The three-day strike begun Friday was the first by the airlines cabin crews in 13 years and disrupted travel for thousands of passengers, especially at England's Heathrow airport, the airline's main hub.
The strike, as of Saturday, had already cost the airline more than $37 million in canceled tickets and contingency costs, analysts told The Daily Telegraph.
British Airways said it hoped to keep flights operating for about 49,000 passengers Saturday and Sunday. It usually handles about 75,000 passengers during a normal weekend day.
"I am deeply sorry. This is a terrible day for BA," the airline's chief executive, Willie Walsh, said in a video message posted online.
Talks over cost-cutting collapsed Friday between the airline and Unite, the union that represents cabin crews. Unite has a second, four-day walkout planned to begin March 27.