Vortex Ring State, is it real?

So? What is it?
It is an aerodynamic phenomenon in which a helicopter essentially descends into its own downwash. The airflow becomes reveresed in the inner portions of the rotor disk.
So what are the conditions required to get into Vortex Ring State?
1. Airspeed less than ETL (google ETL).
2. Vertical descent greater or equal to 300fpm.
3. 20%-100% power applied with insufficient power to stop the descent.
Anyway, just fly the helicopter!
Also, any of you ever had the oppurtunity to ride in a snowcat? Looks fun!