BA and Ryanair have cancelled flights on Wednesday and Thursday as French traffic controllers start their fourteenth bout of industrial action this year, reports BBC News.
Ryanair cancelled 22 flights on Wednesday night and 72 on Thursday.
Aer Lingus also said a number of flights have been cancelled.
Flights that normally route through French air space are affected. Passengers are advised to check the status of their flights.
BA declined to say how many flights had been affected, saying the information goes out of date quickly.
BA said: "Unfortunately, if the threatened strike does go ahead, we will have to cancel some flights, and other short haul flights may also experience some delays and disruption, given how many flights would normally use French airspace each day."
It said it would use larger aircraft, where possible, to help affected customers.
Ryanair warned there could be more delays.