From Easyjet website
A general strike has been announced in France, commencing on the 15th September 2010 and lasting until 23:59 on the 23rd September. French Air Traffic Control will be taking part in this strike action.
As France is centrally located in Europe, this is affecting flights not only to and from France, but also those operating through or near French airspace.
These issues are impacting all airlines and easyJet is working hard to minimise disruption to our passengers during this time.
We therefore strongly advise all customers to check the status of their flight before travelling to the airport.