Ground staff and cabin crew at Spain's Iberia have begun 15 days of strikes in protest at plans to lay off 3,800 workers.
The airline says the stoppages, to be staged over three weeks, will lead to more than 1,200 flight cancellations, including 236 on Monday.
A government decree on minimum services guarantees 90% of long-haul flights, 61% of medium-haul and 46% of domestic flights.
Unions representing most Iberia workers, but not pilots, called the strikes between February 18 and 22, March 4 and 8 and March 18 and 22.
The company says it has found seats on other flights for most of the 70,000 passengers affected.
Iberia - Lineas Aereas de Espana SA - claims economic difficulties oblige it to make lay-offs.
Iberia is linked with British Airways in International Airlines Group.