Ryanair has warned that 26 of its services will not run tomorrow as a result of industrial action by French air traffic controllers.
A number of British airlines have also started cancelling flights ahead the a six-day strike.
UK carrier EasyJet says it is expecting significant disruption to its schedule.
While British Airways has cancelled three Tuesday flights from Heathrow Airport in London to Lyon, Marseille and Toulouse.
The industrial action starts tomorrow and is set to last until the end of Sunday.
The strike is in opposition to the "Single Sky" initiative of the European Commission. It is is aimed at lessening congestion in European airspace and accommodating expected increases in traffic, by allowing planes to fly more direct routes across the continent.
France is set to join Germany, Switzerland, Belgium, the Netherlands and Luxembourg to create a regional authority.
But this proposal has come under fire from unions that are worried about the consequences of the plan, including its effect on jobs.
The networks handle some 9 million flights each year in a region with about 440 airports.
