Air traffic controllers across Europe plan to strike next week.
Passengers due to fly anywhere on Thursday 10th October are being warned that it is highly likely their flight will be delayed or cancelled.
Workers in Germany, France, Spain, Portugal, Albania, Croatia, Malta, Cyprus, Ireland, Italy, Macedonia, Poland, Bulgaria, Romania, Slovenia and Switzerland will be joining the 'action day.'
They are protesting against plans to streamline European air traffic control, which they say will threaten flight safety.
Passengers are being urged to contact their travel agent or airline.