Major airlines have restored some operations after grounding flights across the US, citing communication issues caused by a global IT outage.
The outage – which has also affected banks and emergency services around the world – has been caused by a faulty software update from cybersecurity firm Crowdstrike.
Delta Airlines, which is the world’s second biggest carrier by passenger numbers, had paused all of its flights but later said some had resumed. American Airlines also grounded its flights earlier but has resumed service.
Crowdstrike has apologised and said that the issue “has been identified, isolated and a fix has been deployed”. It is not currently known when the issue will be resolved.
Nearly 28,000 flights have been delayed and more than 3,000 have been cancelled, according to FlightAware.
American Airlines and Delta have told passengers they would be issuing travel waivers for the disrupted services.
Around the world, thousands of travellers have been affected. US tourist Stephanie Thompson was unable to board her flight back to Dallas following a holiday in the UK.
“We couldn’t get an answer from anybody,” she said, speaking from Edinburgh Airport. “I was on hold with American (Airlines) for about an hour and 10 minutes before I finally hung up.
“We just paid $6,800 (£5,260) for a one-way trip home, hopefully leaving tonight. I didn’t know what else to do. I just wanted something to get us home.”
A spokeswoman for Los Angeles International Airport told the BBC that “some flights are taking off and landing”, indicating that the issue is primarily affecting airlines rather than airports.
United Airlines has also been affected by the tech outage, along with a number of smaller carriers.
The first indication of the Crowdstrike issue affecting US airlines emerged late on Thursday, when US airline Frontier said a major “technical outage” had affected its operations.
Commenting on that development, US Secretary of Transportation Pete Buttigieg said his department was “monitoring technical issues” at Frontier that were “leading to cancellations and delays across their network.”
The disruptions affected more than airports, with hospitals also reporting outages.
The New York-based Kaleida Health network, which runs five hospitals in the Buffalo area, said on Friday morning that its systems were momentarily down.
At Mass Brigham General hospitals, in Boston, Massachusetts, all appointments considered non-urgent were cancelled on Friday due to the outage.
The widespread IT outage disrupted air travel far beyond the US.
Japan’s Narita airport, around 60km (37miles) from Tokyo, says airlines JetStar, Jeju Air, Qantas, HK Express and Spring Japan are having issues with their systems.
And in India, Delhi airport says some services have been temporarily impacted.
Amsterdam’s Schiphol airport is one of the latest to report delays caused by the IT outage.
“The outage has an impact on flights flying from and to Schiphol,” a spokesperson said, adding that it was not yet clear how many flights had been affected.