FAA grounds all flights across the US after nationwide communications failure

The United States grounded flights across the country on Friday after a communications failure struck its air traffic control system, leaving thousands of passengers stranded and producing the first nationwide ground stop since January 2023.

The Federal Aviation Administration said in a post on X that a "temporary telecommunications outage" had affected its operations and that, as a precaution, all flights were being halted. International flights would be handled case by case, the agency added.

US Transportation Secretary Sean Duffy said federal technicians were working on the problem. "FAA technicians are investigating the issue. We will provide immediate updates as we have them," he wrote on social media.

About 7,000 flights had been either delayed or cancelled because of the stop, according to the tracking site FlightAware. Some 4,042 flights were already in the air, heading to US airports, when the ground stop was ordered, according to Flightradar24. Those aircraft were allowed to continue to their destinations, but no new departures were permitted while the order stood.

The communication problem affected all 22 air route traffic control centres, the large regional facilities that guide aircraft between airports across the country. When those centres cannot communicate reliably with pilots and with each other, controllers lose the tools they need to keep aircraft safely separated, and the only safe option is to keep planes on the ground.

What happened on Friday

The ground stop took hold during the day on Friday, and its effects spread quickly. Airports across the country saw departure boards fill with cancellations, and passengers described long lines at rebooking desks.

The FAA gave no indication of when the ground stop might be lifted. Some international services were expected to be allowed to depart, with Pacific-bound and transatlantic flights among those being handled individually, but the agency did not publish a timetable for a full resumption of domestic flying.

Homeland Security Secretary Markwayne Mullin told reporters there was no indication that the ground stop had been triggered by a threat to the United States. "Everybody's safe. The flights are accounted for," he said. "This is not another 9/11." He added that President Donald Trump had been briefed on the situation.

For passengers, the practical consequences were immediate: missed connections and cancelled trips. Airlines began waiving change fees and urging travellers to check the status of their flights before heading to the airport, as the backlog of delayed aircraft and crews threatened to spill into the weekend even after the order was lifted.

No sign of an attack — but no cause yet

Investigators have not yet established what caused the outage, and officials were careful not to rule anything out in the first hours. Asked whether a planned rollout of a new artificial intelligence tool designed to help air traffic controllers could be to blame, Mullin said officials had not excluded it. "You just can't rule out anything at this point. We are going through that process," he said.

The FBI does not believe a cyberattack or criminal activity caused the failure, Bloomberg reported, citing an official familiar with the matter. The same official said investigators were examining whether a software update could have caused the outage, though the cause had not been determined.

That distinction matters. A hostile attack on aviation infrastructure would raise an entirely different set of questions, involving national security agencies and the possibility of a deliberate attempt to disrupt American transport. A software fault, by contrast, would point to the fragility of the systems themselves — and to the risks of changing complex, safety-critical technology while it is in daily use.

Either way, the episode will be examined closely. The FAA's systems are among the most safety-critical in the country, and a failure that can halt every departure nationwide, even briefly, is the kind of event that prompts formal inquiries, congressional hearings and demands for a detailed public account of what went wrong.

A system under strain

The disruption is the latest sign of strain on the US air traffic control system, which has been beset by equipment failures, communications problems and shortages of controllers, as the FAA tries to replace ageing infrastructure.

Much of the equipment guiding American aircraft dates back decades, and the agency has been working through a long modernisation programme. Congress approved $12.5bn for the overhaul last year, and the Department of Transportation and the White House asked lawmakers on Friday for another $30.1bn — a request that arrived on the same day the system failed.

The last nationwide ground stop came in January 2023, when a key FAA computer system malfunctioned. Before that, the last time all flights in the country were halted was after the September 11, 2001, attacks. The rarity of such an order underlines how serious Friday's failure was judged to be: officials do not stop the entire system lightly.

For now, the focus is on getting aircraft moving again and clearing the backlog. The deeper questions — what failed, why it failed, and what must change — will follow once the skies are open.