The stoppage, called by the pilots’ union Cockpit, would start at midnight and affect Lufthansa flights at airports across Germany.
Out of its roughly 3,000 scheduled flights, 876 would be cancelled due to the strike, “affecting some 100,000 passengers”, Lufthansa said in a statement.
It is the union’s 14th strike since April 2014.
Cockpit had initially called for a 24-hour stoppage but said late on Tuesday that the strike would continue into Thursday for both long and short-haul flights leaving Germany.
Meanwhile a separate walkout by cabin crew at Lufthansa’s low-cost airline Eurowings led to the cancellation of more than 60 flights at airports in Hamburg and Düsseldorf on Tuesday.
The industrial action was called by Germany’s biggest services union Verdi in a row over pay and working conditions.
The Lufthansa pilots going on strike are demanding a pay rise of an average of 3.66% per year, retroactive for the past five years.
The union says pilots have endured a wage freeze over that time and suffered a “significant loss of purchasing power” due to inflation, while Lufthansa has made billions in profits.
It had offered a 2.5% wage hike.