Weary travellers braced for more flight disruptions on Saturday as service resumed at US airports after an hours-long stoppage that the Trump administration blamed on a botched replacement of old copper wire communication lines.

Friday's nationwide ground stop — meaning no planes could take off — sparked widespread chaos and left hundreds of thousands of passengers in limbo, with some pulled off planes moments before they were due to depart by airline staff who appeared in the dark about unfolding events.

"Tired. Exhausted. Frustrated. Yeah, you know, it's just a mess, right?" Lisa Beraid, 48, who works for an insurance company, told AFP as she waited for a flight Saturday morning at New York's La Guardia airport.

Federal Aviation Administration (FAA) chief Bryan Bedford said that 12,000 flights were cancelled on Friday and between four and five thousand flights out of 41,000 scheduled for Saturday were likely to be cancelled as well.

By early afternoon, tracking website FlightAware had recorded at least 5,000 cancelled flights for Saturday.

Speaking at a news conference in Washington, Bedford offered a "sincere apology to the American travelling public."

He predicted a full resumption of flight schedules by "close of business on Sunday."

US Transportation Secretary Sean Duffy said Friday's four-hour ground stop was declared after maintenance work to upgrade an old copper wire to a high-speed fibre cable had caused "issues" with communication with airplanes and radar feeds.

"Either through contractor error or a faulty piece of equipment...it started flooding other routers in our air traffic control system," Duffy told reporters.

In another embarrassment, Saturday's news conference — where administration officials also appealed for more funds to upgrade outdated systems — was delayed due to technical problems with the audio feed.

Friday's disruption was only the second time such a ground stoppage had been issued in US airspace — which is among the busiest in the world — since the 9/11 attacks.

The nationwide halt was lifted at 8.15pm Eastern Time.

During the outage, footage from airports showed gates full, with planes waiting on taxiways and passengers thronging concourses, desperate for information.

FAA officials reopened the airspace "after restoring full functionality" at air traffic control facilities, according to Duffy.

Early on Saturday, he sought to assure Americans it remains safe to fly but warned it would take time to resume normal service.

Tim Johnson, consumer director at the UK Civil Aviation Authority, said although US flights have resumed, there could be "some follow-on disruption" as airlines re-book passengers and get all services back to normal.

The ground stop not only plunged US air travel into chaos — it also raised serious concerns about the country's ageing infrastructure.

Duffy appealed for US$50 billion in funds to upgrade and modernize the air traffic control system, and called for Congress, which controls the purse-strings of the US government, to "meet this moment."

"Cut the crap," retorted Illinois state governor and prominent Democrat, JB Pritzker, on X.

"Trump and Republicans have controlled Congress and could have funded the system."

New York state Governor Kathy Hochul called on Duffy to resign or be fired by Trump, writing on X: "We're fortunate no lives were lost."

US lawmakers called for investigations into what caused the massive disruption and whether the country is adequately secure from cyber criminality.

"If today proves anything, it's that we need to update our air traffic control system & rebuild our airport infrastructure," Republican Senator Eric Schmitt said on X.

US President Donald Trump was uncharacteristically quiet about the outage that had knock-on effects for international flights to and from the United States. (AFP)





Edited by Tony Sabine