At least 1,350 flights to and from Heathrow were affected, flight tracking service FlightRadar 24 said, and the impact was likely to last several days as passengers try to reschedule their travel and airlines work to get planes and crew to the right places.
Residents in west London described hearing a large explosion, followed by a fireball and clouds of smoke, when the blaze ripped through the electrical substation near the airport.
Some 120 flights were in the air when the closure was announced, with some turned around and others diverted to Gatwick Airport outside London, Charles de Gaulle Airport near Paris or Ireland’s Shannon Airport, tracking services showed.
Lawrence Hayes was three-quarters of the way to London from New York when Virgin Atlantic announced they were being diverted to Glasgow.
“It was a red-eye flight and I’d already had a full day, so I don’t even know how long I’ve been up for,” Hayes told the BBC as he was getting off the plane in Scotland. "Luckily I managed to get hold of my wife and she’s kindly booked me a train ticket to get back to Euston, but it’s going to be an incredibly long day.”
Heathrow is one of the world's busiest airports for international travel. It had its busiest January on record earlier this year, with more than 6.3 million passengers, up more than 5% from the same period last year.
It was too early to determine what sparked the huge blaze about 2 miles from the airport, but there’s “no suggestion” of foul play, Energy Secretary Ed Miliband said.
The London Fire Brigade was leading the investigation with help from the Metropolitan Police, officials said.
Miliband said the fire, which took seven hours to control, also knocked out a backup power supply to the airport. Heathrow said in a statement that it had no choice but to close the airport for the day.
“We expect significant disruption over the coming days, and passengers should not travel to the airport under any circumstances until the airport reopens," the airport said.
