I hope I'm not black listed for the following comment,

but here goes...
I don't know how many times I've read on this forum "If I get into trouble, I'll just use my PLB". Problem solved right? Wrong!
I know the majority in our community are very well versed and prepared. But I sure hope the few others reading our posts don't look at a PLB as there free ticket home. There is a very good chance if you're stuck somewhere, that your rescue can't get to you right away either. This is where the 72-96 hour part comes into play. If you broke a leg on a solo hike, rescue is likely under a day away. Then you can be ridiculed on the news and sites like this for hiking alone. If you are stuck in a nasty snow storm, it could be days before anyone gets to you; regardless of your mighty PLB.
So, while one of the greatest advances in personal rescue, a PLB is less useful than a deactivated cell phone (with reception) that can only call 911 (yea, a PLB will have reception 100 times over any cell phone) but the point is, your only saying HELP. I hope anyone reading these forums will remember that. Whether your mentality is 1911 then 911, or whatever, be prepared to take care of yourself.
Long, long time ago -> HELP!
Long time ago -> The sound of a whistle...
Years ago -> SOS or radio communication
Yesterday -> Cell phone calls 911
Today -> PLB