Every year, mountaineers die because they walked off a glacier into a crevasse field they couldn't see, or descended the wrong ridge in whiteout conditions. Most had GPS. Many had maps. What they lacked was the navigation skill to use those tools when electronics failed — as they always do at the worst possible moment.
The Hierarchy of Navigation Tools
I teach navigation in this order: map first, compass second, GPS third. Not because GPS is inferior, but because map and compass develop spatial awareness that GPS alone cannot. When your GPS dies at 5,000m in a whiteout, you want to be someone who can read terrain and take a bearing, not someone staring at a blank screen wondering what to do.
Understanding the Map
A topographic map is the foundation of route planning and navigation. Contour lines are the key: they show elevation and terrain shape. Learning to visualize a landscape from contour lines takes practice but develops quickly. Steep terrain shows as closely-spaced contours; gentle terrain as widely-spaced ones. Ridges and valleys create V-shaped patterns pointing in specific directions — pointing uphill for ridges, downhill for valleys.
Before any climb, study your map at home. Walk the route mentally. Identify major features you can expect to see: specific cols, obvious ridges, lakes, distinctive peaks. When you're on the mountain, these known landmarks anchor your position in reduced visibility.
Compass Fundamentals for Climbers
A baseplate compass with a declination adjustment is essential. The mirror sighting versions allow more accurate bearings in the field. The three things you need a compass for: taking a bearing from a map, orienting your map to north, and taking a bearing to a feature in the landscape.
Magnetic Declination
This is where people consistently make mistakes. Magnetic declination is the difference between magnetic north and true north. It varies by location and changes over time — your map should indicate the declination and the year it was surveyed. In the Alps, declination is around 1-2° east. In parts of North America, it can exceed 15°. Use your compass's declination adjustment feature — set it once and forget it, and all bearings will automatically be corrected to true north.
Taking a Bearing to a Feature
Hold the compass flat, point the direction of travel arrow at your landmark, and rotate the compass housing until the needle is inside the orienting arrow. Read the bearing number at the index line. This is your bearing. If you're navigating to a known feature — a col, a distinctive rock formation — take a bearing and walk on that bearing. Count your paces if you know your stride length, or use time as a rough guide.
GPS: Powerful but Fragile
GPS has transformed mountain navigation, no question. A device with a paper map and a GPS is safer than either alone. But GPS batteries die, screens crack in cold, and satellite signals drop in deep valleys or under heavy cloud. I've seen GPS units fail on summit days. I've never seen a compass fail.
Use GPS for confirming your position and tracking distance traveled. Mark waypoints at key decision points: the start of a glacier, a col, a crevasse crossing. Download offline maps before your trip — satellite imagery overlaid on maps is invaluable in terrain you're unfamiliar with. But always carry a paper map and compass as backup.
Route Planning Before the Climb
Good navigation starts at home, not on the mountain. Plot your route on a map, noting: approach distance, elevation gain, key waypoints, obvious hazards. Calculate your expected pace — typically 3-4km/h on flat trail, plus 1 hour per 600m of elevation gain. This gives you an estimated arrival time at the col, at the summit, at camp. If you're two hours behind schedule, something is wrong and you need to reassess.
Always plan an escape route. Before you leave camp, identify: if weather comes in, which way do you descend? Where is the nearest safe point? Can you see it from here? Knowing your bail-out option before you need it is the difference between a controlled descent and a panicked one.
Dead Reckoning
When you can't see landmarks, dead reckoning keeps you moving. Take a bearing from your last known position, walk on that bearing for a measured distance, then repeat. Compass errors compound over time, so check your bearing against terrain features whenever possible. In whiteout on a glacier, a rope team can maintain a bearing by having the leader count paces while the second tracks direction on the compass.
What to Carry
At minimum: a reliable baseplate compass, a current map of the area (yes, paper), and a GPS device or smartphone with offline maps. A altimeter watch adds value — knowing your elevation helps confirm your position on a topographic map when combined with terrain features. For serious alpine routes, a dedicated GPS with satellite communication (like Garmin inReach) is worth considering for its emergency beacon capability.
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