On the evening of 20 March 2025, a fire erupted at the North Hyde electrical substation in Hayes, Hillingdon, causing a major power outage that forced the complete closure of Heathrow Airport for roughly 16 hours. The blaze, which started at 23:23 GMT, involved a transformer containing 25,000 litres of cooling oil, leading Energy Secretary Ed Miliband to describe it as a "catastrophic fire" that was "unusual and unprecedented." The closure impacted over 1,300 flights and disrupted travel for approximately 290,000 passengers, with 120 planes diverted to airports as far away as Canada and France. Because the substation provided power to about a third of the airport—including Terminals 2 and 4 and a key road tunnel—the airport's back-up systems proved insufficient, and reconfiguring the power supply took up to 12 hours. Although normal operations resumed on 22 March, the incident highlighted resilience gaps, as only Heathrow and Gatwick have regulations on disruption, and a 2023 National Infrastructure Commission report had already recommended setting stronger standards for critical infrastructure. The fire also underscored Heathrow's vital role as a cargo hub, handling £190bn of goods annually.