Avalanche beacons are specialized radio transceivers operating on the frequency 457 kHz. Because they use radio frequencies, they are subject to problems caused by interference. Interference can be caused by many factors, some of which are under your control, others are not. Your radio, cell phone, GPS device, smartwatch, and even the foil-lined energy bar wrapper in the buried party’s pocket can interfere with a beacon search.
During a search, when the beacon is placed in “receive” or “search” mode, it is critical that the beacon receives possibly very weak signals from the buried transmitting beacon(s). In order to achieve maximum receive sensitivity, turn off all unneeded electronic devices before the start of your tour, or when you depart to an avalanche rescue. Ideally, this means that the searchers (the ones whose beacons are in “search” mode) should turn off their portable radios and cell phones, because these devices can emit sufficient signals to interfere with the ability to pick up very weak transmitting beacons. At the very least, a good practice is to hold your searching beacon an arms length away from your body to ensure a minimum of 20 inches of distance from any electronic device that you have. A cell phone is constantly emitting competing radio noise, even if it is in airplane mode. Some radio equipment synchronizes its location within a radio network by automatically sending data bursts. If possible, those persons who need to communicate with additional resources by radio or cell phone should do so in a designated location outside of the search area, and keep their transmissions to a minimum.
Each avalanche scenario has variables that may be outside of your control, such as the number of rescuers, potentially buried power or other electronic cables that can cause interference, a foil-lined wrapper around the buried party’s beacon, a weaker signal from a buried party due to low battery or depth, etc. It is important to understand how these devices and items can interfere with a beacon search so that you are able to prioritize resources to make the rescue as effective as possible.
Want to learn more? Read this article from our partner, Backcountry Access (BCA), here.