The Federal Aviation Administration’s nationwide ground stop, which paralyzed U.S. air travel for hours, was triggered by routers and copper lines from the 1980s that could not handle the data load, Transportation Secretary Sean Duffy said.
On an otherwise normal travel day, the nation’s air traffic control system collapsed. “We have old switches, old routers. We use 1980s little copper lines. It’s an old system that went down and went down everywhere. It got overloaded,” Duffy said, blaming the failure on decades-old technology. The outage began at 3:36 p.m. ET when the FAA detected “instability for our radar and our communications in our centers, in our TRACONS throughout the country,” he explained. This led to “inconsistency in the data from the radars and our communication with airplanes,” forcing the agency to halt all departing flights as a precaution.
A System Built for a Different Era
The collapse exposed a core problem: the FAA’s infrastructure is a relic of a time when air traffic was far less dense. Air traffic control relies on ground-based controllers who direct aircraft using radar and radio to prevent collisions and manage the flow of traffic. In the United States, this system developed over decades, with early air mail radio stations created after World War I eventually evolving into the modern network. The primary tools today are radar and radio, which controllers use to enforce strict separation rules between aircraft, ensuring they maintain a minimum safe distance.
But the hardware carrying that information is ancient. The routers that process data from radar and communication systems and the copper lines that transmit it are from the 1980s, according to Duffy. When a recent update to the private communications network was introduced, it appeared to overwhelm these outdated components, Homeland Security Secretary Markwayne Mullin said. The system, operated by L3Harris, rebooted and crashed, leading to the nationwide communications outage. The failure affected all 22 FAA Air Route Traffic Control Centers (ARTCCs) and Terminal Radar Approach Control (TRACON) facilities simultaneously, grounding the entire system.
The $875 Million AI Band-Aid
The timing of the failure is striking. Just three days before the outage, the FAA had expanded its new $875 million AI tool, SMART (Strategic Management of Airspace, Routes and Trajectories), to all 22 air traffic control centers nationwide. SMART is a cloud-based system designed to analyze airline schedules, weather, airport capacity, and traffic flow to predict conflicts and recommend optimal routes. The FAA claims the tool has already rerouted 180 flights in the National Capital Region, saving an average of 10 minutes and 80 gallons of fuel per flight.
However, the AI system relies on the same legacy telecom infrastructure that failed. SMART is “completely disconnected from the equipment that” crashed, Duffy said, but it depends on the radar and communication data that the routers and copper lines provide. The company behind SMART, Air Space Intelligence, issued a statement insisting its software was not responsible for the ground stop. The air traffic controllers’ union was also not involved in designing or testing the AI system, signaling potential trust issues with its integration.
The Catch-22 of Modernization
The FAA’s modernization efforts are years behind and billions over budget. The agency’s backlog of upgrades exceeds $1 billion, with critics arguing it moves slower than the technology it’s trying to replace. Last year, Congress approved $12.5 billion over five years for upgrades, but Duffy is pushing for a much larger $50 billion overhaul to address the persistent failures.
The challenge is a catch-22: replacing the system is a slow, complex process, while the technology it’s trying to support evolves rapidly. The FAA tested its systems thoroughly before lifting the ground stop but did not disclose what specifically triggered the data overload. Even after the airspace reopened, Duffy admitted the agency lacks a clear explanation for why the system failed on a day with no extraordinary weather or events. “We don’t have a definitive answer,” he said.
What Comes Next
The consequences of the failure were immediate and severe. By nightfall, more than 7,000 flights had been canceled and 8,000 delayed, according to FlightAware. The chaos stranded thousands of passengers at airports across the country and created a ripple effect that will take days to unwind.
Homeland Security Secretary Markwayne Mullin ruled out a cyberattack, calling the issue a “telecommunications outage”. President Donald Trump was briefed on the ground stop, and officials emphasized the public was never in danger. As the nation’s aviation system struggles to recover, the FAA faces increasing pressure to explain why a system critical to national security and economic activity remains so fragile. The next outage, officials warn, could be worse.
Sources
- Air traffic control
- FAA lifts nationwide ground stop that disrupted thousands of flights, White House says no indication of "nefarious act"
- Old tech blamed for the ground stop that caused flight chaos: 'It got overloaded'
- FAA launched new AI air traffic tool three days before national ground stop
- FAA expands AI advice to manage air traffic congestion across entire US airspace
- Ground stop lifted hours after stranding thousands of flights across the U.S.
Photo: Mike Petrucci / Unsplash (Unsplash License)
