Reliable, effective, safe and simple: Wyssen Avalanche Tower LS12-5.
System setup and function
The Wyssen avalanche tower is designed to trigger avalanches prophylactically with remote-controlled blasting.
To trigger an avalanche, a coded command is sent from the control centre WAC.3 to the control system of the deployment box to initiate the blasting. The deployment box contains 12 prepared explosive charges, which can be individually deployed by remote control. When the explosive charge is dropped, two igniters are pulled and the explosion is set off after a time delay. The charge remains hanging from a cord at a pre-set height above the snow cover, which is completely dropped after blasting. To reload explosive charges the complete deployment box is lifted from the tower by helicopter and brought to a station building or warehouse respectively.
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The solar panels, antenna and a flashing lamp are mounted on the outside of the deployment boxes. The dropping mechanism, the electronics and 12 prepared explosive charges are on the inside of the box and protected against the elements. The compact and sealed design means that maximum system reliability is attained
The explosive charge consists of two orange half-shells with pre-mounted SZ 83 percussion fuse, which are assembled with 5kg (11 lbs) of explosives. The charges are assembled by the operator on-site. We deliver the charge containers and the canvas bag for the retaining cable (7.5m / 25 ft ). Explosives and other pyrotechnical elements are purchased directly by customers from the appropriate suppliers
The greatest degree of success for controlled release of avalanches is achieved by a remote-controlled detonation of an efficient explosive at the right time and in the right place.
From the operator’s point of view, a blasting installation must be extremely reliable and effective as well as being simple to operate and maintain. The installation in the terrain must be as simple as possible and the interference of the installation must have a low impact on this sensitive environment. The Wyssen avalanche tower fulfils these requirements ideally.
Smallest residual risk thanks to the largest effective range
- Blasting above the snow with bigger charges (5kg / 11 lbs) gives the maximum effective range up to 260m (850 ft) in diameter
- Explosives with high detonation speeds produce N-shaped pressure waves which have been proven to lead to the best release effect, particularly at a greater distance from the detonation point
- The possibility of positioning the installation in higher locations in addition to suspending the charge higher enables the effect to be reached in locations of pressure shadow (in couloirs, behind terrain ribs)
- Release of smallest quantities of snow possible, thanks to the greatest effectiveness
- Very good stability test for assessment of the local avalanche danger
No critical or moving parts are exposed to the weather, thanks to its intelligent concept
The solar power supply or wind generator avoids the necessity of vulnerable supply lines in the terrain
Reduced closure times thanks to rapid release, around the clock and in all weathers
Remote-controlled installations allow operation around the clock
Very rapid operation possible
Closure times are reduced in the rule to a maximum of 30 minutes
Clearing away avalanche snow is usually dispensed with, since the avalanche run-outs are short due to the release of smaller portions
Low investment and operating cost in comparison with permanent constructional protective measures
Lowest operational costs thanks to its ingenious system concept
Damage to the infrastructure is avoided by the release of smaller portions
Economic benefits thanks to reduced closure times
Highest degree of safety for the operating staff
No staff in the danger area thanks to remote-controlled release
Preparation of the charges takes place in protected areas
The mobility of the deployment boxes means that no maintenance is necessary in the terrain
The smallest interference in nature is very environmentally friendly
Foundation only uses 1m2
Short construction times in the terrain simplify planning and implementation
Blasting over the ground prevents damage to the vegetation cover
Dismantling after operating life possible without any problems
Functional principle Avalanche Tower
|Weight deployment box complete incl. charges||approx. 600 kg (1.300 lbs)|
|Dimensions Deplyment box
(l x b x h)
|1600 x 1050 x 1200 mm
(5.2 x 3.4 x 3.9 ft)
|Dimensions of tower (h x ø)||8000 x 300 mm (26.2 x 1 ft)|
|Inclination of tower||15° in direction of slope
towards the valley
|Number charges per launcher||12 pcs.|
|Amount of explosives per charge||max. 5 kg (11 lbs)|
Mechanism in the deployment box
|Drive unit||DC motor|
|Time for rotating one position||approx. 13 s|
|Transmission Gearbox||gear motor|
|Battery in deployment box supplied by solar panlel||12 V|
|Power supply of computer and relay||230V / battery|
All in one online platform
Operating Software Wyssen Avalanche Control Center WAC.3
The latest software generation including new hardware for operating, monitoring and data storage of the well-proven Wyssen Avalanche Towers, detection systems and weather stations.
- Intuitive web-based operating interface
- Operable from any web-enabled device
(PC, Tablet, Notebook, Smartphone)
- Monitoring of systems 24/7
- Automatic documentation and
archiving of activites and system data
- Data transfer via mobile network or radio connection
- Extensive additional features (explosive documentation, avalanche documentation, weather station, communication tool, snow height measurement etc.)
Transportation by Helicopter
The deployment box is transported by helicopter to the towers in the terrain. Thanks to the guiding system the pilot is able to perform the placement on the tower on his own without a flight assistant. The deployment box orientates itself automatically in the correct position. A safety switch detects the correct position, after which the system becomes operational. The operation can verify the placement of the deployment box on the correct tower on the operating interface immediately thanks to the GPS receiver installed. The system will not be activated if placement is incorrect.
When all charges are used or at the end of season the deployment box can be retrieved from the tower by helicopter. Thanks to the specially made Wyssen Heli link (pictured on the right) no flight assistance is needed in the terrain.
Tower in the Winter with Deployment Box
Tower in the Winter without Deployment Box
Only those persons are permitted to operate and handle the installation who are in possession of a valid certificate for the artificial release of avalanches with explosives and who have attended a certified course by Wyssen Avalanche Control AG. Furthermore, it is very important that the operating staff have the corresponding training and experience for risk assessment, planning of measures, implementation of measures as well being able to assess secondary avalanches and avalanches that could be larger than expected.
The helicopter company must have an authorisation in order to carry loaded deployment boxes. Depending on the country, the intended flight routes with loaded deployment boxes must be approved by the flight authorities.
The helicopter routes taken by which avalanche tower deployment boxes are transported must be so chosen that from the loading place to the avalanche tower a distance of at least 500m is maintained at all times and in all directions away from any persons not involved in the operation. Flying directly over populated areas, open roads as well as people, technical installations (e.g. mountain cableways, mountain restaurants and relay stations) and open ski runs is prohibited.
Approval for storing explosives: for each tower location authorisation must be requested by the customer from the responsible authorities for storing explosives in the avalanche tower deployment boxes during the period of operation.
Basic Principles of Controlled Avalanche Release
It is known from practical experience and from the theory of how avalanches arise in deep winter, that the effect of a detonation above the snow cover leads to the best results with respect to residual risk of unpredictable avalanches. The explosive devices used should give a high detonation speed and produce a large volume of gas with a high work factor. Tests with numerous experiments show that explosives with the above-mentioned properties and charging positions above the snow cover give the highest effective ranges.
The following table from the WSL Institute for Snow and Avalanche Research SLF Davos Report no. 53/1996 shows the approximate effective ranges for dry new snow of various explosive charge sizes in different positions with respect to the snow surface.
In order to test and to safeguard the avalanche release zone, the whole of the potential release area must be subjected to an additional stress (e.g. by a detonation). This is necessary, because the location of the so-called „hotspots“ (super weaknesses) are not known in advance. An acceptable residual risk after blasting operations is only then reached if these „hotspots“ have been subjected to a sufficiently high additional stress and high strain rates within the snow cover with high speed of deformation (= high detonation speed).
Download “Guidelines for Artificial Release of Avalanches”:
Download “Basic principles of controlled avalanche release”:
(Table in imperial measure system)
|Height of detonation point||Charge size||Radius of effective range
to prevent a natural release
|Radius of effective range
to prevent a release by a single skier
|Blasting above the snow (+3 bis 3.5 m)||4 to 5 kg||120 to 130 m||70 m|
|Blasting above the snow (+2 bis 2.5 m)||1.5 to 2.5 kg||80 to 90 m||50 m|
|Blasting above the snow (ca. +1 m)||4 to 5 kg||80 to 90 m||50 m|
|Blasting above the snow (ca. +1 m)||1.5 to 2.5 kg||60 to 70 m||35 to 40 m|
|Surface blasting||4 to 5 kg||50 to 60 m||30 to 35 m|
|Surface blasting||1.5 to 2.5 kg||35 to 40 m||20 to 25 m|
|Blasting in snow (ca. -0.2 m)||4 to 5 kg||40 m||25 m|
|Blasting in snow (ca. -0.2 m)||1.5 to 2.5 kg||25 m||15 m|
|Blasting in snow (-0.7 m)||1.5 to 5 kg||10 m||5 to 10 m|
|Mortar 12 cm (0 m)||3 kg||40 m||–|
|RPG 8.3 cm (0 m)||0.7 kg||20 to 25 m||10 to 15 m|
|Mortar 8.1 cm (0 m)||0.6 kg||15 to 20 m||10 m|
Table from: SLF Davos Report No. 53/1996