Perhaps they make you switch off and put away during takeoff and landing so the satnav does not become a high speed ballistic missile heading for the back of someone's cranium during a crash situation hmm.
Imagine the poor hearse drivers reaction when driving the unfortunately brained individual on his last ride, if a voice comes from the coffin saying "at the cemetary gates, turn left and you have reached your destination".
-------------------- Oh Crikey. I appear to have become the Fat Owl of the Remove.