BERLIN, May 29 (Reuters) - British Airways said a power surge that collapsed its IT systems, leading to travel chaos for thousands of passengers over the weekend, was so strong that it also knocked out its back-up systems, making them ineffective. "Once the disruption is over, we will carry out an exhaustive investigation into what caused this incident, and take measures to ensure it never happens again," the airline's chief executive, Alex Cruz, said in a statement on Monday.
BA's operations were returning to normal on Monday and it said it would fly more than 95 percent of its normal flight schedule. Cruz added BA would fully honor passengers' compensation rights, as set out under EU regulations for delayed and canceled flights.
(Reporting by Victoria Bryan, ,editing by David Evans)