An electrical substation fire that shut down Heathrow Airport, canceling more than 1,300 flights, was caused by a preventable technical fault identified almost seven years earlier, a report found Wednesday.
Europeโs busiest air hub shut for about 18 hours in March after a fire knocked out one of the three electrical substations that supply Heathrow with power. More than 270,000 passengers had journeys disrupted.
Counterterrorism police initially led the investigation into the fire, which came as authorities across Europe girded against sabotage backed by Russia.
Though authorities quickly ruled out vandalism or sabotage, the fireโs huge impact raised concern about the resilience of Britainโs energy system to accidents, natural disasters or attacks.
The government ordered an investigation into โany wider lessons to be learned on energy resilience for critical national infrastructure.โ
The report by the National Energy System Operator said that an โelevated moisture readingโ had been found in oil samples at the substation in west London in July 2018, but action wasnโt taken to replace electrical insulators known as bushings.
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It said that the March 20 blaze was caused by a โcatastrophic failureโ in one of the transformers, โmost likely caused by moisture entering the bushing causing a short circuitโ that ignited the oil.
The report also said Heathrow underestimated the likelihood of losing one of its three power sources, and as a result, โits internal electrical distribution network was not designed or configured to take advantage of having multiple supply points to provide quick recovery following such a loss.โ
Energy Secretary Ed Miliband said that the findings were โdeeply concerning.โ He said that energy industry regulator Ofgem had opened an investigation into whether the substationโs operator, National Grid Electricity Transmission, had breached its license conditions.
National Grid said that Britain has โone of the most reliable networks in the world, and events of this nature are rare. National Grid has a comprehensive asset inspection and maintenance program in place, and we have taken further action since the fire.โ
© 2025 The Canadian Press
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