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How to Choose an Avalanche Beacon

Avalanche Transceivers Decoded

Choosing between avalanche beacons can produce deer-in-headlights paralysis if you aren’t quite sure about all the features, what they do, and what you need. This article will break down the features and give advice according to what user group you’re in.

 

I have divided the market into three user groups:

Recreational users are defined as those who mainly ride the resorts and seldom go beyond the gates.

Enthusiast users are defined as those who spend quite a few days of their ski season in the backcountry and travel with a group of competent partners.

Professional users are defined as riders who either work as ski patrollers, forecasters, or guides.  These individuals are well-seasoned and demand a beacon that has additional functionality.

Since it can help to understand what today’s beacons (aka avalanche transceivers) evolved from, I’ll start with a bit of history. In the late ’60s, a brilliant team of scientists working at Cornell University developed the first production avalanche “beacon.” Known as the SKADI, this hot-dog shaped device emitted a radio frequency that could be picked up by like devices. This revolution in snow safety gave ski patrollers and avalanche professionals added peace of mind on unstable slopes. A half-century later, avalanche transceivers have evolved into devices capable of finding multiple buried victims in a very short amount of time.

Digital vs Analog

In the days of the SKADI, analog devices were the standard. A transmitting beacon would emit a radio pulse that the receiving beacon would interpret as an audible signal. Beep-beep, beep-beep. The closer the searcher got to the buried victim, the louder the signal. As the technology evolved, color-coded lights and arrows were added and the interface became easier to use.

In the ’90s, Backcountry Access (BCA) introduced the first digital beacon. It used a numerical display that gave searchers the ability to see how far away they were from a buried subject. The numerical units combined with directional arrows made searching simpler and more efficient for the lay user.

Today, recreational, enthusiast and professional users rely on digital beacons. However, most manufacturers add an intuitive audible tone to their beacon’s search function to indicate when a searcher is nearing a buried subject. Some professional models, such as the Mammut Barryvox  S, utilize a true analog tone that gives the rescuer the ability to increase their range of search by turning off the digital display. This method takes additional practice to become proficient and is only found in a few models.

Antennas

Having more than one antenna allows a beacon to become more efficient in searches and more easily found while in transmit. Manufactures such as Pieps, Mammut, Ortovox, BCA, and ARVA all produce a three-antenna model. The tri-axis antennas allow for the transmitting device to automatically switch between the optimally oriented antenna to aid in being located. Additionally, the receiving beacon can more accurately locate a beacon that is buried by taking input from multiple antennas and processing the signals into an easy-to-read digital format. This advancement has enabled beacons to speed up searches and differentiate between multiple burials more easily.

A couple of years ago, Pieps released a beacon called the Freeride that uses one antenna and is the size of a small cell phone. I would categorize this as a recreational-level beacon and would recommend it for in-resort riding. Its limited functionality comes at a lower price than most beacons, and it is certainly better than having no beacon. It does have a digital display and intuitive audible tone, but its single antenna limits its other functions.

Three-antenna beacons are becoming the standard, and if you’re planning on going out of the resort (enthusiast and professional user groups), it’s best to stick with three antennas.

Range and Marking

The trend for a lot of manufacturers is to list the range at which they can pick up a signal from a transmitting avalanche beacon. The caveat is that most of these ranges are listed by their optimal coupling position. A rectangular-shaped, three-antenna beacon has x, y, and z-axis antennas. The long axis, x, has the greatest power, and when lined up with the x-axis antenna of a receiving beacon, it is possible to achieve a 60-meter-or-more range. In the practical world of burials and terrain, this range is reduced quite a bit. It’s rare to find a beacon that picks up a signal greater than 55 meters away.

While not always 100% reliable, marking features can be excellent for suppressing the signal of a located subject. Once pinpointed and probed (once you’ve found the victim), the signal can be suppressed, and you can move on to the next buried subject while others dig the first person out. Most beacons incorporate a marking function, but if you’re looking at one that doesn’t and you’re in the enthusiast group, you’ll want to think about the disadvantages of not having the marking feature. People in the professional user group will want this feature.

Keep in mind that marking becomes less reliable when more than two signals are present, due to a phenomenon called “signal overlap.” For scenarios involving more than two victims—which are rare—professionals normally use specialized techniques that do not rely on marking. Read this article for more information on these scenarios.

Additional Features

Beyond the traditional features of an avalanche beacon, certain models have additional functions that are quite useful. Here is a quick list of some of the additional features that users in the enthusiast and professional groups will want to consider:

Frequency drift: Ability to measure how much a beacon’s 457kHz has drifted over time.  +/- 80kHz is the tolerance most manufacturers recommend. Some beacons are more tolerant than others to drifted transmitters. Generally, the greater the published receive range, the less tolerant that beacon is to electrical noise and drifted transmit frequencies.

Scan: This feature can tell you how many beacons are buried with a 5/10/20 unit radius.  Available on the updated  BCA Tracker4 when in “Big Picture” mode.

W-link: This feature allows certain beacons to share additional info on a separate frequency such as the presence of movement or vital signs. It was primarily developed to aid in multiple burial triage situations. Available on the Mammut Barryvox S. (Note: not all beacons have this capability and rescue should not be postponed based on lack of vital signs or movement info)

Auto-revert to send: Most manufactures have this feature built-in to all their beacons. It enables the device to switch back to send when it senses no movement, after a certain number of minutes, or when it hasn’t received a signal in a certain amount of time. This is to give the user protection should a secondary slide overtake the rescue party.

Final Thoughts

Every beacon manufacturer must go through vigorous testing of its models, and they must meet specific criteria before the models are released to the market. Certain beacons perform differently and have additional features that are helpful for different scenarios. The digital three-antenna beacon is certainly the most prevalent, and it has been proven to reduce search times.

Consider where you fall on the recreational-enthusiast-professional continuum and determine what you are most likely to use your beacon for. If you simply want the added protection of a beacon for resort riding, it isn’t necessary to spend $500 on a high-end product. Conversely, if you spend 100+ days in the field and use your beacon often for search and rescue, it makes sense to have added functionality. Remember, the best beacon out there is the one you know how to use and consistently practice with.

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