My Fast Find PLB is registered to an aircraft. The reason being is to notify SAR what they are looking for. I think registration to an aircraft is mandatory. After that driver on the A9 went off the road and lay in the bushes for days, I considered taking my PLB in the car... but then D&D would look for my aeroplane and miss my car in the ditch!
BigEndBob, don't rely on your phone, you may not get a signal.