a. Determine starting zones of probable avalanche prone slopes and cross as high as possible, preferably above natural anchors.
b. Travel on high points and ridges, especially windward sides.
c. When ascending or descending an avalanche prone slope, stay to the side of the start zone and track.
d. Avoid wind-loaded, lee slopes.
e. Favor terrain with anchors, i.e. tree-covered areas over open slopes.
f. Pick areas with flat, open run-outs so that debris burial depth is decreased. Avoid areas that feed into crevasses and cliffs.
g. You can generally find a safe route somewhere in a wide U-shaped valley, but narrow V-shaped ones should be avoided. In V-shaped valleys, avalanches could run from either side and continue up the opposite side, so there may be little or no safe ground.
6. CROSSING AVALANCHE PRONE SLOPES. Certain requirements may make it necessary to cross a suspected slope. This should be done only AFTER all alternatives have been exhausted.
a. Individual Preparation.
(1) Loosen ski bindings; remove hands from ski pole straps.
(2) Leave your pack on and secure the pack straps.
(3) Secure ECWCS hood tightly covering face, trail an avalanche cord if available.
(4) Go straight downhill on foot rather than ski and look for possible escape routes.
(5) Go straight down, do not traverse.
(6) If possible cross as high as possible on concave slopes.
(7) Cross one at a time and if one crosses safely, it does not mean that it is safe passage for the rest. If possible, belay everyone across.
b. Actions if Caught.
(1) Attempt to remove skis or snowshoes.
(2) Assess best line of escape.
(3) Delay your departure, i.e., let as much of the avalanche pass you as possible.
(4) Try and work to the side. There will be less force of the avalanche at the edge of the flow.
(5) Try to swim out using a double action backstroke or try to roll away at a 45-degree angle.
(6) A supreme effort should be made to get to the surface as the avalanche settles.
(7) Make an air space to breath.
(8) Move to position near the surface if possible.
(9) Establish orientation.
c. Avalanche Rescue. Statistically, after about 1/2 hour of burial, the chance of survival is approximately 50%. After an hour the chances of survival drop to 20%. Speed is therefore essential for recovering a live victim. Cold and suffocation is the main causes of death.
(1) Make a careful note of where he was last seen and mark the spot. Also mark any position where he reappeared during his movement.
(2) Make a quick visual search of the area, looking for any sign (i.e., avalanche cord, body parts, or equipment).
(3) If nothing is apparent at first then make a quick surface search.
(4) If nothing is found, a more systematic search should be made from the bottom working up.
(5) If you again fail to find anything, your next step is to probe.
(6) Most Likely Spots to Find an Avalanche Victim.
(a) Start at the last seen location and work down the slope. Look for clues of the victim such as skis, clothing, avalanche cord, etc.
(b) At the outsides of bends of the avalanche path where debris accumulates.
(c) Look on the uphill side of obstacles, such as trees and boulders, where debris builds up.
(d) In the run out zone, debris may be very large and hard to search.
(7) Types of Searches. This will depend on manpower available and time.
(a) Hasty search. By far the most important search for backcountry travel. Speed is essential and the determination whether or not to go for help is a difficult one.
(b) Coarse probe. The idea behind this type of probe is to sacrifice some thoroughness for speed.
(c) Fine probe. Takes 4-5 times longer than the coarse probe. Chances are, the victim will not be recovered alive.
7. ICE HAZARDS. Frozen waterways (lakes, streams, and bays) can be life threatening obstacles when crossing. Ice is classified in three general types: salt water, fresh water, and land.
a. Fresh Water Ice. Fresh water ice begins to form on lakes and rivers under normal conditions, from 3-5 weeks after the daily temperature drops below 32F.
b. Lake Ice is generally weak in the areas of streams, inlets, springs, or outlets. Decaying vegetation on the bottom of a lake may give off air bubbles, which slow ice formation and create weak ice.
c. River Ice formed by warm weather and wind may create a rough surface, which will remain ruff throughout the winter. This ice is filled with air bubbles.
d. Normally, fresh water does not freeze to a thickness greater than 8 feet in a single season. In lakes, the normal ice depth by late March is between 3 1/2 feet and 6 feet, depending on winter temperatures.
(1) The following conditions will speed up freezing:
(a) Low stable temperatures.
(b) High wind-chill factor.
(2) The following conditions will retard freezing:
(a) Fluctuating temperature.
(b) Fast current.
(d) Salt water and other impurities.
NOTE: The strength of ice depends upon ice structure, purity of water, freezing process, cycles of freezing and thawing, crystal orientation, temperature, ice thickness, snow cover, water current, underside support, and age.
e. Special Considerations.
(1) Immediately adjacent to the shore, the ice formation is thin and weak and more likely to develop cracks than ice in the center of a frozen stream. Depending upon the gradient of the riverbed and the thickness of the ice near the shore, it is generally safer to maintain a route near the shore if the ice rests upon the river bottom.
(2) Where an under-ice current of water flows under a large ice area, the ice in contact with the current is subject to a greater variation in temperature over a given time, and therefore thicker than the ice in adjacent areas.
(3) Shallow water ice is usually thinner than deep water ice.
(4) Good quality ice is clear and free from bubbles and cracks. In a body of water containing clear and cloudy ice. The clear ice will frequently be thinner then the cloudy ice.
(5) Lakes containing a great deal of vegetation whose decomposition retards freezing, results in weak ice.
(6) Flooded snow when frozen produces "slush ice" which is white and may contain air bubbles. Slush ice has a load carrying capacity approximately 1/4 less than that of prime natural ice.
(7) Ice that remains unsupported after a drop in the water beneath it has little strength. Reservoirs and lakes with runoffs are examples.
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