British Airways canceled all flights out of London's two largest airports Saturday—the first day of a spring bank holiday weekend in Britain—affecting tens of thousands of travelers. The problem stems from British Airway's IT system, the entirety of which apparently crashed worldwide, the AP reports. According to CNN, the airline says it doesn't appear to have been a cyberattack, but rather a "power supply issue." An aviation expert tells the BBC that British Airways "can't do anything at all." That includes having planes take off, moving baggage, and issuing credentials to passengers. The problem affected call centers, the British Airways website, and its mobile app. While British Airways hopes to have some flights in the air Sunday, the problem could persist for days, one expert says.
On a normal day, British Airways has hundreds of flights out of Heathrow and Gatwick. On Saturday, travelers described chaos at the airports. One such traveler at Heathrow called it one of "most turbulent, badly organized days that I've ever experienced in Britain." With planes unable to take off and blocking gates, passengers on flights arriving at the airports were unable to disembark. Some waited on their planes for four hours only to get off and learn they had no idea where their luggage was. British Airways eventually told passengers to stop coming to the airport. Those affected will be offered a rescheduled flight or refund.