Easyjet's Spanish pilots walked out on Friday, calling for the reinstatement of conditions they enjoyed before the coronavirus pandemic, two weeks after a strike by the low-cost carrier's cabin crew had resulted in a deal.
Coming at the height of the summer tourist season, the new Easyjet stoppages will add to the problems facing the sector.
Cabin crew at budget rival Ryanair have been staging 24-hour walkouts since June, which are likely to continue until January 2023, unions said.
The Easyjet pilots, for their part, are staging a first three-day strike from Friday at the airports of Barcelona, Malaga and the Mediterranean islands of Palma de Majorca and Minorca, the SEPLA union said.
Two more three-day walkouts are planned later in August.
"This is the only possible alternative for the pilots' representatives, after more than six months of negotiations, at which the company has rejected all proposals made," the union said.
The airline cancelled eight flights on Friday, most of them from Barcelona, Spain's second-busiest airport.
"During the worst months of the pandemic, we agreed to lower our salaries to guarantee not only jobs, but the survival of the company itself in Spain," the union said.
Now, however, the company "refuses to recover the working conditions.
"We are not asking for anything that we did not have two years ago," said a union spokesman.
In late July, EasyJet said it took a sizeable financial hit from sector-wide disruptions, notably staff shortages, but still slashed quarterly losses as demand recovered.
Just days later, EasyJet cabin crews ended their strike, after reaching a deal with management to raise wages by 22 percent over three years.