London's Heathrow Airport responded well to a power outage in March that forced it to?shut down?for 18 hours, according to an investigation commissioned by the airport.

The airport¡¯s closure on 21 March caused massive disruption to passengers when more than 1,000 flights were cancelled due to a power outage that was caused by a major fire at an off-site electrical substation.

Findings from the investigation published on Wednesday (28 May) determined Heathrow ¡°made the right decisions in exceptionally difficult circumstances¡±.

¡°Whilst the disruption was significant, alternative choices on the day would not have materially changed the outcome,¡± said former Secretary of State for Transport and?independent non-executive director of the LHR board Ruth Kelly, who conducted the review.?

¡°The airport had contingency plans in place, and the report highlights that further planned investment in energy resilience will be key to reducing the impact of any similar events in the future,¡± she said in a statement.

The airport launched the investigation, known as the Kelly Review, just days after the incident to assess emergency preparedness and scrutinise its response.

The report sets out several recommendations, which Heathrow chairman Paul Deighton said the airport¡¯s management team ¡°will be taking forward¡±, adding that ¡°the learnings identified in the Kelly Review will make Heathrow more fit for the future¡±.

Heathrow CEO Thomas Woldbye, who had been asleep when the power outage was first reported by the airpirt at around 4.30am local time, said: ¡°We¡¯re truly sorry for the disrupted journeys, and we understand the impact this had on so many of our customers.¡±

In a statement he also thanked the airport¡¯s airline partners for their "teamwork", which "helped us recover quickly and restart operations smoothly".

Woldbye added: ¡°The evidence confirms that Heathrow made the right decisions on the day and successfully put safety first without a single injury reported. Investments in energy resilience have been and will continue to be part of our strategy, and our response to this unprecedented incident was effective due to well-drilled procedures."

The UK¡¯s National Energy System Operator is also due to release a report into the incident at the end of June.