GPS and Digital Navigation

What GPS can do well

• Show latitude and longitude or another coordinate format.
• Display position on a digital map.
• Record a track of where you have traveled.
• Measure straight-line distance and direction to a waypoint.
• Store important locations such as camp, trailheads, water sources, and emergency access points.

Common limitations

• Batteries can run down, especially in cold weather.
• Phones can be damaged by water, drops, or extreme temperatures.
• Offline map data may not be downloaded before service disappears.
• A digital map can be outdated or missing a trail or closure.
• Location accuracy can degrade near cliffs, in deep canyons, or under other difficult signal conditions.
• A precise blue dot does not automatically tell you which route is safe.

Prepare the device before the trip

• Download the needed maps for offline use and verify that they open in airplane mode.
• Fully charge the device and carry appropriate backup power for longer trips.
• Protect the device from water and impact.
• Know which coordinate format the group and emergency plan use.
• Mark important waypoints such as the trailhead or camp, but also locate them on the paper map.
• Carry a paper map and compass on trips where navigation matters.

Use electronics to confirm, not replace, thinking

Compare the digital position with the terrain and paper map. If the device says you are beside a stream but no stream exists nearby, investigate before trusting the screen. When following a track, continue watching trail signs, terrain, daylight, weather, and hazards.

Coordinate formats

Latitude and longitude can be written in decimal degrees, degrees and decimal minutes, or degrees-minutes-seconds. Other maps may use UTM or a local grid. A coordinate is only useful when everyone knows the same format and datum. When communicating an emergency location, state the format clearly and repeat the numbers carefully.