Updated Friday, 6:30 p.m. Eastern. The ground stop is still in effect with no confirmed end time. Some Pacific flights out of San Francisco were cleared to leave, cancellations are past 2,000, and officials told NBC there’s nothing connecting this to the Microsoft outage. Details in the new section below.
The FAA stopped every departing flight at every U.S. airport Friday afternoon. The official reason so far is a telecommunications outage hitting the centers that control high-altitude traffic.
Transportation Secretary Sean Duffy announced it on X around 4:16 p.m. Eastern, per NBC News. He said the FAA issued the stop “following a communication issue impacting all Air Route Traffic Control Centers” and that “FAA technicians are investigating the issue.”
The FAA’s own statement, as quoted by CNBC, says “multiple” centers rather than all of them. That’s a real difference, and we don’t know yet which one is right.
What the order says
The alert from the FAA’s Air Traffic Control System Command Center, quoted by CBS News, reads: “By order of the Federal Aviation Command Center all airports are ground stopped.” It says departures “should remain ground stopped until further notice” and that “Inbound international flights will be managed on a case by case basis.”
The FAA called it a stop for “extraordinary circumstances and for reasons of safety.” Flights already in the air kept going. CBS, citing FlightRadar24, put that at about 3,100 aircraft headed for U.S. airports when the stop began.
Update: where it stands at 6:30 p.m. Eastern
The stop hasn’t been lifted. An FAA advisory listed an estimated end time of 10 p.m. Central, according to News 9, but officials haven’t confirmed when departures will resume. Fox Weather reported no updated timeline as of 6:30.
At 5:52 p.m. the FAA posted on X: “Every flight has been accounted for, and international flights will be handled on a case by case basis.” Some exceptions are already happening. San Francisco International said Pacific-bound flights, including to Hawaii and Asia, were “cleared to leave” at 3 p.m. local time, per NBC.
The numbers kept climbing. CBS, citing FlightAware, now has over 10,000 delays and over 2,000 cancellations. Fox Weather put it at more than 10,500 delayed and more than 2,500 cancelled as of 6:30 p.m., without naming its source. Reagan National was at capacity and O’Hare was getting close, a source told NBC, so some planes may divert.
On the cause, nothing new is official. Mullin said communication was overwhelmed at certain levels but hadn’t stopped entirely, per Fox Weather, and that officials “just can’t rule anything out at this point.” Multiple officials told NBC there’s no indication of malicious activity, though the investigation is early.
NBC also noted the ground stop came soon after the FAA expanded an AI system called SMART, and said it’s unclear whether the two are related. The vendor behind it, Air Space Intelligence, said the ground stop is “not based on or a result of the SMART system.”
What officials are saying about the cause
Homeland Security Secretary Markwayne Mullin spoke outside the White House. He said “there was no indication, as of yet, that this was a nefarious act against us” and “It was just a telecommunication outage, as of right now.” He also said officials are “not ruling out anything at this point.”
On whether controllers can still talk to pilots, Mullin said “My understanding is that we can still communicate” and that “there’s redundancy in most communications,” per NBC.
Two law enforcement sources told CBS the TSA is looking into the root cause, and one said it involves radio frequencies and how pilots communicate. That’s sourcing, not an official finding. An internal Alaska Airlines message seen by CNBC blamed communications and radar issues.
Shortly before the nationwide order, O’Hare and Midway in Chicago were already ground stopped over an equipment outage, according to CBS. Nobody has said yet whether that was the start of the same problem.
How big this is
In the first stretch, FlightAware counted at least 8,000 delays and 400 cancellations, per CBS. Those have grown a lot since (see the update above). Cirium told CNBC that 11,000 flights were scheduled to leave U.S. airports after 4 p.m. Eastern Friday. That’s the start of a weekend, and crews who sit long enough run into their duty hour limits, so the backlog won’t clear the moment the stop lifts.
Nationwide ground stops are rare. The last one was in January 2023, when a pilot alert system failed overnight and departures were held for a few hours. Before that, you have to go back to September 11, 2001. Former NTSB chair Robert Sumwalt told CBS this one is “absolutely unprecedented.”
Our read
This is the second big outage in two days, after Microsoft 365 went down Thursday (our post on that). Three senior officials told NBC nothing connects the two. The National Weather Service also reported nationwide internet and communications problems Friday afternoon (our post on that). Nobody official has tied that one to the FAA either, and we’re not going to guess.
What stands out is the phrase “telecommunications outage.” Air traffic control leans on leased phone and data circuits between facilities, and a failure in that layer can take out a lot at once even when the radios and radar themselves are fine. That fits Mullin saying communication still works through redundancy while the FAA stops everything anyway. It’s our interpretation, though, and the FAA hasn’t described the failure in that much detail.
If you’re flying tonight or this weekend
- Check your airline’s app before you leave for the airport. A ground stop holds departures, so your plane may be sitting at the gate with no departure time.
- If your flight gets cancelled, you’re owed a refund if you choose not to travel, even when the cause is outside the airline’s control. Rebooking is usually free in a situation like this, so look for a travel waiver on the airline’s site.
- Expect the delays to roll into Saturday even after departures resume. Planes and crews will be out of position.
We’ll update this when the FAA lifts the stop or says what failed.
Sources: CBS News, CNBC, NBC News, Fox Weather and News 9.