FAA lifts 5-hour nationwide ground stop; outdated routers blamed, weekend disruption expected

A nationwide ground stop covering all departing U.S. flights was lifted by the FAA at 8:15 p.m. ET Friday, ending roughly five hours of disruption that produced more than 10,000 delays and over 4,000 cancellations — the longest such halt in 25 years and only the second since the September 11 attacks. Travelers stranded at airports from Boston to Los Angeles face a slow recovery: as of Saturday morning, more than 3,500 residual cancellations were already logged, and aviation analysts said it could take days for airlines to restore normal schedules.

The immediate culprit, according to senior government sources who spoke to CBS News, was a set of Cisco 600 series routers manufactured between 2001 and 2006. Those routers became overwhelmed and began feeding out-of-sync data packets into the broader air traffic control system, causing static over voice communication lines and making screens flash or go dark. Authorities said they had pinpointed and contained the malfunctioning equipment.

Transportation Secretary Sean Duffy told reporters at a White House briefing Friday evening that the routers were overloaded with data and 'went down,' forcing the FAA to shut the system down as a precaution. Duffy called the air traffic control system 'incredibly old.' Homeland Security Secretary Markwayne Mullin said that newly introduced security patches appeared to 'overwhelm' the older system's routers, and that officials were looking into compatibility problems between the aging hardware and newer technology currently being installed.

We're still working on the details of what went wrong today.— Sean Duffy, Transportation Secretary

Linking air traffic control centers and other FAA facilities, the agency's telecommunications backbone — known as the FAA Telecommunications Infrastructure, or FTI — supports the voice communications and operational data used to manage air traffic. It is operated by L3Harris, which did not respond to a request for comment from CBS News. The FAA awarded Harris Corp., L3Harris's predecessor, a contract to modernize and manage the network in July 2002. A safety review commissioned by the FAA in November 2023 found the FTI network to be obsolete, noted its reliance on an older communications technology known as TDM, and cautioned that an unforeseen failure could sever individual FAA facilities — or even an entire regional air traffic control center — from the wider network.

Multiple sources told CBS News they were receiving conflicting information about the precise trigger, with some saying an update to the private communications network caused the system to reboot, leading to a crash and communications outage. CBS News also reported there has been frustration with L3Harris's communication and response.

The ground stop began at 3:54 p.m. ET. Aviation analytics firm Cirium estimated that around 11,000 flights carrying more than 1.5 million passengers had been scheduled to leave U.S. airports after 4 p.m. ET. Roughly 3,100 aircraft were already airborne when the stop was issued, according to Flightradar24; those planes were permitted to continue to their destinations and land. By 7:05 p.m. ET, at least 827 flights had been diverted, with 670 returning to their departure airports and 157 sent elsewhere, according to Cirium. Authorities evaluated international flights individually, allowing some to take off even while restrictions were in place.

This is absolutely unprecedented.— Robert Sumwalt, former chair of the National Transportation Safety Board

Delta Air Lines led Saturday's cancellation count with 640 flights scrubbed, followed by United with 530 and American with 488, according to FlightAware. Atlanta's Hartsfield-Jackson International Airport, Chicago O'Hare, and New York's JFK were the most affected airports Saturday morning, with about 1,400 additional flights delayed.

Both Duffy and Mullin were emphatic that the public was never in danger and that no cyberattack was involved. Mullin specifically said there was no connection to a separate Microsoft outage that some had speculated about.

I want to make sure everybody understands that there is no connection between this and Microsoft. I know a lot of people are making that jump. This is so far what we've seen. There is actually no cyberattack. We're still working through that process.— Markwayne Mullin, Homeland Security Secretary

Duffy used much of the press conference to press Congress for emergency funding to replace the nation's air traffic control infrastructure, warning that similar failures would recur without it. Mullin contended that updating the system in stages was not enough, and said the Trump administration is seeking a full replacement, which he put at an estimated cost of $50 billion.

I can't build things if I don't have money.— Sean Duffy, Transportation Secretary

But you will have more of these. You will have more of them unless the American people and the Congress tell us to build.— Sean Duffy, Transportation Secretary

A September Government Accountability Office report, cited by former Australian Civil Aviation Safety Authority senior executive Tony Stanton, had already flagged ageing copper cables dating to the 1960s and warned that delays in modernizing the system could cause further disruptions. The report also noted that FAA officials were prioritizing speed over proper scheduling of upgrades, meaning changes were sometimes happening simultaneously and overwhelming the system, according to Al Jazeera.

Before reopening airspace, the FAA said it 'thoroughly tested our systems to confirm they were stable and that operations remain reliable.' By 7:30 a.m. ET Saturday, senior government sources told CBS News, airspace was operating normally and being closely monitored. But Duffy cautioned that resumption of full flight traffic would 'be slow,' urging passengers to check with their airlines on the availability of pilots and flight attendants before heading to airports.

Why it matters — A single set of two-decade-old routers was able to halt all U.S. air travel for five hours, and officials warn the same could happen again unless Congress funds a $50 billion overhaul of infrastructure that government reviews have flagged as dangerously obsolete.

Sources differ on Total flight cancellations on Friday: Over 4,000 (cbsnews.com) vs Over 4,700 (aljazeera.com)

Reported by axios.com, thehill.com, deseret.com, flightradar24.com, cnn.com, cbsnews.com, forbes.com, aljazeera.com