LONDON, March 22 — Some flights began to land at London’s Heathrow Airport late on Friday after a fire at a power station grounded planes at Europe’s busiest air hub, causing travel chaos for thousands of people around the world.

The electricity substation fire shut down the airport for most of the day, leading to the cancellation or diversion of hundreds of flights and raising questions about the infrastructure’s vulnerability.

An AFP journalist saw planes landing on the tarmac at Heathrow late on Friday, while British Airways said it had received clearance to depart eight long-haul flights from 1900 GMT to cities including Johannesburg, Singapore and Riyadh.

Earlier, an airport spokesperson said “some flights” could begin taking off and that the first would be “repatriation flights and relocating aircraft”.

Restrictions on overnight flights have also been temporarily lifted to help ease congestion, according to the UK’s transport department.