Some 185 flights that had been due to depart Portugal on Monday (28 April) and a further 205 from Spain were cancelled owing to the outage across the Iberian peninsula. Another 187 arrivals into Portugal and 208 into Spain were also cancelled.
The power went out shortly before midday and only began to be restored in the evening, with vast knock-on effects for travel to and from – and within – both countries with road and rail networks affected.
According to aviation analytics firm Cirium, 25 flights from the UK to Portugal were cancelled on Monday, and 11 to Spain. In total, more than 500 flights from the UK had been scheduled to depart for Spain (399) and Portugal (105) on Monday.
The problem was limited to the Spanish and Portuguese mainland, with no reports of there being issues affecting the Canary and Balearic Islands, or Madeira and the Azores.
In an update issued at 10.20am on Tuesday, Jet2.com and Jet2holidays said all of its flights were due to operate as normal on Tuesday.
"On 28 April, there was an electrical power outage which affected mainland Spain and Portugal," it said. "Our teams have been closely monitoring the impact of this, and at present, all Jet2.com flights are operating as normal today (29 April)."
The airline and operator added passengers would be informed of any changes by test and email.
EasyJet confirmed it had been unable to operate three flights that had been due to return to the UK on Monday, two to Bristol and one to Luton. It said the outage was had affected some return flights from Lisbon and Madrid, but confirmed its flying programmes at Porto and Faro airports were operating as planned.
However, it stressed the situation "remained fluid". Passengers in Spain or Portugal unable to travel on Monday were being provided free transfers onto alternative easyJet flights within 72 hours, or a flight voucher.
Tui said it was closely monitoring the situation, confirming the Balearic, Canaries, Azores and Madeira were unaffected. The group said anyone travelling to or from mainland Spain or Portugal on Monday or Tuesday should check the status of their flight before travelling.
It added teams were standing by to assist passengers with their travel arrangements should they experience disruption getting to their departure airport or miss their flight owing to the outage.
A state of emergency remained in place across Spain on Tuesday morning (29 April), allowing the country’s regional authorities to request national government assistance should they need it.
At the height of the crisis on Monday, traffic lights in several major cities – including capitals Madrid and Lisbon – stopped operating, metro systems and local transport networks were plunged into darkness and regional and inter-city rail services were halted.
Speaking to BBC Radio 4, Kristian Ruby, who heads up the trade body representing Europe’s power industry Eurelectric, said there had been an issue with the connection between France and Spain, which effectively disconnected Spain from the European power grid.
The Foreign Office has updated its travel advice for Spain, Portugal and Andorra. "We are aware of reports of power outages across Andorra, mainland Spain and mainland Portugal and are monitoring the situation," read the updated advice.
"There may be travel disruption, check with your tour operator or airline for more information before travelling."
Julia Lo Bue-Said, chief executive of The Advantage Travel Partnership, said that the outage would likely prove "hugely disruptive" for "a large number of travellers", despite holiday hotspots such as the Balearics and the Canaries not being affected.
She added issues with access points and ground transportation would likely have longer-lasting knock-on effects.
Early on Tuesday morning, there were a handful of cancellations at Lisbon airport, and a small number at Porto and Faro.