London's main airport, a major gateway for American travelers to Europe, expects disruption for days as a result of a fire at an electrical substation. At least 1,300 flights were affected.

London's Heathrow Airport resumed full operations on Saturday and ordered a probe into how it dealt with a power outage that shut Europe's busiest air hub for almost a day as airlines warned of further delays and cancellations.

A fire at a substation that supplies power to Heathrow forced its closure for most of Friday, leading to thousands of cancelled flights and stranding passengers across the world. While Heathrow said the airport in west London was "open and fully operational" on Saturday morning,