An avalanche is a fascinating and naturally occuring phenomenon that is caused by unstable snow conditions. Since it is practically impossible to predict where and when the next avalanche will occur, significant amounts of information such as weather forecasts and avalanche forecasts are provided for the winter sports enthusiasts to aid their understanding of avalanche dangers and potentially prevent one from occuring.
The following avalanche information is not to be accepted as a set of instructions, it is designed merely provide guidance for those who wish to go off piste, and facilitate informed decision-making. It is also worth noting that avalanches are not the only dangers of off-piste: natural obstacles such as crevasses, buried rocks or cliffs are also potential hazards. It is highly recommended that you take a mountain guide whilst venturing into unknown territory.
The chances of surviving an avalanche are dramatically increased when the group are properly equipped with the standard avalanche equipment, and are trained in how to use it. None of the devices we have listed here will actually prevent an avalanche or prevent physical injury from occurring, but will assist in the recovery process. So what does the basic avalanche equipment consist of?
For anyone going off marked pistes, (including climbers, skiers, snowboarders, snowshoers and walkers); it is advisable that the following items of equipment are carried at all times:
Avalanche Transceivers (beacons)
Digital or analogue, these will send out a signal of where the body is located under the snow and/or assist in detecting the location of buried transceivers
Avalanche Probe
Portable (collapsible) probes are used immediately after a visual search to localise a buried victim, and give exact depth of the body
Snow Shovel
Shovels are essential for excavating the victim, quickly (speed is the name of the game) as the snow deposit is too dense to dig with your bare hands
Probes and shovels are often incorrectly viewed as less important equipment than transceivers, and purchased later. However, the French Avalanche Research Institute reports an exercise where sets of transceivers were buried 1 metre below the surface of the snow. Teams of five were given basic instructions on how to recover the 'victims', snow shoes, and different sets of rescue equipment. The following table shows how they faired (remember 15 minutes is the crucial time-frame where 90% of victims are recovered alive!):
Equipment
Time
Transceiver, Probe and Shovel
16 minutes
Transceiver and Shovel
26 minutes
Transceiver and Probe
50 minutes
Transceiver
60+ minutes
The search teams without complete sets reported problems either having to continually re-searching for the 'victims' as they dug (without probes); or had to resort to using their skis or snowboards and even their hands and to help them dig (without shovels).
Videos from Chamonix - Avalanche Search and Rescue
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Statistics show that in the event of an avalanche accident a buried victim has between fifteen to twenty minutes to be recovered alive. Although the emergency services are excellent at recovering those unfortunate enough to be caught in an avalanche, they cannot always be relied upon to mobilise within this small window. It is therefore essential to be able to carry out a self contained rescue.
For an introduction to avalanche search and rescue we spoke to British snowboard Instructor Roddy Clarke who has been working in the Alps forHAT mountain safety for six years and is a director ofPro Snowboarding Val d'Isere.
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Avalanche Transceivers
Avalanche transceivers work by sending / receiving electromagnetic signals on a frequency of 457kHz. There are many transceivers available in the marketplace using either analogue (older) or digital technology. Digital and analogue transceivers are compatible.
Analogue transceivers working in "receive" mode, convert the signals being transmitted by the "sending" transceiver from underneath the snow into sound waves. The receive signal is transmitted as a 'beep' which gets louder and stronger the closer the receiving transceiver gets to the emitting transceiver.
Digital transceivers interpret the same signal. A microprocessor converts the signals into visual data on screen, assisting with more accurate directional information. Digital transceivers are reportedly simpler to use than analogue ones.
The relatively high price of transceivers (around €300) should not deter you from purchase – at what price your or your companions’ lives? The cost reflects relatively low production numbers - ~60,000 units per manufacturer per year; high research and development costs as equipment has become more advanced; and that a high level of robustness and performance is expected from the manufacture process. An alternative is to rent equipment from a hire shop as you require it, however, as a rescuer in this scenario you are unlikely to be sufficiently proficient to be of help in detecting buried victims as you are unlikely to have practiced enough.
The following is a summary of transceiver tests conducted by French Avalanche Research Institute. Nevertheless, the best performing beeper is the one that you know and practice with!
Types of Avalanche Transceivers
Evaluation Criteria
ARVA 9000*
Barryvox
Ortovox F1 focus
Ortovox M2
Tracker DTS
Minimum Functional Range
**
**
***
***
**
Ease of Secondary Search Phase (Phase 2)
***
***
**
**
***
Precision during Fine Search Phase (Phase 3)
***
***
***
***
***
Ease of interpreting the signal
***
****
***
****
****
Detecting several transmitters
**
**
***
***
**
Using the instrument with gloves
***
**
***
****
**
Turning the instrument on
****
****
****
****
***
Turning the instrument off
****
****
****
****
****
Changing from transmit to receive
****
***
****
****
***
Changing from receive to transmit
**
***
***
***
***
Instructions
**
**
**
**
**
Transmitting Power
***
**
**
**
**
Source: 'a synthesis of subjective assessments' from: Sivardière F., 2000. Que Penser des ARVA de l'an 2000? ANENA, Neige et Avalanches, n° 92 - décembre 2000, p 9
*picture shown is the newer Arva A.D.vanced
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