Heathrow Airport fire caused by 'preventable' power grid failure, official report finds.

 

An official report has revealed that a fire which shut down Heathrow Airport in March 2025 was caused by a failure of the UK’s National Grid to maintain key electrical infrastructure. The blaze led to the closure of Europe’s busiest airport, leaving thousands of passengers stranded and costing airlines tens of millions of pounds. According to the findings, a catastrophic failure occurred in a transformer at a National Grid substation near the airport. Moisture had entered a high voltage bushing, triggering an electrical fault and fire.

Shockingly, the report revealed that the moisture issue was detected as far back as 2018, but no repairs were made. Maintenance was even deferred again in 2022 despite another opportunity to fix the issue. These lapses allowed the fault to go unresolved for seven years. The National Energy System Operator, which conducted the review, confirmed that the fire was preventable. It noted that controls failed to detect that maintenance had not been done. The power grid operator, National Grid Electricity Transmission, had been separated from the system operator only last year.

The UK’s energy regulator, Ofgem, described the event as a preventable technical fault and has launched an enforcement investigation into the company. The regulator will also commission an independent audit to determine if the issue is part of a wider pattern across the National Grid’s assets. Energy Minister Ed Miliband called the situation deeply concerning.

See also: (In US) Ex-doctoral candidate expected to plead guilty to murders of four Idaho students

The fallout from the Heathrow incident has sparked strong criticism and triggered regulatory consequences. Ofgem’s probe will assess whether National Grid Electricity Transmission violated its license conditions and relevant energy regulations in the lead-up to the incident. It aims to find out whether these maintenance failures are isolated or part of a larger systemic problem. The regulator's independent audit will examine the company’s infrastructure across the network to ensure safety and compliance.

National Grid responded by stating it has a robust maintenance and inspection program in place, and that it has implemented further changes following the March fire. A spokesperson acknowledged the need for better cross-sector coordination and resilience in critical national infrastructure. Despite the reassurances, the report has put pressure on the company to account for years of apparent neglect.

Heathrow Airport, in its own May review, said its emergency response to the outage was effective and that alternative decisions on the day would not have significantly changed the outcome. However, the airport was critical of the overall system, attributing the disruption to outdated regulations, poor safety mechanisms, and the National Grid’s failure to maintain vital infrastructure. The incident raised larger concerns about the resilience of Britain’s critical services and the oversight of infrastructure near sensitive locations like major airports. It has reignited debates about public safety, regulatory enforcement, and investment in infrastructure modernization.