LONDON • British Airways (BA) cancelled all its flights from London's two main airports for the rest of the day yesterday after a global computer system outage caused massive delays and left planes stuck on runways.
BA said there was no evidence the problem had been caused by a cyber attack, reported Reuters.
The airline earlier said terminals at Heathrow and Gatwick had become extremely congested because of the IT failure and all BA flights up to 5pm GMT (1am today, Singapore time) had been cancelled.
"Please do not come to the airports. We have experienced a major IT system failure that is causing very severe disruption to our flight operations worldwide," the airline said in a statement.
"We are extremely sorry for the inconvenience this is causing our customers and we are working to resolve the situation as quickly as possible."
The problems, which passengers said had affected flights across Britain, came on a particularly busy weekend with a public holiday tomorrow and many children starting their school half-term breaks.
Travellers said there were long delays at check-in desks as they were unable to check in or use the airline's app.
Mr Henry Tail, a 27-year-old teacher, told the Press Association news agency that the glitch forced him to miss his flight.
"When I went to go through security, I couldn't log in to my booking to get my code," he said. "This meant I couldn't go through security, and by the time I'd gone back and forth to various customer service desks, the flight had closed," he added.
Others reported flights being held on runways.
"Still on the tarmac at Leeds. #britishairways reckon Heathrow is so backed up we can't set off. No way we'll make our Vegas flight," passenger David Raine wrote on Twitter.
Another, journalist Martyn Kent, wrote: "Sat on plane at Heathrow for hour and a half now. @British-Airways Captain describes IT problem as 'catastrophic'."
One passenger said she was unable to buy refreshments on board, reported Agence France-Presse. "We are on the runway.. For hour now.. no offer of drinks.. and because ba only takes cards now, we only have cash...wat we supposed to do!!??," Twitter user Julie Adie wrote.
London's Heathrow Airport, one of the world's busiest, said it was working with BA. Delays were also reported in Rome, Prague, Milan, Stockholm and Malaga.
Passenger Roshni Burt, who was flying from Heathrow to Bahrain with her young son, said there was no news about when her flight would depart.
"When we left the check-in area, there were angry people, people getting frustrated that their flights were coming up or near to departure, people getting turned away," she told Sky News.
The airline has suffered previous IT glitches, with passengers hit by severe delays in July and September last year.
Last month, Germany's Lufthansa and Air France suffered a global system outage which prevented them from boarding passengers.
A check by The Sunday Times showed flights at Changi Airport were unaffected. Two BA flights to London last night, BA16 and BA12, took off on schedule. A BA check-in employee said staff would have to wait for more information from London to determine if flights would be affected today.