Here's what we know after nationwide ground stop at US airports

With air traffic halted nationwide, questions remained about what caused the disruption, whether terrorism was involved, how rare such a move is and how long it could last.

The Details

• By NBC Chicago Staff and NBC News
• Published 10 minutes ago
• Updated 17 seconds ago

A rare scene played out across the United States on Friday as delays were reported across the country after a ground stop was issued at airports nationwide, with the FAA enacting the move “due to extraordinary circumstances and for reasons of safety.”

U.S. Secretary of Transportation Sean Duffy confirmed the ground stop, saying it followed "a communication issue impacting all Air Route Traffic Control Centers " and that FAA technicians were investigating.

Stream NBC 5 for free, 24/7, wherever you are.

WATCH HERE

In a later message, the FAA said the issue stemmed from "a temporary telecommunications outage."

"Out of an abundance of caution all flights have been halted. Every flight has been accounted for and international flights will be handled on a case by case basis," the statement read.

Moments earlier, both major airports in Chicago were listed under a ground stop due to an "equipment outage." It remained unclear if that outage was connected to the ground stop, however.

As the ground stop brought traffic to a halt at airports across the country, questions lingered about any potential link to terrorism, just how rare a move like this is and how long such a disruption could last.

Here's what we know so far.

No sign of a ‘nefarious attack,’ DHS secretary says following nationwide ground stop Department of Homeland Security Secretary Markwayne Mullin said there was no indication the nationwide FAA disruption was a “nefarious attack,” saying it was a telecommunications outage that led to the ground stop.

Speaking to reporters outside the White House,

Mullin repeatedly emphasized that passengers and the public were safe, pushing back on comparisons to the Sept. 11 terrorist attacks.

“As I want to make sure we say this again, there's no reason for the public to be afraid or scared for your loved ones,” he said. “This isn't another 9/11. I just can't repeat that enough...This is a telecommunication outage. This is much different.”

Officials had not ruled out a cyberattack, but Mullin stressed that they did not yet know the cause and did not want to get ahead of the investigation.

As we investigate what caused this, you always got to assume that as many cyberattacks that take place, that you make that assumption," he said. "So, but as of right now, that's not known.”

FAA's rare nationwide ground stop marks only 2nd time since 9/11. What does it mean?

The ground stop marked a "very, very rare" moment, but just how rare was it?

It was only the second time such an alert has been issued in U.S. airspace since 9/11.

The last such ground stop took place in 2023, when the FAA suffered an outage of the system that sends messages to pilots.

At that time, the stop was because of a key FAA computer system failure, which was the result of a corrupted system file. The FAA ultimately decided to reboot the system in an attempt to fix the issue and ordered a ground stop while it did so.

Federal Aviation Administration

More than 250 flights delayed at O'Hare, Midway amid nationwide FAA ground stop Air travel FAA issues nationwide ground stop ‘due to extraordinary circumstances' and ‘safety' Air travel FAA's rare nationwide ground stop marks only 2nd time since 9/11. What does it mean?

Why was the ground stop issued?

Former United Airlines pilot and aviation expert Steve Arroyo said the problem appeared similar to a regional air traffic control communications outage in September that snarled hundreds of flights across the Northeast, except this time on a nationwide scale.

Arroyo said the outage could be linked to the outdated technology used by air traffic controllers.

“If you don’t have that ability, whether it’s because the old wires that they have are just run down or for whatever reason, you’ve got to stop airplanes on the ground,” Arroyo said. “And not put them in the air where you’re going to risk not being able to communicate with them.”

While the investigation remains in its early stages, multiple officials from several agencies told NBC News there is no indication the incident was caused by malicious activity.

Officials said they have not seen the type of activity typically associated with a cyberattack, but cautioned that the investigation is still in its early stages and the information could change.

Three senior officials also said there is nothing to indicate a connection between the FAA incident and Thursday’s Microsoft outage.

More than 250 flights delayed at O'Hare, Midway airports The ground stop led to delays across the country, including at least 250 delayed flights at O’Hare and Midway airports.

As of 5:27 p.m., overall delays at O’Hare averaged 106 minutes. Arrivals were delayed an average of 127 minutes, while departures were running about 84 minutes behind.

Midway experienced average delays of about 101 minutes overall, with arrivals running 100 minutes behind schedule and departures about 102 minutes late.

One traveler at O’Hare Airport told NBC Chicago that airline employees said their flight was on hold “until further notice,” with no timeline provided for when it might depart.