Madrid (CNN) -- Pilots for the Spanish airline Iberia resumed their strikes on Monday, forcing the cancellation of 124 flights, in a grievance over the company's new low-cost carrier, Iberia Express.
The pilots see a threat to their jobs or working conditions from the budget airline, which started flying on March 25 despite 12 one-day pilots' strikes earlier this year.
The earlier strikes cost the company 36 million euros ($47 million). Now the pilots have planned 30 more one-day strikes, every Monday and Friday, through July 20.
On Monday, the 124 canceled flights were 38% of Iberia's 330 scheduled flights, a percentage of cancellations similar to the earlier strikes.
Iberia, which had advance notice of Monday's strike, tried to place passengers, many returning from Easter vacations, on alternative flights.
Iberia lost 98 million euros ($129 million) last year, especially on short and medium-range flights in Spain and nearby in Europe. It launched Iberia Express aiming to cut the costs of operating those routes, an Iberia spokeswoman said.
But a spokeswoman for the pilots union said the new budget airline violates key points of a previous agreement between pilots and Iberia.
The union has offered for pilots to take deep salary cuts if flying for Iberia Express, but negotiations broke off last month.
Iberia has filed a court complaint, seeking to stop the strikes and demanding compensation. A ruling could still be weeks away.
Iberia employs about 1,400 pilots. The airline has made deals with most other employees regarding the budget carrier.
Iberia Express currently serves just four routes, all in Spain: Madrid to Palma de Mallorca, Malaga, Seville and Alicante. But by the end of this year, it expects to carry 2.5 million passengers to 20 destinations, including Dublin, Ireland; Amsterdam, Netherlands; and Naples, Italy. The company would have 14 planes and 500 employees.