Rob Corp
Live reporter

The first overnight flights usually begin landing at Heathrow at around 04:30 GMT - but with the airport closed those jets are now diverting to other cities.

Some early arrivals have landed at London Gatwick to the south of the capital, but that is the UK’s second busiest airport and its own morning rush is about to begin so capacity there could be an issue.

Looking at tracking site FlightRadar24 I can see some Heathrow inbounds are now diverting to airports on the continent.

Two flights from Doha and Bahrain in the Gulf have just landed at Frankfurt while a Cathay Pacific service from Hong Kong has diverted to Amsterdam.

Some passengers may be slightly better off if their aircraft diverts to Manchester - as has an early British Airways service from Nairobi in Kenya.

But the more diversions the greater the knock-on effects as airlines see their aircraft and crews scattered across Europe.

Koh Ewe
Live page reporter, Singapore

British Airways, whose main hub is Heathrow, has echoed the advice of the airport for customer not to travel until further notice.

It said the outage "will clearly have a significant impact on our operation and our customers".

"We’re working as quickly as possible to update them on their travel options for the next 24 hours and beyond," it said in a statement.

"Where possible, we’re redirecting inbound flights already on their way to Heathrow to other UK airports."

Image source, PA Media

A little bit more about the major fire at the substation which has caused the issues.

More than 16,300 homes have lost power in a large-scale outage cause, energy supplier Scottish and Southern Electricity Networks said on X.

It has appealed to anyone who is medically dependent on electricity and who needs help to get in touch with the power company.

We do not have any official figures on how many flights to and from Heathrow are going to be cancelled today, but flight tracker FlightRadar24 estimates it could be at least 1,351.

"That doesn’t include any flights that might be cancelled or delayed due to aircraft being out of position," the tracker added.

It is understood least 120 flights in the air bound for Heathrow will have to divert due to the airport closure.

Heathrow is the UK's largest airport, handling around 1,300 landings and take-offs each day. A record 83.9 million passengers passed through its terminals last year.

Thomas Mackintosh
Live reporter

I am among a few bleary-eyed Scots who attended the match against Greece a few hours ago but were up before sunrise for a flight to Heathrow.

We had cleared passport control and security in good time and as we were queuing for some breakfast a staff member shouted, "all flights to Heathrow cancelled". A glance at the departure board confirmed that was the case.

When we asked why, we were told all flights to Heathrow today will be cancelled due to a fire. We were then huddled among 50 other passengers and walked back through passport control to re-enter Greece.

Plenty of passengers around us were planning on getting a connecting flight up to Edinburgh, Glasgow or Aberdeen. They've been looking at re-booking via other European cities for who knows how much cost at this last minute.

But it does give an idea of the knock-on impact to people's travel plans. Staff at Athens have been very helpful, they've given us vouchers and clear directions. Systems are being updated so for now - like many others - we wait.

João da Silva
Business reporter in Singapore

Australia's flagship Qantas airline has told BBC News that it is "closely monitoring" the situation at London Heathrow.

Its QF9 Perth-London flight which is currently in the air is being diverted to Paris. Flight QF1 which has departed from Singapore will also be diverted from London to the French capital.

Two other flights scheduled to depart London today, QF2 and QF10, are likely to be affected, according to the airline.

Qantas says it will be reaching out directly to its customers whose flights have been affected.

Peter Hoskins
Business reporter, BBC News Singapore

Image source, Getty Images

Some details on flight cancellations are starting to emerge.

US-based carrier United Airlines told the BBC that "following the closure, seven United flights returned to their origin or to other airports".

"Friday flights to London Heathrow are being cancelled," a spokesperson added.

They also said the airline is working with its customers to offer alternative travel options.

Here is some footage filmed at the substation near Heathrow Airport. As we have already mentioned, it is not yet known what caused the fire.

This fire at the substation this morning happened about a mile and a half north of Heathrow Airport in the town of Hayes.

According to the London Fire Brigade, half of a transformer within the substation remains alight, with ten fire engines and at least 70 firefighters having been called out to the fire.

"This will be a prolonged incident, with crews remaining on scene throughout the night," said Assistant Commissioner Pat Goulbourne.

"The fire has caused a power outage affecting a large number of homes and local businesses, and we are working closely with our partners to minimise disruption."

The cause of the fire is not known at this time.

We are starting to get some reaction through from other airports and airlines about how they are reacting to the closure.

A short time ago the BBC News received this statement through from Gatwick Airport:

"We are aware of the situation at Heathrow Airport today and stand ready to support as required. Flights are operating from London Gatwick as normal today."

Here is the full statement from Heathrow Airport, posted to its social media a short time ago:

"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."

A fire has broken out at a west London substation, leading to a power outage that has left Heathrow airport without electricity.

That means Heathrow - the UK's largest airport - will be shut down until midnight on Friday, likely impacting hundreds of flights and thousands of passengers.

A spokesperson has said there is "no clarity on when power may be reliably restored", adding that staff were "working as hard as possible to resolve the situation".

The fire in Hayes has also left thousands of homes without power and caused around 150 people to be evacuated from surrounding properties.

Welcome to our coverage of an incident which has resulted in Heathrow Airport closing all day.

In a statement, the airport said it is experiencing a "significant power outage" because of the fire.

"To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23:59 on 21 March," it said.

"Passengers are advised not to travel to the airport and should contact their airline for further information. We apologise for the inconvenience."

Stay with us for what is likely to be a day of major travel disruption.