LONDON, United Kingdom (AFP) — United Kingdom (UK) air travellers faced more misery Wednesday with nearly 400 flights scrapped across the country, as Britain’s air traffic control service scrambled to recover from a technical glitch which it ruled out as a cyberattack.

After 1,746 flights were cancelled Tuesday following the outage, another 399 were axed Wednesday — the majority to and from London Heathrow, one of Europe’s busiest airports — according to aviation analytics firm Cirium.

More than 330,000 passengers were affected over the two days of disruption, with 155,000 seeing their flights cancelled while around 180,000 experienced delays, industry body Airlines UK said.

“We ended up sitting on our plane for just over five hours,” Matt Ernster, 28, who was returning to Boston via Heathrow from his honeymoon in Paris on Tuesday, told AFP.

When they were finally allowed to disembark from the plane, “it turned into a gigantic, chaotic scene”, Ernster said. The baggage collection “felt like an apocalyptic situation”, and there were no hotels available in a two-hour radius.

“It was the worst travel experience I’ve ever had.”

The head of the National Air Traffic Services (NATS), Martin Rolfe, said “we have at this point ruled out cyber” activity as a cause.

“We don’t believe it was a cyberattack,” he told BBC Radio.

Rolfe said NATS will be doing a “very, very thorough” investigation into what exactly caused the incident.

National carrier British Airways said it had to cancel nearly 550 flights — 200 of them Wednesday — due to the incident, which it said affected 85,000 of its customers.

This week’s travel chaos followed a technical glitch in July last year that saw scores of flights to and from the UK cancelled, prompting anger from airline chiefs.

Britain suffered its worst air systems failure in years in 2023, with more than 700,000 passengers affected after hundreds of flights were delayed or cancelled.

After holding talks with Rolfe Wednesday morning, Transport Secretary Heidi Alexander told MPs she did not believe the issue was “unavoidable”.

Alexander said she had ordered an independent review to establish the cause and “ensure that our air traffic control systems can get passengers to where they need to be”.

It will report within six months.

Rolfe told Sky News he accepted “full responsibility” but declined to say if he was considering quitting his job.

Neal McMahon, chief operations officer at Irish no-frills airline Ryanair, called Tuesday for Rolfe to be fired, accusing him of having “failed UK travellers”.

Caught up by the glitch, healthcare worker Josie Donoghue endured “an absolute nightmare” at London’s Gatwick airport, having had to disembark her flight to Ireland after three hours stuck on the runway.

“Getting through that airport was like trying to get out of Alcatraz,” she told Britain’s domestic Press Association news agency.

Susie Senahe, 55, who was travelling back to Accra in Ghana after visiting her daughter in the UK, had been rebooked onto a Friday flight.

She told AFP on Wednesday she was planning to sleep at the Heathrow terminal until then.

Another woman travelling to the United States, who did not want to be named, said she slept in the airport Tuesday night because nearby hotels were “fully booked”.

Impacted passengers are unlikely to be entitled to compensation because the outage was likely to be considered due to “extraordinary circumstances” under passenger rights rules, the aviation regulator has said.

Manchester, Birmingham and Edinburgh airports were also affected, primarily on Tuesday, while Dublin airport said it had cancelled dozens of flights.

Ryanair has said more than 65,000 of its passengers had been disrupted, with 50 of its flights cancelled, the majority on Tuesday.