Paul Ward
Journalist, BBC Scotland

A flight from New Orleans heading to Heathrow was diverted and touched down at Glasgow around 10:30 GMT. Passengers said they were told about an hour before landing that it had to divert.

For some, there was a scramble to rearrange travel.

Vanessa Connell and partner Simon spent almost £1,000 on flights from Glasgow to Gatwick.

She says: “We have a wedding tomorrow so we have to get back. We’ll hold on to the receipts.”

For others, the diversion made their onward journey easier.

Allan Strachan lives in Edinburgh so was pleased to be landing in Glasgow.

“It’s good for me but I feel sorry for all the people that have to rush to sort things out," he says.

Wesley Stephenson
BBC News data journalist

The closure of Heathrow Airport has impacted travel across the globe, with many flights due to land in London being diverted to other airports.

As you can see in this chart based on FlightRadar data, Amsterdam tops the list with seven flights diverted to its airport. That's followed by Frankfurt, Washington, London Gatwick, Shannon and Paris with six flights diverted to each airport. New York's JFK, Madrid, Manchester and Glasgow have each taken in five diverted flights.

Rich Preston
Reporting from Heathrow

Image source, Reuters

The ripple effects of today’s closure of Heathrow airport will be felt far and wide - and for several days to come.

Hotels and pubs around the airport have crowds of people sitting in their lobbies and at tables, surrounded by their luggage and looking despondently at their phones, desperate for any kind of good news.

I’ve spoken to groups who were supposed to be going on holiday, to weddings, to business meetings.

Some are trying to get home to see family, or are on the last leg of a big trip. Heathrow was the airport with the most international connections in the world in 2024, according to industry travel data provider OAG, so many of these people won’t have even been visiting the UK but are merely passing through as they travel between Asia, Europe, and America.

But as well as people passengers, it’s important to remember cargo.

Heathrow is a major cargo hub - last year it served 234 destinations handling more than £190bn worth of goods. In 2023, 48% of all UK air cargo travelled through Heathrow, according to the airport itself - handling everything from medicines, fresh fruit and veg, books, tech items, fresh flowers - and even live animals.

Even when the airport does get its power back, it will take days before any semblance of normality is resumed with a huge backlog of both goods and people waiting their turn to get through Heathrow.

Heathrow Airport is going to be closed all day because of a fire at an electricity substation which caused a power cut - and travellers are being warned there'll be significant disruption over the next few days.

Here's what you need to know:

As we continue to update you with the latest developments on Heathrow Airport's closure due to a nearby substation fire, we've lined up several experts to answer your questions on what has been called an "unprecedented event".

You can follow along from 12:30 by pressing Watch live at the top of the page.

As a reminder, you can get in touch with us via Your Voice, Your BBC News.

Daniel Sandford
Home Affairs correspondent

The impact of the electricity substation fire near Heathrow has had a devastating impact on a key part of our national infrastructure - the kind of impact that terrorist groups and hostile states would like to have.

At the moment it looks like a fault, but what if it was deliberately started? That question needs to be ruled out urgently.

That is why counter-terrorism detectives are leading the investigation into the cause of the fire. They have specialist forensic skills and can look for any evidence of an explosion or other deliberate act.

Also if at any stage foul play is suspected counter-terrorism detectives will want to have been involved from the start.

If foul play remains ruled out, there is another urgent question: How many other key parts of our national infrastructure do not have a backup electricity supply?

Jonathan Josephs
BBC business reporter

The International Air Transport Association (Iata), says today’s closure of London Heathrow is "yet another case of Heathrow letting down both travellers and airlines".

The director general of the airline trade body Willie Walsh - a former pilot and CEO of British Airway’s parent company IAG - says "it begs some serious questions" about how an internationally important piece of infrastructure can be totally dependent on a single power source.

In a statement he also suggests it is unfair that his members, which are 340 airlines that account for over 80% of global air traffic, will have to pick up the bill for taking care of passengers for an event that is not their fault.

He says that without finding a "fairer allocation of passenger care costs", Heathrow has "very little incentive to improve".

Marta Newman
BBC News at One producer

Image source, EPA

As passengers wonder about their rights in regards to cancelled flights, I've just spoken to Graeme Buck, the Director of Communications at travel trade association ABTA.

He says that if a passenger's flight is cancelled they must be offered the choice of a replacement journey, or a refund.

"That flight should be as soon as possible," he explains. "If you find you have to stay overnight somewhere or you incur extra costs travelling to different airports to get back to Heathrow then you should be compensated for that as well."

If you've booked a package holiday, you may also have additional rights under the package holiday travel regulations, he adds.

Tom Edwards
BBC London Transport Correspondent, reporting from Heathrow airport

Image source, Getty Images

A line of trolleys blocks anyone from getting into the terminals at Heathrow Airport, while there are lots of staff around and a handful of passengers looking at their phones wondering what to do.

I'm inside Heathrow airport, not far from Terminal 3, and it's absolutely deserted as the terminals are locked down.

One couple I met was due to fly to Vietnam and they have had to head home. Another was furious at the lack of information.

This will be an absolute calamity for a lot of passengers and there are bound to be questions about the airport's resilience, and how a fire at a substation can effectively knock out one of the world's busiest airports.

Sources from within aviation have expressed their anger at what has happened. They want to know why there was no back up.

They say Heathrow is an international “laughing stock” and the lack of preparedness is “shocking”.

There is no indication the fire was caused by foul play, the Met Police says in a statement, but adds it is keeping an open mind at this time.

A spokesperson for the force says: “We are working with the London Fire Brigade to establish the cause of the fire which remains under investigation. While there is currently no indication of foul play we retain an open mind at this time.

“Given the location of the substation and the impact this incident has had on critical national infrastructure, the Met’s Counter Terrorism Command is now leading enquiries.

“This is due to the specialist resources and capabilities within that command that can assist in progressing this investigation at pace to minimise disruption and identify the cause."

Danny Aeberhard
Europe regional editor, BBC World Service

So far, the level of knock-on disruption to other European airports, caused by the closure of Heathrow, has been relatively limited.

Apart from cancellations of scheduled flights to and from Heathrow itself, some European airports have seen Heathrow-bound flights diverted. They include the following:

• Five such services landed at Charles de Gaulle Airport in Paris, one of the busiest hubs in Europe after Heathrow. Two had come from Singapore - a Qantas and a Singapore Airlines flight. The others were a Qantas flight from Perth in Australia, an Emirates one from Dubai and a RwandAir one from Kigali
• Seven flights have had to be diverted to Schiphol Airport in Amsterdam. They are Delta flights from Detroit, Boston, and Atlanta in the US, two Cathay Pacific flights from Hong Kong, a British Airways flight from Riyadh, and a Malaysia Airlines flight from Kuala Lumpur
• Frankfurt has seen six diverted planes land. These were a Singapore Airlines service from Singapore, an Air India flight from Delhi, a Gulf Air flight from Bahrain, an Etihad flight from Abu Dhabi and two services from Doha - one a Qatar Airways service, and the other a British Airways one

Meanwhile, Europe's most westerly international airport, Shannon in Ireland, has seen six diverted transatlantic flights land. They are flights from Atlanta, Boston, Orlando and Newark in the US, Toronto in Canada and one from the capital of Barbados, Bridgetown.

Image source, Getty Images

Prime Minister Keir Starmer has just posted an update on social media about the fire at the substation near Heathrow Airport.

"I know the situation in Heathrow is causing distress and disruption, especially for those travelling or without power in their homes," he says.

"I'm receiving regular updates and I'm in close contact with partners on the ground. Thanks to our emergency workers for keeping people safe."

Tom Finn
Visual Journalism Team

At 08:00 UTC on a normal Friday, there would usually be about 200 flights in the air headed for Heathrow.

Here’s a snapshot of air traffic that was bound for Heathrow a week ago at 08:00 UTC on Friday, 14 March.

And here’s traffic at the same time this morning as flights were grounded or diverted to other airports.

Why is Heathrow closed?

A fire at the North Hyde electrical substation in Hayes, west London, knocked out the power supply to Heathrow and other businesses and homes in the surrounding area.

The cause of the fire is not yet known, but emergency services were first called to the scene at 23:23 GMT on Thursday.

Energy Secretary Ed Miliband told the BBC the fire appeared to have knocked out a backup generator as well.

How long will the airport be closed?

Heathrow has said it doesn't "have clarity on when power may be reliably restored", and that it will be closed until 23:59 tonight.

“We will provide an update when more information on the resumption of operations is available," it says, also warning that travellers can expect "significant disruption over the coming days".

Are Gatwick flights cancelled?

No, London Gatwick says it is operating as normal - but some flights originally bound for Heathrow have been diverted to Gatwick.

Our experts will be answering more of your questions at 12:30 GMT live in this page, and you can also get in touch with us here.

Daniel Sandford
Home Affairs correspondent

The BBC understands that counter-terrorism officers from the Metropolitan Police will be involved in the investigation into a fire at a electricity substation near Heathrow.

This is not because of any direct evidence of sabotage, but because of their skills and the need to quickly rule out foul play.

Their involvement was described by a source as "belt and braces" and a "precautionary measure".

Jonathan Smith from the London Fire Brigade is asked about media reports that the Metropolitan Police's counter-terrorism unit is investigating the fire.

The Times reports, external that detectives are being deployed as a precautionary measure rather than an indication of foul play.

The BBC has contacted Met Police for comment.

Smith says the London Fire Brigade is unable to comment on the Met's investigations. However, he says that the Met Police are investigating the nature of the fire with support from the fire brigade.

Smith goes on to say that 29 people from neighbouring properties were evacuated over the fire, adding that around 150 people in total were evacuated to a rest centre.

He says the fire brigade will continue to have a presence in the area throughout the day.

Fire safety and fire investigation officers are working with the Met Police to establish the nature of the fire, he adds.

There remains no power at Terminal 2 or Terminal 4 at Heathrow Airport, Smith says.

We're now hearing from the London Fire Brigade, as deputy commissioner Jonathan Smith addresses reporters with an update on the fire at the electricity substation near Heathrow Airport.

The fire involved a transformer comprising 25,000 litres of cooling oil that was fully alight. 10% is still alight, he says.

Met Police declared it a major incident, he adds, saying that firefighters worked under challenging conditions.

Press watch live above to follow along. We'll bring you more updates shortly.

Several schools in Hayes are closed today due to the fire at the North Hyde Electricity Substation, according to a statement from Hillingdon Council.

The schools that will be closed throughout the day are:

• Nestles Avenue Early Years Centre
• Pinkwell Children's Centre
• Pinkwell Primary School
• Botwell House Catholic Primary School
• Dr Triplett's C of E Primary School
• The Global Academy