Aviation in several European states has been disrupted as air traffic controllers walk out as part of a coordinated wave of strikes.
Action by the European Trade Union Confederation has seen workers down tools in Spain, Greece, Portugal and Italy, with other protests planned in Belgium, Germany, and France.
Organisers are demanding an end to austerity measures, which they say are hindering economic growth and causing unnecessary hardship among members.
Rising unemployment is another key concern, with up to a quarter of the workforce in Spain presently without jobs.
As a result of the action, airlines across the continent have been cancelling and rescheduling flights.
Spain and Portugal – where strikes started at midnight - have been particularly hard hit, with airlines urging passengers to check before they travel.
In Italy, transport workers are expected to join a four-hour national strike, though airlines said they did not expect flights to be disrupted.