While out trekking on the land, not only do I carry a complete compliment of survival gear in my pack, I also will carry an APRS transceiver as seen in the pocket of the pack, allowing communication with my truck parked at the trailhead.
The transceiver is running APRS (Automatic Packet Reporting System) that beacons my position, the beacon heard by the radio mounted in my truck that then forwards the beacon to a distant digipeater allowing my location to be seen on Google maps.
When I don't come home, my wife and kid know where to look.
Expand the photo for a closer look.....
A closer look at the APRS transceiver........