British Airways says it is canceling all of its flights from London's Heathrow and Gatwick airports for the rest of the day because of a "major IT system failure." Passengers at Heathrow reported long lines at check-in counters and the failure of the airline's website and mobile app. British Airways has canceled all flights from London's Heathrow and Gatwick airports as a global IT failure causes severe disruption for travelers. Air travelers faced delays Saturday because of a worldwide computer systems failure at British Airways, the airline said. Passengers at Heathrow Airport reported long lines at check-in counters and flight delays.