Air travel across the United States has begun returning to normal after aviation authorities lifted a nationwide ground stop triggered by a major communications failure within the country’s air traffic control system.

US Transportation Secretary Sean Duffy confirmed that the restriction had been removed, allowing aircraft to resume departures. However, he warned that passengers should expect further delays as airlines work to clear the backlog created by the disruption.

The incident affected airports across the country, leaving thousands of travellers stranded, with some passengers forced to remain inside aircraft while others faced postponed or cancelled journeys.

According to reports by CBS, the technical problem may have originated from an update to a private communications network operated by L3Harris. The update reportedly caused the network, which connects important components of the US air traffic control system, to restart before eventually crashing.

Although investigations are ongoing, US Homeland Security Secretary Markwayne Mullin said there was no evidence suggesting that the incident was caused by a cyberattack. He also assured the public that all aircraft had been accounted for and that passengers were safe.

The Federal Aviation Administration (FAA) had earlier ordered the suspension of departures following a telecommunications outage that affected air traffic control operations. International flights were handled separately, with decisions made on a case-by-case basis.

The disruption also affected international aviation, as European air traffic authorities temporarily suspended flights heading to the United States following a request from the FAA.

Aviation experts described the incident as the most significant nationwide flight grounding since the September 11, 2001 terrorist attacks, although they stressed that the circumstances were entirely different.

The latest disruption has also raised concerns about the condition of America’s aviation infrastructure. Parts of the country’s air traffic control technology have been criticised for relying on outdated systems, prompting calls for major modernisation.

With flights now gradually resuming, airlines are expected to face a difficult recovery period as they rearrange schedules, accommodate stranded passengers and work through the growing number of delays.