Ryanair and Easyjet are urging governments and the European Commission to take action over a strike by French air traffic controllers.
Hundreds of passengers flying with Ryanair, Easyjet and British Airways will continue to face flight cancellations until Tuesday.
Ryanair said it had cancelled about 200 flights while Easyjet said it had cancelled 145 flights on Monday.
The strike is in protest at planned staff cuts.
It has been called by UNSA-ICNA, the third largest French union for air traffic controllers, which has said the cuts are unrealistic due to the "operational needs of control centres".
The union said air traffic was going to grow and it criticised the French Civil Aviation Authority for being too slow to invest in new technology.
Ryanair and Easyjet are two of the five founding members of the newly formed lobby group, Airlines for Europe.
The others are Air France KLM, International Airlines Group and Lufthansa.
Easyjet said in a statement that the group was working with the other carriers "to call on governments and the EU to develop an action plan to minimise the impact of air traffic control strikes on passengers."
Robin Kiely, head of communications at Ryanair, said: "It's grossly unfair that thousands of ordinary European consumers have their travel and holiday plans disrupted by the actions of a selfish few."
The airliner, which has been the most outspoken of the carriers, repeated its demand that the European Commission ban air traffic controllers from striking to prevent passengers being "held to ransom."
Ryanair said the strike was not only affecting travellers going to and from France but also those flying through French air space.
It wants other air traffic controllers in Europe to be allowed to manage flights over French airspace during such action.
The airline also urged consumers to sign its "Keep Europe's Skies Open" petition to the European Commission.
When it has obtained 1m signatures it said it planned to present it to the EU Commission and the EU parliament.
Passengers travelling from Gatwick, Heathrow and Luton Airport are being forced to wait for or reschedule their flights due to the action which started on Sunday.
The DGAC, France's Civil Aviation Authority, said it had requested a third of flights were cancelled to and from Paris-Orly and other regional airports on Monday.
Air France warned of last minute cancellations and delays but said it planned to operate its long-haul services and all flights to and from Paris Charles de Gaulle, which is unaffected.
British Airways refused to disclose how many flights would be affected by the strike, but said it was doing "all we can to minimise disruption to customers affected".
It said it was using larger aircraft where it could.
Gatwick Airport warned customers to check with their airline for flight updates.
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