manfromuncle,
Good question, it is easy to comment on what we do, harder to say what we should do!
Let me start out by saying the lesson is OGE hover safety, and the lesson has two different, and equally important pieces, Performance and VRS. I would bet 95% of all hover descent accidents are the result of performance /overpitching and NOT VRS:
1) Hover PERFORMANCE
A) where the power needs of OGE vice IGE are discussed and demonstrated (use a light helo, and trim IGE, note power, then trim OGE and note power. Pick 3 IGE hover heights and then plot the power post-flight. Look up OGE performance in the RFM to orient the pilot to the weight effects. Then discuss altitude temperature and wind effects.
B) Then discuss marginal OGE hover, and the insidious danger of over-pitching, especially how the rpm decay leads to even lower power so that the fall is accelerated.
C) Then discuss how low rpm leads to Loss of Tail Rotor Control.
D) Then show how an OGE descent at moderate rate can be flown up if one has some good power reserves to just raise the collective. The point to be made is that one can descend at 300 or 500 fpm in any helicopter with sufficient power reserves, and simply raise collective and fly up out of the descent. This is known to all military pilots when they operate NOE, and is not a mystery. The student should be shown, however, that a descent needs somewhat MORE power than a steady HOGE, so that a 300 FPM descent will need about 5% more power than a steady hover. (This is the fact that fuels the "VRS" demos we all are shown, and the reason why descents lead to overpitching).
2) Vortex Ring State
A) At 3000 feet or higher, slow to a steady OGE hover. Begin a descent at moderate vertical speed and accelerate the descent until you are at 75% of the downwash speed. (I can show how to calculate this for any helo). At this ROD note the lurches as the thrust bucks by +10%, and the aircraft has torque surges of 10 to 20%. This is incipient VRS, and all that is necessary to show, fly out of it by lowering the nose to accelerate and break the reingestion that is feeding the VRS. The lesson is vastly different that the above OGE power lesson.