A single system built on 1980s technology brought every commercial flight in the United States to a standstill for more than four hours today.
The Federal Aviation Administration shut down virtually all air traffic shortly after 12:30 p.m. after switches and routers on its aging analog network became overwhelmed with data, scrambling communications with airlines and control towers.
The culprit was time-division multiplexing, a dated copper-wire technology still used to carry voice and radar data across the FAA. No cyberattack or foreign adversary was involved. The network simply buckled under the load, and the strain of patching it exposed just how fragile the foundation had become.
The stoppage lifted around 5:15 p.m. as technicians rolled out fixes that eased the overload and brought control towers and radar facilities known as TRACONs back online, though delays and cancellations are expected to ripple for days.
Transportation Secretary Sean Duffy laid the blame squarely on neglected infrastructure, pointing out that almost none of the nation's communications networks still run on 1980s equipment except the one that guides its aircraft.
More than 3,500 planes were airborne when the order came down, leaving tens of thousands of travelers stranded. FEMA moved in to ensure passengers did not miss lifesaving medication, and college football teams scrambled to find ground transportation to weekend games.
Modernization is already underway with $12.5 billion secured through the Trump-backed Big Beautiful Bill, but Duffy is pressing Congress for an additional $50 billion to finish the job.