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Understanding Avalanche Transceivers/Beacons
If you spend any time skiing, snowboarding or snowshoeing in the backcountry, you and your buddies must each carry 3 vital pieces of gear: an avalanche transceiver (also called an avalanche beacon), a probe and a shovel. A transceiver in the hands of a trained and practiced user can make the difference between life or death if an avalanche strikes.
But beware of the false sense of security that people sometimes have while wearing transceivers. They are not a substitute for thorough understanding of snow conditions, smart route-finding and a willingness to turn back if necessary.
For an overview of all your avalanche gear options, see the REI Expert Advice article, Avalanche Safety Gear.How Do Avalanche Transceivers Work?
Avalanche transceivers are devices that emit a pulsed radio signal. If one gets buried in an avalanche, other transceivers carried by the party pick up the signal being emitted from under the snow. The receiving transceivers interpret the signal into a visual and audible display that assists the search.
Transceivers are effective only when carried as the manufacturer recommends. They must be strapped around the waist or over the shoulder—worn underneath the outer layer of clothing (which keeps the batteries warm and also helps keep it from being torn off your body during the ride)—rather than stowed in a pack.
So when your group heads for the hills, you should all be wearing transceivers and have them set to "transmit" or "send." If anyone is buried in an avalanche, that person's transceiver will be sending out a signal to tell the others where he or she is. The other transceivers then need to be switched to "receive" to pick up the signal. Always check the transceiver of every person in the group before departing.
Each must be set to "transmit" mode while the group is underway. When buried, a transceiver set to "transmit" mode will continue sending its signal. Other transceivers in the area can then be set to "receive" mode to receive the signal.
When searching for buried victims, speed really matters. It's critical that you understand your avalanche transceiver and regularly practice using it before you ever enter the backcountry. Each manufacturer provides detailed instructions on how to use its technology. Practice using it at home and take an avalanche safety course with a qualified instructor.
WARNING: Avalanche victims can die from either asphyxiation or trauma. For those victims who are buried alive, transceivers can be highly effective tools in saving lives. There are no guarantees, however. First and foremost, you must recognize and avoid dangerous avalanche conditions.
Types of Transceivers
All avalanche transceivers intended for use in North America transmit and receive electronic signals in the same way. How they process or interpret that signal for the user to read differs among models.
Nearly all transceivers sold these days are digital models, as they are easier to use and generally faster at locating victims. Many digital transceivers include an analog mode so they can be compatible with both types of transceivers.
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The main difference between analog and digital transceivers is the range and accuracy. A transceiver's "range" indicates the area in which the initial signal can be detected. A transceiver with high accuracy will be able to narrow the search into a smaller digging area than a transceiver with lower accuracy. Analog transceivers tend to have a greater range than digital ones; this allows for a quicker starting time when searching for a buried person. Digital transceivers, on the other hand, generally have greater accuracy which can shave off a few crucial minutes at the end of the search.
While digital transceivers are easier to use, especially for amateur enthusiasts, analog transceivers can be extremely effective; in the hands of an experience user, they can retrieve buried skiers quickly.
These pictures show the difference between the displays of digital and analog transceivers. Notice the digital display showing direction and distance to travel along the flux line.
Common Attributes of Avalanche Transceivers
Though different companies make different types of transceivers, all transceivers share a few common attributes. When transceivers are turned on and are in their locked position they automatically transmit an electromagnetic signal in what is called a flux line (see Figure 1) pattern. In order to receive a transmitted signal, all transceivers can be turned to "receive."
All transceivers will sound a series of beeps that get louder the closer a searcher is along the flux line to the transmitting signal. As the beeps get louder, a searcher can turn their transceiver to a lower level in order to zero in on the location of the transmitting signal.
Figure 1
The Transmitting Transceiver and the Flux Line
Regardless of what type of transceiver you have, it transmits a signal in what is called a "Flux Line." This means that the transmission signal does not radiate uniformly from a single point. Figure 1 shows what the electromagnetic flux line looks like. Its radial signal allows seekers to follow the flux lines to a buried victim.
The Receiving Transceiver
When a Transceiver is set to "receive," it picks up a signal from the transmitting transceiver. The strength of the signal depends on distance from the transmitting transceiver and ones position along the flux line. Digital transceivers that have distance and direction monitors tell the distance and direction to move along the flux line, NOT the distance to the transmitting transceiver.
Frequencies and compatibility
Practice, Practice, Practice
No matter what transceiver you buy, the most important step is to practice, practice, practice. Remember that finding a single transceiver in a parking lot is far easier than finding multiple buried transceivers in a realistic situation, especially when a loved one is under the snow. Many mountain locations now have automated or semi automated transceiver trained centers. These allow one to practice both single or multiple victim rescues, solo or as a group. Check with your local Avalanche Forecast Center for a transceiver training facility near you.
Caveat
Tramsceivers only work if you practice regularly with them and most people don’t practice enough. As a result, transceiver use has not increased survivability rates as much as one would hope. For people who practice regularly, however, transceivers have saved many lives and they work very well. In addition, about a quarter of avalanche victims die from hitting trees and rocks on the way down, so transceivers can only help the other three quarters who survive the ride before getting buried.
Which Transceiver Is Right for You?
Most transceivers today feature 3 antennas. This offers the critical advantage of having 3 points of orientation and 3 signaling apparatus.
Transceivers most strongly broadcast the plane in which the antenna is oriented. Thus, a horizontally oriented searcher and a horizontally buried victim line up best. Advanced transceivers can identify the best potential antenna signal to more quickly pair up the orientation of victim and searcher.
Key Features
Proprietary Technologies
The leading manufacturers each offer their own technologies:
Transceiver Search Methods
Speed really matters, so it's critical that you understand your avalanche transceiver and practice using it. Each manufacturer provides detailed instructions on how to search quickly and efficiently using its technology.
Whatever transceiver you use, the basics are these: Once you identify a buried transceiver, you will save time if you positively identify the location using a probe, then dig down using a sturdy shovel designed for moving snow quickly.
Beacons
Rocket Miller from Lake Louise, Alberta describes how avalanche beacons work.
Search
Rocket Miller hone's in on the signal and teaches us about pinpoint searching in beacon rescue.
Probe
Rocket Miller shows the proper way to probe for buried victims
Shoveling
Once you locate the victim the real work begins! Rocket teaches us the best and fastest way to shovel.