"Unacceptable... With so many flights going over water. Please don't say they are not designed to be picked up in 150' of water. "
OK, I won't say it.
I think the point is that there could be a floating beacon in the fin that is released by a hydraulic pistol at (say 10m) depth.
AFAIK, no aircraft are fitted with this. I can think of best part of $200 million that could have been saved by a general fitment.