The Utah Avalanche Center Shares Additional Questions Regarding the Wilson Glades, UT Avalanche That Killed 4 Skiers Last Month

Guest Author | | AvalancheAvalanche

This article was originally published by the Utah Avalanche Center

Below are questions we received about the Wilson Glades avalanche accident during a live Q&A session. We couldn’t answer all the questions that people submitted during that session. We have put them into this blog and provided some answers and some links to get more information. The questions have been loosely sorted under categories listed in bold.


Q: There were many questions regarding the timeline of when the avalanche happened and how quickly different people were dug out of the avalanche debris.

A: These are tough questions to answer. Imagine yourself in that situation? As in most avalanche accidents, all the times are estimated. Usually, the most concrete times come from communications with 911 and SAR. In this case, the initial 911 call was made at 11:40. The first rescuer arrived on-scene at 13:40 and all six people who had been buried had been found and dug out. Beyond that timeframe, everything else is a guess.

Q: As I read the report on the Wilson Glade avalanche, I kept wondering about a lesson learned for using Walkie Talkies on the designated channels of 1-9 (highway 190) for BCC and Millcreek and 2-10 (highway 210) for LCC. During a UAC presentation at the beginning of the year, these new “standards” were discussed and recommended for backcountry travel. This avalanche may be a lesson that parties in a drainage should attempt to contact others who are in or near the same drainage in order to coordinate.

A: We feel that FRS radios will eventually become commonplace in high-density areas such as the Wasatch Range.  They are a great idea.

Q: In what ways have the stresses and restrictions related to the coronavirus pandemic affected the number of triggered avalanches and avalanche deaths?

A: This is hard to gauge at this time without a team of social scientists.  We do have some research from Colorado and Utah from last spring that suggested that it was not beginners per se getting caught but intermediate/advanced backcountry recreationalists.
Decision Making

Q: Did you all calculate a “FACETS” score for the two parties?  Are there AAA standardized reporting on the influence of human factors?

A: We do not calculate a FACETS score but typically offer some other insights into decision making.  I do find it interesting that the AAC’s Accidents in North American Mountaineering have boxes to check regarding “contributory factors”, so it may be time for the avalanche community to follow (a similar, if not updated) suit. More info about “FACETS” are in two articles in The Avalanche Review (Part 1Part 2).
Event Details

Q: Do we know if it was triggered by Group A or Group B?
A: It is impossible to determine.

Q: It seems avalanche incidents, in general, are more skewed toward experienced backcountry travelers. There are obvious exclusions, but generally speaking, this seems to hold true. What is the background of those caught, and how do we change the narrative from scaring the inexperienced to humbling those that have gotten lucky… risking more than they realize?

A: This is the holy grail as it applies not just to avalanches, but to all risk activities and even the pandemic.  Consequences can seem so esoteric until we (or friend/family) experience them first hand.
Finding Safe Terrain

Q: I’m wanting to get out and xc ski, snowshoe, trail run, etc. however, I’m wanting to adhere to the avalanche warnings being issued, any advice on places to do these activities that won’t be in the danger zone?

A: We built this Selected Routes list a few years ago.
Human Factor

Q: We’d really like to know more about their mindset that day. Were they knowingly entering dangerous terrain and taking a calculated risk? yes, we are always taking risks when we enter the backcountry….but I guess we’d just like to know how safe they thought they were being. thank you so much for doing this!

A: This is terrain that some of them have been before and we’ve outlined that the Glades often lure people into this terrain bc it is perceived to be low risk terrain.  There have been a number of close calls over the years.
Interpreting Tests

Q: Is there a reason we don’t perform ECTP score on the crown in avalanche reports? Especially on incidents that include fatalities. The downside is that if the ECTP is always low on fatal accidents, it may inspire confidence in lower-score ECTP pits. We get feedback on slope angle, snow conditions, but it would be great to close the feedback loop on ECTP measurements.

A: We often do report stability test scores in avalanche reports. However, tests are going to be flawed for any number of reasons. We commonly get mixed results with tests performed in the crown. One issue with performing an extended column test at the crown is that may not be where the avalanche was triggered – it may have been triggered remotely (elsewhere on the slope.) Another major issue is that the weak layer has already collapsed and failed; sometimes there is a reason the snow above the crown is still in place.

Q: If we dig pits roughly 6′ deep how would one know if there’s a weak layer outside of that range? Is it ever worth digging a pit all the way to ground-level to be certain of what lies below?

A: This is the tricky thing with persistent weak layers! If you are in a new zone or snow climate, it is worth digging down to the ground to see if there are weak layers below. A weak layer buried 6’ (~2 meters) deeply is unlikely to be affected by a human traveler, but in some thinner areas, that weak layer may only be 2’ deep, and triggering an avalanche from a thinner area is possible.

Q: What is UAC’s assessment here?  Should they have even been on that slope on this day?  If I remember the warnings that day we were advised not to be on anything over 30 degrees.

A: Everyone who enters the backcountry does so with their own personal level of risk tolerance. The avalanche forecast for February 6 was High above 9,500’ and Considerable below 9,500’. The avalanche occurred at 9,600’. A Considerable danger rating lists human-triggered avalanches as “Likely”, and “Very Likely” for a High danger rating.


Q: I’m very interested in learning more about safety but covids made getting to an Avi training course difficult. Are there any solid online ways to learn this info that don’t require an overnight trip to somewhere in the field?

A: The UAC has a free online course! – Know Before You Go.

Q: One of the things that stood out to me in this incident report was that the victims were probably buried deeper because they were ascending so their skis did not release. Following this logic, my guess would be that splitboarders are likely to be buried deeper than skiers whether the avalanche happens on the ascent or the descent since bindings do not release in either case. Is there any data on this? Also, as splitboarding becomes more popular, (other than avoiding being in an avalanche altogether) are there any other risk mitigation tips for splitboarders specifically?

A: Releasable binding are important. Having skis or a board remain strapped to your body may cause a deeper burial. Another major issue is no wearing wrist straps on ski poles. There is at least one brand of ski binding that is releasable when the toe piece is in “uphill” or “walk” mode.

Q: What could have been done differently to avoid this accident?

A: Several things. Obviously, the two parties could have avoided this terrain given that it was a slope steep enough to avalanche. They also could have chosen a less-steep ascent route. Although avalanches were still possible while they were descending, it is possible there would not have been as many burials.

Q: What are the general and specific lessons that we all can learn from this accident?

A: This is a very good question, and we all owe it to ourselves and our community to try and learn from this tragedy. We need to ensure we can identify avalanche terrain, and use careful consideration where we place an uptrack. Also – persistent weak layers are impossible to manage, and be sure to give yourself a wide margin of safety in avalanche terrain when there is a persistent weak layer present.

Q: Did the buried skiers still have their skis connected to boots?

A: Yes. And this may have contributed to the deeper burials.

Q: When avalanches are triggered, how often is it the skiers first lap vs. a 2nd or 3rd? Why was it triggered later instead of on the way up the first time?

A: This is partly why deeply buried persistent weak layers (PWL) are difficult. Avalanches involving PWLs can be triggered remotely, from lower-angled terrain, as well as after numerous ascents or descents of the slope. In fact, this phenomenon can occur with many other types of avalanches.

Q: Has anybody examined the psychology/group dynamic that is also at work in the backcountry — in other words, the social science factors that might also shed light?

A: Although we are not aware of the dynamics within the two parties in Wilson Glade that day, much research has been done on what is known as “human factors” in avalanche accidents. One well-known example is known as FACETS.

Q: Why do you think the myth that Wilson Glade is go-to safe terrain was so widespread in the Wasatch backcountry community? ( I previously fell into this category with my own close call there).

A: Although we are unsure how widespread the sentiment is that Wilson Glade is safe during elevated avalanche danger, there is a sense it is not that steep, especially when coming in from the top where the pitch is initially less than 30 degrees. There are also some large trees at the base of the slope that may give a sense avalanches do not travel that far down off the slope. Once you enter a slope steeper than 30 degrees, it is avalanche terrain. Wilson Glade has avalanched several times in the past, including a close call with an avalanche professional several years ago.
Limiting Access

Q: Given the high number of fatalities this year, has there been any discussion of somehow restricting backcountry access? I know Little Cottonwood was cut off.

A: Backcountry closures are enforced when it comes down to public safety involving avalanche control work, danger to infrastructure, danger to highways, danger to workers, or danger to search and rescue operations.

Q: Is there a better way to learn more about new terrain you haven’t been to? I think about this accident, and worry that if I were to identify an area that looks to be low angle, that I may end up finding something completely different and potentially dangerous upon arrival. I understand there are limitations to digital mapping, so I’m wondering if there are other tools or methods available to use. Is the only solution to explore new areas on days with low avalanche danger?

A: Digital mapping is a great tool. The key is to understand the limitations of digital tools using data from satellites. There is no substitute for evaluating terrain and measuring slope angles in the field. Digital tools can help a lot, and it is important to consider using mapping platforms to identify low-angle terrain and runout zones. Exploring new areas on a lower danger day, while still using safe travel practices, is a good way to identify route features that may not show up on a map.
Multi-group Involvement

Q: One of the dynamics that I’m having trouble with is two groups interacting in the slide but not before, owing to their different approach routes. How many accidents in past were triggered by another party above? I recall Bruce Tremper saying it’s almost always the victim or the victim’s party who triggers the slide, but in the Wasatch, crowds may lead to more of these situations. Is there any research done on this?

A: 90% of avalanches are triggered by the party or member of the party, so less than 10%. Perhaps these statistics may change in the future with more data. A much greater issue in this accident and others is when more than one person is caught in the avalanche. This creates a serious situation. Read more about it HERE.

Q: There are many near misses (catch/carry, burials) in this range. Doesn’t the plethora of these events create a sense of inevitability to this type of accident?

A: There has been research done on the education and experience of people involved in avalanche activity. It has been found, as training and experience increase, so does time spent in avalanche terrain. I think the same idea applies, the more time spent in this range in avalanche terrain, the more accidents we could see. Read more in this study.

Q: Are there any presumptive lengths of time for CPR when the victim is unresponsive with no pulse or breathing?

A: If possible preform CPR as long as you safely can until the rescuer is too fatigued to continue, the victium has obvious signs of life, or advanced help arrives. In most cases 90% of patients who will respond to conventional CPR do so within 16—24 minutes. Read more HERE.

Q: With multiple burials & multiple rescuers, should rescuers split up to search & dig multiple burials out at the same time?

A: The short answer is that it depends and you’ll have to make a judgment call on how to divide your resources. When it comes to any burials and multiple burials, there’s a good chance someone won’t survive. Rescuers should split up so they aren’t all repeating the same task. When it comes to actually digging that depends on the number of resources you have and how quickly you can extract someone. The quicker the airway is exposed, the higher the likelihood of survival. The resources may be best utilized to quickly expose one airway at a time before moving on. Given it could take less time for more people shoveling to expose an airway, than solo rescuers trying to recover multiple victims.  If you have enough resources that you can break into two separate groups and effectively recover and shovel in less time, then it would make sense to split up.

Q: What do you think about the value of calling EMS/911 in such a substantial accident with regards to the likelihood of improving live recoveries?

A: Calling 911/EMS is important, depending on location and whether it can increase the likelihood of live recoveries – especially live recoveries of those with substantial trauma or cold injuries that could not self evac. The first priority is to get someone out of the debris because they need air. It is equally important to give SAR teams a heads up so that they can be preparing to respond.

Q: At what stage is it recommended to call 911? Does that differ based on proximity to a ski resort? Thank you UPD & WBR for all your efforts in the recovery.

A: The answer can vary depending on the situation. Generally, companion rescue should be performed first. Time is of the essence. Survivability is drastically reduced after the victim has been buried for greater than 15 minutes. If you have enough people, consider having one person call 911 while the others start the rescue. Consider a satellite type signaling device if you are in an area with poor cell phone service. Go to this page on our website for a summary of backcountry emergencies.

Q: Perhaps a worthwhile discussion for everyone would be to discuss the best way to make a quick 911 call and provide the right info.

A: The quick version: Transmit the “who, what, where, and when” information. Who, your name and call back number. What, describe the accident number of patients, and overall seriousness. Where, general location, route, exact GPS coordinates if you have them. When, time of the accident.
A more in-depth breakdown on a 911 way call for a wilderness emergency:
  1. Tell the 911 operator, “I am calling from a wilderness location and I do NOT have a street address.”
  2. Tell the 911 operator, “I’m going to give you some information that you normally do not need or ask for. I want you to relay ALL of it to county Search and Rescue.”
  3. Exact location of the accident. If you’re at a well-known spot like a trail head, campground, or climbing route, start with that. Provide GPS coordinates.
  4. A verbal description of terrain, map location, or climbing route. Give this in addition to your GPS coordinates. If the coordinates get messed up somehow, the verbal description is a backup.
  5. The caller’s name and phone number, and your call back number, or perhaps two.
  6. List of injuries, most serious first.
  7. Patient name, age and gender.
  8. The time of the accident.
  9. The local weather conditions.
  10. Number of people in your group.
  11. Your plan for treatment. Stay put and wait for help, or maybe start moving to a specific location. Generally, once SAR knows where you are, even if you’re mobile, they want you to stay put.
  12. A request for what form of help you think you need, such as litter, sled or helicopter. If you have a very serious injury and think you need a helicopter, you can make this known, but it’s no guarantee you’re going to get one.
  13. What county you are in, if known. SAR is typically coordinated by the county sheriff. If you make a 911 call from a wilderness location, depending on the cell towers you reach, the 911 call might go to a  county that’s not the one you’re in. The operator may transfer you to the correct county, let them make this decision.
  14. Patient’s emergency contact person and phone number.
  15. Ask the 911 operator to REPEAT this information back to you.

Q: Is the method of instructing the uncovered victims to turn off their beacon better than having them switch to search mode?

A: Most of the time, turning them off is the simplest and best solution. It depends on the scene safety and knowing the personal beacon you own. If the scene has any form of hang fire, and the beacon reverts back to transmit if inactive (in the case of a second avalanche), turning the beacon to search is preferred. If the scene is safe, or turning the beacon to search would hinder the rescue efforts and does not revert, turning the beacon off can be an option.

Q: Once the first two burials were rescued to what degree were they able to assist in search/recovery? What if any life-saving measures were initiated on the deceased burials?”

A: Nate from party two was able to assist in all of the search and recovery actions. Ethan’s airway was cleared; otherwise, he remained buried and unable to assist. CPR was initiated on Sarah. No other life-saving measures, outside of clearing the airways were initiated on the remaining burials.

Q: If someone is found unconscious and no pulse, if no other buried victims, is there any chance to revive them? How long should you try? Even if chances may be slim please be specific, bc there is no worse feeling than finding out you could have done more.

A: Clear the airway and perform CPR until advanced help arrives or you are too fatigued to continue. Continuing the CPR as long as possible increases the chances of survival. Read more HERE.

Safe Travel

Q: Had they previously staged at the same point to cross that slope? If so were they all grouped in the same spot to stage the crossing? (Assuming they crossed on their same skinner each time)

A: Group A regrouped at the big tree towards the top of the slope where the slope gets just a bit steeper to cross one at a time each time they came back up.  So yes, they stopped every time to cross one at a time on all their ascents.

Q: What are your thoughts about the added weight of group B on the slope which may have contributed to the failure/fracture of the slope?

A: It’s really hard to tell when dealing with strong, thick slabs. What we find with explosives is that it doesn’t often require a bigger explosive, but it requires putting an explosive in the just the right spot to trigger an avalanche. In terms of human triggering, it means impacting the slope in a specific place. Ultimately, we just don’t know what, why, or how this avalanche was triggered.

Q: Did group A use same uptrack for all the laps? Was there any group discussion about the uptrack?
A: Yes, they used the same track for all laps.  To my knowledge, they talked about where the uptrack should go and were cautious about how to travel up it.
Skin Track

Q: On Trent’s point, was there anywhere on this particular face that could be safely relied upon as either out of avalanche terrain, or which offered safe, navigable islands which were out of avalanche terrain? Are uptracks getting to steep and is this contributing to safety?
A: When Trent visited the site, he thought the safest uptrack would have been to climbers uphill right and down the ridgeline a few hundred vertical where there were some aspens and lower angled terrain.  Drew visited the site last week and he said it didn’t look like that side was much better.  The safest route is up the ridgeline to the left (east).  The issue with that route is that it requires about 40 switchbacks and therefore it’s easy to stray off the ridge. The steepness of a skin track doesn’t matter.  The simple fact is any terrain 30° or steeper is avalanche terrain.  So it’s all about what you’re on and what’s above you.


Q: From what I understand, avalanches can break on 30 degree slopes or higher. It seems pretty wild that something so massive broke on 31 degrees. Does this suggest that avalanches have the potential to break on 28-29 degree slopes.
A: In some cases, avalanches have failed on slopes angles of 25° before, however, it’s rare.  Almost all avalanches happen within 30-45 degrees. Read more about slope angles and avalanches on page 26 HERE.

Q: Curious if you have any thoughts as to why the slope above them didn’t slide? Looks to be steeper than 37 degrees. There are trees, but it doesn’t look like enough to anchor the snowpack.
A: We are not sure why it didn’t avalanche either.  The snowpack is a variable medium and there are still many mysteries.

Q: The slope angle at the crown is stated as 31deg. The slope angles looker’s left are stated as 37 and 40 deg. Do you think this is actually where the slide started and if not were these steeper slope angles a contributor to the slide?
A: The slide happened because a crack started somewhere in the weak layer and the slab helped to propagate this crack across the entire slope. Once the weak layer failed and collapsed, slope angle allowed the slab to overcome friction and move downhill. The reason avalanches typically don’t happen on less steep slopes is that the slab can’t overcome the frictional forces.  Don’t get hung up on the different slope angles. The main point is that they are all greater than 30 degrees which is avalanche terrain.

Snow Science

Q: Would Wilson glade be safer to ski now that it has slid?  In other words, do deep slides take the persistent weak layer with them?
A: After we looked at the crown we noted 30 cm of faceted snow still left below the bed surface that was left even after the slide. In the short term, that slope would have been safer from avalanches. In the long term, it is possible that a new slab can form and then cause an avalanche. We often call the slopes and these avalanches “repeaters”.

Q: Was there wind loading happening while they were skiing laps? Or anything else that might explain why the avalanche did not occur until their last ascent?
A: We do not think the slope was being loaded by the wind at the time of the slide.  Slab avalanches are tricky because tracks are not a sign of stability with this type of avalanche.  You can sometimes put hundreds of tracks all over the place and it just takes one person to find a spot on the slope where they can affect the weak layer and then the slope collapses and the avalanche takes out all the tracks. Watch this video to see it happen.

Q: I’m wondering what are the weather factors and things that help a weak snowpack heal? How long does it typically take if perfect ‘healing’ conditions exist?
A: What we need to heal the snowpack is more snow.  In the short term, we will continue to have dangerous conditions, but over time the depth of the snowpack helps it to heal.  When you increase the depth of the snowpack you remove the temperature gradient that causes the snowpack to become weak.  When you remove the gradient the snow actually begins to bond and become strong.  There is no specific time frame in which this happens, some years it never happens, other years it can happen in a few weeks or days.

Q: Can you speak to if the morning sun/temperatures had any affect on the cohesiveness of the slab by the 3rd run/skintrack and if that had anything to do with how it was triggered or how big it went?
A: Sun and temperatures had nothing to do with this avalanche.  The simple fact is that the slope was unstable and needed a trigger.  The weight of the snow was already added to the slope and there was a well defined weak layer across the terrain. That weak layer had produced avalanches that night and that morning. Once someone was able to collapse the slope and affect the weak layer the avalanche happened as a result.  The slab was strong and that’s what allowed it to propagate over a wide area.

Q: When following and monitoring weather forecasts which things/changes/events should we be looking for in order to identify the formation of weak layers?
A: Clear, cold, nights followed by sunny days and no snowfall.  This is the set up that leads to all our weak layer formation in Utah.

Q: It seems intuitive that a slope with trees would be less likely to avalanche than a slope at the same angle without any trees. If this is true, is there a general adjust to safe slope angles that can be made for runs that are tree-covered with a continuous tree stand? (assuming there are no open slopes above).

A: Slopes with or without trees should not make a difference in decision-making.  If the slope is 30 degrees or steeper it’s avalanche terrain, plain and simple.  For trees to help anchor a slope they need to be so tight that you can’t turn or ride through them anyway.

Q: What are tell tale signs that things are ‘different’ than prior years?
A: This avalanche wasn’t because we had a crazy different year.  In fact in 70% of all the avalanche accidents in Utah are caused by this same weak layer and slab combination.  Persistent weak layers are common here. What’s important to recognize is that some winters have more dangerous and unstable conditions than others. When we have a year like this, we simply travel more conservatively than other winters when things seem, overall, more stable.

Q: How high above the last (highest) skin track do you think the crown released?
A: 30-50 feet

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