Industrial action by air traffic controllers in southern France on Saturday and Sunday is likely to cause disruption to flights across the Continent.
Staff at the Marseille Area Control Centre are due to walk out from 6.30am on Saturday for 48 hours.
Eurocontrol said the minimum level of service will be provided in the Marseille Flight Information Region.
While the walk-out is most likely to cause delays and cancellations to flights in southern France, it could also affect flights that cross French air space.
Ryanair says it is expecting some disruption to flights, mainly in France, Italy and Spain – but it should also be noted that these might be caused by strikes by its own crew, which are due to take place this weekend.