Much of the air traffic across the U.S. was suddenly shut down Friday after the Federal Aviation Administration ordered a nationwide ground stop for all departing flights “due to extraordinary circumstances and for reasons of safety.”
The unexpected and highly unusual alert, which was issued at 3:54 p.m. ET, contained no other information beyond stating that “all departing traffic should remain ground stopped until further notice.”
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“Inbound international flights will be managed on a case by case basis,” the FAA said.
When the FAA issued the alert, 4,042 flights headed for U.S. destinations were airborne, according to Flightradar24, a Swedish service that displays real-time aircraft flight tracking information.
Homeland Security Secretary Markwayne Mullin said there was “no indication as of yet” that there was anything “nefarious” that caused the ground stop. He said it was the result of a telecommunications outage “as of now.”
Mullin said President Donald Trump has been briefed and they are “are not ruling out anything at this point” in terms of what caused the communications issue. He said those currently on flights have no reason for concern. “We are assured that everybody is safe,” he said.
While the investigation into the failure is in a very early stage, there is no indication that the incident has been caused by malicious activity, officials from multiple agencies that are involved in the situation tell NBC News.
They say they haven’t seen the type of activity that would normally be associated with a cyberattack. The officials, however, cautioned that the assessment could change as investigators learn more.
Three senior officials say there’s nothing that indicates a connection between Friday’s incident with the FAA’s systems and the Microsoft outage.
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 runway, the likelihood increased that some of these planes would have to be diverted to other airports, the source 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 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.
Aviation safety expert Jeff Guzzetti called the outage “extraordinary” and said he doesn’t know what would cause it.
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.
He added that the situation is moving from a safety issue to instead becoming a massive logistics problem. Airports are becoming crowded with planes trying to land as the aircraft currently on the ground aren’t able to depart. Planes on the ground may have to move and park on taxiways, Guzzetti said.
There are different layers of communications — high-altitude, midlevel and then the towers on the ground. The high-altitude control centers are 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.
Deveren Werne 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.”
United Airlines issued a statement acknowledging the ground stop. “United flights that are already airborne will continue,” the statement said. “New domestic flights will not depart while the FAA ground stop remains in place.”
Nationwide ground stops are extremely rare.
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, blaming a failure in the Notice to Air Missions system, which alerts pilots to a host of potential dangers.