Router Flood in Fiber Upgrade Triggered Nationwide FAA Ground Stop, Duffy Says

Transportation Secretary Sean Duffy said Saturday that the nationwide flight grounding on Nov. 13 began with a router installed during a telecommunications upgrade, which flooded the air traffic control network with traffic. The BBC reported that the stoppage was the longest nationwide grounding of U.S. flights since the Sept. 11, 2001, attacks.

Duffy said Saturday that operations are back to full, but airlines are still working through the backlog. FlightAware counted more than 5,900 cancellations and more than 7,000 delays in the U.S. on Saturday.

What did officials say caused the ground stop?

According to Duffy, a government contractor, L3Harris, was replacing old copper lines with fiber at a remote site Friday afternoon. The BBC reported that the company installed a router there, and that the device began sending 1,000 connection attempts every four to five seconds to other routers in the system. Business Insider reported that the FAA shut the router down.

FAA Administrator Bryan Bedford said 17 of 22 air route traffic control centers had unstable voice and ground communications as a result. Duffy and Homeland Security Secretary Markwayne Mullin said there was no sign of a cyberattack or an artificial intelligence problem. Business Insider reported that the maker of a new FAA air traffic tool, SMART, also said the system was not involved, and Duffy agreed.

Who is being blamed, and what does L3Harris say?

Duffy said the work was routine and has been done many times over the decades, and he asked whether the contractor made mistakes or whether the router was faulty, according to Business Insider. He added that officials would examine whether human error or equipment was responsible, and that the practice of allowing such upgrades during the day would be reviewed, the BBC reported.

L3Harris said it is supporting the FAA’s investigation. According to Business Insider, the company said it has completed more than 70% of the planned conversion from copper wires to fiber optics.

Bedford said it took the FAA 45 minutes to find the source of the problem because maintenance is logged manually on paper. Because it could not yet identify the cause, the agency decided as a precaution to ground all flights, he said.

What is the government asking Congress to do?

Duffy and Mullin called on Congress to provide $50 billion to modernize air traffic control, up from the $30 billion pitched in September, Business Insider reported. Duffy said the system needs a complete overhaul, the BBC reported. Mullin said the public was never in danger.

How bad was the disruption, and is it over?

FlightAware said the ground stop led to more than 8,500 delayed and nearly 8,000 cancelled flights Friday. Business Insider put the combined number of cancellations on Friday and Saturday at about 12,500.

On Saturday, the BBC reported, Delta Air Lines and United Airlines each cancelled 20% of their flights, JetBlue cancelled 40% of its scheduled flights and American Airlines cancelled 520. WKMG reported that travelers at Orlando International Airport were still facing delays and cancellations. One traveler, Terry Grimes, said he and his wife had been awake for 26 hours before they gave up on a trip to Puerto Rico after their flight was canceled around 2 a.m.

What does this mean for passengers whose flights were canceled?

Airlines generally do not owe compensation for air traffic control problems, the BBC reported, and Business Insider said passengers have little recourse for meals or hotels because the airlines were not at fault.

Federal rules still apply. Under the FAA Reauthorization Act of 2024, the BBC reported, a canceled or significantly delayed flight, defined as three hours for domestic flights and six hours for international routes, must come with an offer of alternative travel or a full refund if the passenger chooses not to fly. WKMG advised travelers to check with their airline for flight status before heading to the airport.

Earlier on Around Prague: FAA Ground Stop Is Over: What Caused the Nationwide Outage and What It Means for Your Flight

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Around Prague, based on reporting by BBC, WKMG, Business Insider