Surging inflation across Europe has led to millions of workers struggling with a higher cost of living, prompting trade unions to demand higher wage increases often backed by strike calls.
Airlines and airport operators across Europe have also struggled with staff shortages to handle the flow of passengers as demand for travel bounces back with the end of most COVID-19 restrictions. Workers at several other airlines, including British Airways, are also planning strikes this summer.
Ryanair cabin crew unions in Belgium, Spain and Portugal called a three-day strike starting on Friday. Staff in France and Italy were expected to walk out over the weekend. Crews in Spain are set to strike again on June 30 and July 1-2.
Workers say the Irish airline does not respect local labour laws covering issues such as the minimum wage and urge Ryanair's bosses to improve working conditions.
"Conditions are terrible," said Ricardo Penarroias, president of SNPVAC, the union behind Portugal's walkout. "A crew member is not even allowed to take a bottle of water on a flight."
Ryanair did not immediately respond to a request for comment on Friday, but told Reuters last week it had negotiated labour agreements covering 90% of its staff across Europe and that it did not expect widespread disruption this summer.
While much of the labour unrest has focused on the transport sector as it deals with a return to travel after pandemic lockdowns, there are signs of that spreading to other sectors - French trade union CGT is organising a one-day strike on Friday to seek higher wages for oil refinery workers after talks with operator TotalEnergies broke down.
With inflation running at more than 8% in the euro area, a 40-year-high of 9.1% in Britain, and in double digits across some central and eastern European economies, authorities are worried of a wage-price spiral developing in which higher wage demands add to inflationary pressures.
European Central Bank chief Christine Lagarde has warned that the longer inflation remains high, the more likely it will influence wage negotiations.
Pilot and cabin crew unions of Brussels Airlines, the Belgian subsidiary of Lufthansa, also started a strike on Thursday. Over the three days, Brussels Airlines expects to cancel about 60% of its 533 flights.
Belgium is likely to be the hardest hit by the Ryanair strike, with local media saying 127 flights at Brussels' Charleroi airport would be cancelled, affecting 21,000 passengers.
In Lisbon, two flights were cancelled on Friday so far, both to Brussels. A total of 18 Ryanair flights between Brussels and Spanish cities were cancelled on Friday and Saturday, Spain's cabin staff union, USO, said.
In Spain, the government forced the company to operate 73%-82% of flights over the strike period to maintain minimum services, obliging most to go to work.
The SNPVAC union said not many flights would be cancelled from the Portuguese airports because the airline placed strikers on stand-by and asked cabin crew in other countries to replace them. Ryanair has said SNPVAC only represented 3% of its staff in Portugal.
Outside Lisbon airport, American Michael Rossides, 59, said he booked an EasyJet flight because he thought Ryanair would cancel but that ended up not happening.
"We have wasted a fair amount of time, an extra couple of hours, and a few hundred dollars," he said.
(Reporting by Catarina Demony, Patricia Rua and Miguel Pereira in Lisbon, Inti Landaro in Madrid and Philip Blenkinsop in Brussels; Editing by Alex Richardson)
By Catarina Demony and Miguel Pereira