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((With only one survivor and issues of decency towards the deceased, this could not have been an easy report. As this is such an important and record setting accident, we publish an annotated ((with double quotes)) and CONDENSED version below. For the full report with images and such, see the CAIC website. The report alludes to human factors but doesn’t address them directly. Read on to learn and perhaps ponder if we as backcountry riders need to rethink our whole approach to avalanche safety. Also, I’d normally not take the emotional dive of this sort of commentary. But this accident is a different animal. It indicates something might be broken about how we learn and behave regarding avalanche danger when our intention is to have a short, safe ski tour (as the report implies these guys were after). Thus, I’ll take the plunge. When you comment, please be ultra respectful of the deceased and the lone survivor. Please also see our other Sheep Creek posts.))
CAIC Avalanche Comments
……. The avalanche was a hard slab, ((on April 20, at approximatly 10:15 AM)) triggered by one or more party members at the bottom of the slope. The avalanche was medium size relative to the avalanche path, large enough to bury or destroy a car… and broke into old snow layers and to the ground …. The crown face ranged from less than 1 foot (25cm) to over 12 feet (380cm) deep, with an average crown height of 5 feet (155cm). The slide was 800 feet (244m) wide, and ran 600 vertical feet (180m), and broke small tree branches up to 2 inches (5cm) in diameter.
CAIC Weather Summary
……. Periods of convectively-enhanced snowfall occurred on the day of the accident. Snowfall totals for the week prior to the accident were around 3.5 feet at Loveland Ski Area 1.7 miles west of the accident site, with over 3 inches of snow water equivalent at Loveland Basin SNOTEL site (Figure 1).
CAIC Snowpack Summary
……… By mid-April, the snowpack near Loveland Pass was 150 to 200 cm deep, but some wind-loaded areas were over 3 meters deep. The upper meter of the snowpack had stiff slabs… slabs 10 to 70 cm thick. There was a prominent layer of depth hoar capped by a thin crust, 20 to 30 cm above the ground. The bottom 25 cm of the snowpack consisted of well developed but rounding depth hoar…. The rapid, heavy load from the April storms initiated a deep-slab avalanche cycle in the Front Range and Vail-Summit forecast zones. Large deep slabs, running on the buried depth hoar layer, were triggered naturally and by backcountry travelers in the several days leading up to the accident on April 20th. This included a fatal accident in the Vail Pass area …and a natural cycle in the Straight Creek area on April 18th. All of these deep slabs, including the avalanche discussed in this accident, ran on similar terrain: north-facing slopes, 32 to 42 degrees steep, and in the near-treeline elevation band. All of these avalanche released from low down in the start zone.
((Above are the red-flag warnings that many of us are mystified about, as to how the warnings were apparently not enough of a factor to change the group’s behavior to the point of preventing or at least mitigating the accident. Extrapolating from that, we are wondering if the avalanche safety community needs to re-think the whole way we approach decision making, and how it is taught.))
CAIC — Events Leading to the Avalanche
…… A large group of backcountry enthusiasts taking part in the Rocky Mountain High Backcountry Gathering met in the parking lot of the Loveland Ski Area.
((This is where we can’t help by think that problematic human factors came into play. As in previous blog post, this is where I start looking in the mirror. How many times have I dropped my guard because of being involved with an event or semi-event, letting social interaction get in the way of cool calm and collected decision making? I’m guilty. Of course no way of knowing for sure if that’s what went on here, but we need to make a few assumptions so we can learn something from this.))
…… The event was organized to promote backcountry snowboarding and avalanche safety.
((It would be insulting to the reader’s intelligence to not acknowledge the horrible irony in the above. And, it’s not the first time. Just a few years ago a man died while taking an avalanche safety course near Aspen. Extrapolating, I’d agree that an element of luck and fate are involved in these things, and since avalanche safety courses are in the field a lot, looking for avalanche conditions to evaluate, they will get involved in avalanches. Though they were associated with an avalanche safety oriented event, the Sheep Creek group wasn’t an avy safety course, but they were indeed part of a culture that has frequent exposure to avalanche terrain due to their chosen form and style of recreation. Yet ultimately, people shouldn’t die like this when associated with an avalanche safety event or program. The fact that this happened again indicates we may need to re-think our whole approach.))
…… Several smaller groups departed the ski area parking lot between 9 and 10 a.m. for some short backcountry tours, with the intent of meeting back up in the parking lot in the early afternoon.
((Following is important, and while looking good on the surface indicates something was off. I’m having trouble putting my finger on it, but it reminds me of when I’ve dug snow pits that had some iffy data, yet somehow rationalized continuing up a suspect area. Or worse, when I’ve just simply thrown caution to the wind due to extenuating circumstances such as moving through a storm and needing to reach shelter. Or, I’m embarrassed to admit, simply wanting to reach a cozy hut sooner than later so I could have beer. Sad, I know, but yeah I’ll admit to some pretty dumb decision making over the years.))
A smaller group of 6 ((the group that would be caught))… departed the parking lot shortly before 10 a.m. and headed up towards Loveland Pass on U.S. Highway 6, intending to do a short (~1 hour) tour in the Sheep Creek drainage. The group read the CAIC avalanche bulletin together, and discussed the deep persistent slab problem. With this in mind, they decided that they would head in from the upper-most switchback (Scotty’s Corner) on the old summer road, cross the Sheep Creek drainage gully, and ascend a few hundred vertical feet onto northwest-facing slopes of Mount Sniktau.
((Ok, following is where the breakdown in safety procedure perhaps occurred. They decided to enter what they apparently _knew_ was the runout zone, ostensibly without due consideration of how dangerous the possible hard slab conditions were, the possibility of triggering a slide from the bottom, and the large size of their group. In many people’s opinion (mine included) 6 is a large group size and requires quite a bit of extra hazard mitigation and style changes to move safely.
Also regarding runout zone, as we spoke of extensively in our previous post, the concept of alpha angle is an important thing for anyone traveling in avalanche terrain to learn. (Alpha angle is simply the overall angle of the slope threatening you from above, from your feet up to the top of where the avalanche could start. Conservative rule of thumb for Colorado is if your alpha angle is at or greater than about 22 degrees you could get hit by the avalanche.) I spoke to a CAIC investigator about this, and he told me that while due to the structure of the CAIC website they don’t state an alpha angle for this slide, they indeed figured it was 24 degrees. That means if the group had sighted the alpha angle with proven techniques (inclinometer, etc.) they would have know for certain they were in range of the avalanche. It is unknown if they did this or not.
That being said, 24 degrees is perhaps on the “safe” looking side of things, so if the group was estimating their exposure they could have easily assumed they were in an area that was unlikely as a runout, or even out of danger. But the report indicates they knew they were in danger (spacing themselves out, etc.) so I might be grasping at straws here in trying to give benefit of the doubt. More, the terrain trap was also present and exacerbated any danger exponentially.
The report below states the group DID decide to cross in the “runout” zone. So perhaps they did have good concept of alpha angle and extent of run, and just chose to roll the dice. Easy for me to write that pat take, but really, you have to wonder if in a group of 6 there might have been a few people who actually did not know how much if any danger they were in.))
…… They aimed to avoid the more north-facing slopes which they recognized as a threat, by crossing well below the start zone, in the runout zone, to reach what they deemed safer terrain.
…… The group, in climbing mode, traveled a few hundred yards from the highway down the old summer road until it emerges from the the trees into the open alpine area of the Sheep Creek drainage.
…… They decided to spread out with approximately 50 feet between people as they crossed below the north-facing slopes
((apologies and respect to all involved, but 50 feet is really nothing in this situation. Even two times that, 100 feet, would have been nothing though could possibly have saved a few of the group as the resulting spacing would have totaled around 600 feet.))
…… and head for a small stand of trees on a small knoll on the far (northeast) side of the open slopes. The first two members in the group had reached the small stand of trees, with the other 4 group members close behind, when they felt a large collapse and heard a whumpf. It took several seconds for the crack to propagate uphill and release the deep slab. In those several seconds, they all ran for the far end of the slope and towards the small stand of trees.
…… The avalanche was quite large and engulfed the entire group from above at approximately 10:15 a.m. The avalanche pushed all group members between 5 and 20 feet into the Sheep Creek gully. Five of the six members of the group were completely buried.
((Following is grim and hard to read, I’ve redacted, it’s on the CAIC website. Main point is the sole survivor was trapped in the snow and could do nothing to effect a rescue of his friends. Our hearts reach out to him.))
…… The survivor was third in line at the time of the accident…
…… Two highway avalanche forecasters from the Colorado Avalanche Information Center (CAIC) drove over Loveland Pass to Berthoud Pass on the morning of the 20th. They noticed the avalanche around 12:15 p.m. from Interstate 70 as they were driving back from Berthoud Pass. They headed up Loveland Pass to investigate, and by 12:45 p.m. they were walking down the summer road to the edge of the debris. They turned on their beacons to search mode, but did not detect any signals. The victims were out of range on the far side of the avalanche debris.
((I’m not a big proponent of increased range being a beacon feature that we base shopping decisions on, but in this case, hmmmm.))
…… They used binoculars to inspect the debris field and look for tracks leading into the avalanche, but did not see any signs of human involvement. The CAIC forecasters then drove back down to the Loveland Ski Area arriving around 1:30 p.m., and asked participants at the Rocky Mountain High Backcountry Gathering if they knew of the avalanche and/or if anyone in their event had triggered it. At this point several people at the gathering mobilized, knowing that a group of 6 had headed towards Sheep Creek that morning.
…… The first two responders (including a Loveland ski patrol member) arrived at the avalanche site around 1:45 p.m. and initiated a beacon search.
((Remainder of this section describes the recovery of the deceased and rescue of the sole survivor. See CAIC website for this part of report. Thanks goes out to the individuals who did their best to save lives.))
…… At least two members of the group were wearing avalanche airbags, but neither were deployed. Other group members were wearing Avalungs, but no victims were found with the Avalungs in their mouths.
((Above is of course a core sentence of the whole report. As we put more and ever more faith in technology that could save us in an avalanche event, Sheep Creek shows us that a fairly common circumstance (terrain trap and bottom of runout, combined with fast moving hard slab) made all the technology moot. Again, this keeps me thinking that I need to reassess my whole approach to my decision making. Could one of these people have been me? You? Time for some introspection as we grieve for these young lives lost.))
Comments from CAIC
((Forecast excerpt redacted; it was a good forecast that if heeded with more care might have prevented the accident.))
…… It is rare that we have as clear of evidence of a deep-persistent avalanche problem as we did the week leading up to this accident. Some of the group likely drove by fresh evidence of the problem in Straight Creek on their way to Saturday’s event. Before their tour, the group read about the conditions in the avalanche bulletin and identified deep-persistent slabs as the primary avalanche problem. They selected terrain that was less likely to produce a deep-slab avalanche, but to get there they traveled through a dangerous area. Unfortunately, the travel technique employed to mitigate the risk was not effective for the size of the avalanche that released. At least 3 members of the group reached the “island of safety” they had identified, only to be subsequently caught and buried in the avalanche.
…… It is easy to underestimate the consequences of getting caught in a deep-persistent slab avalanche, because these slides are often much bigger than most of the avalanches witnessed by backcountry recreationalists.
((Above is where the “experienced” chimera raises up. One measure of experience is having observed numerous, perhaps hundreds of avalanches, including large destructive hard slabs. Without this true experience it is difficult to apply informed judgment. Perhaps some of the group had this experience. If so they let their guard down. If someone didn’t have that kind of experience, then again we must consider how avalanche education and current recreation style gave them the “tools” to have made such a tragic mistake.))
…… Deep-persistent slabs do not form every year, like storm and wind slab avalanches. The only effective travel technique for this avalanche problem is to avoid areas where deep slabs might release, or if the risk is deemed acceptable, expose a single group member to the danger.
…… Spreading out often does not mitigate the risk to the group because these avalanches are always large and destructive.
((Above sentence in the CAIC report is the only statement I take issue with. Spreading out actually does often mitigate the risk, provided it is done in light of accurate risk assessment. The problem with Sheep Creek is it’s quite obvious the group did not know how much risk they were exposed to. I mean no disrespect with that, it is purely axiomatic based on the outcome.))
((A bit more is redacted as are the graphics, check full report on CAIC website before you comment — but civil comments are appreciated and could save lives. Do we need to rethink our whole approach to avalanche safety education and technique? Could your normal approach to things have gotten you into this situation? Let’s see some self examination.))