Spanish flag-carrier Iberia has petitioned courts in Spain in an attempt to prevent pilots from taking further industrial action.
Pilots union SEPLA has called 30 days of strikes later this year to protest against the recent launch of low-cost carrier Iberia Express.
Unions see the new business as a threat to jobs, with up to 30 days of strikes called for between April and July.
Company bosses say it is vital to increasing profitability at the International Airlines Group-owned carrier.
In an attempt to prevent the strikes, and to seek compensation for previous industrial action in 2011, Iberia petitioned the High Court in Spain to ban the strikes.
Iberia is requesting the court declare the strikes abusive and illegal, arguing they target peak travel periods.
“Such strikes have a huge cost for the airline and almost none for the striking pilots,” Iberia said in a statement.
Iberia said damages were currently estimated to cost more than €3 million per day.
Pilots held 12 days of strikes between December and March.
New action is planned every Monday and Friday from April 9th to July 20th.
Action has also been a launched against cabin crew union STAVLA, which it accuses of taking industrial action in solidarity with the pilots.
Iberia plans to transfer 40 planes from the main airline to the low-cost subsidiary, eliminating 8,000 jobs, pilots argue.