Why One FAA Network Failure Grounded Every Departing Flight in the US
The FAA grounded every departing flight in the United States on Friday, November 13, after communication failures knocked out radar and radio at several air traffic control centers. About 3,100 planes were in the sky at the time. Officials blamed overloaded routers on an aging network and said there were no signs of a cyberattack.
The FAA issued the nationwide ground stop on Friday afternoon, November 13, 2026.
About 3,100 aircraft bound for US airports were airborne when departures stopped.
FlightAware counted 9,159 cancellations and 7,190 delays across the day on Friday.
Officials blamed overloaded routers in the FAA's telecom network, not a cyberattack.
The administration wants about $50 billion to replace the air traffic control system.
What happened when the FAA stopped every flight?
The FAA ordered all takeoffs across the United States halted on Friday afternoon after controllers at several centers lost radar and radio. The outages hit Air Route Traffic Control Centers, which oversee aircraft moving between airports. The agency released a brief statement as the ground stop took effect:
"The FAA issued a nationwide ground stop for all U.S. airports following communication issues impacting multiple Air Route Traffic Control Centers."
Flights that were already airborne landed safely, but no aircraft could take off. The FAA said it would handle international flights on a case-by-case basis. Nav Canada put traffic measures in place at Toronto Pearson, Montréal-Trudeau, Calgary and Vancouver, but said its own systems were operating normally.
Nationwide ground stops are uncommon. The last one came in January 2023, when a damaged database file crashed the FAA's system for issuing notices to pilots. The best known followed the September 11, 2001 attacks.
The ground stop was lifted Friday evening, more than four hours after it began. FlightAware counted 9,159 cancellations and 7,190 delays for the day, the second worst day for US airlines this year. On Saturday, Transportation Secretary Sean Duffy said it was safe to fly but warned that delays would continue as airlines repositioned crews.
Overloaded routers, not hackers, got the blame
Officials said the outage came from network hardware that could not handle its own traffic. At a Friday news conference, Duffy said the routers became overloaded with data and sent out inconsistent information, so the system was shut down. He called the air traffic control system incredibly old.
Homeland Security Secretary Markwayne Mullin said new security patches added to the older system appeared to overwhelm the routers. He said there was no indication yet of a cyberattack or any nefarious act. Mullin also said the outage did not appear to be linked to a separate Microsoft outage.
Both men stressed that the findings were preliminary. Investigators were still working through the outage on Saturday, and the FAA's statement said its information was subject to change. The agency has not released a final root cause.
The FAA's network runs on technology phone companies left behind
The FAA's own safety reviewers warned in 2023 that this network could fail. Its backbone is the FAA Telecommunications Infrastructure, or FTI, which connects air traffic facilities and is operated by L3Harris. A safety review team chaired by former FAA Administrator Michael Huerta described it bluntly in its November 2023 report:
"FTI is based on time-division multiplex (TDM) technology that is no longer supported by the telephone companies' lines on which the signals are actually carried."
The review team found that the FAA kept using the old network for budget reasons. The agency awarded Verizon a contract in March 2023 to replace FTI with an internet protocol network called FAA Enterprise Network Services. The review team called it a 15-year program.
The reviewers also warned about the years in between. Until the new network is fully built, a single facility or an entire en route center could lose contact with the rest of the system. On Friday, that warning appeared to come true on a national scale.
An AI scheduling tool went live three days earlier
The FAA expanded a new AI-powered scheduling system to all of its en route centers just three days before the outage. On November 10, the agency announced that its Strategic Management of Airspace, Routes and Trajectories system, called SMART, would now be used at all 22 centers.
SMART went live in the Washington, D.C., region on September 21. It is a cloud-based system that pulls in roughly 200 data streams, such as weather and controller staffing. FAA specialists in Washington review its recommendations and send them to the national command center in Warrenton, Virginia. The FAA says SMART has rerouted 180 flights since September, saving an average of 10 minutes and nearly 80 gallons of fuel per flight.
The timing raised questions on Friday. Mullin said officials were looking at SMART as part of the investigation. Air Space Intelligence, the company that built SMART, said in a post on X that the ground stop was not caused by its system.
The fix comes with a price tag of about $50 billion
The administration says only a full replacement of the air traffic control system will prevent outages like Friday's. Duffy unveiled the plan in May 2025, and he framed it this way in the announcement:
"Decades of neglect have left us with an outdated system that is showing its age."
The plan would replace old telecom lines at more than 4,600 sites with fiber, wireless and satellite links. It adds 25,000 radios and 475 voice switches, replaces 618 radars and builds six new air traffic control centers, the first since the 1960s.
After Friday's outage, Duffy repeated his call for emergency funding from Congress and warned that more outages would come without it. Mullin said piecemeal upgrades would not be enough and put the cost of a full replacement at about $50 billion.
Will the next outage be shorter, or bigger?
The ground stop turned a long running budget fight into something millions of travelers felt firsthand. A modern network built on fiber, wireless and satellite links would remove the single outdated backbone that failed on Friday. It would also give controllers redundant paths, so one congested router could not bring down several centers at once.
Rebuilding air traffic control is also an opportunity for Silicon Valley. Network, software and AI companies will compete for contracts in a system that is spending billions to modernize.
Autonomous aircraft builders are watching too, because they will fly in the same airspace and depend on the same control systems. Traverse Aero chief executive Scott Parker laid out a practical plan for autonomous pallet air transport on Sparknify's Silicon Valley Unplugged. Ideas like his need a dependable airspace backbone to scale.
The rebuild carries real risks. Friday's failure followed patches applied to old equipment, which shows the danger of updating a fragile network while it is running. The network swap is a 15-year program that leaves years of exposure, and contractors must coordinate across agencies. Funding is also uncertain, since Congress has not approved the emergency money Duffy wants.
The outage also reopened the debate over AI in air traffic control. Skeptics will ask why the FAA added new software and patches to a network its own reviewers called obsolete. They will also ask why officials would not rule out SMART on the first day. Supporters say SMART only offers recommendations to human controllers, that its maker denies any link and that the real culprit is the old network.
Five things will show which way this goes.
The FAA's final root cause report on the November 13 router failure.
Whether Congress approves emergency air traffic control funding before the year ends.
Any FAA pause or change to the SMART rollout at its 22 centers.
Progress on Verizon's replacement network for the old FTI backbone in 2027.
Cancellation counts on the next big travel days, starting with Thanksgiving week.
One overloaded network grounded a nation of travelers, and Congress now holds the bill for making sure it does not happen again.
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Questions & Answers
Q1: Are delivery drones like Zipline's in the same airspace system that failed and caused the FAA ground stop?
Friday's outage hit the en route centers that guide airliners between airports, not the low routes that delivery drones use. Both are part of national airspace and subject to FAA rules, and drone delivery networks add traffic to manage. Walmart is adding 300 Zipline drone delivery sites, so the low sky is about to get much busier.
Q2: I am working on a startup with aviation software that could help modernize air traffic control. How do I get on the radar of investors and government buyers?
The administration is seeking about $50 billion to replace radars, radios and telecom lines at more than 4,600 sites, so buyers will look for proven technology. Startups need credibility with investors and policymakers, and a curated introduction to an investor or government stakeholder can help at sparknify.com/startup-pr-service.
Q3: I am planning an investor event in Silicon Valley with speakers flying in from different places. What should I do to plan for another FAA ground stop?
Friday's stoppage canceled 9,159 flights, and Duffy warned that more failures will come unless the system is funded. Plan a backup arrival day for speakers and a way for them to present remotely if a flight does not make it. Event planning help with speaker invitations and video production is available at sparknify.com/event-planning-inquiry.
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