U.S. air traffic was brought to a standstill Friday after the Federal Aviation Administration ordered a nationwide ground stop for departing flights that lasted more than four hours.
The FAA lifted the ground stop at 8:15 p.m. ET, after more than 7,000 flights were canceled and airports across the country became packed with stranded, irritated passengers.
The sudden and stunning alert was issued at 3:54 p.m. ET, “due to extraordinary circumstances and for reasons of safety,” the FAA said. It offered no other information beyond stating that “all departing traffic should remain ground stopped until further notice.”
Hours later, Transportation Secretary Sean Duffy, in a White House news conference Friday evening, blamed the outage on an outdated air traffic control system in which the routers “got overloaded with data.”
By Friday evening, Delta Air Lines, United, American said they were resuming flights.
What caused the ground stop
Duffy explained that once the routers became overloaded, it led to “instability for our radar and our communications in our centers, in our TRACONS throughout the country.”
TRACON stands for Terminal Radar Approach Control and is an air traffic control center.
“The TRACONS and the centers, we started to have inconsistency in the data from the radars and our communication with airplanes,” Duffy said.
That instability was detected at 3:36 p.m., he said.
Duffy said the FAA did not lose all telecom or radar capabilities but because of the instability, the ground stop was issued as a cautionary measure.
It’ll take time for the airspace to recover from the ground stop as crews and planes are out of place and staffers may have reached on-duty shift limitations. However, Duffy said he anticipates American airspace will catch up before Thanksgiving travel rush.
Homeland Security Secretary Markwayne Mullin said there was no sign of a cyberattack and the public was never in danger.
“FAA was able to handle it. We did it out of an abundance of caution,” he said in a news conference from the White House Friday night. Earlier on Friday, he described the issue as a telecommunications outage.
At the time of the ground stop, there were over 3,500 airplanes in the air, Duffy said. When the FAA issued the alert, 4,042 flights headed for U.S. destinations were airborne, according to Flightradar24a Swedish service that displays real-time aircraft flight tracking information.
Friday’s ground stop is perhaps the most severe consequence of what Duffy described as a decades-old air traffic control system using analog equipment, which has led to several issues and outages over the past few years.
In May 2025, radar screens at Newark Liberty International Airport’s went black during a 90-second outage.
Duffy said the legacy equipment will continue to fail and pushed Congress to approve $50 billion to overhaul the system. Congress last year approved $12.5 billion over five years to upgrade air traffic control, Reuters reported.
Mullin said earlier Friday that President Donald Trump was briefed on the ground stop.
Mullin said though authorities cannot rule out a cyberattack, there was no evidence to suggest that. “There’s nothing completely certain right now. It doesn’t appear that way,” he said.
Meanwhile, Air Space Intelligence, the AI tech startup that is a vendor for the FAA on its new SMART system for air traffic control, insisted its software was not responsible for the nationwide ground stop.
“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 in a statement posted to X.
Duffy said the SMART system is “completely disconnected” from the equipment that suffered issues Friday.
Packed airports
Several hours after the ground stop was announced, a top aviation expert estimated that anywhere from 300,000 to 400,000 passengers were stranded — and it was anybody’s guess when they would get to their destinations.
“Daily, we have about 25,000 flights in U.S. domestic markets,” Vikrant Vaze, a Dartmouth professor who specializes in commercial aviation logistics, wrote in an email to NBC News. “I would say we should have around 3,000 to 4,000 flights held up at this time over the past 2 plus hours.”
But by 6 p.m., Reagan Washington National Airport in Arlington, Virginia, was at capacity, and Chicago O’Hare International Airport was nearing capacity, meaning there was no place for the planes to park, a source with knowledge told NBC News.
With planes stranded on runways, the likelihood increased that some of these planes would have to be diverted to other airports, the source said.
Aviation safety expert Jeff Guzzetti called the outage “extraordinary.”
Guzzetti emphasized that pilots are trained to operate through communications outages and that there are redundancies in place for such instances. Pilots “could get information relayed through other means” to ensure planes are spaced properly for landing.
There are different layers of communications — high-altitude, midlevel and the towers on the ground. The high-altitude control centers are the ones affected by the outage.
At Newark Liberty International Airport, personnel in the control tower said the situation is “a whole mess right now,” according to LiveATC. “We’re running out of space” and “there’s significant gate issues” were comments also heard on the live audio feed.
“I’m as much in the dark as everyone else. I’m not getting any information from anybody,” one controller at Newark said, according to the feed.
Shortly before the FAA issued its alert, both major airports in Chicago — O’Hare and Midway International Airport — were listed on a ground stop alert due to an “equipment outage,” NBC Chicago reported.
Don’t get lost was on an American Airlines jet that was about to take off from Indianapolis to Chicago when suddenly the pilots announced that all flights were grounded.
“At first, the pilot announced that there was some kind of radio issue,” Werne, 55, of Greenville, South Carolina, told NBC News in a telephone interview. “Then a little while later, the pilot said something like, ‘There is something going on that’s more serious than that.’”
Werne, a consultant who helps manufacturers and other industries adapt AI technology, said he is a frequent flyer and this was a first for him. He said there was “a mixture of emotions” from his fellow passengers on hearing the announcement.
“Then I started hearing from other friends who were on planes, including one in Chicago who was stuck on a runway,” Werne said. “Right now, our plane is heading back to the terminal, so at least we’re going to be able to deplane.”
Medical flights, such as for organ transplants, were not stopped during the ground stop, Duffy said.
Nationwide ground stops are extremely rare
Ground stops across the nation are a rarity in U.S. history.
After the Sept. 11, 2001, terrorist attacks, the FAA ordered an unprecedented nationwide ground stop. All civilian air traffic across U.S. airspace was halted and airborne planes were ordered to land at the nearest available airports.
In January 2023, the FAA grounded all flights for a few hours, blaming a failure in the Notice to Air Missions system, which alerts pilots to a host of potential dangers.
Officials at the time blamed contract personnel for the outage, saying they accidentally deleted files while working to correct the synchronization between databases. The error prompted a computer outage that lasted approximately an hour and a half, Department of Transportation officials said at the time.
Source: www.nbcnews.com
