A strike by Lufthansa cabin crew disrupted hundreds of flights on Friday, stranding thousands of passengers who faced further delays over a busy holiday travel weekend from a rolling series of stoppages about pay and cost cuts.
Germany's biggest airline said it cancelled most of the 360 scheduled arrivals and departures at its Frankfurt hub during Friday's eight-hour strike which followed the breakdown of 13 months of talks with the UFO union.
UFO, which represents around two-thirds of Lufthansa's 19,000 flight attendants, did not rule out further stoppages over the weekend and said it could call for industrial action at other airports "today or tomorrow".
"It depends a lot on what Lufthansa's response is," UFO head Nicoley Baublies told Bayerischen Rundfunk radio, warning the airline not to pressure workers to break the strike.
The stoppages were initially focused on flights to and from Frankfurt, Germany's largest airport, but might affect the airline's wider European and global network and could cost it millions of euros a day in lost revenue.
Lufthansa said it would try to place passengers on trains and alternative flights.
"The call to strike action may lead to unscheduled flight delays and cancellations at Lufthansa. Long-haul flights are the uppermost priority and, wherever possible, should not be cancelled. Nevertheless, delays must be anticipated," Lufthansa said in a message to passengers on its website.
Most parts of Germany are in the midst of their summer holidays, with regions such as Bremen, Lower Saxony, Saxony and Thuringia ending them on Friday.
Long lines of passengers waited at Lufthansa service counters in Frankfurt where peanuts and bottles of water or apple juice were offered to disgruntled travellers.
Helga Froesch, munching sausage and bread while holding sparkling wine in a plastic glass in her other hand, said her flight to Malta has been delayed by a day. "We are now eating our breakfast," she said.
"We are used to strikes in France, but not here," said Sara Vassallo, travelling with her husband and two children from Cape Town en route to Marseille.
Like most global airlines, Lufthansa is battling high fuel prices, weak demand from cash-strapped passengers and economic slowdown, as well as fierce competition from low-cost carriers such as Ryanair.
Lufthansa, which operates around 1,850 flights daily, mostly from Frankfurt and Munich, needs to generate more profit to pay for EUR€17 billion of new aircraft on order.
The UFO union wants a 5 percent pay rise and guarantees that Lufthansa will not outsource jobs and use more temporary workers, as it has already done in Berlin.
Lufthansa says cabin crew must contribute to the cost-cutting programme.
UFO warned this week the industrial action could continue for a very long time and widen into nationwide stoppages if Lufthansa does not meet its demands.