Alf Alderson skiing through deep snow, French Alps

What's new in modern avalanche safety devices?

This month's new regular feature on sports technology looks at the gadgets fighting the 'white death', which, as the recent tragedy of the trekkers in Nepal shows, remains a grave danger for mountaineers.

Over the last 30 years or so my life has revolved around outdoor sports. However, my outdoor career almost came to an abrupt end before it had even started.

Rewind 30 years, and a young geology student is clambering up a snow-laden gully in the Cairngorms on his first ever winter mountaineering trip.

Near the top of the gully there's a sudden 'crack!', and the entire snow slope breaks away and starts tumbling and bouncing downhill in the skier and mountaineer's worst nightmare – an avalanche.

Avalanche survival equipment

The undergraduate was me. I survived the 150m ride down the mountain, albeit battered and bruised, but I was incredibly fortunate: had I been buried by the avalanche, my chances of survival would have been virtually nil. This was for two reasons.

First, I had not one jot of safety equipment with me, simply because at the time none worthy of the name existed. Secondly, any rescue team would have been similarly hampered since their own gear would have consisted of little more than avalanche probes (thin poles thrust into the snow to try and find a victim), shovels and sniffer dogs (which are up to eight times faster at locating victims than humans).

However, if the same thing happened to me today my chances of survival could be in excess of 90 per cent thanks to modern avalanche safety devices. So what's changed over the years?

First off came the introduction of avalanche transceivers. In effect these are small radio beacons, operating at 457kHz, which are designed specifically for locating people buried under snow.

You strap the transceiver onto your chest beneath your ski jacket and turn it on before skiing; the transceiver emits a low-power pulsed beacon signal, which will work in temperatures as low as -20°C. If you're buried in an avalanche, rescuers can use similar transceivers, tuned to receive rather than transmit, to become a radio direction-finding device to locate you.

Transceivers were not in common use until the 1990s and were initially analogue format, transmitting the pulsed signal as an audible tone to the user, with the tone becoming louder the nearer you get to the transmitting beacon.

In recent years, digital transceivers have become the norm. They use two or three built-in antennas to take the strength of the signal and the emitted dipole flux pattern of the victim's transceiver and compute distance and direction to it. This is indicated by an arrow on a small display screen and a pulsed tone that becomes louder or more frequent as you get closer to the buried device.

More sophisticated avalanche transceivers may have a second supplementary frequency known as a 'W-Link', which, among other things, can differentiate individual transceivers in multiple burials, transmit and receive the wearer's vital signs and ignore signals from a victim who has already been found.

If you are actually buried in an avalanche, a system such as Black Diamond's 'AvaLung' can literally provide valuable breathing space until your rescuers reach you. A breathing tube, built into the shoulder strap of a backpack, uses a valve mechanism, which pulls incoming air from near the breathing tube mouthpiece and expels contaminated CO2-rich exhaled air far from the intake source. Black Diamond CEO Peter Metcalf says: "The AvaLung has saved multiple lives over the years."

Planning ahead

It is, of course, better not to be buried in the first place, and knowledge of factors, such as snow conditions, slope angle, wind loading and recent weather events, plays a vital part in staying safe in avalanche terrain.

Indeed, as Bruce Edgerly, vice-president of US avalanche safety company Backcountry Access (BCA) emphasises: "We consider education just as important as equipment; there has been an impression that our new technology somehow made it less important to stay out of avalanches in the first place."

BCA are one of several companies that manufacture 'avalanche airbag systems', the latest weapon in the war against the 'white death'. This is basically a backpack with an airbag system built into the top of it.

The original manufacturer, German company ABS, provides a system whereby if a skier is caught in an avalanche, they pull a handle integrated into one of the shoulder straps on their backpack; this is linked to a compressed nitrogen gas canister system, which inflates twin airbags in the top of the pack within seconds.

Each of the two airbags uses automobile airbag grade materials and has a volume of 85 litres when inflated. They are inflated simultaneously but have separate closure and suction valves, so if one of the airbags is damaged, the other one will remain inflated. The internal pressure is about 0.1 bar.

This system allows an avalanche victim to float above the snow mass and offers protection to the head and neck. The success rate of the ABS system is remarkable – independent research by the Swiss Avalanche Institute has shown that in 97 per cent of avalanches during which ABS systems were activated, the airbag was visible on the surface when the avalanche came to a halt, while 84 per cent of all avalanche victims who activated the system remained unharmed.

Equipment manufacturer The North Face use ABS systems in their top-of-the-line backpacks (expect to pay in the region of £750 for one). "The high cost of these systems does not seem to be putting people off from purchasing. Once you pose the question of 'How much is your life worth?' or 'How much do you spend on health/life insurance annually?, then the price is not such an issue," says equipment production manager Mark Maffe.

He also points out that "due to the high-cost/low-profit margin for these products I do not see prices falling much in the future".

He doesn't see much changing in terms of design and technology in the near future either. "Often when you make changes, you face unknowns and when it comes to life and death situations, where you depend on your gear to save you, there is no room for unknowns; the more simply the systems are engineered, with less parts and no electronics, all the better to work with and all the more peace of mind for the user."

"As far as ease of deployment goes, I have yet to see anything that works better and is easier to deploy than the ABS trigger system."

Nothing beats knowledge

We've come a long way from the day when I rode down a Scottish mountain on a gigantic wave of snow. As respected international mountain guide Nigel Shepherd says: "Today, largely driven by mass participation in mountain sports, manufacturers have money to invest in reliable technologies that make life in the mountains in winter simpler and a good deal safer."

But has it made life in the mountains better? "Yes, because as well as being safer it allows more folk to experience the wild sloped snow," says Shepherd.

But he adds the caveat: "And in a small way 'No', too. Because there are those who believe this new technology makes them invincible and they venture thoughtlessly into terrain of which they have very little understanding.

"Safety equipment can help to save your life," Shepherd adds, "but it doesn't prevent avalanches. Knowledge is still the greatest advantage you can have in wild places."

Alf Alderson is an award-winning adventure sports journalist.

Recent articles

Info Message

Our sites use cookies to support some functionality, and to collect anonymous user data.

Learn more about IET cookies and how to control them