A large-scale power outage swept across Spain, Portugal, and parts of southern France on Monday, leading to significant disruptions to air traffic and critical infrastructure. Flights to and from Madrid, Barcelona, and Lisbon were notably affected, according to the European air traffic agency Eurocontrol.

Eurocontrol stated that it was still "too early to say how many flights would be affected," as assessments continued throughout the day.

The blackout, which began around 12:30 p.m. local time, impacted not only airports but also metro systems, train services, traffic control, and communication networks across major cities. Public transportation in Lisbon and Madrid came to a halt, with metro lines evacuated and traffic gridlock reported in many urban areas. Emergency generators were activated in hospitals to maintain vital services.

In Portugal, the situation remained particularly critical. Lisbon's electricity grid operator, REN, confirmed that the extent of the disruption made it difficult to forecast a timeline for full restoration. "At this time it is still impossible to predict when the situation will be normalised," REN said in an official statement, adding that it had "all resources deployed" to resolve the crisis.

Lisbon and Madrid are climbing on our disruption ranking, because of the widespread electrical outages affecting Spain and Portugal. pic.twitter.com/6hmvpN515v

— Flightradar24 (@flightradar24) April 28, 2025

Grid Collapse

Early investigations suggest that the blackout may have been triggered by severe oscillations in high-voltage power lines, possibly caused by rare atmospheric conditions, leading to cascading failures in the interconnected European grid. However, authorities have not ruled out the possibility of a cyberattack. Spain's National Cybersecurity Institute (INCIBE) is reportedly looking into the matter, though no conclusions have been reached yet.

Spain's grid operator, Red Eléctrica, estimated that full restoration could take between six to ten hours, although work was ongoing throughout Monday evening. Meanwhile, authorities urged residents in affected areas to remain calm and avoid unnecessary travel.

Read more: Europe struggles with costly energy shift amid crisis fallout: NYT

The blackout has exposed vulnerabilities in the region's energy infrastructure, especially as European countries continue to integrate renewable energy sources. Officials are now calling for a comprehensive review of cross-border grid stability to prevent similar occurrences in the future.