Safety
Information How
to avoid being avalanched and what to do if you are caught out Risk
Assessment and preparation
General Tips
Types of Avalanche Risk
Assessment and preparation. Avalanche
Avoidance The golden
rule of back country or off piste skiing and snowboarding is to AVOID avalanches.
Everyone should be properly equipped and trained to deal with an avalanche but
nobody should ever have to ! The key to safety is Local Knowledge. The problem
is that the best slopes to board and ski down are the most avalanche prone. If
you are touring then you can plan your route to avoid dangerous slopes but if
you are looking for steep powder runs then you are deliberately putting yourself
in a dangerous position. Backcountry boarding and skiing is hazardous and you
should be aware of the risks. Snowboarding and new ski technology has opened up
the backcountry to people with limited alpine experience who treat it as a video
game style competition and the avalanche accident rates have risen accordingly!
You have as much right to be there as anyone else but everyone should be armed
with a healthy fear of avalanches. 1.History You
should be aware of the local conditions before you go out. When did it last snow?
Are there any slopes that always avalanche? Has it been warm or cold? How many
snowfalls have there been this season? How windy has it been? Have there been
many avalanches this season? All these questions give you an idea of the risk
you are facing. There is no substitute for local experience and knowledge. You
are most at risk just after a snowfall and the more snow that fell the greater
the risk. New snow
added in 3 days compared with observed avalanches Up
to 10cm - rare avalanches, mostly loose snow
10 - 30 cm - very occasional
slabs, frequent sloughs
30 - 50 cm - frequent slabs on slopes 35 degrees
50 - 80 cm - widespread slabs on slopes down to 25 degrees 2.
Slope selection If
you are happy with the general snowpack conditions, you then need to consider
the slope or terrain that you wish to use. All faces look fantastic covered in
fresh powder but there are some important questions to be answered about each
slope. How steep
is it? Below 25 degrees is not steep enough to slide, above 50 degrees is too
steep to hold a lot of snow, anywhere between is prime avalanche territory Is
the slope concave or convex? Convex slopes do not support the weight of the snow
high up very well and are more prone to avalanche What
is the slopes aspect? North facing slopes are less affected by the sun and colder
just after it has snowed, south facing slopes consolidate more quickly and are
safer a few days after the snowfall. This is especially true in the springtime
where south slopes consolidate quickly and north facing ones can remain dangerous
for days or weeks after a snow fall. Is
the snow wind affected? If the wind has been from behind the slope it will have
deposited a lot of snow on the slope and given it a pillowed effect. There is
now a great weight of snow to be supported and the risk is higher. If the wind
was strong as well it may have formed a slab, where the snow has been blasted
together in one huge lump. In this case the risk is high and if there is an avalanche
it is sure to be a big one. If the wind was up the slope it will be scoured, and
most of the loose snow will have been removed , this will be safer but the conditions
not as good. A cross slope wind will give both conditions at different places
on the slope. The ideal is for the snow to fall in still wind conditions but that
happens only when there is a blue moon! What
time is it? How much sun has your slope received today. A slope can be safe at
10.30, dodgy by midday and downright dangerous by 1.30. The avalanche risk changes
all the time, just because there are tracks does not mean it is safe! What
is the 'run out' like? If your slope fans out into a wide gentle area, an avalanche
will slow down and spread out reducing your chances of being completely buried,
if it runs into a gully or depression you may be buried under many metres of snow
and digging you out could take hours 3.
General tips. If
your assessment has revealed that the slope is too risky then you must walk away.
It is tempting just to say 'sod it I'm going down' especially if the snow conditions
are good, and you may escape incident this time. But that attitude will eventually
get you killed. You can ride many more slopes in ten years safely, than skiing
all the slopes all the time until you get killed. Hopefully
you have answered all these questions and decided it is ok to ride down. That,
after all, is why you are there. These hints will further increase your security.
At the start of
the day check all transceivers are on, switched to transmit and have good batteries.
It is worth actually testing all the transceivers. Never take it off during the
day. Never board
or ski alone, big groups are also dangerous because of the weight and difficulty
of controlling everyone. 4 is the ideal size of party. Loosen
your backpack and pole straps. This can easily be dumped if the worst happens. If
you do end up in a dangerous situation, only one person should move at a time,
the others should be watching him/her in case he/she is avalanched Try
to move from one safe spot to another, i.e. the top of the slope to below the
big rocks halfway down and on the left side. If there is an avalanche that someone
else starts you don't want it to get you as well Use
the edges of bowls and not down the middle Ski/Board
down ridges and spurs rather than bowls and gullies Do
not bunch up. This places extra stress on the snow pack and weakens it, plus leaves
no one to do the rescue-ing Do
not board directly above someone else, you are putting them in danger Do
not traverse slopes. If this is unavoidable traverse as high up as possible. Never
traverse above other people. Watch
and listen for cracks and movement in the snowpack, you may get a warning to be
very careful! Avoid
boarding/skiing under cornices. They are evidence of wind loading and may fall
off and cause an avalanche. An
avalanche needs something to start it. It is a myth that loud noises trigger avalanches.
In 99% of cases it is the person that starts their own slide. This is normally
caused by the person crossing a weak spot or 'trigger point'. This can be anywhere
on a hollow slab or where the slope suddenly steepens. It can be along an obvious
feature like the bottom of a row of trees or an old fracture line in the snow.
It can also be undetectable like where the ground changed from scree to grass
and the snow could not bond as well. You cannot know where the trigger point is
but you can avoid the most obvious ones. This is the reason you never traverse
above other people because your long cut in the snow may become the trigger point.
Don't start something that you cannot stop! This
is a very brief summary of things you should know and think about. There are several
books devoted to this subject. Avalanche safety for skiers, climbers and Snowboarders
by T.Daffern is an excellent example. This book covers all these topics and more
in greater detail and with more authority than I have here. Backcountry Snowboarding
by C Van Tilburg also has a lot of information. There is no substitute for experience.
Attending an Avalanche Awareness course is an excellent way to improve your skills.
You can never eliminate the risks of backcountry boarding but you can do your
best to reduce them to an acceptable level. There are accidents every year involving
experienced climbers, boarders and skiers so never become complacent.
Despite
all your efforts and using the above techniques you may still be involved in an
avalanche, or you may come across someone in an avalanche who needs your help,
now you need to have an avalanche transceiver, shovel and the skill to use them.
I repeat, there is no substitute for experience. You should have practised search
techniques until you can locate a buried victim in under five minutes. This
page is not about how to use a transceiver but about not having to use one. If
you are searching an avalanche site never forget the possibility of a subsequent
avalanche. If possible post a look out to protect the searchers. If this happens
quickly switch your transceiver back to transmit, try to move out of the path
of the avalanche and hope there is somebody left to do the searching. If
you are in an avalanche or see one coming then there are a few things you can
do. It may not be possible to do any of them but if you can, you should Jettison
your poles and backpack (already loosened ). You may want to keep your axe if
the avalanche is small and there is a chance of holding your ground. Try to move
out of the way or to the side of the avalanche path, prior planning will tell
you which way to go. Once in the avalanche try to go down feet first to protect
you from rocks and obstacles, If not using your arms to protect your head from
debris try to do a double arm backstroke movement. This will stop you sinking
too deeply into the snow. If the slide is cold and powdery try to cover your mouth
and nose with your jacket or glove to reduce the risk of suffocation. Keep your
mouth shut! Save most of your effort until you feel yourself slowing down, then
try to fight your way towards the surface. Being on or near then surface will
greatly increase your chances of a speedy rescue. You should also try to create
an airspace around your head. As
you feel yourself stop make a supreme effort to push yourself up towards the surface.
It might be the last thing you do, but it could make all the difference
Types of Avalanche 1.
Soft Slab Avalanche This
is the most common type of winter avalanche and associated with the build up of
fresh snow on lee slopes. The snow is moved by wind of 10-30 m.p.h. After a heavy
snowfall it could occur on any slope. The slab is released as a single unit but
breaks up as it flows over the ground. If there is enough fresh snow and the slope
is steep enough then it may become a powder avalanche. 2.
Dry Powder Avalanche
This type is most common in cold dry conditions and after
a fresh snow fall. If it snowed heavily, at 2cm per hour or more, then it is especially
risky. As little as 20 cm of fresh snow poses a threat. The snow starts to move
as a soft slab and gathers speed and more snow. The snow will ride up on a cushion
of air and become an airborne powder avalanche travelling in excess of 100 m.p.h.
In front of the avalanche will be a blast wave. Inhalation of snow and suffocation
is often a problem with this type of avalanche. 3.
Hard Slab Avalanche
The hard slab represents one of the greatest dangers,
not because of it’s frequency but because it’s solid appearance gives
a false sense of security to those travelling over it. The combination of strong
winds (more than 30 m.p.h.) and cold temperature favour it’s formation. If
it remains cold then the danger may persist for some time. The slab can even be
covered by further snow falls. The slab releases in one unit like a soft slab
but breaks up into great chunks of snow and ice that have enormous destructive
power. Watch out for sudden local subsidence, cracking or dull booming noises
as clues that you may be on a hard slab. 4.
Wet Avalanche
Common in spring and thaw conditions, water flowing through
the snow or between the snow and ground has weakened it’s adhesion. These
travel at relatively slow speeds but carrying a huge weight of snow and water.
These are the easiest to predict due to the weather conditions for their formation.
Cracks in the snow and large snowballs rolling down are visible clues
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