Lufthansa expects to operate only a fraction of its flights on 7 September as cabin crew plan to strike at most of its major airports in Germany throughout the day.
German flight attendant union UFO has announced 24-hour walkouts at Lufthansa's main hubs in Frankfurt and Munich as well as Berlin, Dusseldorf, Hamburg and Stuttgart.
The airports of Cologne, Hannover, Bremen, Leipzig, Nuremberg and Dresden are not included in the industrial action. These are smaller bases in Lufthansa's network, however, and many of their services are operated by its regional partners and low-cost subsidiary Germanwings - which are not included in the strike.
Lufthansa has cancelled two thirds of its approximately 1,800 flights per day. But the remaining schedule largely comprises flights by its regional partners and subsidiaries.
A Lufthansa spokesman tells Flightglobal that a "small number" of Lufthansa mainline flights will be operating, with long-haul routes being prioritised.
There is little prospect for a potential arbitrator to defuse the clash between the airline and its cabin crew, the spokesman adds, because such discussion would be limited to wage increases alone.
The industrial action technically hinges on a disagreement over nominal salary increases, with Lufthansa offering to raise wages by 3.5% while UFO demands 5%.
But the soured relationship stems from a dispute over the maintenance of existing salary structures with built-in increases, as well as the use of external staff for cabin crew positions - issues which cannot legally be used as justification for strikes.
Lufthansa has signalled that it may consider abandoning its insistence on the use of external staff. But it wants to restructure the salary system for future cabin crew employees, which would curtail pay increases.
UFO claims that the new remuneration structure will effectively reduce work as cabin crew to a "budget job" which would not be financially feasible as a career for life.