Heathrow Airport is gradually returning to normal following widespread disruption caused by a fire at an electricity substation that led to more than 1,000 flight cancellations on Friday.

The blaze, which broke out at a substation in Hayes on Thursday night, resulted in a major power outage, forcing operations at Europe’s busiest airport to grind to a halt. Approximately 200,000 passengers were affected, as airlines scrambled to respond to the unprecedented shutdown.

Deputy Commissioner Jonathan Smith from the London Fire Brigade described the incident as a “major hazard,” with a transformer containing 25,000 litres of cooling oil fully alight, alongside live high-voltage equipment that complicated the emergency response.

Energy Secretary Ed Miliband has now ordered an urgent investigation by the National Energy System Operator (Neso) into the cause of the outage, invoking powers under the Energy Act. Ofgem is also involved in the probe to determine how such a critical failure occurred.

Heathrow Fully Operational — But Travellers Urged to Check Flights

A Heathrow spokesperson confirmed over the weekend that the airport is now fully operational, with a full schedule of more than 1,300 flights expected to run on Sunday.

“Today we will operate another full schedule of over 1,300 flights,” a statement said. “We apologise for the inconvenience caused by our decision to close the airport on Friday following a significant fire at an off-site power substation. Yesterday, we served more than 250,000 passengers, with punctual flights and almost all passengers waiting less than five minutes for security.”

Additional staff were deployed across terminals on Sunday to support passengers and smooth operations.

Transport Secretary Heidi Alexander praised the swift response by emergency services and airport staff but emphasised the importance of learning from the incident.

“Heathrow is a massive airport that uses the energy of a small city, so it’s imperative we identify how this power failure happened and learn from this to ensure a vital piece of national infrastructure remains strong,” she said.

Ongoing Disruption Possible

While the airport is officially “back to business,” authorities have warned that minor disruption may persist in the coming days as airlines and staff catch up with the backlog.

British Airways, one of the most affected carriers, said it expected to run a “near-full schedule” on Sunday but also advised passengers to check with their airlines before travelling.

The disruption has raised further questions about resilience planning and infrastructure vulnerabilities at major transport hubs.

Travellers are encouraged to monitor updates closely and plan their journeys in advance.