|
|
 |
Moutain-related articles from WINTER-SPORTS.COM |
 |
|
|
 |
The ABS system or "Avalanche System Airbag : an important improvement in the off-piste skier's security |
|
|
 |
The ARVA's limits |
|
|
Despite the fact more and more off-piste skiers have ARVAs (avalanche transceivers) with them, the death toll due to avalanche accidents is still high. This is due to the fact one criteria in particular is essential to determine the skier's chance of surviving: his or her burial in the snow. A buried skier that is not quickly found and rescued has a very slim chance of surviving : after 15 minutes, these chances decrease dramatically. This period of time is clearly too short to rely solely on waiting for the rescues and one must therefore rely on the skiers that might be in the area, even if they face multiple difficulties (they might not be used to using the ARVA, it's a very stressful situation, it's difficult for skiers that are further down to move around, etc). A study from the Davos Research Center on Snow has shown that only 50% of all completely buried skiers survive, while 97% of all partially buried or non buried skiers survive.
Among the security systems that exist, the ABS system or "Avalanche Airbag System" is the only system that minimizes the burial risks and should therefore improve the survival rates.In fact, the theoretical potential of this product has been confirmed by the first results regarding its use, which, despite their limited statistical value, are very encouraging. |
|
|
The ABS system or "Avalanche Airbag System" : inverse segregation |
|
|
| The ABS system takes advantage of a characteristic of granular materials: inverse segregation This complicated term describes a simple phenomenon: when a granular material crumbles (landslides, avalanches, etc.), the smaller particles settle on the bottom while the larger particles remain on the surface. Once inflated, the ABS system maximizes the skier's volume thus minimizing the risk of him or her being buried. |
|
The ABS sytems take advantage of the INVERSE SEGREGATION principle
The larger particles tend to rise to the surface. |
| Warning, this is not due to a "flotation" phenomenon created by Archimedes's buoyancy principle : it is the skier's volume, not his/her density that matters! > |
|
 |
|
|
How the ABS system works : the airbag's role |
|
|
A handle located on the bag's strap releases a 9mm blank cartridge whose expansion gas, through a pipe, will trigger the striker located in the bag. This striker, in turn, will pierce the cartridge's seal thus releasing the gas that will inflate the "airbag" balloons.
The handle is protected by a tab and a Velcro to prevent the airbags from accidentally inflating. |
|
The inflation phases of the ABS system's airbag |
|
A very specific technical design |
|
|
One might think the ABS is simply the combination of a car airbag and of a mountain backpack. However, this is far from being the case, and its technical design justifies the cost of an ABS, which might seem at first to be quite high.
For instance:
The differences in altitude and therefore in pressure imply strong technical constraints, that led to the installation of a valve that regulates the pressure in the « airbag » balloons. The bag itself was designed so that it would withstand the extreme mechanical stresses it is exposed to in an avalanche.
The 9mm cartridge is covered in a special wax to protect it from humidity.
The gas cartridge was specifically designed and engineered to resist important variations in pressure due to strong internal pressure and altitude (mountain use and when checked on a plane)
|
| |
|
 |
|
|
The ABS system's effectiveness |
|
|
| Even if one still lacks today perspective and a extensive statistical study, the first findings are very encouraging.The Davos Research Center's study shows that the survival rate of skiers that wore an ABS system and successfully inflated it when caught in an avalanche is very high (76 survived out of 77).
|
| |
|
 |
|
One must note that these statistics, even if already very satisfying, are most likely skewed due to the fact that a certain number of accidents that didn't require rescue services weren't reported. The real survival rate is therefore certainly higher that the official one.
However, while the ABS seems to considerably improve the skier's security, the ABS can by no means fully guarantee the skier's survival or even his or her non burial. In the previously mentioned study, 5 skiers were completely buried (out of these 5, 4 were buried close to the surface, their balloons were still partly visible, thus enabling their quick rescue and their survival). The skier that didn't survive was buried 170 cm deep ( 5,58 feet deep).
It seems indeed that the ABS is barely effective or not effective at all in the following cases :
1. Skis stay on (meaning the snow has a strong grip on the skis),
2. The avalanche occurs in a flat area or a spot with a depression in which the snow accumulates, thus burying the immobile skier (there is no flow and inverse segregation therefore can't happen). |
|
|
The ABS system's drawbacks |
|
|
The ABS systems require careful and proper handling and use. Mishandling it or using it in an improper way can pose a threat to the skier or to others. For example, the accidental inflation of the airbag on a chairlift can have serious consequences. Carefully reading the user's manual provided with the ABS is strongly recommended.
The weight of the ABS can also be a hindrance in the sense that it is approximately 1,5 to 2 kg (3,5 to 4,5 pounds) heavier than a regular bag of similar volume.
The IATA (International Air Transport Association) includes the ABS systems in its Potentially Dangerous Goods Regulatory list. As such, the ABS system are only allowed on planes, whether in the cabin or checked, if the airline authorises it. However, obtaining the airline's authorisation may take some time and isn't, apparently, always easy to get.
Heliskiing companies usually accept the ABS systems but the storage conditions in the helicopter are often very strict. |
|
|
Our opinion: an important improvement in the off-piste skier's security |
|
|
The ABS system cannot, by any means, guarantee the skier's survival when caught in an avalanche and therefore cannot replace following elementary security measures:
checking the weather reports and the risk level,
carefully choosing an itinerary,
Going through 1 at the time in risky areas,
Carrying an ARVA avalanche transceiver
Carrying a cell phone with you,
etc.
Under no circumstances should being equipped with an ABS increase your readiness to take risks by disregarding the basic rules on preventing avalanche risks.
Nonetheless, the ABS systems is a very effective addition to these elementary safety measures.When used in this framework, the ABS considerably improves the skier's security. As a result, when compared with the increase in survival rates the system allows, its drawbacks (cost, weight, air plane transportation, strict conditions of use) seem fairly minimal.
An increasing number of mountain professionals (guides, piste services, rescue services) are now using the ABS system, which increase this unique system's credibility. |
|
|
Links |
|
|
| The German distributor's site : http://www.absairbag.de/home.php?chid=1&lang=uk&m=17 |
|
|
|
|
 |
|
 |
|
