Air Berlin, the German airline partly owned by Gulf carrier Etihad, said passenger numbers fell 5.0 percent in June.
Germany's second largest airline after Lufthansa carried 3.3 million passengers in June, it said on Friday.
Its load factor dropped by 1.0 percentage point to 79.03 percent, while the number of seats it offered fell 3.8 percent.
Air Berlin has been trying to shrink itself back to profitability by cutting routes, seats and delaying plane orders.
