PLB use 406 first then 121.5 to home in. a co worker is a pilot with the CAP. the way I understand it is that they currently are using SPOT but are soon to be changing over to the PLB. The PLB can track and send OK also. We've had two plane crashes in the last few weeks, both during storms, both found about a week later. the co worker didn't go on these two missions but watched their tracking on the net. It was interesting.
I'm still researching these but of those I talk to locally sure seems that alot started with SPOT and are now changing to PLB.
Cletis