US Flights Resume After Nationwide Ground Stop, But Officials Warn Recovery Will Be Slow

On Friday afternoon, travellers at Chicago O'Hare learned that something had gone wrong the way many passengers do now: by looking up at the airport screens, which showed delays spreading across the board. Some began weighing whether to stay overnight or find another way to reach their destinations. The cause was a nationwide ground stop, ordered by the Federal Aviation Administration after communication problems hit its regional air traffic control centres.

The FAA said "extraordinary circumstances" tied to those communication issues had forced it to halt departures nationwide. It was investigating a problem affecting all 22 regional centres, the facilities that direct aircraft travelling between airports across the country. Later, the agency lifted the stop and flights were cleared to take off again. Transportation secretary Sean Duffy warned that returning operations to normal would be a slow process.

The scale of the disruption was considerable. Aviation analytics company Cirium counted at least 827 diverted flights. As of 7.05 pm EST, 670 had been sent back to their departure airports and 157 had been redirected to other airports. Washington Dulles, Los Angeles International, Cincinnati/Northern Kentucky and Nashville were among those receiving diverted aircraft. Around 11,000 flights carrying more than 1.5 million passengers had been scheduled to leave US airports after 4 pm EST, which left open the possibility of further cancellations and diversions. United Airlines and American Airlines said flights already in the air would keep operating. American said in a statement on X that it would be "all hands on deck" to get customers moving once the stop was lifted. Alaska Airlines said some flights within Alaska and Hawaii were unaffected.

Homeland security secretary Markwayne Mullin said there was no indication of a cyberattack or any deliberate attempt to target the country. He described it as a telecommunications outage and told people that everyone was safe and that those with relatives flying had no reason to worry. International flights were being assessed case by case, he said, with some expected to depart Friday evening.

Duffy blamed an overloaded, ageing analogue system. The stop was the first nationwide one since January 2023, when a malfunction in a key FAA computer system disrupted operations. Before that, the last such suspension came after the September 11, 2001, attacks.

The episode has put the technology behind US air traffic control under scrutiny. Congress approved $12.5 billion for modernisation last year, but the overhaul is unfinished: miles of copper wire are still being replaced with fibre-optic lines, and radio systems are being upgraded gradually. The Trump administration raised its funding request to $50 billion late Friday, up from the $30.1 billion that Duffy and the White House had sought earlier. "This is an emergency," Duffy said, asking what could matter more than an air traffic control system that works. Mullin called for more funding as well.

Investigators will also look at whether the outage was connected to the FAA's rollout of a new artificial intelligence system that identifies problems and recommends alternative routes. It operates from a single location near Washington, DC, and sends its recommendations to the control centres.

Aviation safety expert Steve Arroyo, a former United Airlines pilot, compared the event to a September communication outage that affected hundreds of flights in the Northeast, only on a national scale. If controllers cannot communicate with aircraft, whether because of worn-out wires or something else, planes must be kept on the ground rather than sent up where contact might be lost, he said. He added that, unlike after September 11, pilots on Friday were not told to land immediately and were likely still able to talk with ground controllers at airports.

What to watch now is how quickly the backlog of diverted and delayed flights clears, what investigators find about the cause, including the AI system, and whether Congress acts on the larger funding request.