Accurate navigation is all the more imperative in winter.
With the shorter daylight hours comes the increased likelihood of you having to descend in the dark. There is the increased risk of poor visibility, or even white out conditions when windblown snow particles can blur the boundaries between earth and sky, (known as the ‘white room’). Paths, streams, boundaries and even lakes can disappear under a blanket of snow. Once, on Aonach Mor in the Scottish Highlands I was searching for the summit cairn only to be told it was under my feet, buried by the snow.
Good navigators know where they are at all times, and can follow their progress on a map. This is so important in winter conditions, when icy snow slopes and corniced edges can increase the hazards you face.
The essential tools for winter navigation are the map and compass, an altimeter can be useful too, (more of which later).
Keep your map in a soft plastic map case, folded so the area you are hiking in is shown. This should be kept handy, inside your jacket or in a secure pocket, it’s no use to you in the bottom of your rucksack, get it out and use it.
Your compass should be of a high quality, the mountaineering bodies in Ireland and the UK recommend the Silva 4 Expedition model. Use the lanyard to fix it to your rucksack strap or a toggle on your jacket, so you won’t lose it, and remember to keep it away from electronic devices, as these will deflect the needle and give inaccurate readings. In the windy conditions often experienced in winter maps and compasses can easily be blown away and lost, so practice good map management, (and carry a spare just in case).
Don’t be tempted to rely on GPS or phone app systems for your navigation, they can be a useful back up, but cold kills batteries and your unit may fail, leaving you stranded.
Preparation is the key. It is important to check the weather forecast several days before you go, if there is a risk of snow check out any available avalanche forecasts too. Do not try to take on too much, progress is slow in winter and daylight hours are few. Plan your ascent and descent routes taking into account potential hazards and plan an escape route in the event of abandonment. Draw up a route card and break down your journey into a number of navigation legs, try to keep the legs short to reduce inaccuracies when navigating in poor visibility.
When beginning any navigation leg, or trying to determine your position, the first thing to do is to orientate the map. This is also called setting, and involves lining the north south grid lines on the map with north on the ground. In good visibility this can be achieved by sighting features in the landscape and lining them up with the corresponding feature on the map. In poor visibility you may need to orientate the north south grid lines with north by using the north (red) end of the compass needle.
Sometimes this may be all you need to do to determine your direction of travel and to identify your objective, but in poor visibility it may be necessary to walk on a bearing.
When navigating in poor visibility consider the 4 D’s before each leg; Distance, Direction, Duration, Destination.
Measure the distance to your next target using either the compass romer or the measuring scale on the edge of the housing. To know how far to walk you should use either pacing or timing, or both. Pacing is the technique of counting the number of double paces to your objective. Knowing how many paces you take to walk 100 metres in different conditions and terrain, you can then count out the multiples of 100 metres until you reach the distance measured. Pacing works best over shorter distances of several hundred metres, for greater distances timing is often used. Timing relies on knowing how fast you are walking, say 4 km/hr, and doing a calculation to determine how long it will take you to reach the objective.
These techniques may sound complicated, but they are one of the cornerstones of good navigation, and become easier with practice.
To determine which direction to walk in you must take a bearing from the map with your compass. Estimate it first, this will help avoid errors, particularly the often made 180 degree error, where south is mistaken for north on the map, or you have the compass pointing from the objective to your current position instead of the other way round.
Once you have your bearing you must adjust it to take account of the magnetic variation between magnetic and grid north, check the map before you set out as the information you need is in the legend. Sight along the compass to an object in line with the bearing and walk to it, repeat this process until you reach the objective.
If visibility is so poor you cannot see anything ahead, send a companion ahead of you and adjust their position until they are in line with the bearing, walk toward them and repeat the process.
Taking and walking on bearings can seem daunting, and requires training and practice, but there are a number of online resources to help, some useful sources are listed at the end of this article.
What do you expect to see when you reach the objective? You should have at least 3 features or characteristics of the target to enable you to confirm you have arrived in the right place. When you reach the objective ask yourself the question, ‘Do I see what I expect to see?’
To avoid overshooting, determine what feature will tell you that you have gone too far, this is a catching feature, and could be a stream, a change of slope, or a boundary.
It is a good idea to identify features you might see or cross on route, by noting these features as you pass them you can confirm your position. These are called tick features as you ‘tick’ them off as you go, they also give a good deal of confidence that things are going according to plan!
How long will it take to reach the objective? This is linked to the timing mentioned earlier, and again you need to know how fast you walk and the distance to the objective.
Altimeters are a very useful tool in winter navigation. It can be important to know how far up or down a slope you are, particularly if you have to make a change of direction when descending a spur. By reading the contour height from the map and relating it to the altimeter reading it is possible to accurately determine your position. Remember to calibrate the altimeter regularly at spot heights and summits, as they often rely on barometer readings, which can change rapidly in winter.
Finally, if it all goes horribly wrong and you can’t recognise anything in the landscape, don’t panic. Take a breather, have a warm drink or a sugary snack. As long as you have been walking on your bearing and know how far and how long you have been walking, you can always turn your compass by 180 degrees and return to your last know position, the beginning of the navigational leg. This is a back bearing and can return you to a place you can identify on the map, from here you can re-calculate the 4 D’s and begin the leg again.
Navigating in winter will test the skill of the best navigators, and requires all the above techniques and a lot of practice to become completely proficient. However, when you have learned the skills and gained the experience the winter mountains are open to you in all their magical beauty.
If you want to learn to be a competent and self-reliant winter navigator you can join one of our Mountaintrails navigation courses.
Other useful resources:
British Mountaineering Council: https://www.thebmc.co.uk/articles/Walking/Skills
Mountaineering Ireland: http://www.mountaineering.ie/TrainingAndSafety/SkillsVideos/default.aspx