A plane prepares to land
An Air Algerie Airways plane prepares to land at Houari Boumediene Airport in Algiers July 24, 2014. An Air Algerie flight crashed on Thursday en route from Ouagadougou in Burkina Faso to Algiers with 110 passengers on board, an Algerian aviation official said. Reuters/Louafi Larbi

Air France has announced it will be operating only 40 per cent of its scheduled flights on Wednesday, as the labour strike of its pilots' union enters the second day on that day.

The airline firm urged their passengers to postpone their trips scheduled between Sept 17 to 22. It said it will accommodate flight changes and rebooking "at no extra cost" to the passengers.

Frederic Gagey, Air France's CEO, said the talks with unions to end the strike were "permanent and ongoing."

Yet, he said they would stick to the present realities occurring in the workforce. "We prefer to be realistic rather than optimistic. For the moment, we are organising our flights on a day-to-day basis," he said in a statement.

Pilots of Air France are striking over the company's plans to transfer jobs to Transavia, its low-cost subsidiary. The union claimed such plans will negatively affect work and pay conditions.

But Air France maintained the expansion would enable it to compete with Ryanair and Easyjet in the low-cost airline market.

While Air France said it is open to negotiating the benefits of pilots who agreed to work for its low-cost airline, it will not allow that Transavia pilots carry the same terms as those flying under Air France.

Transavia pilots are paid less than Air France's.

The protest, which started on Monday, is expected to last for a week. More than 65,000 passengers were affected on the first day.

Jean-Christophe Cambadélis, leader of the French Socialist Party, urged for the immediate cessation of the work stoppage. "We must keep a sense of proportion, you can't pile up advantages, we can compare salaries but we can also look at what French people are going through today."

The financial cost of the work stoppage could be between $12.9 million and $19.4 million a day, Gagey said.

Air France's balance sheet will likely be in the red again this semester should the pilots continue their abandon work stance through Sunday.

"Air France regrets this situation and is making every effort to minimize the inconvenience this may cause to its customers," the airline said in a statement.

"Since last week, close to 900,000 texts and messages have been sent to inform customers due to travel between 15 and 22 September, individually and in real time."