Video- OS Malfunction in the mist

Mist like this can come in very quickly in this area. It can be quite scary if it has not happened to you before. Nelly & Gordon are quite experienced with these things. In this situation, the worst that can happen is that they come down the wrong watercourse, but their GPS trace will tell us exactly where they have been. This sort of situation does not arise that often. It is remarkably difficult describing your position to some-one if you cannot see any landmarks at all. Numbered tributary sheets are a big help in this situation, as long as you are actually correct in being where you think you are.