Avalanche

:This article refers to the natural event. For other uses, see Avalanche (disambiguation)

Human survival and avalanche rescue

Even small avalanches are a serious danger to life, even with properly trained and equipped companions who avoid the avalanche. Between 55 and 65 percent of victims buried in the open are killed, and only 80 percent of the victims remaining on the surface survive. (McClung, p.177). Thus, there is at least a one in five chance that you will be killed if caught in a significant avalanche.

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Research carried out in Italy (Nature vol 368 p21) based on 422 buried skiers indicates how the chances of survival drop:

Related Topics:
Italy - Skiers

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• very rapidly from 92% within 15 minutes to only 30% after 35 minutes (victims die of suffocation)
• and near zero after two hours (victims die of injuries or hypothermia)

:(Historically, the chances of survival were estimated at 85% within 15 minutes, 50% within 30 minutes, 20% within one hour).

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Consequently it is vital that everyone surviving an avalanche is used in an immediate search and rescue operation, rather than waiting for help to arrive. Additional help can be called once it can be determined if anyone is seriously injured or still remains unaccountable after the immediate search (i.e., after at least 30 minutes of searching). Even in a well equipped country such as France, it typically takes 45 minutes for a helicopter rescue team to arrive, by which time most of the victims are likely to be dead.

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In some cases avalanche victims are not located until spring thaw melts the snow, or even years later when objects emerge from a glacier.

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Search and rescue equipment

Chances of a buried victim being found alive and rescued are increased when everyone in a group is carrying and using standard avalanche equipment, and have trained in how to use it. However, like a seat belt in a vehicle, using the right equipment does not justify exposing yourself to unnecessary risks with the hope that the equipment might save your life when it is needed.

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Avalanche cords

Using an avalanche cord is the oldest form of Equipment - mainly used before beacons became available. The principle is simple - an aprox. 10m long, red cord (similar to parachute cord) is attached to the persons belt. While skiing/snowboarding/walking the cord is dragged along behind the person. If the person gets buried in an avalanche, the light cord stays on top of the snow. Due to the color the cord is easily visible for rescue personnel. Typicly the cord has iron markings every 1m that indicate the direction and length to the victim.

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Beacons

Beacons - known as "beepers", ARVAs (Appareil de Recherche de Victimes en Avalanche, in French), LVS (Lawinen-Verschütteten-Suchgerät, Swiss German), avalanche transceivers or under various trade names (including Ortovox, Barryvox, and Pieps), are important for every member of the party. They emit a "beep" via 457kHz radio signal in normal use, but can be switched to receive mode to locate a buried victim from 10 to 20 meters away. Analog receivers provide audible beeps that rescuers interpret to estimate distance to a victim. To be effective, beacons require some amount of practice. Some older models of beepers operated on a different frequency (2.275 kHz) and a group leader should ensure compatibility within the group.

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Recent digital models also attempt to give visual indications of direction and distance to victims and require less practice to be useful. Some inexpensive beacons also operate only as transmitters, relying on others not to become buried with the only receivers. There are also passive transponder devices that can be inserted into equipment, but they require specialized search equipment that might only be found near an organized sports area.

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Mobile phones can seriously disrupt the ability of an ARVA to locate buried victims; phones should be switched off at the same time as the ARVA is switched on in the morning.

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Probes

Portable (collapsible) probes can be extended to probe into the snow to locate the exact location of a victim at several yards / metres in depth. When multiple victims are buried, probes should be used to decide the order of rescue, with the shallowest being dug out first since they have the greatest chance of survival.

Related Topics:
Yard - Metre

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Probing can be a very time-consuming process if a thorough search is undertaken for a victim without a beacon. In the U.S., 86 percent of the 140 victims found (since 1950) by probing were already dead. Outside Online, Feb 2000 Survival/rescue more than 2 m deep is relatively rare (about 4 percent). Probes should be used immediately after a visual search for surface clues, in coordination with the beacon search.

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Shovels

When an avalanche stops, the decelleration normally compresses the snow to a hard mass. Shovels are essential for digging through the snow to the victim, can be many times faster than digging by hand. With a shovel it typically takes 10 minutes to free someone buried 1m deep, but 45 minutes using skis and hands.

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A large scoop and sturdy handle are important. Shovels are also useful for digging snow pits as part of evaluating the snowpack for hidden hazards, such as weak layers supporting large loads.

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Other devices

Other rescue devices are proposed, developed and used, such as Avalanche Ball, Avalung vest and avalanche airbags (most deaths are due to suffocation). There are also passive signalling devices that can be carried or inserted into sports equipment, but they require specialized search equipment which might only be found near an organized sports area.

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More back-country adventurers are also carrying EPIRBs (Emergency position-indicating rescue beacons) containing GPS. This device can quickly notify search and rescue of an emergency and the general location (within 100 yards), but only if the person with the EPIRB has survived the avalanche and can activate the device manually. With modern mobile phone developments, an emergency GPS transmittter may also become more widely available (again, for use by a rescuer, because a victim may be unconscious or completely immobilised beneath dense snow).

Related Topics:
Emergency position-indicating rescue beacon - GPS - Mobile phone

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Prior to the arrival of beacons, some brave skiers carried a 50-ft ball of nylon cord, tied to the skier, with direction and distance markings attached at intervals. When traversing a dangerous area, the ball would be dropped or thrown and the unravelled string would trail behind. If caught in an avalanche, the hope was that a segment of the string would be quickly found and indicate the distance and direction to the victim.

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Although it will be very inefficient, some rescue equipment can also be hastily improvised: ski poles can become short probes, skis or snowboards can be used as shovels.

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A First aid kit and equipment will also be useful for assisting survivors who may have cuts, broken bones, or other injuries, in addition to hypothermia.

Related Topics:
First aid - Hypothermia

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Witnesses as rescuers

Survival time is short, if a victim is buried. There is no time to waste before starting a search, and many people have died because the surviving witnesses failed to do even the simplest search.

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Witnesses to an avalanche that engulfs people are frequently limited to those in the party involved in the avalanche. Those not caught should try to note the locations where the avalanched person or people were seen. This is such an important priority it should be discussed before initially entering an avalanche area. Once the avalanche has stopped, and there is no danger of secondary slides, these points should be marked with objects for reference. Survivors should then be counted to see who may be lost. If the area is safe to enter, a visual search of the likely burial areas should begin (along a downslope trajectory from the marked points last seen). Some victims are buried partially or shallowly and can be located quickly by making a visual scan of the avalanche debris and pulling out any clothing or equipment found. It may be attached to someone buried.

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Alert others if a radio is available, especially if help is nearby, but do NOT waste valuable resources by sending a searcher for help at this point. Switch transceivers to receive mode and check them. Select likely burial areas and search them, listening for beeps (or voices), expanding to other areas of the avalanche, always looking and listening for other clues (movement, equipment, body parts). Probe randomly in probable burial areas. Mark any points where signal was received or equipment found. Only after the first 15 minutes of searching should consideration be given to sending someone for help. Continue scanning and probing near marked clues and other likely burial areas. After 30-60 minutes, consider sending a searcher to get more help, as it is more likely than not that any remaining victims have not survived.

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Line probes are arranged in most likely burial areas and marked as searched. Continue searching and probing the area until you can live with the fact that your companion may be dead because you didn't try hard enough to find him or her. Avoid contaminating the scent of the avalanche area with urine, food, spit, blood, etc, in case search dogs arrive.

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The areas where buried victims are most likely to be found are: below the marked point last seen, along the line of flow of the avalanche, around trees and rocks or other obstacles, near the bottom runout of the debris, along edges of the avalanche track, and in low spots where the snow may collect (gullies, crevasses, creeks, ditches along roads, etc). Although less likely, other areas should not be ignored if initial searches are not fruitful.

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Once a buried victim is found and his or her head is freed, perform first aid (airway, breathing, circulation/pulse, arterial bleeding, spinal injuries, fractures, shock, hypothermia, internal injuries, etc), according to local law and custom.

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Victims

Victims caught in an avalanche are advised to try to ski or board towards the side of the avalanche until they fall, then to jettison their equipment and attempt swimming motions. As the snow comes to rest an attempt should be made to preserve an air-space in front of the mouth, and try to thrust an arm, leg or object above the surface, assuming you are still conscious. If it is possible to move once the snow stops enlarge the air space, but minimise movement to maximise the oxygen supply. Warm breath may soon cause a mask of ice to glaze over the snow in your face, sealing it against further air.

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