How to React
Avalanche Reaction
Avalanche Facts
65% Suffocation
25% Trauma from collision with trees, rocks or other obstacles
10% Hypothermia and shock
It only takes 8 to 10 minutes to suffocate, so every second counts.
Initial Reaction
Remember, time is crucial; every minute counts when someone's life is on the line. It is also important never to go into the backcountry alone; in avalanche cases there truly is safety in numbers.
In the event of an avalanche, skiers not buried in the avalanche should:
- Gather everybody's gear together in one location; this eliminates confusion when one is searching for signs of the buried individual.
- Perform a preliminary survey of the avalanche field noticing where the buried individual was last seen and the slide path of the avalanche.
- Designate one person to perform the beacon search; this should be the individual with the most experience who still maintains composure.
- Turn off all beacons except for the one designated to perform the search to avoid confusing signals with the buried individual.
- If skiing with a large group, everyone except for the one is performing a beacon search should be looking for signs of the buried individual on the surface of the slide area.
- When the individual performing the beacon search narrows the search area, everyone should line up shoulder to shoulder and thrust their avalanche probes all the way into the snow in three different areas in front of them.
- Once a probe catches what could be a person, at least two individuals should dig in that spot while the others keep probing.
Common Burial Zones
In the toe of the debris pile.
On a bench.
On the uphill side of an obstacle.
On the outside of a bend.
Searching Techniques
Tangent Method
Though several techniques of avalanche beacon use have been used over the past few decades, most experts agree that the "Tangent Method" is the most effective. While each beacon might not have the same displays, this method can be used with both analog and digital beacons. One should follow these steps:
- Turn your beacon on its highest setting for receiving and start to move towards the place where you last saw the buried individual. If you do not pick up a signal, traverse back and forth across the entire snowfield moving slightly downhill until you pick up the first signal.
- Align your beacon with the flux line of the transmitting beacon. Hold the beacon with the display facing toward the sky and the bottom held close to your chest. While facing the direction of the slide area, turn your body to the left and to the right 180° listening for the strongest signal. Do not turn all the way around because this will disrupt the flux line signal. The strongest signal will be indicated by the loudest beep, the maximum number of lights flashing, or the minimum distance reading depending on what type of beacon you are using.
- Walk in the direction of the strongest signal.
- Regularly correct your alignment along the flux line. This can be done by repeating Step 2 about every five meters.
Tangent Method Illustration
Grid Method
An alternative to the tangential method of signal location is the grid method, also known as the bracket method. This method is easier to master, but generally slower than the tangential method. In situations where the tangential method does not yield adequate results, this method should be employed.
Grid Method Illustration
Orient the beacon:
- After locating a signal with a coarse search, orient your beacon to the maximal signal. While holding the beacon, rotate the beacon vertically and horizontally to find the loudest signal. Very important: maintain this beacon orientation throughout the search!
Making a bracket:
- Reduce the volume to the minimum level that is still audible.
- Begin walking in a straight line. Any direction will work. If the sound decreases in intensity immediately, turn 180° and continue walking.
- When you hear the sound peak and begin to decline, stop. Turn your beacon down again until it is barely audible.
- Mark that location. This will serve as one end of your first bracket.
- Follow your chosen line backward until it peaks and becomes barely audible.
- Mark this location. This will serve as the other end of your first bracket.
Preparing for the next bracket:
- Find the center point of the first bracket. Mark it with a wand or other marker.
- From this central marker, turn your beacon down again until the sound is barely audible.
Repeating:
- From the central mark, walk at a right angle to your first search line. Repeat the "Making a bracket" step to create a bracket perpendicular to the previous one.
- Repeat the bracket making procedure from the center point of each subsequent bracket. Remember to alternate brackets at right angles
- Continue until your final bracket is six feet in length.
Fine search:
- With your beacon near the snow, perform criss-crossing sweeps listening for a loud signal.
- Mark the area of loud signal and prepare for probing and excavation.
Regardless of what methods you choose to use it is essential that you practice. Get to know your beacon by practicing in fields. These methods need to be second nature so that you will be able to perform them under pressure.
References:
Mountaineering: The Freedom of the Hills, 6th edition, edited by Don Graydon and Kurt Hanson, Seattle 1997
http://www.uoregon.edu/~opp/snow/avalanche/rescue.htm April, 2005
http://www.couloirmag.com/gear/avy_gear/beacons99.htm April, 2005