The April 28, 2025 blackout across Spain and Portugal was not a distant power-sector curiosity for aviators. It was a live demonstration of how a rapid, system level electrical failure can propagate into aviation operations through degraded communications, stopped ground systems, and constrained airport capacity. Public investigations concluded the proximate technical trigger was a sudden voltage instability and a cascade of disconnections in southern Spain, amplified by insufficient synchronous generation and planning shortfalls at the transmission level. Those findings matter because they show the problem sits outside any single airport or tower and can remove grid power to entire regions in seconds.

Operational picture from the day: airports remained open by switching to emergency supplies, but communications nodes provided by commercial telecoms were disrupted and radar and voice links degraded in some sectors. ENAIRE reported that their centres relied on redundant power systems and contingency procedures to preserve safety, and that telecommunications failures were a key limiter while they recovered connectivity. In short, safety was preserved because contingency systems and procedures worked, but traffic capacity and normal operations were heavily constrained, creating cascading delays and cancellations.

From the cockpit and the tower those facts translate into three hard lessons. First, redundant on-site generation alone is necessary but not sufficient. ATC centres and airport operational systems also depend on telecom provider nodes, fuel supply, and external support that can be single points of failure. Second, autonomy time matters. A generator that lasts a few hours buys time but not resiliency for a multi‑hour, whole region outage. ENAIRE pointed out its own generator autonomy can reach multiple days, and that capability materially eased recovery at the centres affected. Third, contingency is only effective when exercised and when the supply chain behind it is robust. Fuel deliveries, spare parts, and alternate communications must be part of a validated continuity plan.

If you accept that large scale grid events are a plausible hazard, aviation regulators and operators must move from voluntary preparedness to minimum mandatory requirements. Below are practical, operationally focused mandates I would press for now.

1) Minimum on-site autonomy: require air navigation service provider core facilities, major airport operational centres, and critical CNS nodes to have a certified minimum of 72 to 96 hours of autonomous power at full operational load, with testing evidence recorded annually. ENAIRE’s existing multiple‑day autonomy shows this is achievable and operationally valuable. Shorter targets invite the same scramble we saw in April.

2) Dual fuel supply chains and refuel agreements: mandate redundant fuel contracts and automated refueling arrangements so on‑site generators are refueled within defined time windows during prolonged outages. The rule should require written supply agreements with two independent suppliers and fuel reserve rotation procedures to prevent stale or contaminated fuel. This is a supply chain problem, not a generator problem.

3) Telecom resilience for aeronautical links: require that telecommunications providers who host aeronautical voice and data nodes maintain the same resilience standards expected of ANSPs. That means dedicated backup power at telecom nodes that serve CNS links, diverse physical routing, and an aeronautical service level agreement that compels rapid restoration. ENAIRE specifically called out degraded telecom links as a limiting factor during the Iberian event.

4) Battery/UPS bridging and black start coordination: require modern UPS and battery energy storage systems sized to bridge the gap between grid failure and generator pickup for every critical system, and mandate coordination exercises with grid operators and black start-capable plants. Portugal’s subsequent moves to expand black start capability underscore the importance of restart planning at the national level.

5) Regular, regulator-verified continuity drills: require live and table top drills at least twice per year covering full loss of external power, comms failure, and staged fuel disruption, with participation from ANSPs, airport operators, airlines, telecom providers, and national grid authorities. Drill results should be reported to the civil aviation authority and be subject to corrective action plans. The technical teams ran contingency procedures in April. Let us make those procedures auditable rather than ad hoc.

6) EU harmonized minimums and funding support: ask EASA and the European Commission to publish harmonized minimum resilience standards and create funding windows for smaller airports to meet them. The Iberian outage showed national grid effects cross borders and that piecemeal rules will leave gaps. A harmonized baseline prevents safety differentials between states and enables pooled procurement or financing for resilience projects. International coordination also improves cross border recovery when one state needs imports to restore supply.

Practical implementation notes for operators and pilots

  • For ANSPs and airport ops: use the April event to map every external dependency for each critical system, assign ownership, and formalize service‑level contracts. If your remote radar site depends on a single commercial telecom node for voice or data, replace that link with a second path or satellite fallback.

  • For airline operations control and flight crews: ensure dispatch has contingency plans tied to the mandated autonomy windows. If an airport declares reduced capacity due to a grid event, have clear diversion and crew recovery plans that anticipate multi‑day local impacts.

  • For regulators: require evidence, not promises. A certificate that a generator exists is no substitute for a documented refuel chain and a successful full‑load run in simulated outage conditions.

The April 28 outage was a wake up call. Aviation survived because people and systems improvised under pressure and because contingency equipment existed. We should not treat improvisation as the strategy for the next regional blackout. We need measurable mandates that cover power, fuel, communications, and exercises. Those mandates will cost money. They will also prevent the kind of operational paralysis and safety risk that comes when entire metropolitan areas suddenly lose the grid. Invest now in resilience that preserves safety and keeps traffic flowing when the lights go out. The alternative is more nights of stranded passengers, interrupted cargo chains, and last minute triage of services that are, by definition, critical.