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ATR SCALE ADVISORY RECOMMENDATIONS
The highertheATRScale classification,thegreater theneed
to minimize the uncertaintyof snowpackstability.Another
way to express this is to say that the greater the probability
of severe injury ordeath in the event an avalancheoccurs
on a given slope,the more important it isto have a high
level of confidence that the snowpack is strong enoughto
support the weight of one individual orthe entire touring
group before they venture onto the slope.
ItisworthwhilereiteratingthattheATR Scaleisin-
tended foruse byindividualswhomitisassumedhave
adequate education, competence and equipment to be in
the backcountry, andthat thetouringgroupwishes to mini-
mize the risk from avalanchesas much as is practical.The
advisories in this section are also based on these assump-
tionsandareoffered toassistinthe evaluationofsnow
stability and to prepare forthe potential risks of proceed-
ing onto the slope.
Class 1 Advisory: Minimizing uncertainty of snowpacksta-
bilityis notnecessary.Minimal precautions are needed.
Theseslopesareoften used astestslopes tohelp assess
thesnowstrength on higherriskslopeswith similaras-
pects at similarelevations.Some notion of the potential
forthe snowpack to fail is helpful.Precautions necessary
to help avoid injury from a simple fall in that event should
betaken.Theriskofsevereinjuryordeath fromdeep
burials on Class 1 slopes is effectively zero.
Class 2 Advisory: Minimizing uncertainty of snowpacksta-
bilityis helpful.The precautions listed for Class 1 slopes
as well asstandardpersonal precautionsfor potentialburial
are recommended.Thesewould include potentialvictims
securing openingsinclothing,looseningpack andpole
straps.At least a ski pole test or handtest of snow layering
and some notion of the potential for the snowpack to fail is
advised.The group shouldbe preparedfor a shallowburial
rescue.Rescue skills should be good.The risk of severe
injury or death from deep burials on Class 2 slopes is low.
Class 3 Advisory: Minimizing uncertainty of snowpacksta-
bilityisadvised.Atleastonerepresentativesheartest
should be conductedbefore accessing the slope if there is
a reasonable question concerning snow strength.If shear
testsorotherindicatorssuggest potentialfailureplanes,
the group should expect and be prepared fora potentially
deepburial rescue. Rescueskills should be very good.The
risk of severe injury or death from a deep burial on Class 3
slopes is moderate.
Class 4 Advisory: Minimizing uncertainty of snowpacksta-
bility is necessary.One or more representativeshear test(s)
should be conducted whether ornot weakness is evident
orsuspected.Specialattentionshouldbegivento
potentiallyvariablesnowpackstratigraphyacrossthe
startingzone.Representative sheartestsshould becon-
ducted before accessingthe slope if variable conditions in
thestarting zone are suspected.Knowledge ofperform-
ance historyundera variety ofsnowpackconditions in-
cluding those that exist at the time is helpful.Rescue and
evacuationskillsandpreparednessshouldbeexcellent.
Theriskofsevereinjuryordeath fromdeep orlengthy
burial,impactwithobstacles,and/orstrongavalanche
forces on Class 4 slopes is high.
Class 5 Advisory: Minimizing uncertainty of snowpacksta-
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bilityis essential.Numerous representative shear tests in
all potential starting zones are advised on a periodic basis
throughoutthewintertodocumentchangesinsnow
stratigraphy.Aperformance historyunderavarietyof
snowpack conditions including those that exist at the time
shouldbeknown.Representative sheartestsshouldal-
ways be conductedprior to venturingonto theslope.Ready
accesstoadvancedlifesupportandrapidevacuation
shouldbeavailable.Preparationforbodyrecoveryis
advised.The risk of severe injury ordeath from deep or
lengthy burial,impact with obstacles,and/orstrong ava-
lanche forces on Class 5 terrain is extremely high.
DISCUSSION
The ATR Scale is intended to help quantify the risk level
of the terrain being considered by the touring group.It is
notintendedin anywaytohelpdeterminethe levelof
acceptablerisk for the group.Each group must determine
for itself the level of risk that is acceptableto achieving its
desired goal.
WhenusingtheATRScale, askingthefundamentalques-
tion, "Whatarethe potential consequencesof being caught
in an avalanche on this slope?" is the first step.If the an-
sweris that a person would,without doubt,be violently
tumbled, contactapotentiallyinjurious terrain feature,and/
orend up in a deep orlengthy burial,then the slope is a
Class 5.If the answer to the question is that the chances
are notcertain,butbetterthan 50% thatone ormore of
those thingswill happen,then the slope isa Class4.If
thereisnoexposuretoalong-runningavalancheor
potentially injurious terrain features, but a deep burial is
probable,then the slope is a Class 3.Ifthe slope is rela-
tively short,there are no potentially injurious terrain fea-
tures, and only a shallow burial is likely, then the slope is
a Class 2.And finally, if the chancesof being hurt or bur-
ied are negligible, the slope is a Class 1.Inther ecr ea-
tionalsetting,itisadvisablethateachindividual know
andunderstand the goals of his or her group.These goals
shouldbediscussedand agreed tobeforethetripstarts
and as frequently as necessary en route.One errantmem-
bercan cause strife within the group at critical times.He
or she can also seriously jeopardizethe safety of the group
through careless ordaring acts which eitherharm others
orcreate the need fora rescue and evacuation.The ATR
Scale can be used as one means of agreeing on the group
goals by discussing the risk level that is most appropriate
forthe occasion.
Professional mountain,touring, and heliski guides are
charged with setting and maintaining the goals andsafety
parameters for their groups.However, it is very important
that guides communicate the risk levels to their clients so
thattheclientscanmakeaninformeddecisionasto
whether ornot to accept those risks.The ATR Scale is a
useful tool forthis purpose.Likewise,it can help guides
avoidunwanted risklevelsinthe face ofcommonenvi-
ronmentalfactors suchas fatigue,clientpressures, logistical
failures, temptingincentives, or managementpressures.As
withanysystemdesignedtosafeguardpublic safety,it
should be noted that the ATR Scale,orany othersystem
usedinan atmosphereofindifference, complacency,or
incompetencewilleventuallyfail with catastrophicresults.
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