A routine copper-to-fiber swap at a remote site may have flooded the Federal Aviation Administration’s network and halted every departure in the country for more than four hours. The administration’s explanation has shifted more than once, and the equipment that failed was due for replacement in 2006.
A router installed by government contractor L3Harris Technologies may have caused Friday’s nationwide ground stop, the longest halt to American air travel since the September 11, 2001, attacks, government officials said Saturday. Transportation Secretary Sean Duffy said the cause is still open: “We’re working to determine whether we had incompetence, meaning was it user error or installer error from L3Harris, or did they install a faulty router? We haven’t determined what the fault was,” he said, according to Reuters.
The Federal Aviation Administration (FAA) stopped all departures from U.S. airports at 3:54 p.m. Eastern Time on Friday, November 13, and lifted the order at 8:15 p.m., ABC News reported. By 11:30 that night, nearly 10,000 flights had been canceled, Reuters reported, citing the tracking site Flightradar24. The disruption carried into Saturday, when more than 5,000 flights within, into or out of the United States had been canceled by 2:48 p.m. Eastern, according to FlightAware figures cited by Yahoo News.
What the coverage has missed
Most coverage has framed Friday as a story about old equipment. That is half of it. By the administration’s own account, the failure began at the point where new equipment was being connected to old equipment, during a modernization program Congress has already funded, on a Friday afternoon heading into a weekend travel surge.
The official explanations have also moved. On Friday night, Duffy told reporters that “all of the new equipment that’s been deployed did not go down” and that “this is all the old legacy equipment,” the Associated Press reported. At the same briefing, Homeland Security Secretary Markwayne Mullin said the FAA was installing “new equipment, new technology” and “it was overwhelming the older system.” In remarks reported by Reuters on Saturday, Duffy described new routers that flooded older routers with more than 1,000 connection attempts every four to five seconds. The two versions can be reconciled, since the old routers were what failed and the new ones were what overloaded them. But the public was told three slightly different stories in under a day, and the root cause has not been established.
How the afternoon unfolded
Duffy said trouble began at 3:36 p.m. Eastern, when air traffic control centers experienced instability in radar and communications systems. Aviation Week reported that the FAA pointed to overloaded analog switches and routers. Eighteen minutes after the first instability, the FAA ordered every airport ground stopped “due to extraordinary circumstances and for reasons of safety.”
The agency’s only written statement, posted on its newsroom page and labeled preliminary, said the stop followed “communication issues impacting multiple Air Route Traffic Control Centers.” Duffy’s post on X said the issue affected “all” of them. Reuters later reported that the problem overloaded communications at 17 of the FAA’s 22 en route centers, the large facilities that handle aircraft at cruising altitude between airports.
Duffy said that at no point did controllers completely lose radar or radio contact. “Our switches, our routers actually got overloaded with data and they started to give us inconsistencies in the data from those routers and because of that we shut the system down,” he said. More than 3,000 aircraft in the air at the time were landed safely, according to Mullin. At least 827 flights were diverted by 7:05 p.m. Eastern, according to the aviation analytics firm Cirium, as reported by the AP. Cirium also counted about 11,000 flights carrying more than 1.5 million passengers scheduled to leave U.S. airports after 4 p.m.
Is it really the longest since 9/11?
Yes, on the available record. Reuters and the AP both describe it as the longest nationwide ground stop since the 2001 attacks, which kept civilian airspace closed for days. The only other nationwide stop since then came on January 11, 2023, when the system that sends safety notices to pilots failed after a contractor unintentionally deleted files. That stop lasted about 90 minutes.
Reported durations for Friday vary between “four hours” and “nearly five hours.” Both are defensible. From the ground stop order at 3:54 p.m. to its lifting at 8:15 p.m. is 4 hours and 21 minutes. Counting from the first instability at 3:36 p.m., it is 4 hours and 39 minutes.
The contractor and the router
The L3Harris connection first appeared on Friday through unnamed sources. Reuters reported that the outage “appeared to be affecting a telecommunications network overseen by L3Harris Technologies, according to two airline officials.” Those officials were not named, and RSN found no independent confirmation of their account before Duffy addressed it publicly.
Duffy has since confirmed the L3Harris role on the record. According to Reuters, he said the company was doing routine maintenance to move telecommunication lines from old copper wire to fiber at one or more remote locations. He also said the routers being replaced are about 25 years old and were supposed to be replaced in 2006. “We need L3Harris or whoever provided that router to us to do a better job,” he said.
One further detail rests only on unnamed sources: officials told Reuters there may have been problems with routers installed in both Arkansas and Texas. Neither the FAA nor the Department of Transportation has confirmed those locations publicly, and RSN has found no independent confirmation.
L3Harris has not admitted fault. In a statement, the company said it was “supporting the FAA in its investigation to understand the conditions that led to the Nov. 13 ground stop of our nation’s air travel.” It said it has completed more than 70% of the planned conversion from copper to fiber. The administration put the figure at 68% on Friday, according to Reuters.
Cyberattack and AI questions
Mullin said there was “zero evidence” so far of a cyberattack or a rogue artificial intelligence system, though investigators had not ruled out either. “It appears this was mechanically driven. However, we’re still looking,” he said, adding that the National Security Agency was assisting the Department of Homeland Security (DHS). “This isn’t another 9/11. I cannot repeat that enough,” he told reporters, according to KSAT.
The AI question arose because of timing. On November 10, three days before the outage, the FAA announced it would use its Strategic Management of Airspace, Routes and Trajectories (SMART) system in the airspace of all 22 centers. The FAA describes SMART as a cloud-based platform that pulls together 200 data streams to recommend schedules. Duffy said Friday’s failure was not linked to SMART. KSAT reported that SMART runs from one location near Washington and only sends recommendations to the centers. No evidence published so far ties SMART to the outage, and RSN does not suggest one.
Background: a system flagged for years
The weaknesses were documented well before Friday. In 2024, the Government Accountability Office (GAO) found that the FAA had classified 51 of its 138 air traffic control systems as unsustainable and another 54 as potentially unsustainable, Reuters noted. That is 105 of 138 systems, or about 76%.
In September 2026, a circuit failure at a Philadelphia facility, followed by a construction crew cutting the backup fiber line in New Jersey, delayed or canceled about 9,500 flights in a single day. FAA Administrator Bryan Bedford said at the time: “When it fails, we just don’t have the redundancy that we would get if we had a modern architecture.” The FAA spends $1 billion a year maintaining its old copper network, according to Reuters.
Modernization is not a new idea either. RSN covered President Trump’s air traffic control reform initiative in June 2017. Congress finally approved $12.5 billion for the overhaul in July 2025. Earlier on Friday, before the outage, the White House and the Department of Transportation asked Congress for another $30.1 billion, including $10.1 billion for air traffic control. By Friday night, Duffy was asking for $50 billion. “What we have is an incredibly old air traffic control system,” he said. “Give us the money to fix it.”
Deep dive: money is not the only gap
RSN analysis: Duffy’s case for more money has a real foundation. A 25-year-old router that was due for replacement in 2006 is the product of roughly two decades of deferred spending under administrations and Congresses of both parties. But the record shows that funding is not the only weakness.
In September, the GAO warned that the FAA lacked a reliable cost estimate and an integrated master schedule for the modernization program. As of May, the agency was running 11,389 separate project schedules that were not coordinated with one another, raising the risk of repeated work, delays and cost overruns. The FAA aims to finish the first phase by December 2028.
Friday’s failure fits that warning. Work at one or more remote sites was able to destabilize communications at 17 en route centers, which suggests the network had no effective way to isolate a misbehaving device before it spread. Duffy himself acknowledged the timing was poor, saying the FAA would reevaluate doing network work at smaller facilities during the day. That is a management decision, not a budget line. Taxpayers are entitled to know who approved the timing of the cutover work, what testing preceded it, and what the L3Harris contract says about liability.
Stranded travelers are absorbing the cost in the meantime. Because the failure was the FAA’s and not the airlines’, carriers are not required to compensate passengers, Reuters reported, though travelers who cancel because of a long delay are entitled to refunds, KSAT reported. Bedford said Saturday that airlines were waiving their terms and conditions for affected travelers.
The other side
Democrats rejected Duffy’s attempt to put the blame on Congress. Sen. Tammy Duckworth of Illinois, the top Democrat on the Senate aviation subcommittee, wrote on X: “You’ve literally controlled Congress for the past two years.” Republicans do hold majorities in both chambers of the current Congress, and Senate Republicans re-elected John Thune as their leader this week. House Minority Leader Hakeem Jeffries called the outage an “unprecedented breakdown” and said “American travelers deserve timely answers from the Trump Administration about how and why this happened.”
There is a fair defense of the administration too. The ground stop worked as designed. Faced with unreliable data and no identified root cause, the FAA kept aircraft on the ground rather than launch them into airspace where controllers might lose contact, and no one was hurt. Aviation safety expert Steve Arroyo, a former United Airlines pilot, told the AP that without reliable communications “you’ve got to stop airplanes on the ground.” Lawmakers from both parties have said Congress will investigate.
What is established, disputed and not established
Established (on-record statements and data):
- The FAA stopped all U.S. departures from 3:54 p.m. to 8:15 p.m. Eastern on November 13, 2026, the longest nationwide ground stop since 2001.
- Nearly 10,000 flights were canceled by late Friday (Flightradar24) and more than 5,000 more by Saturday afternoon (FlightAware).
- Duffy said overloaded routers and switches caused unreliable radar and communications data, and that an L3Harris copper-to-fiber cutover was under way at a remote site.
- Mullin said there was no evidence of a cyberattack so far; the NSA is assisting DHS.
Disputed:
- Whether “all” en route centers were affected (Duffy on Friday) or 17 of 22 (Reuters on Saturday).
- Whether the failure stemmed from old equipment, new equipment, or the connection between them; officials have described it all three ways.
- Whether Congress or the administration bears responsibility for the pace of modernization.
Not established:
- The root cause. Duffy said officials have not determined whether it was installer error or a faulty router.
- The Arkansas and Texas router locations, which rest on unnamed officials quoted by Reuters.
- Any link to a cyberattack or to the SMART AI system. Officials say there is no evidence of either, but neither has been formally ruled out.
Sources: FAA General Statements (Nov. 10 and Nov. 13, 2026); Reuters, Nov. 13; Reuters analysis, Nov. 14; Reuters, Nov. 14 (L3Harris); Associated Press; ABC News; Aviation Week; KSAT; Yahoo News live coverage.
Featured image: The FAA’s Oakland Air Route Traffic Control Center in Fremont, California. Photo by ECTran71, CC BY-SA 4.0, via Wikimedia Commons.
How this article was made: Right Side News researched and drafted this article with the help of AI tools. Sources are linked so readers can check them. Spot an error? Tell us in the comments and we will correct it.
