davekeiller wrote:If walking in the UK, how much do they add compared to a mobile phone (fully charged and turned off to save battery)? If you dial 999 then they can triangulate your position, and they've also developed a system called SARLOC which mountain rescue teams all use - this sends a text message to your phone which interrogates the GPS and sends a message back to the MR team with your co-ordinates to speed up their search.
A personal locator beacon feels like a lot of money for an extra safety net that will probably never be used given that you'd need to be conscious and in an area with no mobile signal on any network and unable to reach a spot with signal. Taking a whistle and telling someone where you're going and when you'll be back seem to be more cost effective solutions to the problem.
A few years ago I had a serious accident (windsurfing, not mountaineering!!!) as a consequence of which I was over 6 weeks in hospital. This experience made me realise that the folk that suffer when someone has an accident or serious mishap are the victim's nearest and dearest, rather than the victim him/herself - if you're fairly well knocked about, you're pretty well out of it in practice.
I do a lot of walking, including scrambling, in quite remote spots, so I got a PLB to give my family greater peace of mind, and for me the £200 has been worth every penny for that reason alone.
As regards reliability, my understanding is that you effectively always have a signal, since they rely on satellite, not terrestrial technology. Certainly my sailing friends say they are highly effective for sailing (for which I believe they were originally conceived), and the rescue folk apparently respond very quickly indeed to any distress call. But for the type I have, you do need to be conscious to activate it.