Aviation workers in France have started a three-day strike to protest the streamlining of traffic flows in European airspace. Colleagues in 10 other countries are to follow suit.
Two airports in Paris, Charles de Gaulle and Orly, and others at Nice, Lyon, Marseille and Toulouse were affected, but there was no big chaos.
The French Civil Aviation Authority said the first leg of the strike on Tuesday saw about 1800 flights cancelled.
Deutsche Welle reports airlines were asked to reduce their flights by 50 percent, the DGAC added.
Long-haul flights were hardly affected by the strike. Air France said it cancelled only short and mid-range tours.
Lufthansa announced it stopped 174 flights on Tuesday, but Air Berlin indicated its Paris and Nice routes were not affected by the stoppage at all.
Air traffic controllers said they were protesting a planned restructuring of Europe's airspace control system under a ingle European sky programme. They fear it would lead to more difficult working conditions and job cuts.
Critics also say the plan goes a step too far in breach of national sovereignty.