Navigation goes wrong slowly. Almost nobody takes one dramatic wrong turn. What happens is that you stop paying attention on an obvious path, the cloud comes down, and twenty minutes later you are standing somewhere that does not match anything on the map, with no clear idea how long it has been since you last knew for certain.
Everything below is worth knowing, and none of it is a substitute for being taught in person. Reading about a compass bearing and taking one in a whiteout with cold hands are different skills. If you plan to go on high ground in bad visibility, do a navigation course with a qualified instructor, and then practice in daylight somewhere familiar until it is boring.
Contours carry the information
Beginners read maps for paths and names. Experienced navigators read them for shape. Contours tell you what the ground does: close together means steep, a V pointing uphill is usually a stream line or gully, a V pointing downhill is a spur. Get good at this and you can identify where you are from the way the ground rises under your feet, long before you can see anything.
It also tells you which routes are plausible. A line that looks short on the map but crosses eight contour lines in a quarter mile is not a shortcut, it is a scramble. Reading the shape is what stops you planning a descent into ground you cannot descend.
Two habits that prevent most errors
- Set the map. Turn it so its north matches the ground's north, so features on paper sit where they sit in front of you. It feels awkward reading a map upside down until the first time it saves you from walking off the wrong side of a summit.
- Thumb the map. Hold your thumb on your current position and move it as you go. The point is never having to reconstruct where you are from scratch, which is exactly the task that becomes impossible in fog.
What the compass is actually for
A compass does one thing well: it lets you walk in a straight line you cannot see. To take a bearing, lay the compass on the map with the long edge running from where you are to where you want to go, direction-of-travel arrow pointing that way. Turn the housing until the orienting lines inside it sit parallel to the map's north-south grid lines, with the orienting arrow toward map north. Adjust for magnetic variation. Then lift the compass off the map, hold it flat in front of your chest, and turn your whole body until the red end of the needle sits inside the orienting arrow. Walk the way the travel arrow points.
Look up the current magnetic variation where you are walking. It differs by place and drifts over the years, which is why no article should hand you a number for it. Your map's legend or the mapping agency has the current value.
Walking a bearing accurately is harder than it sounds, because everyone drifts. Pick something ahead that is on the line, walk to it, then pick the next thing. In featureless fog that might be a rock ten yards away, or a companion you send ahead and wave onto the line.
Distance and time
Pacing is how you measure distance without landmarks. Count double paces, meaning every time your right foot lands, over a measured hundred meters on flat ground, and remember the number. It is personal, so measure your own rather than borrowing anyone else's, and know that it stretches uphill, in deep heather, and in snow.
For timing, Naismith's rule is the old standby: allow an hour for every three miles, plus an extra half hour for every thousand feet of ascent. Treat it as an optimistic floor. It makes no allowance for rest, heavy packs, rough ground, difficult descents, navigation stops, or a tired group at the end of a long day, and it is close to useless in deep snow. Time yourself against it a few times and you will learn your own correction factor.
Techniques that make poor visibility survivable
- Handrails. Follow a linear feature that runs your way: a wall, a fence, a stream, a forest edge, the crest of a ridge. Far more reliable than a bearing across open ground.
- Catching features. Pick something past your target that tells you you have gone too far, like a stream, a track, or the point where the ground starts dropping steeply.
- Attack points. Navigate the easy way to an unmistakable feature near your target, then take one short, careful leg from there. Two hundred meters of precise navigation beats two kilometers of hopeful navigation.
- Aiming off. If you are heading for a bridge on a river, aim deliberately upstream of it. Then when you hit the river you know which way to turn, instead of guessing.
The phone question
A mapping app with your position on it is genuinely excellent, and pretending otherwise is silly. Use one. Download the maps for offline use before you leave, carry a power bank, and keep the phone in an inside pocket, because cold batteries lose capacity fast and a phone that was on 60 percent can die in minutes at low temperatures.
The limits are worth being honest about. Screens are hard to use with wet gloves, phones break when dropped on rock, and a blue dot tells you where you are without telling you which way out is safe. That last one matters most: the dot will happily sit on a line that goes over a crag. Carry a paper map and a compass, keep them somewhere you can reach without taking the pack off, and know how to use them when the screen goes black.
When you don't know where you are
- Stop walking. Every minute of wandering makes the search area bigger and the problem harder.
- Work out the last point you were certain of, and how long ago that was. Time multiplied by your speed gives you a radius to search within on the map.
- Look at the ground around you. Which way does the slope fall? Use the compass to measure the aspect of the slope you are standing on and compare it with contours inside your radius. It narrows things down remarkably fast.
- If that gives you a confident answer, navigate carefully to a definite feature to confirm it. If it does not, go back the way you came to your last known point rather than pressing on into unknown ground.
- If light or weather is running out, stop and think about shelter rather than continuing to move. Getting benighted somewhere sheltered is an inconvenience. Getting benighted while descending unknown steep ground is how people get hurt.
Tell someone your route and your expected return time before you leave, and tell them when you are back. If you need help and cannot get down, six blasts on a whistle, a minute's pause, then six more, is the recognized distress signal, and six flashes of a headtorch does the same job after dark. Both carry further than shouting and cost you almost nothing to bring.