While this would've been handy two years ago, I wouldn't say "auf wiedersehen" to say goodbye in Germany. That's the formal farewell that isn't used often. Tschüss (pronounced like "choose") is what you'd say of the time.
GERMAN NEWS REPORT: Co-Pilot of Germanwings Airbus Was MUSLIM CONVERT …’Hero of Islamic State’? - All evidence indicates that the copilot of Airbus machine in his six-months break during his training as a pilot in Germanwings, converted to Islam and subsequently either by the order of “radical”, ie. devout Muslims , or received the order from