Counter-terror police are leading the investigation into the “unprecedented” electrical substation fire that has closed down London Heathrow, stopping more than 1,300 flights, as engineers tried to restore power to the airport on Friday.
Airlines face days of disruption with hundreds of thousands of scheduled passengers already unable to fly in and out of Europe’s busiest airport, after what ministers said was an “unusual and unprecedented incident”.
London fire brigade was called shortly after 11pm on Thursday to a fire at an electrical substation in Hayes, west London, with power also cut to thousands of homes.
More than 70 firefighters tackled the blaze, which at 8am on Friday the brigade said was under control, with more than 20,000 litres of oil having caught fire in a transformer. Officers said that despite the acrid smell, there was no air quality danger to the public.
The cause of the fire is unknown, although police and security sources indicated there was no immediate indication of foul play.
Downing Street urged “caution against speculating” about the cause of the fire, pointing out that it was premature to identify the cause while it was still partially burning.
Substation fire in Hayes, London causes widespread outages and Heathrow airport closure – video
A spokesperson for the Metropolitan police said: “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 inquiries.
“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.”
Heathrow is regarded as a potential target for terrorism or sabotage, incidences of which have been rising in recent years backed by state actors. National Grid said substation fires were “extraordinarily rare” and it was not able to “rule anything in or out”.
It is understood there are discussions within Whitehall about whether a Cobra meeting is necessary, which could take place if the closure at Heathrow drags on for a second day. Downing Street would not say on Friday whether it was confident the airport would fully reopen by Saturday, saying it was “clearly a fast-moving situation”.
More than 1,350 flights had been scheduled on Friday to and from Heathrow, Britain’s biggest airport and one of the busiest in the world. Power was still cut off to two of the airport’s four terminals, T2 and T4, by late morning.
National Grid said at 2pm that the network had “been reconfigured to restore all customers impacted, including the ability to resupply the parts of Heathrow airport that are connected to North Hyde”.
Heathrow was understood to be implementing backup systems and starting to redirect power to the affected areas, in a process that could take many hours for assurance in safety-critical parts of its operations.
The immediately cancelled or rerouted flights had capacity for up to 291,000 passengers, with a significant proportion connecting onwards, as well as carrying freight.
Airline operations around the world will be affected, with the knock-on effects expected to last several days.
According to the online flight-tracking service Flightradar24, 120 flights to Heathrow were in the air when the closure was announced. Some arriving flights from Asia and Australia were diverted to other airports around Britain and Europe while others coming from the US returned to their departure points.
A Heathrow spokesperson said: “To maintain the safety of our passengers and colleagues, we have no choice but to close Heathrow until 2359 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 know this will be disappointing for passengers and we want to reassure that we are working as hard as possible to resolve the situation.”
British Airways, which operates just over half of the flights from Heathrow, said: “This will clearly have a significant impact on our operation and our customers and we’re working as quickly as possible to update them on their travel options for the next 24 hours and beyond.”
Planes parked at Heathrow Terminal 5 on Friday. Photograph: James Manning/PA
The International Air Transport Association said it was “yet another case of Heathrow letting down both travellers and airlines”. Willie Walsh, Iata’s director general, added: “How is it that critical infrastructure is totally dependent on a single power source without an alternative? If that is the case then it is a clear planning failure by the airport.”
The UK’s biggest carriers based at other airports, easyJet and Ryanair, said they would be adding extra capacity to help stranded passengers. EasyJet will fly bigger planes on some key European routes and Ryanair has added additional flights from Ireland to London Stansted.
Flights scheduled in next seven days
National rail and coach services operating to Heathrow have all been cancelled on Friday.
The UK energy secretary, Ed Miliband, said it was an “unusual and unprecedented incident”. He said the government would be doing everything it could to restore power to the airport, after supply lines were changed to restore electricity to most of the 67,000 homes affected on Friday morning.
The transport secretary, Heidi Alexander, said she had spoken with Heathrow’s chief executive, Thomas Woldbye, and was “reassured they’re working tirelessly to reopen the airport as soon as possible”.
Alice Delahunty, the president of National Grid’s transmission business, said it had been “a very significant and serious incident, which is extraordinarily rare in our network” and that it was not possible to verify any “rumours and speculation” over the cause of the fire.
She added: “We’re not in a position to rule anything in or out. Our focus has been getting homes and businesses back on supply safely. There will be a time for a full and thorough investigation, but the focus has been on restoring power.”
The fire damaged the substation’s primary transformer, while the backup transformer sustained heat damage during the blaze, Delahunty said.
The London fire brigade assistant commissioner Pat Goulbourne said firefighters had worked “tirelessly in challenging conditions to bring the fire under control as swiftly as possible”.
Emergency services were called to the scene at 11.23pm on Thursday. The fire forced more than 100 people to evacuate. Firefighters led 29 people from surrounding properties to safety, and reported no casualties.
While Heathrow has experienced significant disruption from external events such as the air traffic control outage in August 2023 and the mass groundings during the Covid crisis, the last time the airport was fully closed for an extended period was during heavy snowfall and freezing conditions in December 2010, when 4,000 flights were cancelled.
Heathrow is the best-connected airport in the world, according to analysts OAG, serving about 230 destinations. A record 83.9 million passengers used it last year and it claims to be the largest single-site employer in the UK, with about 90,000 people in total working there.
Additional reporting by Jamie Grierson, Elias Visontay and Kate Lamb
