The short version:
- On Friday 13 November, the Federal Aviation Administration — the US agency that runs air traffic control — ordered every departing flight in the country to stay on the ground.
- The stop lasted about four and a half hours, from mid-afternoon until 8:15 p.m. Eastern time.
- More than 10,000 flights were delayed and more than 2,000 cancelled, according to flight tracker FlightAware.
- Officials blame a communications failure inside the air traffic control system, not a cyberattack.
- It was only the second nationwide ground stop since the aftermath of the September 11 attacks.
For four and a half hours on Friday, the busiest airspace in the world went quiet. No passenger jet took off anywhere in the United States. Planes already in the air were allowed to land, but nothing new left the ground — from New York to Los Angeles, from Miami to Seattle.
The order came from the Federal Aviation Administration, the FAA, the federal agency that controls American airspace. At 3:36 p.m. Eastern time, its controllers began seeing unstable radar and communications data at the country’s Air Route Traffic Control Centers, the regional facilities that guide high-altitude flights. Within minutes, the agency decided it could not trust what its screens were showing — and chose to stop departures altogether.
“There has been a temporary telecommunications outage — out of an abundance of caution all flights have been halted,” the FAA said in a statement issued at 4:02 p.m. A formal advisory followed, instructing all departing aircraft to remain on the ground until further notice, citing “extraordinary circumstances” and safety.
A timeline of the stoppage
3:36 p.m. ET: Instability appears in radar and communications systems at air traffic control centers. Around 3,500 aircraft are in the sky.
~3:54 p.m. ET: The FAA’s Command Center issues the nationwide ground stop. Departures freeze at every US airport. Inbound international flights are handled case by case.
4:02 p.m. ET: The FAA publicly confirms a temporary telecommunications outage and says flights are halted out of caution.
Evening: Delays climb past 10,000 nationwide and cancellations past 2,000. Air Canada cancels all flights to and from the United States. Europe’s air traffic body, Eurocontrol, suspends US-bound departures from its 42 member countries at the FAA’s request.
8:15 p.m. ET: The ground stop is lifted, about four and a half hours after it began. By then fewer than 400 aircraft remain in the sky. Airlines warn that schedules will stay disrupted through the weekend, with planes and crews stranded far from where they need to be.
What actually broke
Transport Secretary Sean Duffy, speaking at the White House on Friday night, pointed at the age of the system itself. The failure, he said, was a legacy network problem: routers and switches overloaded with data, producing inconsistent information at the control centers. “It was a legacy network problem,” he said, and used the moment to press Congress for $50 billion to modernise air traffic control.
Homeland Security Secretary Markwayne Mullin, standing beside him, said the introduction of some new technology into the old system had overwhelmed it. He was blunt about what it was not: there is “zero evidence” the stoppage was caused by a cyberattack or by artificial intelligence, he said. The National Weather Service reported communications problems of its own on Friday, though officials have not said the two are connected.
Exceptions were made throughout the stoppage for medical evacuation flights, life-saving cargo and law enforcement aircraft. Everything else waited.
Why this matters
The shock of Friday was not just the delay count. It was the scale of the decision. A nationwide ground stop is the bluntest tool the FAA has, and it has now been used twice in the modern era: once in January 2023, when a key computer system failed, and now. The only earlier occasion was the aftermath of the September 11 attacks in 2001 — and that was a security shutdown, not a technical one.
That makes this the first time the system has ever stopped itself because it could no longer trust its own data. Duffy’s $50 billion ask will now be hard for Congress to ignore, but money alone does not fix a system that has to be rebuilt while it is running. Every upgrade has to happen without ever switching the network off, because the network never switches off.
For travellers, the practical damage runs into the weekend: rebooked flights, hotel nights, missed connections. For everyone else, Friday was a reminder of how much of modern life rests on infrastructure most people never think about — until the departure boards all turn red at once.
The FAA has promised further updates. The full technical explanation of what overloaded, and why, is still to come.
Source: FAA Newsroom
