Air France said it’s bracing for the most disruptive strike since 1998 tomorrow as pilots walk out over management plans to expand low-cost operations using flight crew paid less than at the mainline carrier.

The French arm of Air France-KLM Group, Europe’s biggest airline, expects to cancel 52 percent of services on the first day of an action due to run through Sept. 22. The dispute will cost 20 million euros ($26 million) a day in revenue, it said.

“We’re telling people who don’t absolutely have to travel to postpone their trip,” Air France Head of Operations Catherine Jude said in a briefing at the carrier’s Paris Charles de Gaulle airport base. “Talks with unions are continuing.”

Pilots are staging the walkout as Air France-KLM Chief Executive Officer Alexandre de Juniac seeks to end decades of short-haul losses. Former Dutch charter unit Transavia will be further expanded into France with a fleet that could double in size, the company said this week, confirming plans that unions say will prompt job losses and pay cuts at the main airline.

This week’s action could have the biggest impact on travel at Air France since an eight-day strike 16 years ago over the French government taking the airline public, a dispute that involved 3,000 pilots and forced 75 percent of flights to be scrapped at a cost equivalent to $166 million today.

No Substitution

About 60 percent of pilots are expected to strike tomorrow and fewer in subsequent days, Jude said. The ability to cope with the walkout is limited, and pilots “who fly one aircraft can’t be substituted for another,” she said, declining to give a breakdown of likely long-haul and short-haul cancellations.

Air France’s SNPL union wants pilots across the company to be paid the same wages and to have the same working conditions. Jean-Louis Barber, the labor group’s president, said this week that it’s still open to negotiating even as the strike looms.

De Juniac said Sept. 11 that if pilots don’t accept the company’s strategy, the expansion of Transavia’s French unit may be put on hold. Flights could added through a new Transavia Europe division that might be based elsewhere.

Transavia, with 41 planes carrying 8.9 million people spread across French and Dutch units, will have a fleet of 100 jets carrying more than 20 million people a year by 2017, according to the CEO’s plan, which parallels moves at Deutsche Lufthansa AG focused on the Germanwings discount brand.

Air France operates about 1,000 flights a day, or 1,500 with regional unit Hop!, which isn’t involved in the strike.

To contact the reporters on this story: Andrea Rothman in Toulouse at aerothman@bloomberg.net; Mark Deen in Paris at markdeen@bloomberg.net. To contact the editors responsible for this story: Benedikt Kammel at bkammel@bloomberg.net. 

Photo Credit: Air France pilots in the cockpit of an A380. Andy Mitchell / Flickr