British Airways said a power supply issue was to blame for a global computer system failure which sowed confusion and chaos at London’s two biggest airports, with thousands of passengers queuing for hours and planes left stuck on runways. “We believe the root cause was a power supply issue and we have no evidence of any cyber attack,” Alex Cruz, Chairman and CEO of British Airways, said in a video message on Twitter. “We are extremely sorry for the huge inconvenience this is causing our customers and we understand how frustrating this must be especially for families hoping to get away on holiday,” he said.