Simultaneous pilot strikes of the two biggest European airlines, Air France and Lufthansa, may cause severe travel disruptions across Europe, as according to a statement, published on the Air France website, the company expects to operate less than half of its flights on Tuesday.

“Air France expects to operate 40% of its flights on Tuesday 16 September 2014, given an estimated 60% of pilots planning to strike,” said the statement, published on Monday, adding that Air France regrets the situation and will try to minimize any inconvenience to customers. The company has sent close to 600,000 texts and messages to warn passengers about possible schedule changes.

The Air France strike began on Monday as a protest against the company’s plans to transfer jobs to its low-cost subsidiary Transavia, which, according to the union, will negatively affect work and pay conditions. The protest is expected to last for a week, making it the longest strike since 1998, when pilots went on strike against a pay freeze on the eve of the World Cup soccer championship, causing worries and inconveniences for fans and teams.

On Tuesday, pilots of another major European airline, Lufthansa, have also planned an eight-our walkout at the carrier’s Frankfurt hub – supposedly, the last one in the series of strikes held over the past three weeks, as a protest against cutting early-retirement benefits.

The last Lufthansa eight-hour strike, held on September 10 in Munich, caused the cancellation of 110 flights, mainly short-haul.

Passengers stuck in airports for days or having to reschedule their travel plans are not the only ones affected by the strikes. According to analysts, questioned by Bloomberg, the protests at Air France and Lufthansa threaten to undermine the prolonged efforts by the companies” management to bring costs in line with European budget carriers, such as Ryanair and EasyJet.

“Short-haul operations of both airlines are in quite a lot of trouble and they’re having to cut costs quickly,” said Robin Byde, an analyst at Cantor Fitzgerald, as quoted by Bloomberg.

As the data, gathered by the European Organization for the Safety of Air Navigation (Eurocontrol), suggests, in 2013 the low-cost segment represented 26 percent of European air Traffic, earning 6 percentage points over the last five years. Traditional-scheduled flights, still representing 55 percent of traffic, lost 3 percentage points over the same time period.