National strike will take place in France on September 12, 2017, and will also affect air traffic control. This will not only affect flights within France but may delay or cancel flights that need to use French air space.
Air France is allowing passengers change their flights including origin/destination if they are scheduled to travel on September 12.
You can access Air France’s page for strike information here.
Here’s what their rebooking guideline lines are:
If you have a valid Air France ticket, issued on or before September 09, 2017, for a flight September 12, 2017, departing from or arriving in one french destinations, you can anticipate at no extra cost between 10 and 11 september or postpone at no extra cost onto a later flight from September 13 until September 15, 2017 included.
Save time by changing your booking directly online, in the “Your reservations” section of the website or in the mobile app. You can change your booking at no extra cost for the same travel cabin. You can also contact your travel agent.
You may also choose to postpone your flight to after 15 September 2017, change your country of destination or origin or cancel your trip. In this case, you will be entitled to a non-refundable voucher valid 1 year for Air France, KLM or HOP! flights.
This national strike is due to the new president trying to push through some labor reforms (likely needed).
If your flight ends up canceled, you are obviously entitled to full refund. Airlines in Europe are bound by the EC 261/2004 legislation that requires them to provide duty to care even in the case of strikes.
Airlines are required to rebooked affected passengers to their final destination even on on competing services and provide accommodations and meals in case of long delays. Cash compensation due to delays doesn’t apply, however.