Your Voice, Your BBC News
Perisha Kudhail

Alex Money from Oxford was due to land in London today.

Instead his flight was rediverted from Cape Town to Barcelona, where he has just stepped off the plane after being on the tarmac for over two hours.

“It’s my birthday today. Not how I imagined spending it”, he says

Despite the change of plans, Alex says the full flight still seemed “remarkably good humoured despite the situation.”

He’s now waiting at the terminal in Barcelona for his bags and hoping for the best.

While passengers have been left frustrated by cancelled flights, we've also been hearing from residents who had to evacuate their homes in Hayes as a result of the fire.

Katrina Clements tells BBC Radio London how she and her husband were asleep when they heard knocking at the door and were told to leave their home.

Once she'd left, Katrina says she saw "a lot of people on the road" who had some from nearby to look at the fire.

"We just want to go home," she says.

Since evacuating, the Hayes resident adds that she's had little communication from authorities, though she says the council have tried to source hotel rooms for the night.

As we've been reporting, at least 1,351 flights to and from Heathrow Airport could be cancelled today, according to flight tracking website Flightradar24.

No flights are landing at Heathrow and planes that are already on the way there are being diverted to other airports, or back to their origin.

The video below compares today's air traffic in the vicinity of Heathrow to yesterday's.

As we've been reporting, the London Fire Brigade has said the fire at the North Hyde Electricity Substation in west London is now "under control".

They are expected to remain on the scene throughout the day to assist the National Grid in assessing the site.

Let's take a look at what we know, and don't know, so far:

• The London Fire Brigade received the first report about the fire at 23:23 GMT
• It sent 10 fire engines and around 70 firefighters to respond to a burning transformer within the substation
• Firefighters safely evacuated 29 people from neighbouring properties and a further 150 people were evacuated as a precaution
• More than 4,900 homes have been left without power
• There have been no reports of any injuries and the fire was under control by 06:28 GMT
• It's still unclear what caused the fire - Energy Secretary Ed Miliband described it earlier as an "unprecedented event"

Image source, UK Pool

Image source, PA Media

We've referred a lot this morning to a substation that caught fire in Hayes. Here's a bit more information about what that is.

Substations play an important part in the UK’s national electricity grid.

There are two types: transmission substations and distribution substations.

Transmission substations handle high-voltage electricity transmission over long distances, while distribution substations bring down the voltage for local distribution to homes and businesses.

Increasing and lowering the voltage of electricity for these purposes is one of the main roles of substations - and the process is done via a piece of equipment called a transformer.

According to the London Fire Brigade, a transformer within the electrical substation in Hayes caught fire.

Image source, Getty Images

Frustrated passengers might ask this morning why there was no backup plan at Heathrow in case the airport's usual power source failed.

Aviation expert John Strickland tells BBC 5Live that there are backup systems in place for key systems, but stresses the scale of the challenge of keeping an airport moving.

"There are just so many systems at an airport used by so many different players, not only the airport itself and the airlines, but handling agents, engineering companies, catering companies, you name it", he says.

"You could be talking about anything from switching on lights in a toilet to the far more serious stuff" he adds, citing "air traffic control functioning, aircraft manoeuvring around airports [and] baggage being loaded"

Despite this, Strickland suggests that the airport could "theoretically" do the minimum of landing an aircraft safely on its emergency systems.

And, he says the question about backup will be "the biggest topic of discussion once the dust settles".

More now from travel journalist Simon Calder, who has been speaking to BBC News.

He says the disruption at Heathrow "shows up once again how little slack there is in the system".

"This just points out the sheer lack of resilience. The one reason that there are people in Amsterdam, in Lyon in southern France, in Iceland right now is because there isn't enough room in south-east England to divert those planes," he says.

"The natural diversion airport would be London Gatwick," he says, adding that airport did take flights but then had to say "sorry, we're full, we are the busiest single-runway airport in the world".

Sean Dilley
Transport correspondent, reporting from Heathrow airport

We are as close to Heathrow Terminal 2 as we are allowed to be.

Some passengers have not taken advice that they should not turn up and not attempt to travel from Heathrow.

They’re being turned away on the bridge that leads to the closed airport

The skies are silent, the air traffic is nearly zero. About 10 minutes ago, two circling helicopters were seen and heard gathering pictures for the media, as the world watches the spectacle of an empty Heathrow Airport.

The last time I remember Heathrow being closed fully was in 2010.

Image source, Getty Images

The fire at a substation that has caused a massive blackout at Heathrow Airport has been brought under control - and aerial footage shows thick smoke billowing from it.

Fire crews can be seen working nearby, and planes can be seen parked at the airport.

Michael Race
Business reporter

With Heathrow being such a busy and important airport for passenger journeys and global trade, questions are being asked whether it has back-up systems in the event of power cuts.

The BBC understands that Heathrow does have back up power for its key systems, but kickstarting these alternative power supplies for the whole airport takes time.

A source says it isn’t possible to switch the power back on immediately.

And even once the power is back one, there are countless systems which need to be rebooted and checked to ensure they are working properly and are stable.

Your Voice, Your BBC News

Have your flights been cancelled, diverted or delayed due to the Heathrow Airport disruption? Or have you been evacuated from your home in west London after the fire at the Hayes electrical substation?

If so, you can get in touch via Your Voice, Your BBC News.

Send us your story at www.bbc.co.uk/yourvoice, email bbcyourvoice@bbc.co.uk or WhatsApp +44 7756 165803.

John Campbell
BBC News NI economics and business editor

Image source, PA Media

The flight path between Heathrow and Dublin is one of the busiest international routes in Europe - 34 flights, 17 in each direction, were scheduled for Friday.

Graeme McQueen from Dublin Airport Authority told broadcaster RTE there were a lot of passengers at the airport early this morning who were unaware of the disruption and are trying to rebook flights.

He added that passengers due to fly to Heathrow over the weekend should be prepared for potential further cancellations.

In total around 70 flights to and from the island of Ireland could be cancelled on Friday.

Shannon Airport in the west of Ireland has said it has facilitated several diverted flights originally scheduled to land at Heathrow on Friday morning, including flights from Toronto, Atlanta, Bridgetown Barbados, Boston, Orlando and Newark.

Sarah Fowler
Live reporter

Like thousands of passengers today, my travel plans have been completely thrown into the air.

My alarm went off at 04:00 GMT as we had an 08:15 flight from Heathrow to Inverness - and the first thing I saw was the BBC alert about the London airport's closure.

We couldn't believe our bad luck. It was a trip years in the making - and much delayed due to the Covid pandemic - to celebrate my dad's 70th birthday by tracking his ancestral routes in the Highlands.

We have my three-year-old with us and decided flying would be simpler than inflicting a 1,068-mile (1,719km) round trip on him. Once seeing the news, we decided to cut our losses and hit the road anyway.

We're now three hours into the journey - we've got another six to go and morale is high. We're some of the lucky ones able to find an alternative route and avoid the chaos. Others are clearly not going to be so lucky today.

Transport for London has urged commuters to avoid travelling to Heathrow Airport given today's airport closure.

In King's Cross, posters and signs were swiftly put up to warn those who missed news of the fire, and subsequent airport closure in west London, not to travel to Europe's busiest airport.

The Elizabeth Line, which runs trains to Hayes (the site of the electrical substation fire) and to Heathrow's terminals, warned that there would be "no service between Hayes and Harlington and Heathrow Airport".

More than 4,900 homes have been left without power after the large fire broke out at North Hyde Electricity Substation in Hayes.

Below, the map shows how disruption from the fire spread to Heathrow airport a few miles away.

Kevin Peachey
Cost of living correspondent

The rules around compensation and refunds can be tricky, and it is usually a high-stress situation when you need to know about them.

We’ve already outlined the key points, but it is important to remember that your airline has a contract with you to get you to your destination as soon as possible. If you take a refund, then that duty ends.

Lots of us book parts of holidays separately and so losses with, for example, accommodation require - hopefully - some goodwill from the provider.

Otherwise, it may need a claim to your credit card provider if you paid that way or through travel insurance. It’s important to keep all your receipts for any extra costs incurred.

If the problem was the fault of the airline, then you are entitled to extra compensation - but that’s clearly not relevant today as it was beyond their control.

Image source, Getty Images

We've been hearing from passengers who have been impacted by Heathrow Airport's closure.

Tori Dunzello, who was on board a flight and travelling for her father's funeral when the disruption began, tells BBC Breakfast she saw the plane she was on making "a big U-turn" on the in-flight map which shows the flight's path.

Travel journalist Simon Calder says he believes this is the first time London Heathrow has completely shut down since 2010.

"This is the busiest day of the week at the busiest airport in Europe," he tells the BBC.

"Fifteen years ago was the last time we saw the skies close down at Heathrow," he adds.

The 2010 Eyjafjallajokull volcano eruption sent a huge ash plume several kilometres into the atmosphere, grounding thousands of flights across Europe. A snowstorm in December that same year also caused chaos for days in the lead-up to Christmas.

Charlotte Gallagher
Reporting from Heathrow Airport

Despite roads around the airport being closed some people have decided to come to the airport by foot.

We’ve seen some dragging their suitcases towards the terminals only to be turned away by police officers.

The message is: don’t come here as you will just sent back home or to your hotel.

Image source, Getty Images

Birmingham Airport says there will be no delays to their customers due to diverted flights from Heathrow Airport.

"Airports regularly take diverts as part of normal operations, and flights inbound to London Heathrow will use multiple airports around the UK, and Ireland, or alternatively may return to their departure airport," a spokesperson says.

“We will assist with landing any diverted aircraft during the Heathrow closure today and work with those LHR airlines to repatriate their customers upon arrival into Birmingham.”