A loss of power forced London’s Heathrow airport, one of the world’s busiest, to shut down on Friday morning, prompting chaos and disrupting travel for tens of thousands of air passengers.
In a post on social media website X, the airport blamed a fire at an electrical substation in North Hyde in Hayes, west London, for the power outage and said it did not expect to reopen until early on Saturday.
Flights were reported to have been diverted to Amsterdam, Frankfurt, Paris, Shannon and Manchester.
It is not yet clear what, exactly, caused the fire. A spokesperson for Prime Minister Keir Starmer’s office told the UK’s Guardian newspaper on Friday afternoon that the incident would be thoroughly investigated. “There are questions to answer on how this has happened and what can be done to prevent the scale of disruption we’ve seen from happening again, once the situation is under control,” the spokesperson said.
Here’s what we know so far about what happened and the disruption the closure has caused.
Due to a fire at an electrical substation supplying the airport, Heathrow is experiencing a significant power outage.
To maintain the safety of our passengers and colleagues, Heathrow will be closed until 23h59 on 21 March.
Passengers are advised not to travel to the airport… pic.twitter.com/7SWNJP8ojd
On Friday, the London Fire Brigade’s deputy commissioner, Jonathan Smith, revealed that as well as the airport itself, 67,000 households had their power cut. No one was hurt, but firefighters evacuated nearly 180 people. Earlier, officials advised residents in the area to shut windows and doors due to huge plumes of smoke.
In a statement posted on X early on Friday, Heathrow airport advised passengers and staff to stay away from the premises and said it was not expected to open again before midnight.
“Passengers are advised not to travel to the airport and should contact their airline for further information. We apologise for the inconvenience,” the statement read.
Passengers who were already at Heathrow before the shutdown told of chaotic scenes.
Marhea, 74, who was booked on a Brussels Airlines flight to Liberia said there was darkness and confusion when she arrived, with no staff in sight to explain what had happened.
“They didn’t let us into terminal five. People were standing at the door everywhere […] It would have been nice if they had people at the door to explain what had happened,” she said. The airline later booked her on a Saturday flight with a separate carrier.
Others were refunded. One traveller, identified as Ellen, said she was booked on a British Airways flight before Friday’s chaos.
“We were supposed to fly to Venice this morning from Heathrow for a day trip for my 30th birthday present, it was a surprise booked by my cousin for the two of us,” Ellen told Al Jazeera. “We have been offered a full refund by the airline so won’t be travelling now this weekend but will try to rearrange for another weekend soon,” she said.
Passengers with suitcases wait on a nearby road after an electrical substation fire knocked out power to London’s Heathrow airport on Friday, disrupting flights for hundreds of thousands of passengers at one of Europe’s biggest travel hubs [Kin Cheung/AP]
What caused the fire?
The cause is still unknown.
On late Friday morning, the London Fire Brigade’s deputy commissioner, Jonathan Smith, said the fire had been made worse by fuel in a transformer “comprising of 25,000 litres of cooling oil, fully alight”.
Several UK media outlets, citing unnamed officials, reported that counterterrorism officials had been sent by the London Metropolitan Police to investigate the causes of the fire as a precautionary measure.
The Metropolitan Police was quoted saying it would “retain an open mind” but that there were no suspicions of sabotage.
Speaking to LBC Radio earlier on Friday morning, UK Energy Secretary Ed Miliband said: “There is no suggestion that there is foul play.”
On Friday, experts were questioning why the airport’s backup plans appeared to have been “inadequate”. Dr Alan Mendoza, from the UK-based Henry Jackson Society, a foreign policy and national security think tank, told The Times: “Fires happen. But they shouldn’t be capable of taking out an entire airport as it suggests backup systems are inadequate. A full national audit is required to prevent recurrences.”
In a statement issued later on Friday, Heathrow claimed its backup systems had kicked in, but that they are “not designed to allow us run a full operation”. Rather, the statement clarified, the systems allow for aircraft to land and for people to be evacuated.
Alice Delahunty, president of National Grid Electricity Transmission, told UK media: “We have a number of very strict protocols, remote monitoring; security is something we take very seriously. The site is certainly secured.”
Where is Heathrow and where did the fire occur?
Heathrow is located on the outskirts of west London, in the borough of Hillingdon. The airport is the busiest in Europe and one of the busiest in the world, based on passenger traffic.
The fire occurred in an area close to Heathrow, at the North Hyde electrical substation in Hayes, about a 20-minute drive from the airport.
How many flights have been delayed or cancelled?
At least 1,357 flights have been disrupted, according to air traffic monitor, FlightRadar24.
Some 679 flights had been scheduled to land at the airport, while 678 flights had been expected to take off, the monitor said.
Most flights that were to land at Heathrow were diverted to Amsterdam’s Schiphol Airport. Others were rerouted to Frankfurt andManchester. UK media reported flights being diverted to Paris and Shannon in Ireland as well.
Flightradar24 said 120 aircraft waiting to be diverted were still in the air on Friday morning after the disruptions.
Some passengers said they had been informed of cancellations and diversions hours before their flight, while many others were stuck at Heathrow or connecting airports.
Lloyd, 34, who was planning to travel to the United States via Heathrow to visit his partner, received an email as he was en route to Glasgow Airport on Friday morning informing him that his 6:35am flight had been rescheduled to a later time and to a different airport in the US. By the time he got to the airport, his flight had been cancelled and he was advised not to travel from Glasgow to Heathrow.
“Perhaps because we hadn’t set off to London yet, we weren’t as upset as those now stuck in Heathrow,” Lloyd told Al Jazeera.
Firefighters
Firefighters wait at the area around the North Hyde electrical substation, which caught fire on Thursday night and led to a closure of Heathrow airport in London, on Friday, March 21, 2025 [Kirsty Wigglesworth/AP]
How many flights and passengers pass through Heathrow?
According to Heathrow’s data, some 67 million passengers pass through the airport every year. That is close to the population of the whole of the UK.
Passenger traffic broke records in 2024 when the airport recorded more than 83 million passengers – about 220,000 people a day.
The airport handles about 1,300 flights daily.
