Fenestron
RVDT - Thank you, questions answered. You clearly have lots of EC135 experience, glad to know this phenomena has never been seen on this aircraft.
Arkroyal - I see your point but just trying to add to the corporate thought process. Even at very low fuel states I have paused and loitered to observe something that caught the eye, especially when close to base, and even at night without the benefit of NVG/NVD. It is in the nature of this form of flying and I know police crews do the same.
I now remember why I do not post very often - do try not to be dismissive of ideas and alternative views, they all add to the knowledge base and just sometimes might hit the nail right on.