On April 28, around 12:30 p.m. (CEST), a massive power outage swept across Spain and Portugal, bringing the countries to a standstill and disrupting airport and train service. Spain remained in a state of emergency for April 28 and 29, but more than 99 percent of energy demand in Spain had been restored, while all power was restored in Portugal.

While there were no complete closures at airports across Spain and Portugal, many flights were canceled — on Monday, more than 500 flights of them. Lisbon (LIS) was most affected, grounding 45 percent of departures. Seville (SVQ) canceled a third of its departures, while Madrid (MAD) and Barcelona (BCN) grounded about 50 flights.

TAP Air Portugal advised travelers not to go to impacted airports, suspending flights at Spanish and Portuguese airports. Air Europa also released a statement to customers, advising them to anticipate delays. At least one British Airways round-trip flight from London (LHR) was canceled. These cancellations and delays left many travelers stranded in Spain and Portugal.

Beyond flights, the outage also affected other aspects of travel. Train services were impacted, with some rail services still suffering into April 29. Some passengers spent the night in train stations. Even vacation rentals suffered: Airbnb properties with electronic locks stopped working, locking out guests from their accommodations.

The Madrid Open was also suspended April 28 due to the outage, with play resuming on an altered schedule on April 29. Mobile networks, WiFi, ATMS and card machines were rendered inoperable in the blackout. Even the televised debate between Portugal’s Prime Minister Luís Montenegro and Socialist Party’s Pedro Nuno Santos was postponed.

The cause of the outage remains a mystery. No unusual meteorological or atmospheric occurrences were reported by Spain’s meteorological agency, and no sudden temperature fluctuations were recorded at any weather stations. Foul play was also dismissed by Portugal’s National Cybersecurity Center April 28.

That said, Dan Jorgensen, the European Union’s energy commissioner, announced on April 29 that Brussels will be conducting a “thorough investigation” of the blackout.

The blackout closely follows another European blackout, which affected London Heathrow Airport’s power supply and forced the airport to close for 18 hours, stranding more than 200,000 passengers March 21.

Did the Spain and Portugal outage affect your travels? What are your thoughts on these two recent outages? How do you think airlines, airports and other transportation services should better adapt to these possible incidents? Email us at letters@globaltravelerusa.com. Please include your full name and location.