The day the cloud comes down

There's a particular kind of quiet that settles on a hillside when the mist closes in. Landmarks you were leaning on ten minutes ago — a rocky outcrop, a distant cairn, the curve of a valley — simply aren't there any more. On a clear day you can navigate the British hills almost by instinct. In poor visibility that instinct needs a backup, and the backup is a map, a compass and a bit of practice.

The good news is that walking on a bearing isn't difficult. It's a short set of skills, repeated patiently, that will get you off a foggy summit and back to the car with your dignity intact.

Set yourself up before you need it

Do the fiddly work while your hands are warm and you can still see. Take the map out at the last stile or summit shelter, orient it to the ground, and identify where you are. Look for handrails — a wall, a fence line, a stream, a forest edge — that run roughly the way you want to go. If you can follow a handrail, you barely need a bearing at all.

Keep your compass on a lanyard around your neck, not buried in a rucksack pocket. Keep it clear of magnetic interference: a mobile phone, a steel gate, a metal trekking pole clip, even a car bonnet can pull the needle off. Check the margin of your map for the local magnetic variation — across most of Britain it's small enough to ignore for walking, but it's worth knowing it exists.

Taking a bearing from the map

Say you're on a summit and you want to reach a col a kilometre away. Lay the long edge of the compass baseplate on the map so it runs from where you are to where you want to be. The direction-of-travel arrow at the front must point towards your destination, not back at you.

• Hold the baseplate steady and rotate the bezel until the orienting lines inside it run parallel with the north–south grid lines on the map.
• Make sure the N on the bezel sits at the top of the map — a 180-degree error here is the classic mistake, and it will send you the wrong way with total confidence.
• Read the number at the index line beside the direction-of-travel arrow. That's your grid bearing.
• Lift the compass clear, hold it flat at chest height, and turn your whole body until the red end of the needle sits inside the orienting arrow — "red in the bed".

The direction-of-travel arrow now points along your route. That's it.

Walking on the bearing

Nose-to-compass walking is slow, slightly hypnotic, and easy to drift off line. A better method is to look up, pick a distinct object in line with the arrow — a boulder, a lone tree, a patch of darker ground — walk to it, then reset the compass and repeat. In thick mist, when nothing distant is visible, shorten the legs: pick a point twenty or thirty metres ahead, walk to it, and start again.

Keep a rough check on distance too. Most adults take somewhere between sixty and seventy double paces per hundred metres on level ground, but this changes with slope, bog and the weight of your pack. Count your paces on a known stretch and you'll have your own figure.

Timing works alongside pacing. On easy level ground, allow roughly four kilometres per hour; cut that to three or less on rough, steep or pathless terrain. If your timing and your pacing agree that you've covered the distance, trust them both. If they disagree wildly, stop and work out where you actually are.

When the ground doesn't cooperate

Aiming off means deliberately heading a few degrees to one side of your target so that you hit a linear feature — a stream, a wall, a track — and know exactly which way to turn when you reach it. It's far better to arrive at a fence line knowing your target is two hundred metres to the right than to arrive somewhere unknown along it and guess.

Back bearings let you check your line. If you've walked a bearing of 240 degrees, then 060 degrees should take you back the way you came. Add or subtract 180 to find it — add if the original is under 180, subtract if it's over.

Contours are your quiet ally in mist. Count them as you cross them and note whether you're climbing or dropping; you'll know roughly where you are even when you can see nothing at all.

Practise it before you need it

The best time to learn bearings is on a bright clear day when you can see your mistakes. Take a bearing to a trig point or a café you can actually see, walk it, and see how close you get. Then try it in drizzle, and then at dusk. You'll quickly learn your own pacing count and how far you truly drift.

Carry a spare compass, keep it warm and dry, and treat the skill as a habit rather than a rescue measure. Mist in the British hills is not an emergency. It's just weather — and with a map, a compass and a little patience, it doesn't have to change your plans.