The recent blackout that paralyzed London-Heathrow airport last March (see AVIONEWS) had a significant impact on International Airlines Group (IAG), the holding company that also includes major airlines such as British Airways, Iberia and Aer Lingus. According to what was announced today, May 9, 2025, on the occasion of the publication of the financial results of the first quarter of the year (see AVIONEWS), the power outage caused by a fire in an electrical substation is estimated to have affected IAG's accounts for approximately €50 million in lost operating profits (equivalent to 56 million dollars).

The incident, which occurred shortly before 11:30 pm local time on March 21, involved London Fire Brigade responding to the North Hyde substation, where a fire had irreparably damaged three transformers in the power grid. This event caused a widespread power outage affecting around 70,000 households and forced Heathrow Airport, the main hub for British Airways, to close almost completely for almost 24 hours.

In its first quarter results, IAG highlighted how this "unexpected event" had a "negative impact" on its operating costs, quantifiable in a reduction of approximately one percentage point of the profits forecast for the first three months of the current year. In particular, the Group specified that "the impact of the closure of London Heathrow airport on 21 March increased non-fuel unit costs by approximately one percentage point". In parallel, on 8 May 2025, the National Energy System Operator (NESO) released the preliminary results of its analysis of the outage at the North Hyde substation. The report indicates that the "root cause" of the fire remains unknown at this time, while forensic investigations conducted by London Fire Brigade and National Grid Electricity Transmission are still ongoing. The Metropolitan Police Service had previously ruled out malicious intent.

The report by NESO also outlined the timing of the restoration of operations. Around 12 hours after the fire broke out, power was restored to all terminals at Heathrow Airport, with its network fully restored by 2.23pm on 21 March 2025. “Once power was restored, a safety check period was carried out to allow all parties operating the airport access to their systems and to ensure that safety-critical systems were fully operational prior to passengers arriving at the airport", NESO said. A limited number of flights were able to resume operations from the airport in the late afternoon of 21 March.

British Airways, as the largest carrier operating from Heathrow, with a strong presence in Terminals 3 and 5, has been particularly affected by the closure of the airport, negatively impacting the financial results of its parent Group, IAG. Today's statements from the Group's management underline the significance of the event and its direct impact on the Group's operating costs in the first quarter of 2025.

On the fire at Heathrow see also AVIONEWS 1 (and related) and 2 (and related).