Heathrow fire: Counter terrorism leads investigation into cause of fire that led to closure of major airport

Flights in their thousands have been affected after a fire at Heathrow Airport.

More than 200,000 air passengers have had their flights to or from Heathrow cancelled because the airport is closed on Friday

Read more here: Flights cancelled at Scottish airports as British Airways departures hit

The fire

A transformer within the North Hyde electrical substation caught fire in west London .

The airport, which is supplied by the substation, said it was among those impacted by the power outage.

Thousands of homes have been left without power and more than 100 people were evacuated

Read more here: Eerie footage shows Heathrow Airport plunged into darkness after sub-station blaze amid full day closure

Counter terrorism investigation

The Metropolitan Police's Counter Terrorism Command is leading the investigation into the cause of the fire at an electrical substation the force said.

The scene at Edinburgh airport after the closure of Heathrow has thrown the country into travel chaos, March 21 2025. | Katielee Arrowsmith / SWNS

Delayed flights

Passengers are being warned to expect disruption for several days, and many planes and flight crews are in the wrong location.

Online flight tracking service Flightradar24 said the closure would affect more than 1,350 flights to and from Heathrow on Friday. This includes 679 scheduled to land and 678 due to take off from the airport.

It said 120 flights to the airport were in the air when the closure was announced.

Online tracking services showed flights being diverted to Gatwick , Charles de Gaulle Airport in Paris and Ireland's Shannon Airport .

A number of flights were also turned around and returned to airports in Canada and the United States .

Gatwick Airport accepted seven diverted flights from locations including Singapore , Johannesburg , Lagos , Cape Town and Doha which were originally destined for Heathrow .

Heathrow is the UK's largest airport, with more than 83.9 million passengers travelling through its terminals in 2024.

This is believed to be the worse disruption at Heathrow since December 18-23 2010 , when thousands of Christmas getaway passengers camped in the terminals because of widespread cancellations caused by snow

A fire in a transformer in Nestles Avenue, Hayes, west London, which means Heathrow will be closed all day on Friday, March 21. Picture courtesy of London Fire Brigade

Read more here: Can I claim compensation for cancelled flights at Edinburgh, Glasgow airports? Scotland advice

Heathrow comment

A Heathrow spokesperson said: " Heathrow is experiencing a significant power outage across the airport due to a large fire at a nearby electrical substation. Whilst fire crews are responding to the incident, we do not have clarity on when power may be reliably restored.

"To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 23h59 on 21 March 2025 . We expect significant disruption over the coming days and passengers should not travel to the airport under any circumstances until the airport reopens.

"We will provide an update when more information on the resumption of operations is available. We know this will be disappointing for passengers and we want to reassure that we are working as hard as possible to resolve the situation."

Energy Secretary Ed Miliband said the fire "appears to have knocked out a back-up generator as well as the substation itself".

He told Radio 4's Today programme this morning: "It's too early to say what caused this but I think obviously we will have to look hard at the causes and also the protection and the resilience that is in place for major institutions like Heathrow ."

The Counter Terrorism was announced this afternoon.