British Airways said its flights were returning to normal after passengers had to endure cancellations, delays and long lines at London airports as the airline suffered its third major computer failure in a little more than two years.

Wednesday's woes are the latest in a string of problems at BA, which was fined $230 million last month for a huge customer data breach and is bracing for potential strikes in a pay dispute with its pilots.

BA, owned by International Airlines Group, apologized to customers for Wednesday's disruption and warned it would take time for operations to return to normal.