Check out this excellent video on Strategic Shovelling from Backcountry Access (BAC). It highlights the research done by Dale Atkins and Bruce Edgerly on the most efficient method of digging your buried companion from under an avalanche.
Here is the text from Backcountry Avalanche Safety to go with the video:
- Leave the probe in place, noting the burial depth. Avoid tramping around directly above your buried companion to avoid injuring them or reducing their air pocket.
- Put your gloves back on once you have finished assembling the probe and shovel.
- If the depth of burial is less than a metre, dig straight down the probe from the downhill side.
- If deeper, mark a rectangle on the snow with your shovel about as wide as your extended arms for a single rescuer, or about 2 m wide for multiple diggers. This is to discourage the digging of an increasingly narrower hole that would eventually slow down access to the person’s airway. The rectangle should extend downhill from the probe a distance of 1.5 times the burial depth.
- Excavate the “starter hole,” working on your knees if necessary, and throwing snow out to the sides of the hole. Chop hard snow into blocks and scoop it out rather than prying. It’s faster and uses less energy.
- Stand up when you need to and continue throwing snow to the sides where it won’t have to be moved again.
- Maintain the full width of the starter hole as you dig deeper.
- When the snow surface gets to be level with your waist, you may need to dig a terrace on the downhill side so that you can throw the snow clear.
- You will now need to excavate to another level. Start at about half the distance to the probe and work toward the probe. This will give you a bench to sit on.
- If the debris is on a slope and the probe is perpendicular to the slope, make sure you keep the probe exposed all the way down. You may need to begin your starter hole a little above the probe,
- When you first reach your buried companion, dig to uncover their head and clear the airway as soon as possible.
- The starter hole should be wide enough for the two rescuers to work side by side, each person throwing snow to their own side. Otherwise the procedure is the same.
- Two of the rescuers should begin digging the starter, hole throwing the snow out to the sides as described above.
- You can deploy extra diggers using the principles of Genswein’s Conveyor Method that employs more people downhill of the primary diggers. In self-rescue situations you are only likely to be able to use two or possibly three extra people effectively for shovelling. Additional people can be part of the rotation or can be preparing to deal with the evacuated person.
- Rotate shovellers frequently.
- The extra shovellers, offset from each other, clear snow from the downhill side of the starter hole so as to create and maintain a ramp toward the burial location.
- The ramp should be flared out at the back to allow the rear diggers room to work. As the starter hole gets deeper it will become easier for the two front diggers to throw the snow up the ramp behind them to where the rear diggers can scoop it out of the way.
- Once the buried person is reached, the extra shovellers can enlarge the hole and maintain the ramp to facilitate extraction while one of the rescue party is attending to the airway.