A departure information board with cancelled flights is pictured in the closed Warsaw airport
Hundreds of flights through Europe have already been canceled ahead of a planned three-day strike by French air traffic controllers.

Travelers crossing through Europe by air are about to hit a three-day patch of turbulence as air traffic controllers in France initiate a widespread protest Tuesday against a proposal by the European Commission to accelerate the integration of air-traffic-management systems across the continent. While France will be the epicenter of delays and cancellations through early Friday morning, many other European countries are expected to see more limited labor actions this week that could exacerbate delays.

Contingency plans are well under way, including a request by France’s civil aviation authority that airlines serving Paris, Bordeaux, Lyon, Nice, Marseille and Toulouse slash their schedules by at least 50 percent.

Air France said Monday afternoon that it expected to transport all of its customers on long-haul flights to and from Paris Tuesday. It recommended that all travelers with a reservation on short- and medium-haul flights, however, postpone their trips during this period at no extra cost, as “last-minute delays and cancellations can be expected.”

“Air France is doing everything to minimize the inconvenience this strike action may cause,” the airline said. “Airport teams and Air France commercial staff remain mobilized to inform customers.”

The French flag carrier said it would notify customers of delays and cancellations on their mobile phones or by email and its AF Connect service, which is available in 13 languages for passengers worldwide.

Lufthansa, meanwhile, said delays and cancellations of flights into and out of France were to be expected through Thursday. The German airline had already axed nearly 160 flights Monday evening, and said affected passengers could refund or rebook their flights free of charge online or at a call center.

Low-cost carrier Easyjet said it was forced to preemptively cancel about 128 flights for each day of the strike, which is set to begin at 6 a.m. local time on Tuesday and continue through Friday at 5:59 a.m. Thirty-five of those flights were scheduled into or out of Paris Orly and Paris Charles de Gaulle, while Nice had 17 departures and arrivals, Toulouse 11, and Lyon nine.

All passengers scheduled to travel on canceled flights will be advised via email, and details of the cancellations can be found on Easyjet’s Flight Tracker webpage. Affected customers are eligible for a full refund or free transfer to another flight.

Low-cost rival Ryanair canceled 102 scheduled flights for Tuesday. The carrier said it would announce flight cancellations for Wednesday and Thursday as needed 24 hours ahead of time. All affected passengers will be notified by email or SMS with information detailing their rerouting or refund options.

Ryanair publicly condemned the EU Commission’s “continuing failure to act on its repeated call for the removal of the right to strike from Europe’s air traffic controllers, who are again attempting to blackmail Europe’s passengers with strikes.”

“It is unacceptable that the skies over Europe are repeatedly closed or flights are delayed by the unjustified strike action of tiny numbers of air traffic controllers,” Robin Kiely, head of communications at Ryanair, said. “These public servants are among the most overpaid and protected in Europe and yet they repeatedly opt for the strike weapon as a first, rather than a last resort.”

Kiely said the solution to the problem was simple: Remove their right to strike in the same way that air traffic controllers in the U.S. are prevented by law from striking. “Until then, it is up to the EU Commission and French government to ensure there are no further cancellations on Wednesday and Thursday as a result of these unwarranted strikes.”

The demonstration was scheduled to coincide with a speech planned for Tuesday by the European Union’s transportation commissioner, Siim Kallas, who's expected to announce changes to European legislation that would speed the transfer of responsibility for a number of air-traffic-management functions away from the European Union’s member states to a central body in Brussels. Included in the proposal are stricter performance-improvement goals for air traffic controllers aimed at lowering management fees and reducing congestion.

The Brussels-based European Transport Workers’ Federation, which represents more than 25,000 workers involved in air-traffic management, has indicated that unions in more than a half dozen countries, including Belgium, Hungary, Italy and Portugal, could join in the protests. These actions, however, would likely provoke delays more than outright cancellations.

All travelers flying through European airspace over the next three days are encouraged to check for updates directly through airlines’ websites and social media. Under European Union regulations, all passengers are entitled to either a full refund of the unused portion of a canceled flight or a chance to be re-routed to a destination as soon as possible, though many airlines also offer rebooking at a later date at no additional cost. Regulations also state that, when a flight on an EU airline or from an EU airport is canceled, the airline is liable to pay for the cost of a hotel and subsistence, within reason.

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