Getting Started

Avalanche Safety Equipment

An Avalanche Beacon - This device is a radio transmitter and receiver that aides in finding buried victims. In order to find a person, the victim must have a beacon as well as the searcher. For this reason, every person in a party should carry one. Searching with avalanche beacons requires specialized techniques that must be practiced before an accident. More information on beacons is provided below.

Shovel - A shovel is absolutely a must for assessing avalanche danger and rescuing buried victims. There are several light-weight, collapsible shovels commercially available.

Probe - A snow probe can be anything used to probe the snow searching for a victim (e.g. ski poles or ice axes). Commercial probes are by far the best alternative. They are generally collapsible aluminum rods.

Wands - Common in mountaineering, wands are bamboo sticks with highly-visible flags. They are used to mark locations where a victim was last seen, any gear is found and beacon signals are detected. They are useful, but not essential.

Snow Saw - A serrated plastic or metal blade is used to cut snow. They are typically used for creating snow-shelters, but are invaluable to perform tests on the snow condition.

Understanding Avalanche Beacons

How Beacons Work

Common Attributes of Avalanche Beacons
Though different companies make different types of beacons, all beacons share a few common attributes. When beacons 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 beacons can be turned to "receive." All beacons 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 beacon to a lower level in order to zero in on the location of the transmitting signal.

Figure 1

The Transmitting Beacon and the Flux Line
Regardless of what type of beacon 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 Beacon
When a Beacon is set to "receive," it picks up a signal from the transmitting beacon. The strength of the signal depends on distance from the transmitting beacon and ones position along the flux line. Digital beacons that have distance and direction monitors tell the distance and direction to move along the flux line, NOT the distance to the transmitting beacon. This is also shown at the top of Figure 1.

Analog Vs. Digital Beacons

There are two main types of avalanche transceivers: analog and digital. Both kinds transmit an analog signal from a single antenna, but the digital beacon receives the signal with two antennas. The digital beacon can use the additional information provided by the two antennas and a built in microprocessor to perform two main functions: (1) receive the analog signal and (2) provide direction and distance, along the flux line, to the transmitting beacon (see Figure 1).

Analog beacons receive the transmitted signal with a single antenna. The signal creates a loud "beep" which increases in volume as the receiver is aligned with the flux line of the transmitting beacon.

The main difference between analog and digital beacons is the range and accuracy. A beacon's "range" indicates the area in which the initial signal can be detected. A beacon with high accuracy will be able to narrow the search into a smaller digging area than a beacon with lower accuracy. Analog beacons tend to have a greater range than digital ones; this allows for a quicker starting time when searching for a buried person. Digital beacons, on the other hand, generally have greater accuracy which can shave off a few crucial minutes at the end of the search.

While digital beacons are easier to use, especially for amateur enthusiasts, analog beacons can be extremely effective; in the hands of an experience user, they can retrieve buried skiers quickly.

The following pictures show the difference between the displays of digital and analog beacons. Notice the digital display showing direction and distance to travel along the flux line.

Analog

Digital

Compatibility

With the exception of a few outdated models (any beacon using 2.275 kHz), all beacons receive transmissions from all other brands.

Brands and Gear

http://www.skimountaineer.com/EquipInfo/Equipment2.html

References:
http://www.telemarkski.com/html/how_beacon_select.html, April 5, 2005
http://www.couloirmag.com/gear/avy_gear/beacons99.htm, April 5, 2005