Publications

AMC Outdoors, May 2003

By Michael Lanza

The ability to find our way through a natural environment is fundamental to everything we do in the mountains. So it's curious that many hikers possess only a rudimentary knowledge of backcountry navigation.

If you include yourself in that group — or if you just feel that a refresher course can't hurt — here's a quick tutorial in everything from map reading and using a compass to figuring out what to do when you aren't quite sure where you are. But this is an overview of a complex subject — to really learn it, take a class so these skills become a ready part of your backcountry repertoire. (See also a sidebar for tips on what to do if you get lost and our AMC Outdoor Adventures for map and compass classes.)

The Essential Tools
It begins and ends with your map. Take a close look at the map before you set foot on the trail. At the trailhead, orient it (see below) and let everyone look over your route. Knowing your direction of travel on the map will improve your sense of direction on the ground and help you know which way to turn at key trail junctions or other landmarks. Consult the map frequently, both to avoid missing a turn and to maintain an approximate idea of your location.

Practice reading a topo map's contour lines — the lines that connect points at the same elevation and display the shape, angle, and height of the ground — and translating that information to the terrain around you. Get in the habit of using the map to identify peaks, lakes, valleys, and other landmarks within view. If you get lost, this skill will help you use the map to "read" the terrain and figure out where you are.

Remember that a map's scale and contour intervals will determine what natural features it can show: If the interval between contour lines is 100 feet, a 30-foot cliff won't appear. A fun way to familiarize yourself with contour lines is to cut a topo map (or a photocopy) into eight or 10 pieces, then try to fit them back together.

On good trails, you may never need your compass. But venture off the trail, or get turned around and disoriented, and a compass can save you from hours of aimless wandering.

The skills described below will seem confusing unless you read with map and compass in hand. Remember that magnetized objects, including certain rocks, other compasses, and metal objects, throw off compass needles. Be conscious of where you store your compass — at home and in your pack.

Let's start with the basics. On your compass, you'll see two arrows: a red needle that will always point toward the magnetic north pole, and a north-south arrow on the compass housing (the dial you turn). The first step is to figure out the direction of true north. To do this, you must know the declination where you're standing — or the angle east or west of true north that magnetic north lies, measured in degrees. This changes depending on your geographic location; your map will indicate the local declination. For example, the declination for Mount Washington is 17 degrees west, meaning that magnetic north lies 17 degrees west of true north there. (California's Mount Shasta, by comparison, is about 16 degrees east of true north.) In the Mount Washington area, you would turn the compass housing to 17 degrees, "boxing" the red half of the needle inside the housing's north-south arrow (put the "red in the shed") so that the needle points to magnetic north and the base-plate arrow points to true north.

Orienting your map simply means turning it so that its true-north arrow actually points north. Do this, and landmarks will appear on the map in the same direction as on the ground — for instance, if the map shows a summit to your immediate left, you should be able to look and see it in that direction. Simply line up the compass needle with the magnetic north line on your map, and your map is oriented.

Getting Your Bearings
When going off-trail or in limited visibility, you may have to take a compass bearing between two points to figure out which direction to go. Lay the compass flat on the map so that the compass base plate's arrow points from your current position to where you want to go. Then rotate the compass' face plate until you put the red in the shed — in other words, until the north-south arrow points to magnetic north. Now you can put away the map, hold the compass horizontally in your palm, and — keeping the needle inside the north-south arrow on the housing — et the base-plate arrow point you to your destination.

Sight ahead a short distance and pick a feature to walk toward (boulder, tree, etc.), walk to it, then stop and repeat the process, always keeping the needle pointing to the north mark in the housing.

You may have to navigate around a natural feature like a cliff. Take a bearing on the new direction required by the cliff; count the paces you're walking off-course, then once around the cliff reverse the bearing (head 180 degrees in the opposite direction) the same number of paces to get back on your course.

The High-Tech Solution
Altimeters and GPS receivers are becoming more affordable and common. An altimeter measures barometric pressure to determine altitude, and knowing that can help pinpoint your location on a map — valuable information almost anywhere, and indispensable for mountaineering. Altimeters are affected by changes in barometric pressure, so they must be regularly calibrated at known elevations (such as when standing on a summit) to remain accurate.

A GPS receiver uses signals from Global Positioning System satellites to precisely calculate your coordinates in latitude and longitude or other coordinate systems. GPS receivers can lead you to any location whose coordinates you know. Many weigh less than a pound, fit in your pocket, and are powerful enough to work in dense forests, deep valleys, and virtually any weather. Their accuracy makes them invaluable in deep wilderness, especially in terrain that's hard to read on a map — flat tundra, dense forest, canyons, etc. Get one with a battery-saver feature and a long-life, rechargeable lithium battery, which weighs less and withstands cold better than an alkaline battery. But don't let a GPS give you a false sense of safety: You still must apply the information the device gives you to a map in order to determine your location.

Wrong Way
We all do it — take a wrong turn, miss a trail junction, follow a rogue path. Here's what to do when that happens.

Besides frequently consulting your map, watch the trail and its markers, as well as your surroundings, to perceive immediately when you're going the wrong way.

Watch the time so you can estimate how far you've gone, based on your hiking pace, and have an idea of when you should reach landmarks like trail junctions.

Look in all directions for trail markers. It could be you're on the trail but it's been obscured by a fallen tree or snow.

If you're off-course, chances are you're not far from the trail. Don't set off aimlessly. Identify a distinctive landmark like a big tree or rock, so you'll recognize this spot again. Remember which direction you came from; mark it if necessary.

If possible, backtrack to the trail. If that fails, figure out how much time has passed since you were definitely on the trail, which will give you some idea of how far you could be from the trail.

Look at your map and surroundings and try to identify land features, which might help you pinpoint your location. Above all, stay calm. Panicking can distort your sense of time and lead to poor decisions. Practicing navigation and direction-finding when you know exactly where you are is going to help you keep a level head if you do get lost.

—Michael Lanza is author of The Ultimate Guide to Backcountry Travel, from AMC Books.