Heathrow Airport Shutdown: Cause of Power Outage Remains a Mystery, Says Interim Report
London, UK — The fire that shut down Heathrow Airport in March, disrupting over 270,000 journeys, still has no confirmed cause, according to an interim report by the National Energy System Operator (Neso).
The fire broke out at 23:21 GMT on 20 March at the North Hyde electrical substation in Hayes, west London, leading to a massive power outage across Heathrow and other areas. The airport remained closed for much of 21 March, marking its worst disruption in over 20 years.
According to Neso’s preliminary findings, a transformer caught fire and triggered a complete disconnection of power. However, the report states that the exact cause of the fire is still unknown. A full report is expected by the end of June.
Investigation So Far: No Evidence of Foul Play
The Met Police Counter-Terrorism Command investigated the incident but found no signs of suspicious activity. Authorities declared a major incident shortly after midnight, and Heathrow closed all operations at 01:11 as a precaution due to safety concerns during the power switch-over.
Despite power being restored to terminals by 10:56, flights only resumed after 18:00, following extensive safety checks. Full airport reactivation was completed by 14:23, with power to all other affected customers restored by midday.
Why the Delay in Reopening?
Heathrow’s CEO Thomas Woldbye explained the airport had emergency backup systems, but due to the complexity and scale of the airport, leadership chose to suspend operations temporarily to ensure the safe transition to alternate substations.
Neso confirmed that critical safety systems, such as runway lights and landing equipment, were powered throughout by diesel generators and batteries.
Fire Response and Hazard Details
According to the London Fire Brigade (LFB), the fire involved a transformer filled with insulating oil, creating a significant hazard. Firefighters had to wait for the unit to cool before safely cutting into the casing to extinguish hidden flames.
Neso and local power distributors, including SSEN and National Grid, welcomed the interim findings and await the final report for clarity on the fire’s origin and prevention strategies.
Government Response
Energy Secretary Ed Miliband ordered an urgent investigation after the shutdown, urging Neso to deliver initial findings within six weeks. In a recent statement, he emphasized the importance of the final report to enhance UK energy grid resilience and protect critical infrastructure.
