||Rise in use of Rescue Beacons
An increased awareness and a rise in the number of rescue beacons in use have resulted in a slight rise in the percentage of successful self-rescues. Swiss records show this clearly: for 13 years up to 1995 the rapport survivor/victim remained steady at 50:50. This changed in 96/97 to 7 survivors for every 3 victims, and in 97/98 this improved further to 6 survivors for one victim.
- Rescue Beacons are becoming an indispensable and increasingly effective tool
- New groups are increasingly making use of this device (snowboarders, snowshoers, and others)
Wear & Tear
Rescue Beacons suffer from wear and tear and should be substituted every now and again. High impacts (e.g. shock forces experienced in an avalanche) and a lack of maintenance can result in a reduced sensitivity of up to 50% (a maximum range of 100m reduces to only 50m!). This phenomenon is further aggravated if different rescue beacons are used, thereby reducing the maximum range. This can easily result in an effective maximum range of only 20 meters!
The effective range, as defined by European Norms, is 40% of the maximum range (max. range divided by 5 and multiplied by 2).
In order to reduce the search time to levels which offer a high probability of success, the following steps must be undertaken:
1) eliminate twin-frequency beacons (Pieps 3, Ortovox F2 and others)
2) progressively replace first-generation single-frequency beacons (Pieps457, Ortovox F1 + without LED, Fitre Snow Bip 2)
If less efficient beacons are eliminated, then the distance between one search line and the next can be increased from 10m to 30m. The average search time of more than 6 minutes could hereby be reduced to 2-3 mins.
There are four search stages:
-"First stage - search preparation"; observation, division of tasks, choice of terrain.
-"Second stage search for the first signal" using the traditional method of searching along grid lines, twice the distance of the effective range of the least powerful beacon, to the edges and beneath the lip of the avalanche; reception on full and speed of essence.
-"Third stage approach", using "induction lines" (directional search), proceeding more carefully, checking the signal direction and intensity after every five steps.
-"Fourth stage pinpointing the victim", with the cross method, adjusting the volume correctly in order to eliminate external zones (where a different signal could interfere). Beacon held near the ground, probe and recovery.
The directional search, or search via "induction lines", is a new development and must be studied in greater detail, since it brings about a reduction in the search time.
The search via "induction lines" can be carried out with traditional rescue beacons, but is more effective with rescue beacons designed specifically for this purpose. The Ortovox F1 was the first to have directional LEDs and many other models now exist. Whereas these modifications were not substantial, the innovations on the following rescue beacons certainly are.
This unit combines a directional visual search display with an acoustic signal. The display indicates the distance to the victim, the directional intensity of the signal and its direction. Orientation is facilitated through a led which signals when the induction lines have been left.
The acoustic signal is very similar to that of preceding models, with the added feature of a led which indicates when to change the volume control.
This unit proved to be the most adept in every situation, as the combination of its clear visual display and acoustic signal were highly effective in a wide variety of different circumstances (noise, light conditions & other interferences).
One small question mark remains regarding the strapping system (can be used without a neck strap & waist belt). It can all too easily end up in the rucksack during an long, hot ascent - this feature will surely will be modified in the future.
The victim's direction and distance are determined and indicated by five directional LEDs and a numeric display. It is a simple design and can be used by novices, but it has two major drawbacks:
- the maximum range is only 25m (less than the minimum European Norms) and is therefore completely insufficient
- the fact that it has no adjustable acoustic signal means that a search for numerous victims becomes extremely complicated
Option Arva 9000
The tests carried out with this unit proved to be inadequate; this unit combines a directional signal with that of an acoustic signal, but both provide information which is not precise enough.
The maximum range is fairly low and a search for a number of victims is difficult with this beacon. Some design features are interesting but need to be backed up by an improved search system.