The 3-by-3 Method
Informed decision-making and appropriate behaviour can reduce avalanche risks to an acceptable level. The individual phases of a tour, from the planning stage at home to the downhill run through deep snow, call for multiple re-assessments of the conditions, terrain and human factors.
Werner Munter’s original 3-by-3 method is a proven technique for assessing the avalanche danger. It facilitates the classification of information and observations in three categories, namely conditions, terrain and human factors, in the three phases planning, assessment in the field and individual slope.
1. Planning
Good trip planning is an essential ingredient of rewarding adventures in the mountains. Obtain information about the avalanche and weather conditions in the area you intend to visit. Plan the route by consulting mountain guide publications and the slope angle map. Carry the proper equipment, give consideration to both the composition of the group and everyone’s expectations.
2. Assessment on-site
Throughout the day, continuously pay close attention to the conditions, terrain and human factors in relation to known cruxes. Do the avalanche and weather conditions, the terrain, and the ability and fitness of the group members concur with the assumptions that were made when planning the tour?
3. Individual slope
While making allowance or adjustments for special circumstances, give consideration to the key factors – namely the conditions, terrain and human factors – not only separately, but also together, and then make a decision. When deliberating on the advisability of venturing onto a slope, the following decisions are possible:
- Yes, we can proceed without difficulty
- Yes, we can proceed, but only subject to certain conditions (e.g. descend one at a time or only as far as the next decision-making point)
- No, we cannot proceed. In this case, select a planned alternative or abandon the tour.
A more detailed explanation of the 3-by-3 method is given on our interactive avalanche prevention platform White Risk.