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How a Beacon Search Works

Everything went wrong.

You misread the snow conditions and the first one to drop triggered a massive slide. Everyone watched as closely as they could, but lost sight of your friend and don’t have a clue where he is. This is the moment you’ve feared (and prepared for) since you started backcountry skiing. You pull your beacon from its chest pouch, switch it to receive, and begin one of the scariest things you’ll ever do in your life. This is what will happen during those hour-long minutes …

The Beacon

Any beacon  (aka transceiver) made after 1986 transmits a signal at 457 kHz, so any beacon you buy these days works with any other beacon. No matter how many features your beacon has, it still transmits in the same way. In the simplest terms, the beacon transmits a radiating circular signal. This is important to understand when you start searching.

The most important thing is to make sure your beacon is transmitting. It’s not enough to simply make sure it’s on. Before you leave the trailhead, one person in your party should turn their beacon to receive and check everyone for a signal. Then that person needs to turn their beacon to transmit and someone needs to check them. Then, when everyone is on transmit, you start skinning.

 

Searching / Receiving

When you switch a beacon to receive, it gives you both the distance and direction (along a curved path) to any signals within its maximum range. If the victim is further away than the max range it will not provide any information, yet.

Above are the three steps to performing a beacon search. The solid line is the path to be taken by a single searcher, and the dotted lines are the paths for multiple searchers.

Signal and Coarse Search

The first step in a search is to turn everyone’s beacons to receive so there aren’t confusing signals. If your beacon doesn’t receive a signal immediately, you should begin your search by crisscrossing the slide path until you find one. In each pass, don’t go further down than the range of the beacon or you may miss the signal. When you find a signal, the beacon will give you both direction and distance along the curved path. It’s important to keep in mind that this circular pattern means that you won’t be able to just follow the signal in a straight line. Instead, follow the direction indicator on your beacon and adjust your direction as it turns. If you start moving and the distance indicator goes up instead of down, just turn 180 degrees and go the other way.

 

Fine Search

Once you get within a short distance, the direction indication on your beacon will disappear. This is because the victim is under the snow and no longer at a distance readable as a direction along the surface.

Hold the beacon close to snow and parallel to the slope. Move forward until the signal gets weaker and mark the spot. Then move backward and do the same. Repeat this going left and right as well. The middle of those four marks is the strongest signal and where you should start probing.

 

Features to Look for in a Beacon

Some more advanced beacons come with features that indicate multiple signals or even lock out everything but the strongest one. What this means is that you can concentrate on the closest signal and find that person first, without interference from other signals. This makes a drastic difference in multiple-burial situations.

Another feature to look for is signal marking, which some high-end beacons come with. If more than one person was caught in a slide, you’ll be very happy to have this feature. You can mark a signal as found, which allows you to go on to other victims without interference from the beacon you just located, while your friends probe and dig for the first buried victim.

 

Beacon Search 101

 

Probes

Without a probe, you can’t pinpoint a victim, so you would have to excavate far more snow in order to locate someone. This can be the difference between seconds of digging and minutes of digging, which may be the difference between your friend living or dying.

 

How to Use

Pull the probe from your pack and set it up quickly, but make sure it’s solid. You don’t want it coming apart on you in the middle of a search. Begin your probe in the center of the four marks you made during your fine search. Probe at a 90-degree angle to the slope every time to make sure you don’t create blind spots. If you don’t hit anything, then probe again, working your way around and away from the center point in a spiral pattern until you feel contact. When you do, leave the probe in place. It will guide your digging in terms of both location and depth.

 

Probing 101

 

Shovels

A good aluminum-blade shovel is absolutely necessary. Avalanche debris sets up like concrete, so plastic-blade shovels, helmets, and hands are pretty much useless.

 

How to Use

If your shovel has an extendable handle, extend it before you start digging. It’s worth the extra few seconds in the long run. Go to the downhill side of the probe and start digging about 1.5 times the depth of the burial away. Throw all the snow downhill. This will be far easier and faster than digging straight down from above. Plus, removing a victim from the hole is much easier to do from the downhill side of a slope than it is from straight out the top. If you’re lucky enough to have multiple rescuers during a search, a simple assembly line will expedite the digging process. Two diggers should start shoveling downhill from the probe, moving the snow as far behind them as possible. Other rescuers will assist by clearing the shoveled snow from around the pit, making it easier for the lead diggers.

Illustrated on the left is the technique for a single rescuer. On the right is an example of multiple rescuers and how the “assembly line” helps clear snow from the pit.

 

Shoveling 101

 

First Aid

If the victim isn’t breathing, you want to start CPR as soon as you possibly can. Even if this means doing it while they’re still half buried. If they’re breathing, then be very careful when removing them from the hole. It’s important to remember that a high percentage of avalanche deaths result from trauma, so you want to make sure nothing is broken before you stand them up and give ‘em a big holy-s#!-I’m-so-happy-you’re-alive hug.

 

The Call

If someone is doing CPR, then someone else should be on the phone calling in the cavalry. Don’t make the call until you’ve found the victim, because the call will take time from the search, and getting them out of the snow fast is priority number one. If the slide was visible from populated areas like highways and ski resorts, then you should be making a phone call even if the victim is just fine. You want to let a potential rescue party know that their assistance is not needed. Any rescuers will have to go into the same terrain as you, and clearly things are a bit sketchy, because you just triggered a ripper. You don’t want to expose more people unnecessarily. 

 

Training

This guide is meant simply to give potential backcountry travelers and idea of how to perform a beacon search, and maybe serve as a cheat sheet during practice sessions. An avalanche 101 class should be considered the bare minimum of preparation needed to head into the backcountry. Not only will this class teach you how to perform a beacon search, but you will also learn safe travel techniques that will help you stay out of trouble. Even if you have taken a class, you should practice until the entire process is second nature. When things go really wrong, people don’t rise to the occasion—they fall back on their training.

To find a training center near you and other avalanche resources, visit Avalanche.org or checkout the AIARE’s course list.

Illustrations and videos courtesy of Backcountry Access.

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