Heathrow Airport, Europe's largest airport and the fifth busiest in the world by passenger volume, resumed limited flight operations late afternoon on March 21, 2025, following a twenty-hour closure caused by a fire at an electrical substation in Hayes, a district west of London.

Initially, long-haul flights were allowed to depart, but full traffic recovery was expected to take several days.

The disruption impacted approximately 1,350 flights, affecting nearly 300,000 passengers, as numerous aircraft were diverted to other capitals such as Madrid, Paris, and Dublin, stranding thousands of travelers.

The fire at the substation not only halted operations but also temporarily deprived about 100,000 residents of electricity, necessitating evacuations from nearby homes.

While British authorities have stated that there are no indications of criminal activity behind the incident, an investigation has been launched to determine the cause.

Speculation has arisen amidst concerns over critical infrastructure vulnerabilities, particularly given the context of geopolitical tensions and fears of hybrid warfare.

Reports indicate that while Heathrow has redundant systems in place to ensure operational continuity, the incident highlighted potential weaknesses in emergency response capabilities.

The power outage effectively grounded operations at one of the world’s major air travel hubs, which handled nearly 84 million passengers the previous year.

Concerns regarding security have surged, particularly in light of recent events in Europe related to increased aggression from Russia against nations supporting Ukraine.

Some commentators have raised questions about whether the power outage could be connected to broader security threats, although London officials continue to assert the investigation is standard procedure.

On March 21, significant disruptions were reported across the aviation sector, with alumni of Ryanair taking advantage of the situation, announcing additional flights from Dublin to London Stansted.

This strategy aimed to accommodate the surge in demand from passengers affected by the closure of Heathrow.

In contrast, airlines operating at Heathrow had to cancel numerous flights, leading to adverse effects on share prices across the airline industry, including declines for major carriers such as Air France, easyJet, and Lufthansa.

British Airways recommended that passengers refrain from traveling to Heathrow until further notice, while airport officials utilized social media to provide updates on the situation.

The overall impact of the incident on air travel is expected to be felt for some time as airlines and airports adjust to the ongoing situation.