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There are two "rules" which are commonly stated with how to wear an avalanche beacon which are closely related, but not quite the same:

  • You should wear it over your bottom layer.
  • The avalanche beacon may never be visible.

The reasoning for the first is simple: If you wear it further up and need to take that layer off (too warm), you need to take off the avalanche beacon which is a bad idea (potential to forget to take it back on, brief moment where it's no use). The reason for the second is usually given as the risk of the beacon getting "ripped off" and lost when you get into an avalanche. I can simply not imagine there being enough attack surface for a sufficient force to rip off the beacon. My personal hypothesis is, that this is a typical myth that evolved from out of the first rule, as it requires that first rule and is pretty simple and illustrative to remember.

Is there a significant/practical risk of an avalanche beacon worn on top getting lost when you get into an avalanche?

I am looking for any evidence (tests or anecdotal) or clear, fact based arguments (as opposed to opinions). I am not looking for alternative ways to handle avalanche beacons that prevent a potential problem in the first place (reason being, I already know some and wearing them in the "harness" is the common and manufacturer recommended way).

  • 2
    Given various other gear that has been ripped off people in avalanches, why would a beacon be immune? – Jon Custer Mar 18 at 18:04
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    @JonCuster I am not aware of such. If you can recount/point at instances where similar equipment has been ripped off, then I'd be grateful if you could write that up as an answer. My admittedly not entirely adequate go-to counter-examples are avalanche-airbags/lungs/balls, which would be pointless if ripped off (I am aware backpack straps are a bit more sturdy, but they are also much bigger). – imsodin Mar 18 at 18:45
  • you don't seem to have read many first-person accounts of avalanches, or the brief overviews of avalanche rescue training where they tell you to look for clues to those buried including hats and gloves. Now, some things like packs one would hope people would drop early on to improve chances, but stuff is going to come off in the giant mix-master of an avalanche. – Jon Custer Mar 18 at 19:17
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    The lectures by Henry at his Avalanche Talks have includes pictures of tests with clothed dummies placed in the path of triggered avalanches. They show clothes having been ripped off. – AdrianHHH Mar 18 at 19:38
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    Henry has been giving free lectures in Val d'Isere (where he is based) and in neighbouring ski resorts. I referred to those lectures. The link was to give context for who he is. The straps on beacons are intended to be strong and not break in an avalanche. Clothes are intended for warmth and are, typically, not as strong. You want the beacon to remain attached to the person and having its straps loose enough to be comfortable over clothing means they may be loose enough to slip off without breaking. It is undesirable for the rescuers to find a beacon plus clothing and not find the person. – AdrianHHH Mar 19 at 8:43
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Given that your avalanche beacon has the potential to be your partner's lifeline (or your own), it makes sense to protect it. Rocks, branches, skis, poles, ice tools, there's a lot that could potentially damage this important piece of equipment before you even enter avalanche terrain.

In the event of an avalanche, it's not just the pressure of snow on the attack surface of the beacon itself - one unfortunately-located tree branch or rock could very easily separate you from your beacon.

Am I being paranoid? Yes, definitely! These are unlikely scenarios, and beacons are designed to be rugged. But in the unlikely event that you actually need your beacon, you'll want to have have done whatever you could have done leading up to that point.

  • Agreed. It must be the worst feeling ever, to get caught by an avalanche, and feel the avalanche beacon getting torn off. Your friends are going to look for you, and only find the beacon. If the anxiety of dying ever lets you have a rational moment, you'll be livid at yourself. – Stian Yttervik Apr 24 at 18:40
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Beacons are tough. Tougher than you if you get thrown against a rock or a tree or buried under the snow. With that in mind, if things were so bad that there was any concern about my beacon being damaged in an avalanche I would certainly be more worried about whether I could survive the impact. Clothing is not going to provide much shielding against the sort of impact that could damage a beacon.

That brings me to the harness. The biggest risk to the harness is the buckle coming unclipped, breaking, or the straps being severed. Unless the straps were to get caught on something very sharp, high tension alone would not be enough to break the straps. If you wear your harness every day on top of your layers and maybe store it in the sun, then sun bleaching can definitely weaken the harness. I don't know exactly how strong the average harness strap is, but Black Diamond QC labs tested sun-bleached versus shiny new slings and found that while the breaking force was reduced by sun bleaching, the force required to break a sling or cordelette tied into a loop was in excess of 10kN (https://www.blackdiamondequipment.com/en_CA/experience-story?cid=qc-lab-old-vs-new-gear-testing). Considering that you'd be hard-pressed to generate loads like that even when rapelling, it is hard to imagine a scenario where snagging a harness would cause the strap itself to break. Granted, avalanche harness straps are't rated for climbing, so the threshold would be lower.

I postulate that the weak point isn't the strap, it is the buckle. Check out this video in which they test the tensile strength of the sort of strap you'd find on a backpack: https://www.admet.com/outdoor-gear-buckle-and-webbing-breaking-strength-tensile-test/. Notice that the strap breaks at the buckle where the webbing connects. The graph is tough to see, but it looks like the breaking point was just under 100 lbs of tensile force, compared with ~3000lbs for sun-bleached climbing webbing. With that in mind, I'd be most worried about the ability of the buckle on the beacon harness to withstand a dynamic impact in the event of a snag. Make sure you keep that harness snug!

Considering the data, if you were really paranoid about the strength of the beacon harness, you could fashion your own harness with climbing webbing using only knots to close the loop. As long as it fits snugly I'd have no concerns about the integrity of such a harness in an avalanche, whereas I'd be worrying about the buckles on a commercial harness. Just make sure you use appropriate knots because some will slip or reduce the force required to break the webbing/cord.

Overall, I like the reasoning you use in your post: if you have to take the beacon off when you delayer, you're putting yourself at risk by being beacon-free for as long as it takes to delayer. For me that's reason enough to keep my beacon under my layers.

  • +1. Honestly, I think this is the correct answer. – tempest_col Mar 22 at 16:55
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The biggest reason I've always believed that you wear your beacon next to your base layer is battery life. Cold is well known to reduce battery life. By keeping the beacon close to your body you r beacon will function longer and may even have a stronger signal because the batteries aren't fighting the cold. I don't know how much of a difference this makes but it makes enough sense to me that I wouldn't wear my beacon outside my jacket.

Additionally wearing the beacon next to your base layer protects it from all manner of hazards. Some common hazards include; spilled drinks, sticks and branches, falling on ski poles, rocks, shenanigans by your friends, etc. I know my jackets have taken abuse from all of those things and more. By being under a layer or two you can protect and extend the life of your beacon. I don't know about you but I'd rather buy new skis instead of replacing my beacon prematurely.

Between the boost in battery life and device longevity I would encourage everyone to wear their beacon next to their base layer.

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    I totally agree. In addition to protecting the beacon from physical damage, and keeping it from being separated from you (I would HATE to dig up only a beacon) the performance of the batteries is greatly affected by the cold. Keeping them even a little warm extends their useful life. We test per the ETSI standard, but I can't control what temperatures you're in. Why not give your beacon every reasonable chance to save your life? – user103218 Jun 27 at 14:01
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Can't speak to avalanche beacons. However, I have lost a GPS hiking in bush. My suspicion is that I broke the cord, but never noticed it.

I have also lost compasses that were strung around my neck.

I've had a friend pulled off a canoe when his compass and whistle cord snagged on a branch.

We are dealing with low probability events. I can easily see losing a beacon in the swirl and tumble of an avalanche.

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