The Federal Aviation Administration lifted an unusually broad nationwide ground stop late Friday after more than four hours, but the disruption left the U.S. air travel system in turmoil, with thousands of canceled flights and passengers stranded at airports.
At a White House briefing Friday night, Transportation Secretary Sean Duffy attributed the crisis to aging technology that became overwhelmed, creating “instability” and “inconsistency” in radar and communications used by the air traffic control system.
Duffy urged Congress to approve billions of dollars to replace and modernize the nation’s critical aviation infrastructure, describing the situation as an “emergency.”
Asked whether the communications failure could have been caused by a cyberattack, Homeland Security Secretary Markwayne Mullin said there was no evidence pointing to one at that time. “There’s nothing completely certain right now,” he said, while adding, “It doesn’t appear that way.”
The FAA’s ground stop triggered widespread cancellations, and officials cautioned that restoring normal operations would take time even after departures resumed.
“It’s going to take us some time to unwind what’s happened this afternoon,” Duffy said. He added that officials hoped “tomorrow we are going to start to see far better movement.”
Duffy also said he expected the system to be “back up and operational” as the country moved toward the Thanksgiving travel period.
The technical problems began shortly after 3:30 p.m. ET, when the FAA detected “instability for our radar and communications” at Air Traffic Control Centers and Terminal Radar Approach Control facilities, Duffy said.
At 3:54 p.m., the agency ordered a nationwide ground stop, halting departures across the country. Duffy said roughly 3,500 aircraft were already in the air when the order was issued.
The FAA said the decision was made “due to extraordinary circumstances and for reasons of safety.”
It marked only the second nationwide ground stop since the Sept. 11 attacks. The previous one came in 2023, when the FAA’s NOTAM system failed and pilots were unable to access required pre-departure information.
According to Duffy, the ground stop ended at 8:15 p.m. ET.
During the White House briefing, Duffy said the disruption stemmed from “an incredibly old air traffic control system” that relies on what he described as “analog telecom.”
“Our switches, our routers, actually got overloaded with data … and started to give us inconsistency in the data from those routers. And because of that, we shut the system down,” he said.
Much of Duffy’s remarks focused on the need for Congress to invest in an overhaul of the country’s aging air traffic control network.
He called for billions of dollars to fund what he described as a “complete overhaul” of the system.
“We didn’t think we would have this kind of outage,” Duffy said. “The systems that were deployed kept everybody safe — everyone landed. We’re able to review what went wrong and then reboot the system and go. But you will have more of these. You will have more of them unless the American people and the Congress tell us to build.”
Soon after the ground stop was announced, Mullin said the federal government was examining every possible explanation for the communications failure. At that point, he said, officials were not ruling out a cyberattack.
“As we investigate what caused this, you always got to assume that, as many cyber attacks that take place, that you make that assumption,” Mullin said. “But as of right now, that’s not known.”
AirSpace Intel, the contractor developing the SMART AI system being introduced at facilities nationwide, said in a statement 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.”
When asked whether the rollout could be connected to the ground stop, Mullin replied that officials were “looking at that.”
By the late-night briefing, Duffy said investigators had identified “old legacy equipment” as the source of the failure.
“So there was no possible way SMART would have impacted what happened today,” Duffy said.
The disruption quickly drew demands for answers from lawmakers, several of whom called for accountability Friday evening.
House Democratic Leader Rep. Hakeem Jeffries described the incident as an “unprecedented breakdown.”
“American travelers deserve timely answers from the Trump Administration about how and why this happened and assurances that steps are being taken to ensure that our air travel system remains safe and functional,” Jeffries said in a statement.
Sen. Tammy Duckworth, an Illinois Democrat, wrote on X that the “safety of our skies is built on redundancies.”
“Whatever led to the nationwide ground stop will warrant a thorough and complete investigation,” she said. “As Aviation Subcommittee Ranking Member, I’ll be demanding answers from the FAA.”
Senate Transportation Committee Ranking Member Maria Cantwell said her staff was communicating with the FAA about the nationwide stoppage.
“Technology issues related to how planes communicate through primary frequencies, backup frequencies, and other issues will be something the Commerce Committee will be reviewing,” the Washington Democrat said.
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