Also known as a beacon, an avalanche transceiver works by using a radio signal to guide rescuers to a buried victim.
In an avalanche, victims can be deeply buried anywhere within a large area. Avalanche transceivers are used to quickly find their exact location. Here, we will get an overview of how they work and how to use one in an avalanche rescue situation.
We carry and train with avalanche transceivers routinely while ski touring in Scotland. If you are winter hiking on the other hand, you may decide not to bother with transceivers and instead manage avalanche risk by good route choice and navigation. This is a common approach in Scotland. But transceivers are more routinely used by mountaineers in the greater ranges worldwide. With that, let’s look in more detail at what an avalanche transceiver is and how it does its job.
⚠️ Go and learn these skills on an avalanche awareness course. Articles and videos are a poor substitute for expert training in a snowy mountain environment.
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Avalanche transceiver basics
An avalanche transceiver (or avalanche ‘beacon’ in the US) is a small but essential piece of electronic equipment on your ski touring kit list. Every skier/boarder in a group wears one and sets it to ‘Send’ mode. Transceivers in send mode repeatedly transmit a 457kHz radio signal. If the wearer switches their device to ‘Receive’ (or ‘Search’) mode, it will stop transmitting and instead begin ‘listening’ for any other sending transceivers. If it detects one, it will try and guide the wearer to that device, using sounds and lights on its display. This is how a rescuer finds a buried avalanche victim.
Parts of a transceiver
Avalanche transceivers are complex electronic devices which vary a lot in appearance. However, they are all designed to be simple to use in an emergency and share the same basic parts: an on/off button, loudspeaker, digital display, Send/Search switch, ‘Flag’ button, batteries and a tether or harness.
Wearing an avalanche beacon
When deciding what to wear for ski touring, how you wear your transceiver is very important. Backcountry skiers and hikers usually wear their transceiver in a harness under their outermost layer. This means the device is protected and securely attached in the event of an avalanche. You could also carry your transceiver in a zipped-up trouser pocket. This could help avoid interference from other devices, but it MUST be a ‘sewn in’ pocket and have a strong tether attached.
Analogue vs digital
Modern transceivers use a digital signal. As a result, they can display exact distance and direction information on a screen. The beacons of yesteryear used an analogue signal and converted it to a sound. The louder the sound, the closer you were to the victim! They had a huge range, but were much harder to use. Interestingly, new analogue functions are being tested to combat the increasing problem of signal interference.
Self and Partner Checks
To check that all avalanche transceivers in a group work correctly, there are a couple of checks to do at the start of each tour. First, the device will do a ‘self check’ when turned on, this will alert you to any problems with batteries, transmission, etc. Second, it is wise to do a simple ‘Partner check’. There are several ways of doing this, but they all achieve the same thing, which is checking the send and receive function of each device.
Choosing and looking after your avalanche transceiver
Many backcountry skiers and boarders just hire avalanche kit for the duration of their trip. However, owning a set means you can become much more familiar with it – and hopefully faster in an emergency. Therefore, choose a model that isn’t too confusing and that you feel comfortable using (BeaconReviews.com is an excellent database of transceiver reviews). What ever device you have, the manufacturer will proide detailed instructions for handling, storage and servicing.
⚙️ Looking after your beacon
- Avoid strong heat sources (eg: radiators, car vents). Transceivers are waterproof already and you run the risk of causing damage through overheating or condensation.
- Take care with batteries. Only use alkaline NON-rechargeable batteries. Rechargeable batteries can quickly lose power in cold conditions and lithium batteries can damage sensitive electronics
- Remove batteries during summer to prevent leakage
Service your beacon every 2-5 years. For a small fee, manufacturers will certify that your avalanche transceiver is working correctly. This involves checking the signal, updating software, replacing seals, etc.
Avalanche transceiver search
Searching is an important part of ‘Companion Rescue’. This is the process through which nearby skiers and mountaineers find an avalanche victim and give them first aid. See below for the steps involved in ‘1 victim’ Companion Rescue.
Single burial search
Time needed: 15 minutes
Basic avalanche Companion Rescue (1 victim)
- Organise
Several steps must be taken quickly, including assessing risk of further avalanche, the victim’s ‘point last seen’ and who does what during the rescue. All transceivers must be switched to ‘Search’.
- Signal search
Start at the victim’s Point Last Seen. Use 20m ‘search strip widths’. Search in a zigzag pattern, or straight downhill (depending on size of avalanche and number of searchers). Signal first detected at approx 40m range (ideally).
- Coarse search
Quickly follow transceiver prompts to about 3m range.
- Fine search
On hands and knees, working out the minimum distance (depth) to the victim. Also known as ‘Bracketing’.
- Probing
Physically pinpointing the victims depth and location. This where you need to know How to use an avalanche probe.
- Digging
Fast, organised digging below the probe to uncover the victim.
- First aid and evacuation
Just doing the basics of Companion Rescue is likely to lead you to the casualty. However, there are many adjustments you can make to hopefully increase speed and victim survival chances. When I am teaching this, here are some points I recommend:
- During the Signal search don’t look at the device screen, but instead look for visual clues on the snow and listen for the device prompts.
- During the Coarse search keep the device level and in the same orientation, to help it process signals accurately. Second, if the distance numbers are INCREASING, turn 180 degrees and continue following the device. Third, skiers could keep skis on for the Signal and Coarse searches, but must remove them for the Fine search.
- During the Fine search ensure the avalanche transceiver has a long enough tether so you can get it to the snow surface easily (tip: deploy it from under the hem of your jacket).
🛜 Signal range and interference
Many factors can affect the signal quality during transceiver search. To try to reduce the risk of signal interference, manufacturers recommend transceivers are stored away from other electronic devices: at least 20cm in Send mode and at least 50cm in Search mode. See below for other issues which can affect transceiver search:
The transceivers (both receiving AND sending devices):
- Software updates
- Device age
- Damage
- Device model
- Rescuers in Send mode
- Battery level
- Signal lock or not
- Position (depth, distance, orientation)
The rescuer(s):
- Search pattern
- Number of rescuers
- Experience and training
Nearby gadgets:
- Mobile phones (even in airplane mode)
- Smart watches
- GPS units
- Action cameras
- Drones
- 2-way radios
- Bluetooth headphones
- Pacemakers
Nearby objects:
- Power cables
- Metal equipment
- The victim (ie: lying on top of their transceiver)
- Rocks
In Companion rescue, 15 minutes is the time window in which to find and dig up victims. Statistically, the chances of survival drop rapidly after this (although a tiny minority of people survive being buried much longer than 15 minutes).
Multiple burial search
Multiple burials are even more complex and stressful than a single burial. In the same amount of time you have more people to find and also more decisions to make. For example: do you dig out the first victim you find, or the one nearest the surface? Your decision will depend on the number of rescuers and their skills and equipment, plus several other factors.
Multiple burials are even more complex and stressful than a single burial
Avalanche transceivers usually lock onto the nearest signal. But, to find another victim, you will have to ‘break lock’ with the first. This is achieved through ‘flagging’, using micro search strips/expanding circles, and/or multiple burial mode.
🚩 Flagging
A big advantage of digital avalanche beacons is the ‘Flagging’ function (also known as ‘Suppressing’ or ‘Marking’). When you press this button, the device will ignore the current signal and search for the next closest one. This can be super-helpful in a multiple burial situation, but if used wrongly can waste a huge amount of time. Furthermore, different models of device do it slightly differently.
🎯 Micro search strips and Expanding circles
Because the flagging function might be absent, or unfamiliar, it can be wise to know an alternative method of searching for multiple victims. The first is ‘Micro search strips’ and the second is ‘Expanding circles’. Although they each have their pros and cons, both of these search patterns cover a small area in detail and are a good failsafe alternative to flagging.
👪 Multiple burial mode
If more than, say, 4 signals are detected, most modern avalanche beacons will enter a ‘Multiple burial’ mode to try and help you find them all. What this mode looks like depends on your device model, so you will need to learn your particular one.
Signal overlap
Unfortunately, multiple signals can be so close together that your avalanche transceiver cannot distinguish between them. This is called ‘signal overlap’ and most devices will alert you if this happens. One of the most reliable ways to combat it is to dig down to the first transceiver and switch it off.
So, it can be seen that multiple burial situations are complicated and take a lot of resources. The bottom line: learn your device thoroughly and avoid getting into a multiple burial situation!
Practising Companion Rescue
Because real-life avalanche rescue is so stressful, practise WILL make a big difference. So, invest in an Avalanche Awareness course to learn the right techniques (for example: Avalanche Awareness for Skiers and Splitboarders). In addition, buy, borrow or hire avalanche beacons, shovels and probes and go and get some good quality practise. If that means burying the device in the undergrowth, so be it. But it will be much more effective to practise full Companion Rescue in snow and awkward terrain.
I consider an avalanche transceiver to be a vital part of my backcountry kit. That’s because the risk of avalanches in Scotland (where I work most) is high enough to justify wearing one. Furthermore, it’s not just about me being found, but also that I can find someone else if needed. Although mostly easy to use, they need time and practise to use effectively. And like first aid, learning the right procedure BEFORE an emergency will make you much quicker and confident if the worst happens.
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