After an 18-hour standstill on 21 March due to a fire in an electrical substation, London Heathrow Airport has resumed full operations. Now questions are being raised about the hub’s resilience by senior aviation industry stakeholders.
The blaze, in a National Grid substation at North Hyde, 3.2 km north of Heathrow, cut power supplies to the airport, meaning flights had to be cancelled and tens of thousands of passenger journeys were disrupted. Operations there normally require as much electricity as a small city, but the hub appears not to be connected to any secondary energy source, even though there is one at Laleham, south of the airport, energy analysts Montel Group have said.
🚨Heathrow Airport Fire🚨
— Taymur Malik (@Taymur959) March 21, 2025
Heathrow Airport shuts down until midnight due to a massive fire at a nearby power substation! Over 1,350 flights grounded, 16K+ people without power. #Heathrow pic.twitter.com/oxcErJmgnc
A single power source without an alternative?
Willie Walsh, Director General of the International Air Transport Association, questioned why there was no back-up in place for such a significant cog in the UK’s economy. “How is it that critical infrastructure – of national and global importance – is totally dependent on a single power source without an alternative?”, he said.
Sources at the National Grid have said there are back-up diesel generators and uninterruptible power supplies for key elements of the airport systems but the substation fire damaged a “particularly important bit” of the grid, meaning it took time to implement sufficient secondary sources to get operations up and running again. There is now an investigation under way to find out why disaster preparedness planning failed to prevent the blackout.
The airport has already defended itself, pointing out the National Grid is responsible for the blackout, which affected thousands of homes in the nearby area where residents described hearing an explosion at the substation. Heathrow CEO Thomas Woldbye told press “the situation was not created at Heathrow Airport,” claiming that a solution was found relatively quickly. “The airport didn’t shut for days. We shut for hours,” he said. Woldbye also noted that Heathrow’s power supply arrangements are not unusual. “Most airports operate this way,” he said.
Flights have resumed at Heathrow, and we are open and fully operational. All terminals and all car parks are open across Heathrow. (1/2) pic.twitter.com/VKv8DL8BEg
— Heathrow Airport (@HeathrowAirport) March 22, 2025
Wider questions about UK airport disaster planning
Meanwhile experts have noted that Heathrow and Gatwick are the only airports in the UK with any level of regulatory scrutiny of their resilience standards. If questions are being asked about their preparedness then other airports are likely to be in an even worse position, because, “These are actually the better airports in the UK for how their resilience is assessed and regulated,” Robin Potter, a researcher at think tank, Chatham House told the BBC.
Having warned that repercussions from the day-long shutdown might last for days, Heathrow was planning to return to 85% of its scheduled capacity on 22 March 2025, when it said “hundreds of additional colleagues” would be working and “added flights” to the schedule would “facilitate an extra 10,000 passengers traveling through.”
Even though Heathrow airport announced that “we are open and fully operational,” passengers are still advised to check their flight information before travelling to the airport.
