It's the last thing Germany's biggest airline needs Lufthansa already has to find the money to pay for 17 billion euros worth of new planes they have on order. And now its cabin crew has begun a series of strikes, forcing Lufthansa to cancel a quarter of flights at its Frankfurt hub. They walked out on Friday over pay cuts and worries that jobs will be outsourced and more temporary staff used. That's already the case at its Berlin operation. Nicoley Baublies is from UFO, the union representing Lufthansa's cabin crew (SOUNDBITE) (German) HEAD OF LUFTHANSA CABIN CREW UNION "UFO", NICOLEY BAUBLIES, SAYING: "One thing that has to disappear is Lufthansa's demand of a 20 to 30 percent pay cut. Apart from this 3 percent pay hike over a period of 36 months, that's of course something we will not discuss. Only once there is a substantial improvement will we consider returning to the negotiating table." The eight-hour strike came after 13 months of negotiations broke down. Thousands of passengers were left stranded. The cabin crew have threatened to walk out again - and if it affects their wider network it could cost Lufthansa millions of euros a day in lost revenue. The airline says it's willing to resume talks. (SOUNDBITE) (German) LUFTHANSA SPOKESMAN, KLAUS WALTHER, SAYING: "The door is wide open. We offered a 3.5 percent salary increase. On top of that, we are ruling out operational layoffs and additional contract workers for the duration of the wage agreement. These are after all facts which can be talked about. What we expect from the cabin crew is about two more hours of work per month which we believe during the current times is something that can be done in order to save jobs at Lufthansa, also in the future." But Lufthansa's not the only airline facing tough times. Like many other flag carriers, it's battling soaring fuel costs, passengers spending less, and it doesn't look like the global economy will be taking off any time soon. Joanne Nicholson, Reuters