The shutdown of Heathrow Airport following a substation fire last month has highlighted systemic vulnerabilities in power resilience across critical infrastructure, according to Finning UK & Ireland. While the airport was forced to cancel or divert more than 1,300 flights, essential services and businesses in the surrounding area remained operational, many supported by independently installed diesel standby generation systems.
The fire, which broke out at the North Hyde substation on 20 March, cut power to one of Heathrow’s key supply lines. Despite two other substations remaining fully operational and capable of supplying the airport, Heathrow was unable to switch to an alternative feed in time to avoid disruption, which affected an estimated 290,000 passengers.
Finning, which supplies and maintains standby power systems across the region, confirmed it supports several local facilities that remained online throughout the outage. These include mission-critical data centres.
Glen Richards, Customer Account Manager at Finning UK & Ireland said, “Where diesel standby was in place and properly integrated, critical operations continued, including Finning-supported sites. This incident wasn’t about a lack of available power. It was about how quickly and effectively that power could be accessed.
“Had those standby systems failed, or not been present, the story might have been far worse. Data centres, industrial sites and public infrastructure in the area were all exposed to the same grid event. The thing that made the difference was local, engineered resilience.”
Heathrow’s emergency backup generators, designed to maintain essential safety systems such as air traffic control and runway lighting, activated as intended during the outage. However, these systems were not configured to support full passenger operations, including terminal services and baggage handling. According to Heathrow CEO Thomas Woldbye, the airport’s backup systems functioned correctly but were not sized to run the entire airport.
While two other substations remained operational and capable of supplying sufficient power to the airport, transitioning to these sources required a comprehensive and time-consuming process. This involved safely shutting down existing systems, reconfiguring them to accept power from the alternative substations, and systematically restarting operations. The complexity and safety considerations of this contributed to the duration the airport was closed.
Richards added, “We expect further details to emerge as the investigations make progress, but what’s already clear is that the impact of the outage wasn’t equal. Some sites continued operating without disruption and the common denominator was a correctly-sized and well-maintained standby power system.
“This incident should renew focus on how organisations plan for grid loss, including system integration, load testing and automated transfer capability. Standby systems are often under-tested until they’re needed, and this event demonstrated the difference that readiness can make.”
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