Thomas coupling,
Just out of curiosity, can you explain this please?
When the a/c hits the water there is a very high chance that the occupant is knocked out even for a brief moment. During that time WITHOUT a life vest, they will drown??
As far as I have learned from various HUET courses, you need to be consius to get your ass out of the sinking helicopter(let alone inflating the jackets)
If you're ''knocked out'' on impact, I would think you'll drown with a perfectly usable lifejacket around your neck INNSIDE the helicopter.