US air travel ground stop lifted, flights set to resume

The US Federal Aviation Administration has lifted a nationwide ground stop after a communications failure at air traffic control centres triggered the longest nationwide shutdown since the 11 September 2001 attacks.

More than 4,700 flights were cancelled and 10,000 were delayed yesterday, while another 700 had already been cancelled for today, according to FlightRadar24.

More than 1.5 million passengers were scheduled to depart US airports after 4pm ET (2100 GMT), shortly after the ground stop began, according to aviation analytics firm Cirium.

'Old hardware' was to blame for the US air travel stoppage, US Transportation Secretary Sean Duffy told reporters at a White House press briefing.

Mr Duffy said switches and routers had become overloaded with data and went down.

It was not immediately clear what caused the equipment to overload.

In a statement, Aer Lingus said that some of its flights from the US are now being cleared to depart, after previously being on hold.

"We are continuing to monitor the situation closely and will communicate directly with customers who are impacted by the disruption, the statement said.

"Customers should continue to check aerlingus.com for the latest updates," it added.

The FAA lifted the ground stop after more than four hours, but Mr Duffy warned that it would take time for air traffic operations to return to full capacity.

The Department of Homeland Security said there were no signs the outage was caused by a cyberattack.

The shutdown came on the same day the White House and Transportation Department sought another $30.1 billion (€27.3bn) from Congress to upgrade airports and air traffic control, including $10.1 billion for air traffic control modernisation.

The failure is the latest sign of strain on a US air traffic control system struggling with equipment and communications problems, controller shortages and aging infrastructure.

The only other nationwide ground stop since the 11 September attacks came in January 2023, when the FAA halted domestic departures for around 90 minutes.

Back Up Systems Under Strain

The Government Accountability Office reported in 2024 that the FAA had classified 51 of its 138 air traffic control systems as unsustainable and another 54 as potentially unsustainable.

An incident in September demonstrated how one communications failure could be compounded by another.

After error messages appeared on a telecommunications circuit serving a Philadelphia air traffic control facility, the FAA's contractor switched to a backup fiber-optic line.

A construction crew then accidentally severed that line in New Jersey, contributing to widespread disruption. About 9,500 US flights were delayed or cancelled that day.

US Congress approved $12.5 billion in July 2025 to modernise the country's ageing air traffic control infrastructure, including telecommunications and radar systems.

The administration said Friday that 68% of the FAA's legacy copper telecommunications network had been replaced with high-speed fiber..

In September, the Government Accountability Office (GAO) warned that the FAA lacked a reliable cost estimate and an integrated master schedule for its air traffic control modernisation program.

Instead, as of May, it had 11,389 separate project schedules that were not coordinated, raising the risk of repeated work at the same facilities, delays and cost overruns.

The FAA aims to complete the first phase of modernisation by December 2028.

However the GAO warned that inadequate planning increased the risk of delays, potentially leaving the agency dependent on outdated systems prone to failure for longer.