As idiot-proof as the newest GPS units are, I still needed assistance to make sense of all those lat-long numbers in relation to navigation. Several sources recommended this guide (third edition) which has indeed been most helpful.
The best use of a GPS receiver is to complement your present skills, so do not abandon the navigation techniques you have already acquired. For the beginning navigator, a receiver can help you improve your present skills because it can verify the measurements you make using manual techniques.
After a spectacular flight, the helicopter lands near the lake and you disembark with plenty of time to set up camp. Just as planned, you are fishing the lake the next morning at 4:00 am and catch a fine breakfast. When it is time to go, you turn the receiver on, but it seems to take much longer than usual to lock onto the satellites. When a receiver loses its memory, has not been used for a few months or when it is moved more than 300 mi. from the location where it last locked, it can take up to 12.5 minutes for a single channel receiver to get a position fix. The time between turning the receiver on and locking on to the satellites is known as Time To First Fix (TTFF).
Altitude Profiling. One of the best features of topographical databases is altitude profiling. After the user draws a route on the map, the computer instantly produces a cross-section showing all the changes in altitude along the path. Try profiling a trail on a paper map and you will see the power of this feature. Profiling allows you to see in advance which sections of the trail will be challenging and which will be easy.
The three circles are each 30 m (98.4 ft.) in diameter.
Generating a profile of a trail is one of the most useful and powerful features of a topographical map database.