British Airways Looks to Resume Flights After Lost Day in London

British Airways said it will try to operate most of its scheduled departures from London on Sunday, after a computer system failure paralyzed its operations at the start of a three-day holiday weekend in the U.K, according to Bloomberg.

The carrier scrapped all Saturday departures from Heathrow and Gatwick airports, after originally halting services from late morning until 6 p.m., following what it called a “very severe disruption“ worldwide. It ordered passengers to leave the terminals and urged other travelers to stay home.

The airline is looking to operate the majority of its Heathrow departures on Sunday and “a near normal schedule“ from Gatwick, although aircraft and crews are out of position and have to be relocated during the night, it said in a website posting late Saturday.

“We are extremely sorry for the huge inconvenience this is causing our customers, and we understand how frustrating this must be,“ British Airways Chief Executive Officer Alex Cruz said in a video message filmed at the carrier’s operations center near Heathrow.

“We believe the root cause was a power supply issue, and we have no evidence of any cyber attack,“ Cruz said.

Long-haul flights into London are expected to arrive as scheduled on Sunday, British Airways said in an emailed statement. The breakdown, which also affected call centers, prevented passengers from rebooking or from retrieving luggage that had already been loaded onto their planes.

Travelers took to Twitter from late morning in Europe to complain of flight postponements, long lines to check in, and waiting for long periods on the tarmac after boarding planes. Once services were canceled, passengers from grounded planes or at gates at Heathrow endured large crowds at passport control desks to re-enter the country. British Airways staff told customers to find hotels on their own for reimbursement later by the airline. Payments will include 200 pounds ($260) per night for lodging, 50 pounds round trip between the airport and the hotel, and as much as 25 pounds for refreshments, according to leaflets from the company.

“I would estimate, given the timing of the bank holiday weekend, that this has affected a hundred flights and a thousand passengers already,“ said John Strickland, director of aviation at analysts JLS Consulting, “Considering the reimbursements for canceled flights and the costs of lodging stranded passengers, this will have an impact on revenue and the magnitude of the cost will depend on how long the outage lasts and how long it takes to resolve.“

The disruption coincides with the start of the annual end-of-May Bank Holiday weekend in the U.K., as well as the three-day Memorial Day weekend regarded as the unofficial start of summer in the U.S.

Last September, a computer network failure brought down British Airways’ check-in system, causing worldwide service delays, while earlier this week, London Gatwick airport reported problems with its baggage-sorting system.

Spokeswomen for Heathrow and Gatwick airports, London’s largest and busiest, were unable to provide information on how many flights had been canceled. A spokeswoman for British Airways declined to comment on the number of services or passengers involved.

Some of the affected computer systems are back up, the airline said late Saturday.

British Airways is a unit of International Consolidated Airlines Group SA. No widespread delays were reported at the company’s Spanish division, Iberia, or at its Irish brand Aer Lingus.