The Training Hole
Before digging a snow cave to hide in for training, first check the spot you plan to dig with an avalanche probe (a long, thin, metal stick). Then you know the thickness of the surface of snow on that spot. Take care to find a layer of snow at least two yards (2 m) thick in which to dig a hole. Start by digging vertically to clear the part of the snow in front of the future entrance all the way down to the ground. This will make it easier to dispose of the snow from the hole. Dig the entrance as straight as possible: around twenty inches (50 cm) in diameter and a yard (1 m) in length. Now it’s time to start digging the hole proper. To ensure it is solid enough, clear the snow by working in an arc. The ideal hole is shaped like an igloo on the inside.
Figure 12.4 The hole should be dug where the snow is at least two yards (2 m) thick and where there are no large rocks inside the snow.
Figure 12.5 Make a twenty by thirty-six inch (50 cm x 100 cm) cylindrical entrance. Then dig an arched cavity measuring about thirty-six inches (1 m) in diameter and thirty inches (75 cm) high.
The hole should have a lot of headroom—enough for a helper to sit up, because lying down will lower the body temperature. The helper should feel comfortable. The dog must also be able to enter and turn around in the hole. The helper sits on one or more insulation mats. No part of the helper’s body should be in direct contact with the snow wall. If there’s enough room in the cave, you can also make a little niche for a candle. This gives the helper a bit of light and warmth.
Figure 12.6 The snow from the entrance and hole should be cleared in an arc to ensure the hiding place is solid enough.
Safety in the Hole
Take good care of your helpers. People with a phobia or illness should never serve as a helper in the hole. A panic attack can be dangerous, not only for them, but also for everyone present. There should always be two people with shovels on the surface ready to clear the entrance to the hole immediately in emergencies.
Outside the hole there is also a person with a working avalanche beacon that controls the probe put in the hole, by which a helper inside the cave can give signals to the outside. In the cave the helper has a transmitting avalanche beacon under his or her clothes, a walkie-talkie, and the sock toys of the different dogs.
It is remarkable that someone in a snow cave, just as in the rubble, can hear everything from outside, but someone outside can barely hear a helper calling. Therefore, after each searching dog or its handler has opened the hole, go to the entrance of the hole and ask how the helper is doing.
Figure 12.7 Always maintain contact with the helper at the entrance of the hole, listening carefully to his or her responses.
Getting Enough Oxygen
People taking part in avalanche dog training for the first time are often frightened about getting into the hole. They have an idea it could easily collapse, suffocating them. These concerns are completely unfounded. First and foremost, the snow layer where the hole is dug must always be two yards (2 m) thick. Second, the roof of the hole should be arched. Before it is put into use, test the hole by walking on top of it.
There will always be enough oxygen in the hole. The snow walls release a lot of oxygen. After a while, a layer of ice might form on the inside wall of the hole from the helper breathing or because of the candle; if this happens, prick some holes in the wall to be sure there is enough oxygen available. Helpers can sit in such a hole for a few hours without any problem.