The carrier expects to cancel about 3,800 flights through Friday, affecting more than 425,000 passengers, airline spokeswoman Barbara Schaedler said. Lufthansa Cargo and its budget airline Germanwings were also affected by the strike, which the company estimates will cost it ''tens of millions'' of euros (dollars).
The pilots' union Vereinigung Cockpit announced the strike in advance, giving Lufthansa time to prepare by canceling flights and offering passengers alternative travel arrangements. Some were rebooked on trains or different airlines, Schaedler said.
''We sent out more than 200,000 text messages to inform our customers about the upcoming strike and also increased our capacities at our call centers to help passengers rebook their trips,'' the spokeswoman said.
As a result, Lufthansa terminals in Frankfurt and Munich, the company's hubs in Germany, were mostly empty.
Berta Paiva, a 61-year-old Brazilian waiting for her flight at Berlin's Tegel airport, did not seem upset.
''It's OK because I was traveling to Munich today and from there to Sao Paolo, and they just changed me - I fly to Frankfurt and from there to Sao Paolo,'' Paiva said.
One of the main demands by the pilots is that Lufthansa continue to provide a transition payment for those who want to retire early at age 55. The airline wants to cut those payments. The pilots are also asking for a salary increase of 10 percent.
Manfred Weiss, a 60-year-old German cook, showed little compassion for the pilots' demands.
''They cannot let this happen, this should be forbidden,'' Weiss said, arriving home in Berlin from holiday on Lufthansa competitor Air Berlin. ''I also think that they have sufficient salaries (...) you can't just make the passengers pay for it.''
The carrier has been trying to cut costs amid tough competition from European budget carriers and aggressively expanding government-owned Gulf airlines.