Key Takeaways
- The FAA issued a nationwide ground stop for all U.S. airports on November 13, 2026, after communication problems affected multiple air route traffic control centers, and the stop lasted more than four hours.
- Transportation Secretary Sean Duffy said on November 14, 2026, that the FAA ground stop came after L3Harris updated an older communication system while switching it from copper wire to fiber optic cable.
- FAA Administrator Bryan Bedford said there was zero evidence that the November 13 FAA outage was caused by anything nefarious, and Homeland Security Secretary Markwayne Mullin said there was no cyberattack.
- More than 9,000 U.S. flights were canceled on November 13, 2026, and more than 3,700 on November 14 as of 9:40 a.m. Eastern time, according to FlightAware figures reported by CBS News, NPR, and CNBC.
What happened
The Federal Aviation Administration (FAA) issued a nationwide ground stop for all U.S. airports on Friday, November 13, 2026, "following communication issues impacting multiple air route traffic control centers." These centers handle aircraft flying at high altitude between airports.
The FAA halted departing U.S. flights around 4 p.m. Eastern time, and the stop lasted more than four hours, CNBC reported. SecurityWeek reported that the order was lifted at 8:15 p.m. Eastern time. About 3,100 aircraft were in the air bound for U.S. airports when the stop began, CBS News reported, citing the tracking site Flightradar24.
CNBC described it as the longest halt in departures to U.S. airports since the September 11, 2001, attacks.
What caused the outage
At a press conference on November 14, Transportation Secretary Sean Duffy said the ground stop came after updates to an older communication system made by L3Harris Technologies, according to CNBC. The work was part of a switch from copper wire to fiber optic cable, Duffy said.
When one router was moved to fiber optic cable, it "flooded" other routers in the air traffic control system with over 1,000 connection attempts roughly every five seconds, Duffy said, according to CNBC. That caused problems with aircraft communications and radar feeds, he said. FAA Administrator Bryan Bedford said no FAA facilities went dark, but officials grounded flights because of "instability" in the information feeds to the control centers.
The FAA is still investigating. "What we're working to determine was whether we had incompetence, meaning was it user error, installator error from L3Harris, or did they install a faulty router," Duffy said, as reported by CNBC and NPR.
The FAA's preliminary investigation points to Cisco 600 series routers made between 2001 and 2006, and the faulty equipment has been identified and isolated, senior government sources told CBS News. The same sources said they were receiving conflicting information about the cause.
The network involved is the FAA Telecommunications Infrastructure (FTI), which carries voice communications and operational data between air traffic control centers and other FAA facilities, according to CBS News. L3Harris operates it. CBS News reported that a November 2023 safety review commissioned by the FAA described the FTI network as obsolete.
Cyberattack ruled out so far
Bedford said there was "zero evidence" that the problem was caused by something "nefarious" or by anything related to artificial intelligence, CNBC reported.
On November 13, Homeland Security Secretary Markwayne Mullin said there was no cyberattack and that the ground stop was not connected to the global Microsoft outage that week, according to CBS News. Mullin said the National Security Agency, the Department of Defense, the Cybersecurity and Infrastructure Security Agency (CISA), and other agencies were involved in the investigation, SecurityWeek reported. "However, we're still looking, so we're not going to rule that out," Mullin said, according to SecurityWeek.
L3Harris response
In a statement on November 14, L3Harris said that together with its telecommunications partners and the FAA it had completed more than 70% of the planned conversion of airspace communications from copper wire to fiber optic cable. "We are supporting the FAA in its investigation to understand the conditions that led to the Nov. 13 ground stop of our nation's air travel," the company said.
Impact and recovery
There were 9,159 U.S. flight cancellations and 7,190 delays on November 13, according to FlightAware figures reported by CBS News. CNBC noted that some of that day's disruption was due to bad weather. More than 3,700 U.S. flights were canceled on November 14 as of 9:40 a.m. Eastern time, CNBC reported.
Bedford said schedule problems should be resolved by Sunday evening, November 15, and that all affected passengers will be rebooked or receive a full refund, according to NPR. He advised travelers to contact their airlines directly.
Duffy renewed calls for Congress to fund an upgrade of the air traffic control system, according to CBS News and NPR. The last nationwide ground stop was in January 2023, when an FAA system outage also delayed domestic flights across the country, CBS News reported.