GPS - it's a great tool but......
cautionary tale:
low level flight in a Dauphin flying cross country between two jungle/bush helipads on a GPS track.
GPS screen blinks a couple of times and then a message appears
"FACTORY RESET" it says!
There we are miles from anywhere and no ***** GPS. A quick look in the box shows that the system is working but it does not know where it is and all the waypoints have disappeared apart from all those on the Jepp card - useless when you are out in the bush. The story ended OK when we punched in the Lat and Long of the nearest landing site and hit the "Direct To" button.
It happened again a few days later so lesson learnt we changed the receiver and installed another GPS as a back-up.
Have also experienced blank-spots where we would regularly loose the GPS signal.
It's not all as simple as you might think!