As the risk of gloom and doom here is an excellent article first published in "The Avalanche Review" (TAR) which is the American Avalanche Association's newsletter. While we all gear up for the coming season I will put a few more things of interest up. We could easily talk ourselves out of ever skiing a line or doing a tour, but and it's a big but - these insights into how we think or should begin to think are constructive ways to avoid thinking traps (heuristics) and "risk complacency" (risk homeostasis). I have added a few photos of my own just to break up the narrative as its quite wordy.
Note: Ed LaChapelle was born in 1926 in Tacoma, Washington. He spent two years in the U.S. Navy 1944-46 as an electronic technician, then graduated in math and physics from the University of Puget Sound in 1949. Professionally he has been a guest worker at the Swiss Avalanche Institute 1950-51, a snow ranger with USFS at Alta, 1952-72, done glacier research in Greenland and Alaska 1952-1956,and on the Blue Glacier on Mt. Olympus 1957-1970. He was appointed to the faculty of the University of Washington in 1967, retired as Professor Emeritus of Geophysics and Atmospheric Sciences in 1982. He has been active in snow and avalanche affairs for all of his professional life, including retirement.
The Ascending Spiral by Ed LaChapelle
Decisions,
decisions.......the February issue of TAR spoke from several informative points of view and the editor
invited a dialog. Here is one
contribution to the perpetual questions of how to evaluate avalanche hazards,
consider human factors and communicate (or execute) decisions. Here is what I
mean by the title. Rather than seeing
our mastery of snow and avalanche science and decision-making as linear
progression, I see it as the same issues and ideas coming around again and
again, but each time at a more
sophisticated and technically advanced level, hence the ascending spiral. I take as my theme the wisdom that
Whymper (1871) handed to us many years ago.
He spoke of mountaineering in general, but his words are just as cogent
today in this “decision” context: “Climb if you will but remember that courage
and strength are naught without prudence, and
that a momentary negligence may destroy the happiness of a
lifetime. Do nothing in haste, look well
to each step; and from the beginning think what might be the end.”
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| Edward Whymper "Do Nothing In Haste"was a little luckier than his companions on the Matterhorn |
“Do nothing in haste”......this speaks loud
and clear to the pressures of time,
planning and economics, plus the perpetual urge to action that drives
so much of our modern life. Here is where the human factor in avalanche
related decisions comes to the fore. And
this brings us to Elbert’s Rule. When I first worked at Alta in the 1950’s, the
daily mail was brought up the Little Cottonwood Canyon road by Elbert Despain,
who had been doing this for many years, continued doing it for many years and
was still carrying the mail at age 90,
when he achieved the distinction of being the oldest mail carrier in the United States. As we all know, that canyon is beset by a
horrendous series of avalanches. I once
asked Elbert how he managed to miss getting caught in an avalanche in all that
time. His answer was the epitome of
common sense: “After a heavy fall of new snow, wait two days.” Note that even
the United States Mail, famed for a high determination to deliver, could at
least in those times wait two days.
Elbert was mostly dealing with natural releases where his Rule is hard
to beat. Artificial releases, intended
or accidental, can stretch out the safety wait depending on snow conditions,
but the concept of giving the landscape a chance to stabilize, “do nothing in
haste”, points to the fundamental problem of including the human factor in decisions. The idea of waiting two days, or
almost any kind of wait, just doesn’t fit today’s activities in avalanche
terrain. Is there a heli-ski manager who
can get away with asking his guests to wait two days before skiing 50 cm of new
powder? No way! A ski area operator who
will close half his runs in similar circumstances, or a highway foreman who
will garage his plows until the snow sets up?
Only in dreamland! The basic
human problem with decisions in avalanche terrain is not so much personal
attitudes, group interactions or risk management. It is the expectation that human activities
can be scheduled by artificial constructs like calendar and clock in a natural
world that moves at its own independent pace.
A weekend ski tour is not going to be put off until Monday because a
snow dump on Friday created avalanche hazard and we might as well adapt to this
behavior. But at least recognize the
root of the problem in training for decision-making. That tour might still take place on a
hazardous weekend, but with a revised destination.
“Look well to each step” covers many
individual actions or observations on the way to acquiring bases for
decisions. Here I will look at a couple
in detail. First, there is the eternal
business of digging snow pits...how many, how
often, where and in what detail (the ascending spiral is spinning fast
here). McCammon and Sharaf (2005) cite Peter Schaerer’s sensible admonition to
be quick, an approach to snow pits I can readily endorse. Let’s look closer at this whole pit digging
business, one that sometimes can become the tail that wags the very large dog
of avalanche data collection. Snow pit
digging is a necessary but far from sufficient action to understand snow
stability. If it is only part of the
picture why does it so often come so much to the fore? I suggest that this is because we can observe
and record a select body of detail like crystal type and size, hardness,
density, layer thickness, etc. And why do we record these particular
features? Because they are readily
rendered into numerical values and logged in notebooks, an act that may convey
comfort in having acquired “objective” data but not always be what we need to
know. For example, rate of change of
viscosity in a snow layer might be more informative, but this is a tough one in
a cold laboratory and impossible in the field.
So, we are often led down the easy primose path of the possible. Let me
put forth the heretical notion that we do not need more data from a given snow
pit, but less. The act itself of digging
with a shovel is the culmination of the Schaerer Quick Pit concept. By the time I have finished digging a snow
pit, I usually know about 90% of what I am going to find from it about snow
stability.
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Glencoe Feb 2009 same day as pic of Aonach Dubh (below) which was taken on the way up to ski.
A quick pit with easy shears at 30cm on buried hoar.
Not a hard thing to do. Cat 4 High SAIS yet climbers in the classic gullies of ScNL!
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Logging pit details is a good
educational tool and expands knowledge about a wide range of snow properties,
but should not be confused with the backbone of avalanche forecasting. In the
larger picture of snow stability, snow pits provide a quick but static snapshot
of conditions at a given time and place.
From the external perspective of a passing observer, snow on a
mountainside is just sitting there, apparently dormant. The snow cover, however, is neither static
nor dormant, but a positively seething mass of activity. Snow is constantly gliding, creeping and
settling. Layer by layer the physical
properties are constantly changing as crystals metamorphose. Waves of changing temperature sweep through
the snow cover while radiation works at the surface. Snowfall and wind drifting change the amount
and distribution of loading with each passing storm. Understanding the complex behavior of snow is
a problem in rheology, the science of deformation and flow of matter. In this case the problem is further
compounded by the matter in question being a granular visco-elastic solid close
to its melting point. You can’t make it
much more complicated than that.
The
observational role of the snow pit in all this compared with a broader and more
lengthy data collection is clarified by a concept in rheology put forth by
Meiner (1964), the Deborah Number.
Meiner pointed out the
significance of the Prophetess Deborah singing that “the mountains flowed
before the Lord”. In the limited time
frame of human perception, the mountains are static and eternal, but for the
Lord, whose time frame is infinite, they flow. Meiner defined the
non-dimensional Deborah Number as follows:
D =
time of relaxation/time of observation
A high Deborah Number means the subject in
question appears to an observer to be a static and unchanging solid. The brief observation from a snow pit implies
a high D snow cover and hence a static view of what actually is an active
(“flowing”) snow cover. To gain insights
into the dynamic character of the latter, observations extended in time are
needed to lower the value of D. In other words, stability evaluation has to be
an on-going process, the longer the better. Ideally, the estimate of snow
stability evaluation on a given avalanche path begins with the first snowfall
of winter. More about this in a moment.
A
second relevant action, consulting some sort of checklist, appears when George
(2005) describes the NivoTest. This is
where the ascending spiral really starts to spin. Check list have been around for a long time
and in various formats and the NivoTest stands out as possibly the most
sophisticated one to date. Looking into
history, the earliest check list I can find is G. Bilgeri’s Six Points (three
for terrain, three for snow conditions) already in use by the 1930’s, described
by Seligman (1936). Later, as one
example, we have Atwater’s (1952) Ten Contributory Factors, initially with
equal weight but later informally modified by various weighting schemes. I like
the NivoTest because it nicely condenses terrain, snow features, current
avalanche activity and human factors.
However, it is disquieting to see it illustrated in TAR by a photo of a
guide consulting it in the field in the middle of what appears to be avalanche
terrain. This brings the checklist
concept into play far, far, too late. If
you wait until standing on the edge of an avalanche path before considering
snow stability and risks, very poor decisions can ensue. Again, evaluating snow
conditions is an ongoing process, not a single event (reduce the Deborah
Number!). The NivoTest, or any similar scheme, needs to be constantly in play
days prior to any avalanche exposure, when evolving weather conditions
contribute to the checks. Early entries to the NivoTest may be hazy as to
detail, but even then a picture will start to evolve than can be constantly
updated until the final moment of
decision in avalanche terrain.
Seligman
(op. cit.) nearly seventy years ago placed strong emphasis on anticipating snow
conditions from weather patterns long before going into the field. More recently I have made the same point
(LaChapelle, 1980). Of course, the weakness of any checklist system is the risk
of rigidity and thus locking out unusual thinking demanded by unusual
conditions. Whether a NivoTest or any other scheme, check lists
have to be reminders and not substitutes
for constantly paying attention to a wide spectrum of clues about snow behavior. I view George’s mention of mandated us to use
checklists like the NivoTest with much alarm.
Plantiff’s lawyers can have a field day with mandates.
Among
the various TAR articles about decisions, only Stewart-Patterson mentioned
luck, where he named it one of the three main factors in decision-making,
though only in passing. This topic needs
wider recognition. Let’s face it, most
of us in the avalanche game have been saved many times over by luck. George (op. cit.) mentions that even experts
say they are right only 50% of the time.
Now we know that experts don’t get caught in avalanches 50% of the time,
so the obvious conclusion must be that luck along with undocumented skills is
right in there as a major player. This
is not surprising when we consider that most places and most times the alpine
snow cover is stable in the face of normal triggering forces. The whole business of evaluating snow
stability and making decisions hinges on recognizing those fewer times when it
is not. Thus the odds more often favor a
mistake on the safe side than one that raises risk. Of course, by random chance, bad luck as well
as good can follow even the most skilled and careful decisions. “... from the
beginning, think what might be the end.”
This really gets to the heart of the matter, emphasizing the idea of
stability evaluation as an ongoing and continuous process mentioned above. Whymper spoke to anticipating risks in
mountaineering: his words speak with equal force to anticipating risks in
avalanche terrain. Here is where the
experts get sorted out from the beginners.
My idea of an expert is a person who constantly follows evolution of the
snow cover and repeatedly thinks ahead to “what might be the end” for one risk
situation after another. The end might
be an avalanche fall, and even more important might be consequence of an
avalanche fall. I learned this many
years ago from Andre Roch (personal communication) who pointed out that two
questions are involved. First, will an
avalanche occur, and, second it if does occur what will be the resulting
risk? For example, a small avalanche
poses much less risk to a skier if it has a gentle outrun onto safe ground than
it does if it carries a victim over a cliff or into a crevasse.
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Luck! W. Face Aonach Dubh Feb 2009 A 500m x 1m to 2.5m crown wall visible high up on the ridge line.
Anyone climbing the classic ice gullies on the day this spontaneous release occurred would have been
buried in the lower terrain traps where depths exceeded 20m
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The
whole business of expertise is examined by Conger (2005), who allots analytical
skills in decision-making to persons ranging from novice to proficient, but
reserves the role of intuition for experts.
He is onto something here, raising the whole question of just what
constitutes intuition. Perhaps this is
a case of of not being able to define intuition but being able to recognize it
when we see or exercise it. Certainly we
can all recognize the
“seat-of-the-pants” factor in evaluating snow stability, but just what do
we mean? Here I will make a try at
answering this question and defining intuition in this context. To begin,
consider what intuition is not. It is
not some magical quality bestowed on mature people of wide experience along
with gray hair and slowing reflexes. It
is not some sort of extra-sensory perception; quite the contrary. Intuition is the lifetime accumulation of
precisely those sensory perceptions of snow, weather and avalanche behavior
that have accumulated, often in the sub-conscious, that cannot readily be
quantified, logged in a notebook or
clearly explained. Such perceptions,
nevertheless, are based on the physical behavior of the real world, not on
vague mental constructs. An example is
the meteorological perception of a mountain snowstorm evolution based on subtle
changes in the spectral distribution of light filtering through clouds as the
sun descends in the sky and cloud layers come and go in shifting fashion. No doubt a wide-spectrum recording light
sensor could construct graphic records of these changes and eventually build a
quantitative document. But the expert
integrates all this under the guise of intuition and recognizes the likely next
storm trend. Here is another example from my own experience. I once was involved in a field training
program for heli-ski guides. The
exercise was preceded by a very light fall of fluffy snow, followed by a
substantial fall of mixed snow types and mid-range densities. This combination produced widespread
instability with the fluff acting as lubricating layer. Two days of field training produced ski
releases everywhere, excellent for demonstrating how, and how not, to test ski
an avalanche path. On the third day the
first helicopter flight took several of us to a ridge top. One of the experienced guides skied 100 yards
down the ridge and stopped. I followed
close behind and joined him. He turned
and said, “There is no tension in the snow today”. I replied, “I agree”. That day-long exercise never started another
ski release no matter how hard we tried.
So here were a couple of presumed “experts” putting their intuition
accurately to work. What did we actually
sense about the snow? We can throw
around words like kinesthetic perception and psycho-rheology, but what we
actually had was many years of experience with the way our skis and legs
reacted to snow structure, accumulating this experience somewhere in our
heads. Did we actually experience
“tension” as physics would define it?
Probably not, this is another convenient word to toss around, but we
both knew what we meant. How many
readers of TAR know what we meant? As the spiral ascends and scientific and
technical knowledge about snow continues to grow, are we coming closer to
improved training and safety practices for avalanche risk management? Or are we locked into Wilde’s (1994) risk homeostasis trap? The dialog needs to continue.
References
Atwater,
M. & F. Koziol, 1952. Avalanche
Handbook, U.S. Department of Agriculture, Forest Service, 146 pp.
Conger,
S., 2005. Learning to Decide: On
Becoming an Expert, TAR, Vol. 23, No. 3
George,
D., 2005. Natural Born Risk Takers,TAR,
Vol. 23, No. 3
LaChapelle,
E., 1980. Fundamental Processes in
Conventional Avalanche Forecasting, J. of Glac. Vol.26, No. 94
McCammon,
I. & D. Sharaf, 2005. Integrating
Strength, Energy and Structure into Stability Decisions, TAR, Vol. 23, No. 3
Meiner,
R., 1964. From an after-dinner talk
presented at the International Congress on Rheology, Providence, R.I., In:
Physics Today, January 1964
Seligman,
G., 1936. Snow Structure and Ski Fields,
Macmillan, London 555 pp.
Stewart-Patterson,
I., 2005. Developing Good Decisions, TAR Vol. 23, No. 3
Whymper,
E., 1871. Scrambles Amongst the Alps in the Years 1860-69, John Murray, London, 432 pp.
Wilde,
G., 1994. Target Risk, PDE Publications,
Toronto, 243 pp.
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| Bottom of No 2 Gully Filled up from above slide on Aonach Dubh. Depth approx 20m |
