The fire at North Hyde substation in March 2025, which triggered a prolonged shutdown of Heathrow Airport, cast a stark light on systemic vulnerabilities within the UK's critical infrastructure. On the evening of 20 March, the blaze forced the closure of Europe’s busiest airport for around 16 hours, halting over 1,300 flights and disrupting more than 270,000 passenger journeys. The fire not only impacted Heathrow but also left over 71,000 domestic and commercial customers without power, affecting hospitals, transport routes, and data centres. The fallout highlighted not just an operational crisis, but deep issues around crisis response, maintenance oversight, and infrastructure resilience across key sectors.

Despite the widespread disruption, Heathrow’s contingency plan for mass diversions was notably effective. According to an aviation risk resilience expert involved in developing the UK’s mass diversion protocol, the airport’s ability to divert inbound flights safely to partner airports across the UK and Europe demonstrated the value of well-coordinated, pre-established resilience protocols. Operational teams at alternative airports managed the surge in flights commendably, ensuring the safety and security of passengers and aircraft amid chaos. This “quiet resiliency protocol,” while taken for granted, provided essential certainty under extreme pressure.

However, the incident was a foreseeable failure rooted in deferred infrastructure maintenance and governance shortcomings. Investigations by the National Energy System Operator (NESO) confirmed the fire resulted from a catastrophic failure in a transformer bushing caused by moisture ingress, a fault first detected in 2018 but left unaddressed. This lack of action reflected a broader issue of systemic deferred maintenance within National Grid Electricity Transmission (NGET), responsible for the substation’s upkeep. Industry experts frame the fire less as a freak accident and more as an inevitable consequence of inadequate strategic planning and maintenance deferrals, urging the government to undertake comprehensive risk assessments across all critical infrastructure sectors to prevent similar failures.

The incident also exposed Heathrow’s internal vulnerabilities. A unique aspect of the airport’s electrical network design meant that losing just one of its three power supply points could paralyse critical operations, with rerouting internal electrical power taking up to 12 hours. This situation underscores the necessity of embedding redundancy not just externally but within internal systems as well. Former airport executives recommend prioritising redundant network access, duplicating internal energy systems, and incorporating onsite power generation to mitigate severe blackout scenarios and ensure operational continuity.

The fire further revealed challenges in supplier governance. A risk management professional noted that Heathrow might have underestimated the severity of the substation’s condition due to insufficient transparency and scrutiny from National Grid, coupled with potential lapses in communication about maintenance deficiencies. Had the full risk been understood, Heathrow could have insisted on more urgent maintenance or contractual risk-sharing arrangements with suppliers, highlighting the importance of early and clear risk communication between critical infrastructure operators and their suppliers.

Underlying these technical and operational failures is a complex governance dilemma: balancing the drive for long-term resilience against short-term cost constraints and regulatory pressures. Heathrow’s former risk management lead emphasises that the airport’s ability to manage routine disruptions so effectively may inadvertently weaken the case for investing in resilience measures for low-probability but high-impact risks such as power blackouts. Investment choices are constrained by limited capital expenditure budgets regulated by stakeholders like partner airlines, which may favour upgrades with clearer immediate payoffs over critical infrastructure renewals addressing rare events.

Experts also point to a culture gap in managing infrastructure risks. There is often a tendency to dismiss cascading risks as improbable until they trigger high-profile crises with major reputational damage, as occurred here. Questions remain about whether the UK government has a robust, formal mechanism for identifying and tracking systemic infrastructure risks and ensuring proactive mitigation. This incident highlights the need for transparent risk appetite setting and alignment among technical teams, operational decision-makers, and government oversight bodies.

The official post-incident reports have intensified scrutiny. The UK’s energy regulator, Ofgem, has launched an enforcement investigation into National Grid Electricity Transmission’s compliance with its licence following findings that elevated moisture levels in transformer equipment had been detected years prior but left unaddressed. The fire suppression system at the substation also failed. Energy Secretary Ed Miliband described the findings as “deeply concerning,” while Heathrow is reportedly considering legal action to hold National Grid accountable. National Grid has stated that it has reviewed and improved its asset maintenance and fire risk assessment processes since the incident. An independent audit is underway to determine if these issues reflect wider systemic weaknesses.

For risk managers across industries, the Heathrow fire is a cautionary tale about the complexity and interconnectedness of modern infrastructure risk. Real resilience means not only having contingency plans but also ensuring that all parts of a supply chain and infrastructure network are visible, maintained, and aligned well before a crisis hits. Experts advocate for adopting coordinated planning frameworks similar to aviation’s mass diversion protocols in other sectors. They also urge urgent adoption of NESO’s twelve recommendations, which include enhanced asset risk assessments, emergency access arrangements, cross-sector coordination, and legal reforms to strengthen critical infrastructure oversight. Such steps are vital to avoid preventable collapses and safeguard national infrastructure in an increasingly complex risk landscape.

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Source: Noah Wire Services