Updated 1:34 a.m. ET Saturday: The last of the carrier-specific ground stops that followed the nationwide halt has ended. The FAA cancelled American Airlines’ Chicago O’Hare stop at 1:27 a.m. ET, leaving no ground stops tied to the outage on its advisory list. As of about 1:33 a.m. ET, FlightAware counted 8,785 cancellations Friday among flights within, into or out of the United States, and 2,602 so far for Saturday. The FAA has not released a formal technical finding, and its next national airspace update is due at 6 a.m. ET.
Updated 12:37 a.m. ET Saturday: The carrier-specific ground stops that followed the nationwide halt wound down early Saturday. The FAA cancelled Alaska Airlines’ Los Angeles stop at 11:56 p.m. ET Friday and cancelled American Airlines’ Dallas-Fort Worth stop at 12:26 a.m. ET. A stop for Delta flights to Atlanta, added at 11:29 p.m. ET Friday, was cancelled at 12:06 a.m. ET. American’s O’Hare stop, which runs through 1:30 a.m. ET, was the only one still listed as of 12:37 a.m. ET. The disruption was carrying into the weekend: as of about 12:35 a.m. ET, FlightAware already counted 2,410 cancellations for Saturday among flights within, into or out of the United States.
Updated 11:34 p.m. ET Friday: Aviation Week reported that the FAA said overloaded analog switches and routers caused intermittent disruptions to air traffic control communications, with the instability beginning around 3:36 p.m. ET. Duffy gave the same 3:36 p.m. ET start and the router explanation at the White House briefing, ABC News reported; the nationwide stop took effect at 3:54 p.m. ET. The FAA’s own posted statement cited only “communication issues impacting multiple Air Route Traffic Control Centers,” and the agency has not released a formal technical finding. Carrier-specific stops kept shifting. The FAA cancelled Alaska Airlines’ San Diego stop and Delta’s Minneapolis-St. Paul stop at 10:59 p.m. ET (San Diego, Minneapolis), extended Alaska’s Los Angeles stop to midnight ET, and added a stop for American Airlines flights to Chicago O’Hare from 11:03 p.m. ET through 1:30 a.m. ET Saturday. American’s Dallas-Fort Worth stop runs through 12:30 a.m. ET. No other changes had been posted as of 11:34 p.m. ET. As of about 11:30 p.m. ET, FlightAware counted 7,731 cancellations today among flights within, into or out of the United States.
Updated 10:43 p.m. ET Friday: Homeland Security Secretary Markwayne Mullin tied the failure to work on the system itself. The problem came from “putting patches into the system” as new equipment was installed, he said at the White House briefing, adding that “the new technology was overwhelming the older system,” WIRED reported. Duffy earlier blamed old routers overloaded with data, CBS reported. The FAA still has not released a formal technical finding. The carrier-specific ground stops are shifting. The FAA cancelled United’s O’Hare stop at 10:23 p.m. ET and Alaska Airlines’ Seattle stop at 10:29 p.m. ET. It added a stop for American Airlines flights to Dallas-Fort Worth through 12:30 a.m. ET and one for Alaska flights to Los Angeles through 11 p.m. ET, extended Alaska’s San Diego stop to 11 p.m. ET, and extended Delta’s Minneapolis-St. Paul stop to 11:15 p.m. ET. No other changes had been posted as of 10:45 p.m. ET. As of about 10:42 p.m. ET, FlightAware counted 7,443 cancellations today among flights within, into or out of the United States.
Updated 9:41 p.m. ET Friday: Duffy blamed the shutdown on aging equipment. “What we have is an incredibly old air traffic control system,” he said at the evening briefing. “Our routers actually got overloaded with data and … they started to give us inconsistency in the data from those routers. And because of that, we shut the system down,” CBS News reported. The FAA has not released a formal technical finding. Disruption carried into the night at several airports. FAA advisories show ground stops limited to specific carriers’ flights: United to Chicago O’Hare (extended to 10:45 p.m. ET) and Newark (cancelled at 9:34 p.m. ET), Alaska Airlines to Seattle and San Diego (through 10 p.m. ET), and Delta to Minneapolis-St. Paul (through 10:15 p.m. ET). An FAA operations plan said several of the stops are “at airline’s requests,” that its stakeholder hotlines will stay open overnight, and that the next status update on the national airspace is due at 6 a.m. ET Saturday. No other cancellations had been posted as of 9:42 p.m. ET. As of about 9:40 p.m. ET, FlightAware counted 6,757 cancellations today among flights within, into or out of the United States.
Updated 8:47 p.m. ET Friday: Transportation Secretary Sean Duffy and Homeland Security Secretary Markwayne Mullin briefed reporters at the White House after the FAA lifted the nationwide ground stop. Duffy put the reopening of the airspace at 8:15 p.m. ET, NBC News reported; the FAA’s cancellation advisory is timed from 8:16 p.m. ET and was issued at 8:19 p.m. ET. Duffy said the stop followed “instability for our radar and our communications in our centers, in our TRACONS throughout the country,” but that “we didn’t lose all telecom, we didn’t lose all radar.” Mullin said, “So far what we’ve seen there is no cyberattack. We’re still working through that process,” and that things were progressing “in the right direction,” NBC reported. He added, “The public was never at danger through this process. There was never any lives at risk. There was no flights at risk,” ABC News reported. Officials still have not identified a technical root cause. As of about 8:47 p.m. ET, FlightAware counted 6,065 cancellations and 9,023 delays today among flights within, into or out of the United States.
Updated 8:42 p.m. ET Friday: The FAA lifted the nationwide ground stop at 8:19 p.m. ET, more than four hours after it began. A command center advisory said the “nationwide ground stop has been cancelled,” and the agency said departures can resume, the Associated Press reported. Shortly before the lift, an FAA operations plan said the stop remained in effect for a large part of the country, though some coastal facilities had released some international departures. Ground delay programs at Boston, LaGuardia, Las Vegas, San Diego and San Francisco were also cancelled. The FAA has not announced a root cause, and Bloomberg’s report that the FBI is examining a software update remains unconfirmed. As of about 8:40 p.m. ET, FlightAware counted 5,958 cancellations and 9,023 delays today among flights within, into or out of the United States.
Updated 7:35 p.m. ET Friday: The nationwide ground stop remained in effect, and the FAA has issued no new status since its 5:46 p.m. ET advisory, which lists the restriction through 11 p.m. ET. An update to the private communications network that links the air traffic control system caused the system to reboot and crash, multiple sources told CBS News. L3Harris, which operates the FAA’s nationwide communications network, did not immediately respond to CBS, and the FAA has not confirmed a cause. Air Space Intelligence, which makes the FAA’s SMART traffic-planning tool, said on X that the stop “is not based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC.” Cancellations have more than doubled since 6 p.m. As of about 7:35 p.m. ET, FlightAware counted 4,393 cancellations and 10,079 delays today among flights within, into or out of the United States.
Updated 6:07 p.m. ET Friday: The FAA said the nationwide ground stop remains in effect and that flights will be allowed to depart as en route facilities recover, through coordination with the command center. A 5:46 p.m. ET advisory cites a communications failure and lists the restriction through 11 p.m. ET, when the agency expects to issue another update. It has not said when departures will fully resume. Its operations plan calls for a “tiered approach” to releasing traffic as conditions allow. Homeland Security Secretary Markwayne Mullin said earlier there was no indication of an attack. FlightAware counted more than 10,000 delays and about 2,000 cancellations today among flights within, into or out of the United States.
The Federal Aviation Administration stopped every departing flight in the United States on Friday afternoon after a communications failure hit the regional centers that guide planes between airports. It is only the third nationwide ground stop in 25 years and the first since January 2023.
The halt turned an IT failure into a physical one, with planes, crews and passengers stuck wherever they were when the order came down on a Friday afternoon. It also followed a Microsoft 365 outage that knocked out Outlook and other services for businesses worldwide, though Homeland Security Secretary Markwayne Mullin told reporters there was no reason to connect the two.
The order went out at 3:54 p.m. ET in an advisory from the FAA’s Air Traffic Control System Command Center, which cited “extraordinary circumstances and for reasons of safety.” “All departing traffic should remain ground stopped until further notice,” the advisory said. Inbound international flights were handled case by case. The FAA lifted the stop at 8:19 p.m. ET Friday, according to a command center advisory, and said departures could resume.
Transportation Secretary Sean Duffy said on X the stop followed “a communication issue impacting all Air Route Traffic Control Centers,” and that FAA technicians were investigating. An FAA statement to TechCrunch cited “communication issues impacting multiple Air Route Traffic Control Centers,” the facilities that handle high-altitude traffic between airports. Before the national order, centers including Boston, Chicago and New York had reported radio frequency outages, WIRED reported, and the FAA had already halted traffic in Chicago, according to SecurityWeek. A later FAA advisory extended flight plan drop times to 240 minutes for all en route centers “due to nationwide comms failure.”
Just after 5 p.m. ET, the agency called it a temporary telecommunications outage in a post on X and said every flight had been accounted for.
The FAA has not released a formal technical finding. Its posted statement cited only communication issues at multiple air route traffic control centers, and its 5:46 p.m. ET advisory cited a communications failure. Aviation Week reported that the FAA said overloaded analog switches and routers caused intermittent disruptions, with instability beginning around 3:36 p.m. ET; the nationwide stop followed at 3:54 p.m. ET. Duffy said Friday night that overloaded routers had begun sending inconsistent data, prompting officials to shut the system down, CBS News reported. Mullin said separately that the trouble began as new equipment was being added to the older system, WIRED reported. Bloomberg News reported shortly after 5 p.m. ET, citing a person familiar with the matter, that the FBI does not believe a cyberattack or criminality was involved and was examining whether a software update triggered the outage. Multiple sources later told CBS News that an update to the private communications network connecting the air traffic control system, which L3Harris operates, caused the system to reboot and crash. Officials have not confirmed either report. Speaking at the White House earlier Friday, Mullin said there was no indication of an attack and that he could not rule anything out, the BBC reported. “We have not discussed any time frame,” he said. “It’s going to take some time.” After the lift, Mullin told reporters that so far there was no sign of a cyberattack, and Duffy said the stop followed instability in radar and communications at the centers and terminal facilities, NBC reported. Mullin also said “there’s not complete certainty right now,” WIRED reported.
The backlog built quickly. By about 11:30 p.m. ET, FlightAware counted 7,731 cancellations and 8,029 delays Friday among flights within, into or out of the U.S. Its Friday total, as read at about 1:33 a.m. ET Saturday, was 8,785 cancellations. By then, its count of cancellations for Saturday had reached 2,602. Flightradar24 tracked about 3,100 airborne aircraft headed for U.S. airports as the order took hold. Planes in the air could still land, but a passenger at Los Angeles International Airport told the BBC that newly landed flights were not being allowed to move from the tarmac to the gates.
Airlines told customers to wait. United said on its website that it was holding planes from taking off and that flights already in the air would continue, and Delta said its flights were “currently being impacted by an ATC-mandated nationwide ground stop,” Business Insider reported. American Airlines told customers on X its teams were ready to move them “as quickly as possible once the FAA’s nationwide ground stop is lifted.”
A prolonged stop would take days to unwind. Michael McCormick, an Embry-Riddle Aeronautical University professor and former air traffic controller, told WIRED that an outage lasting more than a couple of hours would leave aircraft and crews in the wrong places. “It would take days to get up and back running normally,” he said. Axios aviation reporter Alex Fitzpatrick wrote that airports could run out of gates for the thousands of flights already airborne.
The 2023 stop lasted under two hours. It followed a failure of the FAA’s Notice to Air Missions system, which the FAA’s preliminary findings traced to contract personnel who “unintentionally deleted files while working to correct synchronization between the live primary database and a backup database.” Before that, the FAA had grounded all flights only on Sept. 11, 2001. “Right now all it takes is for one system to go out, and it affects a wide region at once,” Susan Hotle, a Virginia Tech transportation engineering professor who worked at the FAA, told WIRED.
The failure also comes during a busy stretch of technology changes at the agency, which this week expanded SMART, an AI tool that advises controllers on congestion, nationwide. WIRED said there is no evidence the ground stop is related to that tool, though Mullin said officials were looking at whether it played a role, Business Insider reported. Air Space Intelligence, the contractor behind SMART, said on X that the stop was not caused by SMART, any other ASI product or its integration with the FAA. Last week, WebProNews reported that the FAA is replacing floppy drives in its systems.
Mullin said earlier Friday that the focus was on restoring communications and getting every flight on the ground. The FAA lifted the nationwide stop at 8:19 p.m. ET. United said it would cancel most of its remaining flights Friday night, and JetBlue said it expects disruptions to continue into Saturday, ABC News reported. Late Friday, the FAA also listed ground stops for specific carriers at several airports, several of them at airline requests; the last of them, American’s O’Hare stop, was cancelled at 1:27 a.m. ET Saturday. The agency said its next status update on the national airspace is due at 6 a.m. ET Saturday.