The British government has initiated an inquiry into the country's energy resilience following a fire at an electrical substation that caused Heathrow Airport to close for almost a day.

The incident raised questions about the UK’s capacity to protect critical infrastructure from potential threats.

Heathrow Airport announced that it was now fully operational; however, thousands of passengers remained stranded.

Airlines indicated that extensive disruptions would likely persist as they worked to relocate aircraft and crews, and to facilitate travel for affected passengers.

More than 1,300 flights were cancelled, leaving approximately 200,000 individuals unable to continue their journeys on Friday.

Affected passengers expressed frustration over the last-minute cancellations, with accounts of personal distress emerging from travelers.

Energy Secretary Ed Miliband stated that he has requested the National Energy System Operator to conduct an urgent investigation into the fire to identify broader implications for energy resilience.

The report is expected to provide initial findings within six weeks.

Heathrow has also launched its own review under the leadership of Ruth Kelly, a member of the airport's board and former transport secretary.

The review will assess the efficiency of the airport's crisis management plans and its response to the incident.

The fire, which occurred at a substation located 3.2 kilometers from the airport, resulted in a significant power outage affecting not only Heathrow but also over 60,000 properties in the surrounding area.

Witnesses in west London reported hearing a large explosion and observing flames and smoke emanating from the substation, which took seven hours to bring under control.

Despite assurances that the fire is not being treated as suspicious by authorities, the event has prompted scrutiny of the UK's aging infrastructure, much of which has been privatized since the 1980s.

The Labour Party has pledged to enhance the country’s infrastructure—including railways, water systems, and energy networks—as part of a broader strategy to improve reliability and reduce carbon emissions through renewable energy investments.

Heathrow is one of the busiest airports globally, handling approximately 83.9 million passengers in the prior year.

The airport’s chief executive praised the efforts of staff during the disruption but acknowledged that the backup power systems were insufficient to sustain full operations amid the incident, highlighting a potential systemic vulnerability.

The airport's management faces criticism regarding its reliance on a single power source, with aviation officials pointing out significant concerns about planning and infrastructure resilience in light of the fire's far-reaching impacts.

This incident marks one of the most significant disruptions at Heathrow since the 2010 Icelandic volcanic eruption, which grounded flights across Europe for several days.