Reading some other articles about the accident it looks more like an unapproved off-airport landing:
Pilot claims that him plus 1 passenger left EDKB (Bonn-Hangelar) for a scenic fligtht. The passenger allegedly got sick. Pilot decides to make an off-airport landing and by coincidence the son of the pilot along with his girl-friend show up and they all get in the helicopter and fly away.
Thanks for yet another valuable contribution to helicopter safety in Germany.