Air Berlin pilots are preparing to strike at short notice in protest against unfair working conditions.
Members of Vereinigung Cockpit (VC), the same union involved in the short-lived Lufthansa and Germanwings strike, voted last week in favour of industrial action following what it called "months of negotiations".
In a statement yesterday, VC said three-hour warning strikes would take place "in the coming days" but it is not clear when exactly that will be.
A VC spokesperson told ABTN today that a strike could be called with only "a couple of hours" warning, in an attempt to take Air Berlin and its subsidiary LTU by surprise.
Because of this short notice strategy, VC could not give any indication as to how many flights will be affected. "That's really hard to tell, it all depends on which pilots are on duty at the time," VC said.
But VC offered some hope. When asked whether strikes could be averted at the last minute, VC's spokesperson said it was "really up to Air Berlin".
Hans-Christoph Noack, Air Berlin's director of corporate communications, said negotiations were still ongoing and was confident that strikes could be averted.
Noack said he could not predict the extent of disruptions to services, but added that the rest of Air Berlin's workforce was prepared to deal with any resulting delays.
Around 1,400 Air Berlin and LTU pilots belong to VC, any number of which may be on duty at the time of the strike, and on any number of services, long or short haul.
No statement has been released through Air Berlin's website, and it will be hard for the airline to make preparations such as revised timetabling.
Should the strikes take place, affected Air Berlin and LTU flights may not leave the tarmac for at least three hours but the resulting disruptions could last much longer.
Air Berlin and LTU are the latest airlines to be threatened by strike action. Lufthansa and subsidiary Germanwings cut short a four-day pilots' strike thanks to court intervention, and the battle between British Airways and its cabin crew continues to cause uncertainty for passengers.