LONDON—Hundreds of flights to and from London’s Heathrow Airport were canceled on Friday after a fire at a nearby substation knocked out power to Europe’s busiest airport, disrupting travel plans for hundreds of thousands of people around the world.
After a day of chaos, Heathrow began reopening in the evening, with the first plane of the day landing at about 6 p.m. local time. That was just the start of what is expected to be a dayslong process of getting stranded passengers to their destinations and displaced aircraft into the proper locations.
