Mr. Cruz said the failure was caused by a “power surge” at a data center.
Efforts to address customers’ frustrations have been hampered, however, by the domino effect of Saturday’s cancellations. More passengers than normal are waiting to travel, meaning that those who were booked to fly on subsequent days have also been subjected to delays.
“It’s more than just simply saying we know you’ve got a booking and therefore we’re going to issue you with a boarding pass,” said Andrew Charlton, the managing director of the Aviation Advocacy consulting firm and a former chief legal officer at Qantas, the Australian airline.
And while British Airways said it was close to fixing its computer problems, many of its aircraft and crew were still in the wrong place throughout its extensive global network. Restoring that fine-tuned system after hundreds of flights were grounded is a lengthy task, which may require up to two weeks to complete, Mr. Charlton said.
The Situation on Monday
British Airways said it would operate a full schedule on Monday at Gatwick, and would run its full long-haul schedule from Heathrow. A “high proportion” of its short-haul flights will operate, it said.
The airline said it did not disclose individual statistics. But data compiled by the tracking website FlightAware showed that two dozen British Airways and over a hundred Iberia services were canceled worldwide on Monday. In all, FlightAware has tracked 580 British Airways flights that have been canceled since Saturday.
Heathrow, which had chaotic scenes over the weekend as stranded passengers waited to depart, continued to be congested, British Airways said. Passengers were asked to go to the airport, the airline’s largest hub, only if their departure was confirmed.
The airline also continued to provide assistance to customers, responding to hundreds of passengers on Twitter as well as over the phone and via its website.
It was also working on delivering missing baggage to passengers who arrived in London over the weekend, it said.
Spotlight on the C.E.O.
“We absolutely profusely apologize for that and we are absolutely committed to provide and abide by the compensation rules that are currently in place,” Mr. Cruz told Sky News television on Monday.
He promised an exhaustive investigation into the major disruption, but disputed allegations made by a trade union that the computer problems had a link to outsourcing.
The issues arose “around a local data center, which has been managed and fixed by local resources,” Mr. Cruz told Sky News. “All the parties involved around this particular event have not been involved with any type of outsourcing in any foreign country.”
Mr. Cruz, who led the low-cost airline Vueling until last year, has faced questions over his efforts to reduce personnel, and for scaling back or requesting payment for services like checked luggage and onboard dining, which British Airways had been offering free.
“Mr. Cruz is famous for pushing airlines to work incredibly hard with the resources they have,” Mr. Charlton, the aviation analyst, said. The risk with that, he said, “is that you’ve got very little in reserve, very little margin for error.”
How Much Will This Cost British Airways?
This is not the first time British Airways has faced similar issues — it struggled with technical problems as recently as September, leading to hourslong delays — and it is also by no means an outlier.
Last summer, Delta Air Lines canceled 1,000 flights in a single day after it suffered a technology failure. It later said that the failure had cost it $100 million in lost revenue, according to The Associated Press.
Though British Airways has canceled fewer flights than Delta did last year, it also faces costs from having to pay substantial compensation under European Union rules.
It is also likely to suffer an intangible cost to its image. Along with the publicity in the news media, disgruntled passengers have turned to social media to vent their frustration with the airline’s customer service, posting photographs of people standing in long lines and sleeping at airport terminals.