Avoidance of the conditions for possible vortex ring is a very basic concept. The best piece of safety equipment in a helicopter is a well trained pilot
I concur with FH100 that "backwards and down" is a good way to find oneself losing control, but normally speaking, this is not a usual configuration to be in!
Once seen, never forgotten, especially when the aircraft tends to weathercock into the rearwards airflow and pitch nose down due to "upwards" airflow over the horizontal stabiliser. These factors tend to remove the VR conditions but do nothing to help the piot's adrenaline level.
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