A debilitating power outage at London-Heathrow Airport (LHR), caused by a substation fire, has cost British Airways owner IAG around €50 million ($56 million), according to the company.
On March 20, 2025, shortly before 23:30 local time, the London Fire Brigade descended on the North Hyde Substation after a fire broke out, damaging the three supergrid transformers located there.
The incident resulted in nearly 70,000 customers losing power and Heathrow Airport ordering a near-complete shutdown that lasted for almost a day.
On May 9, 2025, IAG which owns British Airways, Iberia and Aer Lingus, published its first quarter results for the year, indicating that the outage had significantly affected its operational costs.
British Airways is Heathrow’s primary customer, with the UK carrier dominating operations there, flying from Terminals 3 and 5.
IAG said the outage had an “adverse impact”, causing a circa 1% hit to its expected earnings in the first three months of the year.
“The impact of the closure of London Heathrow Airport on 21 March increased non-fuel unit costs by approximately one percentage point,” said IAG.
On May 8, 2025, National Energy System Operator (NESO) published an interim finding from the review into the North Hyde Substation outage.
The report said that the “root cause” of the fire remains unknown, with London Fire Brigade and National Grid Electricity Transmission continuing to conduct forensic investigations.
The Metropolitan Police Service has previously confirmed that it had “found no evidence to suggest that the incident was suspicious in nature”.
The report stated that on March 21, 2025, around 12 hours after the fire broke out, power had been restored to all of Heathrow Airport’s terminals and re-energization of the wider Heathrow network was completed by 14:23.
“Once power had been restored, there was a period of safety checking to allow all parties operating the airport to access their systems and to ensure safety critical systems were fully operational prior to passengers arriving at the airport,” said NESO.
A small number of flights began operating from the airport again during the early evening of March 21, 2025.
