Heathrow airport closure: Everything we know about the Hayes substation fire and effects of grounded flights

Shutting airport for 15 hours will have cost millions of pounds after 25,000 litres of cooling oil caught fire at high-voltage substation

Thousands of passengers had their flights cancelled or altered in mid-air after a massive fire ripped through an electricity substation near Heathrow, forcing the airport to close for more than 15 hours.

Up to 300,000 customers had been set to use Europe’s biggest airport on Friday, but 1,351 flights were disrupted by the blaze.

Despite initially saying it would be closed all day, Heathrow later announced some long-haul flights would restart during the evening. While the airport said it was once again fully operational the following day, at least of 100 of the roughly 600 flights which would typically have been expected on Saturday were cancelled.

The blaze which caused the power outage erupted at a high-voltage electricity substation in Hayes, five miles north of the airport, leaving around 67,000 households suffering power cuts.

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Around 150 residents were forced to leave their homes and a 200-metre cordon was put in place around the substation, police said.

Here, The Independent takes a look at all we know about the fire and its effects.

Up to 10 fire engines rushed to Nestles Avenue, Hayes, where 70 firefighters tackled the inferno throughout the night (London Fire Brigade/PA Wire)

What caused the fire?

A transformer at the substation caught fire, but it is not yet known what caused it.

One nearby resident described their room shaking and hearing a loud bang as the substation caught fire.

London Fire Brigade deputy commissioner Jonathan Smith said: “The fire involved a transformer comprising 25,000 litres of its cooling oil fully alight.

“This created a major hazard owing to the still live high-voltage equipment and the nature of an oil-fuelled fire.”

Footage showed the fire ripping through a Scottish and Southern Electricity Networks-managed substation throughout the night (Chris Brogan)

While counter-terror officers initially led the investigation, the Metropolitan Police later said it was not treating the incident as suspicious, but that inquiries were continuing and would now be led by the London Fire Brigade.

The fire brigade said its investigation would focus on electrical distribution equipment.

What is the economic effect?

Economist Stephen Rooney said: “In terms of what's at stake, at the conservative end, we estimate a potential loss of tourism revenue amounting to £4.8m per day.

“We can estimate this loss based on typical inbound arrivals volumes that come to the UK through Heathrow and the average daily spend of those travelling.”

He said his estimates did not include the potential loss of earnings of airport and airline staff, lost income for airport retail and ancillary services such as airport taxis.

Insurance payouts, lost money for affected passengers and other costs to airlines involved would further inflate the damage.

Drone footage shows an electricity substation fire in Hayes, west London (Mixed)

How many passengers were affected?

Up to 291,000 passengers were set to fly from Heathrow airport on Friday, with 1,330 flights scheduled throughout the day, according to aviation analytics firm Cirium.

Up to 665 departures were scheduled, equating to over 145,094 seats, and 669 flights were due to arrive, equating to 145,836 seats.

British Airways chief executive Sean Doyle said the event would have a huge impact on customers in the coming days.

“To give you an idea of the scale of disruption we face which we’re working to minimise, today we were due to operate more than 670 flights carrying around 107,000 customers, with similar numbers planned over the weekend,” he said.

Up to 70 firefighters tackled the inferno throughout the night (AFP via Getty Images)

While the airport was said to be fully operational again on Saturday, as of 3pm on Saturday, 34 flights due to leave the airport had been cancelled, including domestic destinations and international flights to New York and Paris.

And according to Heathrow’s live arrivals board, as of 3pm, 71 flights expected to arrive on Saturday had been cancelled, including flights from Dubai and Doha.

Why did the airport have to close?

Heathrow’s chief executive Thomas Woldbye said the airport had three substations, each with a backup transformer.

The fire broke out at a substation where the backup transformer also failed, causing a loss of power.

Mr Woldbye said the airport could run on power from the two unaffected substations but that they had to “restructure the supply”.

“To do that we have to close down systems – that is safety procedure, we will not go around that,” he said.

He added: “Two substations can run the airport but we need to re-engineer the structure of the power supply for all the terminals and that's what we were doing during the day, and then we have to restart all the systems and that's what we've done, and we now see operation coming back.”

What has the backlash been?

Labour peer Toby Harris – who leads the National Preparedness Commission, which campaigns to improve resilience – said on Saturday: “It’s a huge embarrassment for the country that a fire in one electricity substation can have such a devastating effect.”

Jason Bona, owner of supply chain firm PS Forwarding, told BBC Radio 4’s Today programme the incident had left Heathrow a “laughing stock” in the global freight community.

“It is a clear planning failure by the airport,” said Willie Walsh, a former British Airways chief who now leads the global airline body IATA and has long been a fierce critic of Heathrow.

Mr Woldbye has apologised to stranded passengers and defended the airport’s response to the situation, saying the incident was as “as big as it gets for our airport” and that “we cannot guard ourselves 100 per cent”.

What investigations have been launched into the outage?

Vowing that the government “is determined to do everything it can to prevent a repeat of what happened at Heathrow”, energy secretary Ed Miliband said on Saturday evening that he had ordered the grid operator to “urgently investigate” the outage.

In conjunction with regulator Ofgem, Mr Miliband commissioned the National Energy System Operator (Neso) to carry out the independent probe “to properly understand what happened and what lessons need to be learned” regarding “energy resilience for critical national infrastructure, both now and in the future”.

Neso is expected to report to Ofgem and the Department for Energy Security and Net Zero with its initial findings within six weeks. These are in addition to the work being carried out by the London Fire Brigade, which warned that it could take weeks to determine the fire’s cause.

Heathrow’s chair Lord Paul Deighton has also since announced an internal probe chair has ordered an internal investigation, which will be led by former transport secretary Ruth Kelly, who is now a member of Heathrow’s board.

That review, according to Lord Deighton, will analyse “the robustness and execution of Heathrow’s crisis management plans, the airport’s response during the incident and how the airport recovered the operation with the objective of identifying any improvements that could be made to our future resilience”.