U.S. ends halt on flight departures after nationwide air traffic communications outage

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UPDATE: U.S. Transportation Secretary Sean Duffy and Secretary of Homeland Security Markwayne Mullin confirmed in a nighttime press conference from the White House that the nationwide ground stop had been lifted. They diagnosed the cause as overloaded routers that “experienced instability” beginning at 3:36 p.m. Eastern time when over 3,500 flights were airborne over the U.S.

While Mullin said “there’s nothing completely certain right now” about the cause of the outage, “it doesn’t appear” there is evidence of a cyberattack or threat from rogue AI systems.

“What it appears to be right now is, as Secretary Duffy and FAA was going in and putting patches into the system, they were putting new equipment and new technology, and that new equipment, new technology…it was overwhelming the older system,” he added.

Duffy took a far more definitive stance, amplifying previous calls for funding for the brand new air traffic control system (BNATCS) initiative, increasing his request from Congress from $30 billion to now $50 billion.

“Our fix gives us a pretty good indication that it was a legacy network problem that went down,” said Duffy. “This is an emergency. I want Congress to give us emergency funding.”

Duffy said the nation’s air route traffic control centers and terminal radar approach control facilities were operational again, but expected recovery to stretch into the weekend. “It depends on do we have crews available, or do we have pilots and flight attendants available to fly your flight.”

“We’re going to try to move as many of those as we can tonight, if we have the capacity with crews to to move those flights,” he said. “If not, we’re going to start tomorrow morning with our airline partners moving those aircraft. But it’s going to take us some time to unwind what’s happened this afternoon.”

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UPDATE: U.S. nationwide ground stop lifted as of 8:15 PM ET, air traffic control and airline officials tell The Air Current.

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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 multi-hour ground stop, now the longest since the Sept. 11, 2001 terror attacks, appeared set to balloon into prolonged disruption for the nation. Multiple major U.S. airlines were preparing to tell travelers to stay home to prevent overcrowding at airports with little indication when the ground stop would be lifted and normal operations would resume.

The widespread upheaval of the country’s air traffic system is likely to continue as flights were diverted to avoid overflowing hubs, putting and flight and cabin crews out of their expected locations as they also exceeded duty times, leaving the system in a state of disarray as airlines worked to respond to the uncertainty.

With a televised evening briefing from the White House expected, airline leaders expressed confusion and growing frustration at the pace of updates coming from the Federal Aviation Administration and the broader federal government. As the nation rolled into the evening hours with the ground stop to extend to at least 11 p.m., limited departures to Europe and Hawaii from the mainland U.S. were being permitted, but little else.

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.