Route Choice for navigation means 'selection of features on the map which can be identified on the ground to create navigational legs along a route that avoids major hazards and is practical to follow'. This lengthy definition encompasses three main factors which should be taken into consideration when choosing the route to be navigated:-
- Features - Choose features on the map which are not too far from each other (ideally no more than one kilometre) which you will be able to identify on the ground when you reach them. Examples of features which can usually be found are ring contours, saddles or cols and prominent changes in slope angle. These are all "contour features" which often provide the best information. Streams and lochs can also be useful but in winter they may be covered by snow (or thin ice!).
- Hazards - The features chosen need to follow a route which avoids major hazards. For example, a cliff edge may be a very prominent feature but going to it may draw you into a hazardous situation. Of course, some summits are actually at the top of cliff edges and sometimes it may be best to locate the edge safely and use it as a handrail to find the summit (in poor visibility in a winter storm it may be best not to visit a summit which is on a cliff edge).
- Practicality - Features should be chosen so that travelling from one feature to the next does not waste valuable time and energy. For example, try to avoid choosing features which will result in excessive loss of height which then has to be regained in order to go on to the next feature.
Imagine someone is giving you directions to their house in a town which you have never been to. What landmarks will they use? They will probably try to describe the route by referring to landmarks which you will easily be able to find e.g. a bank, hotel, shop, railway station, roundabout, traffic lights etc. Transfer this concept to choosing a route in the mountains - instead of someone telling you what the landmarks are, you look for them on the map and choose features which you will be able to find.
Fig 1. Image produced from the Ordnance Survey Get-a-map service. Image reproduced with kind permission of Ordnance Survey.
The illustration shows two route choices for going from Carn Ban Mor to Loch nan Cnapan. The red arrow shows the direct route which is 2½ kilometres long and would be difficult to navigate in poor visibility. Following a compass bearing for this distance with no easily identifiable features along the way may result in drifting off the bearing and it will be difficult to keep track of the distance travelled. The other route shown by the blue arrows breaks the journey into four legs. Each leg ends with a prominent contour feature (except the loch which is the final destination). The first leg ends at a prominent change in slope angle - the bottom of the south-east slope of Carn Ban Mor. The second leg travels across flat terrain before gaining 10 metres height to reach the 950 metre ring contour. The result of travelling too far on this leg will be clear - the descending terrain is a catching feature which will highlight the error and enable the navigator to return to the ring contour. The track goes across the top of the ring contour and this is a supplementary feature which may be of use, although in winter it may be covered in snow. The third leg ends at a prominent change in the steepness of the streambed where the track makes a 90 degree bend. The track may not be visible but to the south of the bend the contours show a steep-sided streambed whereas to the north the streambed is comparatively flat. This is a location which can be found without too much difficulty. From here a relatively short final leg crosses a flat-topped spur before dropping down to Loch nan Cnapan. This route incorporates some height gain and loss but it is practical to follow and makes use of prominent features which can be identified in poor visibility.
Being able to select an appropriate route and then following it using the skills which have been discussed on the other pages can be very satisfying, great fun, and most importantly will help you to have successful days out on the hill.
Setting the Map
Ticking off features
Taking & Following a Compass Bearing
Estimating Distance Travelled
Aiming Off, Attack Points, Handrails
Symbols and Grid References
Safety and skills information is provided courtesy of Mountaineering Scotland