More than 525,000 passengers will have been affected by strike action by Lufthansa pilots since last Wednesday.
A total of 4,461 flights have been cancelled, the airline calculated as it put together special flight schedules to tackle two further days of industrial action today (Tuesday) and tomorrow.
The Germany airline estimated that 2,184 out of 3,000 scheduled flights would be operated as planned today, with short-haul services affected. The 816 cancellations will affect 82,000 passengers.
A total of 2,110 flights are due to be operated on Wednesday as the Vereinigung Cockpit (VC) union extends its walkout to include long-haul services from Germany.
The 890 cancellations tomorrow will hit around 98,000 travellers.
Group airlines Eurowings, Germanwings, SWISS, Austrian Airlines, Air Dolomiti and Brussels Airlines are not affected by the strike.
Passengers whose flight is cancelled through the strike action are being told they may rebook once or cancel their flight free of charge.
The airline has contacted some 250,000 people due to travel about cancelled flights by email or text message.