vancouver airports to safely manage traffic volumes. “Travellers should expect delays and check with their airline. Our systems are operating normally,” the Canadian air navigation service provider said.

This is a developing story and will be updated.