• Travelers wait outside the Terminal as Heathrow Airport slowly resumes flights after a fire cut power to Europe's busiest airport in London, Saturday, March 22, 2025. (AP)

UK National Grid CEO John Pettigrew confirmed that there was enough power available for Heathrow to remain operational during the entire period it was shut down on Friday.

Following a fire that forced the North Hyde substation to close, Pettigrew stated that two other substations serving Heathrow were functional and could have supplied the airport with the necessary power.

“There was no lack of capacity from the substations,” Pettigrew told the Financial Times. “Each substation individually can provide enough power to Heathrow.”

The UK government has launched an investigation into the airport’s closure, which caused an estimated £60 million to £70 million in losses for the airline industry and affected more than 200,000 passengers globally.

Energy Secretary Ed Miliband said the government was determined to understand what happened and to learn lessons about the UK’s "energy resilience for critical national infrastructure."

Heathrow's CEO, Thomas Woldbye, defended the airport’s response to the unprecedented power outage, explaining that while Heathrow uses as much energy as a city daily, it lacks backup power for certain systems such as baggage, fuel, and air bridges. He noted, "So whereas the safety systems are working and we can get aircraft in and out, most of the airport infrastructure comes to a standstill when we need to reset, as we did [on Friday]."

Pettigrew, however, maintained that two substations "were always available for the distribution network companies and Heathrow to take power," and that it was a matter for Heathrow to explain why it took the actions it did. "Losing a substation is a unique event – but there were two others available," he said, emphasizing the "level of resilience" in the system.

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While Woldbye acknowledged that the backup systems worked as expected, he said the airport's power supply was a "bit of a weak point." He also remarked that although Heathrow had other substations, switching to them takes time. "I don’t know of an airport that has backup supply that can switch on in minutes to the magnitude of what we experienced yesterday. The same would happen in other airports,” he added.

Pettigrew explained that the fire had damaged all three transformers at the North Hyde substation, including one backup transformer located further away.

Firefighters reported that the fire burned 25,000 liters of cooling oil. The cause of the fire remains unknown, as the site is still too hot for full forensic investigation, and third-party involvement has not been ruled out. "I can’t remember a transformer failing like this in my 30-plus years in industry," Pettigrew remarked.

Initially, counter-terrorism officers from the Metropolitan Police led the investigation, but they have since confirmed that the fire is not believed to be suspicious. The London Fire Brigade is now heading the inquiry, which will focus on the electrical distribution equipment.

Regarding the design of the North Hyde site, Pettigrew explained, "You have to build substations in the space available, and obviously you do all you can to mitigate the risks."

However, he added, "That is something that clearly I think an investigation will look into a bit further."