Hayes substation fire

Electricity sub-station at Hayes on North Hyde Gardens before the fire. The transformer shown on the right was destroyed by the fire

On the evening of 20 March 2025, a fire began at an electrical substation in Hayes, Hillingdon, London, causing the closure of Heathrow Airport. The fire cut electricity supply to the airport which was not able to be managed by back-up systems.

Fire

On 20 March 2025, at 23:23 GMT, emergency services were called to a fire at North Hyde electrical substation in Nestles Avenue, Hayes, Hillingdon. Ten fire engines and 70 firefighters were dispatched as a 650-foot cordon was established. London Fire Brigade reported that one transformer within the substation was alight. By 04:00, half of a transformer remained on fire. Energy Secretary Ed Milliband told reporters that this was a 'catastrophic fire', which was 'unusual and unprecedented' which had also affected a backup generator. As of 13:00 on 21 March, the fire continued to burn at a reduced level, fuelled by 25,000 litres of cooling oil which had been contained within the burning transformer.

Impact

Heathrow Airport

After the fire began, Heathrow Airport announced that it would be closed on 21 March, forcing 120 flights to be diverted to Gatwick Airport, Charles de Gaulle Airport, Shannon Airport, and Goose Bay Airport. Flightradar24 stated that at least 1,351 flights were affected. Cirium, an airplane analytics firm, estimated that 290,000 passengers would be affected. 1300 flights were expected to be affected assuming the airport could reopen at midnight the same day. Flights could not be diverted to other British airports due to lack of capacity, Heathrow being Britain's largest airport and an international hub.

Heathrow airport has some backup power supplies but these are inadequate to run the whole airport. There are two grid substations in the vicinity of the airport, to the north North Hyde and south Laleham, but it is only connected to the northern one. Only two UK airports have any regulation concerning their resilience to disruption, Heathrow and Gatwick Airport, but an October 2023 a report by the National Infrastructure Commission recommended government should set standards for resilience at important infrastructure sites including airports. Other important sites such as data centres, which use similar amounts of power as the airport typically have two grid sources of power plus generators and battery backup sufficient to ensure uninterrupted operation.

Heathrow is also an important cargo airport, carrying £190bn of goods per year, 48% of UK air cargo.

Other transport

A fire near the Heathrow station disrupted Heathrow Express and portions of the Elizabeth line. Trains and London Underground services to Heathrow were suspended or disrupted. The Motorway M4 was closed between junctions 3 and 4, while local roads were also closed affecting bus routes.

Evacuations and outages

At least 150 people were evacuated, and at least 16,300 homes lost power. National Grid reported at 06:00 on 21 March that they had restored power to 62,000 customers, but 4,900 homes remained without power.