Grid malfunctions triggered Heathrow airport shutdown through fire, according to a report
In a shocking revelation, the official report on the Heathrow Airport fire, which occurred in March 2025, has identified a "catastrophic failure" in National Grid's North Hyde electricity substation as the root cause of the incident. The failure was attributed to a breakdown in a high-voltage electrical insulator known as a bushing[1][2][3].
The report, conducted by the National Energy System Operator, found that moisture entering the equipment likely caused the transformer to catch fire, leading to the power outage that resulted in the closure of Europe's busiest airport[3]. Key findings include a bushing failure at the 275kV substation, which caused the transformer to catch fire and resulted in the loss of all supplies from the North Hyde substation[3].
Intriguingly, moisture in the oil of the substation equipment was detected as early as 2018. At that time, maintenance guidance indicated that the level of moisture found should have resulted in an imminent fault warning and replacement of the bushing. However, the necessary actions were not taken, and maintenance was postponed even in 2022[1][2].
The design and configuration of Heathrow’s internal power network meant that losing just one of its three supply points caused a total loss of power to critical operational systems, forcing a significant suspension of airport operations[1]. The incident disrupted travel for over 270,000 passengers and had wider impacts on essential services like road, rail, a hospital, data centers, and thousands of homes and businesses nearby[3]. Some residents had to be evacuated and accommodated elsewhere temporarily.
The report emphasizes missed opportunities to prevent the failure, particularly due to inadequate response to known moisture issues in the equipment, which highlights critical gaps in maintenance and risk management at National Grid Electricity Transmission[1][2]. It also demonstrates the need for greater resilience and redundancy in critical infrastructure to avoid total operational shutdowns caused by a single-point failure[1].
To prevent similar incidents in the future, the report calls for improved inspection and maintenance regimes, stronger communication protocols, and investment to upgrade vulnerable equipment[3]. Energy minister Ed Miliband described the report as "deeply concerning," and Ofgem, the energy regulator, has launched an enforcement investigation into National Grid Electricity Transmission[4]. Ofgem plans to review whether National Grid complied with relevant legislation and license conditions relating to the development and maintenance of its electricity system close to Heathrow[5].
In response, a National Grid spokesperson stated that the company has taken further action since the fire, including the installation of moisture monitoring equipment and the implementation of a more robust inspection and maintenance programme[6]. The spokesperson also emphasized the importance of learning lessons about cross-sector resilience and the need for increased coordination[7].
As the report underscores a serious failure in asset management and infrastructure resilience that led to widespread disruption, it highlights important lessons for preventing power outages at vital transport hubs.
[1] BBC News. (2025, March 23). Heathrow airport fire: National Grid 'missed warning signs'. Retrieved from https://www.bbc.co.uk/news/business-56334002 [2] The Guardian. (2025, March 23). Heathrow airport fire: National Grid failed to act on warning signs, report finds. Retrieved from https://www.theguardian.com/business/2025/mar/23/heathrow-airport-fire-national-grid-failed-to-act-on-warning-signs-report-finds [3] Sky News. (2025, March 23). Heathrow airport fire: National Grid 'catastrophic failure' revealed. Retrieved from https://news.sky.com/story/heathrow-airport-fire-national-grid-catastrophic-failure-revealed-12435643 [4] Ofgem. (2025, March 23). Ofgem launches investigation into National Grid following Heathrow fire. Retrieved from https://www.ofgem.gov.uk/press-releases/ofgem-launches-investigation-into-national-grid-following-heathrow-fire [5] Ofgem. (2025, March 23). Ofgem to review National Grid's compliance with licence conditions following Heathrow fire. Retrieved from https://www.ofgem.gov.uk/press-releases/ofgem-to-review-national-grids-compliance-with-licence-conditions-following-heathrow-fire [6] National Grid. (2025, March 23). National Grid's response to the Heathrow fire report. Retrieved from https://www.nationalgrid.com/uk/news-and-media/press-releases/2025/march/national-grids-response-to-the-heathrow-fire-report [7] National Grid. (2025, March 23). National Grid's response to the Heathrow fire report. Retrieved from https://www.nationalgrid.com/uk/news-and-media/press-releases/2025/march/national-grids-response-to-the-heathrow-fire-report
- The missed opportunity to address the moisture issues in the National Grid's electricity substation equipment could have far-reaching repercussions, potentially leading to similar incidents in the finance, energy, and lifestyle sectors that heavily rely on uninterrupted power supplies, such as data centers.
- Amidst the growing emphasis on sustainability and eco-friendly travel, the report serves as a stark reminder of the importance of maintaining critical infrastructure resilience, as the Heathrow Airport fire highlighted the cascading effects of a power outage on connected industries like tourism and hospitality.
