Heathrow is under scrutiny over its decision to close for almost 24 hours after a fire at a nearby current substation, despite still being able to receive power from other parts of the grid.
Europe’s busiest airport senior management decided to close on Friday, and they fought to restore full power to a complex that uses the same amount of electricity as a small city.
However, John Pettigrew, chief executive of National Grid, which operates the UK’s high voltage transmission network, told the Financial Times that two other substations serving Heathrow were at work throughout the incident.
As concerns grow over the resilience of the UK’s critical infrastructure, Ir Kiel on Monday said there was a “question” for hub executives to answer on the scale of disruption.
Why didn’t there be enough backup power to operate the airport?
Heathrow has enough diesel generators to drive important operations, such as control towers and runway lighting, allowing passengers to safely depart the airport late Thursday night after the outage was first reported. However, the generator does not have the capacity to operate the entire airport.
Simon Gallagher, managing director of UK Networks Services, a consultancy specializing in power grids, said few other airports have better backup supplies than Heathrow.
However, he said other industries are “more resilient” and that “the entire airport industry has this issue of resilience.
Heathrow has launched an internal review of the blackout and subsequent airport closures led by board members and former transport secretary Ruth Kelly.
National Energy System operators are leading another government investigation into the outage and impact on Heathrow and its surrounding areas.
How is Heathrow’s resilience compared?
A nearby data center run by the ARK data center equipped with 12 emergency generators was also affected by the substation fire on Friday, but said that turning on backup supplies helped to avoid confusion.
“I don’t think people who buy services from me will buy them without this resilience built into them,” Ark’s CEO Who Owen said.
Energy Minister Michael Shanks on Tuesday put more pressure on Heathrow, suggesting that “critical redundancy” is embedded in the energy infrastructure surrounding the airport.
“Local network operators and National Grid were able to find workarounds to connect all households within hours,” he told MPS. “We need to consider the resilience of the external networks connecting to Heathrow, but the private networks within Heathrow need to be reviewed.”
A 2023 US government report reported that one large hub airport has enough diesel fuel generators and enough fuel to power the entire airport for three weeks. The airport was considered an outlier, analysts said.
Resilience said it needs to “have a proper balance between risk and costs.” “It’s not simply possible to ensure minimal disruption and maintain operational as much as possible, especially when facing rare and extreme events.”
If power is available, why did it take so long to restart?
The fire stopped Northhide’s dispersion from operation, but the other two were able to power the airport. However, to access power from the remaining two substations, Heathrow said the internal electrical network must be “reconfigured.”
In reality, the airport had to send technicians to their own distribution points. There, they had to physically switch the circuit breaker, disconnect Heathrow from Northhide and reconnect it to another station.
The airport also had to shut down, restart and systematically test hundreds of systems before resuming operations.
Heathrow said: “Given the size and operational complexity of Heathrow, safely reopening operations after this magnitude of disruption has been a key challenge.”
It is unclear how long it took each step in the process, and some experts said they were surprised at the time it took to get the airport back to normal operation.
Heathrow announced it would be closed until midnight on Friday at 4:30am and began rebooting the system by 12:30pm. By 4pm, the airport was “sure that all systems were operating safely,” Transport Secretary Heidi Alexander said. The first flight rebooted around 7pm.
“In a way, this seems to be a failure of the process,” says David Walom, a professor of informatics at Oxford University. “It appears that Heathrow never considered the magnitude of this failure.”
Should the Heathrow be better prepared?
Malte Jansen, an energy policy researcher at the University of Sussex, said every contingent plan requires “the weight of economics.”
“Technical systems don’t fail 100%,” he said. “We didn’t feel this was a reckless design. The system was designed to be reliable and it created a very unlikely case.”
Nonetheless, power industry executives said Heathrow should have been better prepared given its position as Europe’s busiest airport. The ability to switch power quickly “should be a minimum standard,” one executive said.
Firefighters are working to blow flames at the North Hyde substation near Heathrow ©AFP Getty Images
A 2014 report by consulting firm Jacobs, prepared as part of the previous Heathrow Expansion Push, said “Even a short break in a power source can have long-term impacts.”
However, he concluded that “Heathrow is equipped with an on-site generation and appears to have a resilient power supply that complies with regulations and standards.”
Heathrow has spent a total of £7.4 billion on capital expenditures at the airport since 2014, including a new security scanner. However, during a time when landing fees rose, the airlines criticize the owners for spending this money inefficiently, leaving the airport with aging infrastructure.
Additional report by Clara Murray of London. Illustrations by Ian Bott
