A strike by air traffic controllers in France, which started last night, is disrupting the travel plans of 75,000 people.
Flights, including those of easyJet, British Airways and Ryanair, will be affected for 35 hours.
The walk-out, part of a national public sector strike, is due to finish at until 6am tomorrow (Friday).
French authorities have asked airlines flying to and from several airports in France to reduce their flight schedules by 30% in advance of the strike, forcing the cancellation of around 550 flights.
Industry lobbying group, Airlines for Europe (A4E), warned of major delays, re-routings and further cancellations.
It said this is the third ATC strike in Europe so far this year.
Last May, a similar public sector strike in France caused the cancellation of around 900 flights, part of a record year in which travellers were subjected to some 30 ATC strike days in total, 22 of which originated in France.
"Politicians must act immediately to protect the rights of consumers and prevent long term damage to European economies," said Thomas Reynaert, managing director A4E.
"A4E is urging French policymakers, in particular, to improve the predictability of traffic strikes’ impact. By putting in place a 72-hour individual notification requirement for employees wishing to strike, passengers would be better informed about the expected disruptions to their journeys."
Ryanair said it expects flight delays and cancellations and said all customers affected were sent an email and SMS message on Tuesday.
British Airways said the strikes will bring ‘another wave of unnecessary disruption’.
"Like all airlines, we have had to cancel a number of flights but will be using larger aircraft where possible, on other services to help affected customers," it said.
EasyJet said it had also cancelled some flights to France and added: "Flights that do not operate through France may still be affected as 65% of easyJet flights operate through French air space and may be delayed before arriving for your flight.
"Please also be aware that public transport services will be affected by the strike. We recommend all customers allow plenty of extra time to get to the airport and consider alternative transport options where possible."
