I was out deer stalking around the back of Lake Sumner and managed to shoot one. Around 2.30 pm I started off on an unfamiliar down hill track towards the river. It was rough and bluffy. I was following the co-ordinates I had programmed into my GPS before starting out. I had bought the GPS and my Fastfind PLB at the same time recently and was glad to have them with me. After a while I realised the GPS was not functioning correctly and leading me the wrong way. I reset it twice and it gave me two different directions, both wrong so I worked out where I should be heading and set off. The weather was deteriorating by then, getting dark and I was getting tired,cold and surrounded by some very nasty country. Eventually I came completely bluffed and couldn’t go back up, the river was raging down below and I couldn’t track laterally either way. By then it was snowing and I was feeling hyporthermic. I activated my Fastfind PLB and after a while the chopper turned up. The pilot was impressed by the accuracy of the co-ordinates it produced and he arrived overhead. If I hadn’t had my Fastfind PLB with me I would be lost forever and died on the side of that hill. Quentin June 2013.