Silver, Gold cardholders and Business class passengers can access the AirBerlin lounge in terminal C.

The lounge is upstairs, it's unmanned and to enter you have to swipe your topbonus elite card or the code figure printed on your boarding pass. In my case the latest didn't worked, my card was not with me so I had a bit of a problem to enter.

Anyway, after you enter, you walk upstairs. Two rooms, on the right one there's a tea/coffee machine plus a soft drink dispenser. Yes, you dial the related number and the bottle is given down to you. A rack with newspapers and magazines, all in German.

A few small round glass and steel tables and leather chairs, dark brown. Usual monitor with departure information.

Same ambiance on the room on the left, without drinks and newspapers.
The floor is a very light parquet (very light brown), white on all the walls and the windows have a red frame. A few AirBerlin logos around.

From the room on the left (by the way I'm sitting there while I'm writing this) you can see the land-strip and the planes with the flocks of passenger de-boarding and boarding them.

A loudspeaker (or two) per room are providing boarding announcements and updates.

Quite impressed considered the nature of the airline.
Is it a BA lounge ? NO, NO, NO, NO WAY. But it's a nice relaxed place where to seat and wait for your flight.

Wi-fi ? Yes, a few hot spots are present but I have no clue if and how I can connect for free. No one to ask about it.