US flight chaos: FAA lifts nationwide ground stop after legacy air traffic system overload

A communications failure involving the United States' ageing air traffic control infrastructure brought departures to a halt across the country on Friday, leaving thousands of passengers stranded and disrupting travel at airports nationwide. Although the Federal Aviation Administration (FAA) subsequently lifted the ground stop, officials warned that restoring normal flight operations would take time.

US Transportation Secretary Sean Duffy blamed the disruption on an overloaded legacy communications network that began supplying inconsistent data to regional air traffic control centres. The outage triggered a nationwide safety alert, resulting in more than 14,000 flight cancellations and delays, according to initial reports.

The disruption lasted more than four hours, with the FAA lifting the nationwide ground stop on Friday evening. Subsequent reports put the number of cancellations at nearly 5,000, while more than 10,000 flights were delayed or otherwise affected. More than two million passengers faced travel disruption, and at least 827 flights were diverted.

Duffy said the country's airspace had reopened but cautioned that flight operations would not return to normal immediately. Airlines would need time to reposition aircraft and crews, while passengers faced the prospect of further delays over the weekend.

Travellers stranded as plans fall apart

The shutdown caused confusion at airports across the US, with passengers complaining that they had received little information about the disruption or when they would be able to travel.

At New York's LaGuardia airport, 61-year-old Janice Llewellyn feared she would miss her daughter's wedding in Toronto.

"I may lose my mind," she said.

Her husband had travelled all the way from England to attend the wedding, but the grounding threatened to derail her plans. "Oh gosh! I wish they had another flight, I wish I could get another flight, like, now," she told news agency AFP.

Several passengers said neither they nor airline crew members had been given a clear explanation for the sudden halt in departures. At Las Vegas airport, long queues formed at car rental counters as stranded travellers attempted to find alternative ways to reach their destinations.

Some passengers there were initially told that their journeys had been delayed because of wind. Conflicting information from airline staff added to the uncertainty, with one employee reportedly saying the ground stop would last eight hours and another suggesting it could continue for 24 hours.

"The first thing I thought of was doomsday," a woman travelling through the airport told the BBC. Another passenger said he was "shocked" by the announcement, while a third drew a comparison with the Microsoft disruptions reported earlier in the week.

Riley Alexis Holmes, who was hoping to reach Oregon in time for her brother's musical closing night, said her flight was cancelled after a two-hour delay.

"I called my mom and cried, and I'm just like sitting here waiting for information," she told Business Insider.

Kieran Cullen, 27, was also left stranded after travelling for more than 24 hours following the end of his overseas deployment. He was on his way to Jacksonville, Florida, when he was informed that his flight had been cancelled after waiting for hours.

"So far, not a ton of information, other than just live speaker announcements discussing the centres having rotating blackouts on frequencies, but nothing specific. It's over 24 hours of travel, so it's definitely a bummer," he said.

Another passenger, Tiara Johnson, described her frustration at having her plans abruptly disrupted.

"I feel very frustrated because you know, you come to the airport and then all of a sudden your whole plans have changed and you don't know when you're leaving. We're kind of stuck," she told AFP.

A traveller speaking to NBC News said she had never witnessed anything comparable "in all my years of flying", describing the situation as unsettling.

"I have no idea what's going on. I am pretty sure we're not flying anywhere tonight. We're ready to go back to the room. It's absolutely ridiculous," another passenger said.

Why did the FAA ground flights?

Duffy said the disruption originated in an ageing air traffic control communications network that uses outdated switches, routers and copper telephone lines.

"This is a legacy system problem. We have old, 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," he said.

According to the transportation secretary, the system began experiencing instability in radar and communications at air traffic control centres and Terminal Radar Approach Control facilities. The overloaded equipment started providing inconsistent data, prompting officials to suspend departures as a precaution.

Duffy said the disruption was linked to the country's outdated infrastructure and renewed calls for investment to modernise the air traffic control network. He described the situation as an emergency and urged Congress to provide additional funding for the overhaul.

The FAA's decision to halt departures was taken on safety grounds. Aircraft that were already airborne were allowed to continue to their destinations, while some flights were diverted or had to return to their departure airports.

The nationwide ground stop was lifted after more than four hours, but Duffy warned that clearing the backlog would take time. He said officials hoped flight movements would improve over the following day, although the disruption could take several days to fully unwind.

Officials rule out evidence of cyberattack

The incident was described as only the second nationwide ground stop of its kind since the September 11, 2001, attacks. The previous comparable nationwide halt occurred in January 2023, when a failure in the FAA's pilot-notification system disrupted flights.

Homeland Security Secretary Markwayne Mullin said officials had found no evidence that Friday's outage was caused by hostile action or a cyberattack.

"We've seen zero evidence that this was a cyber attack or (AI) attack," he said, ruling out any established connection with the Microsoft disruptions earlier in the week.

Mullin said several government agencies were involved in examining the incident. However, officials indicated that the investigation was continuing and that they had not established every detail of the failure.

The outage has renewed concerns over the condition of the US air traffic control system, much of which relies on decades-old technology. The administration has been seeking funding to replace outdated equipment and modernise the infrastructure used to manage the country's airspace.