Budget airline Ryanair has cancelled 190 flights scheduled for Friday because of strikes by cabin crew in Spain, Belgium, the Netherlands, Portugal, Italy and Germany.
The flights represent 8% of the 2,400 originally scheduled.
The airline said in a statement that all affected customers have received emails or text messages informing them of the cancellation.
About 30,000 customers are likely to be affected out of 450,000 set to travel.
Ryanair’s Kenny Jacobs apologised to customers affected by strikes, "which we have done our utmost to avoid".
Ryanair cancelled hundreds of flights last year due to problems with pilot scheduling, and strikes have led to more cancellations this summer.
The budget airline and pilots have wrangled over working conditions, base transfers and annual leave.