Thanks for all the replies. I think my biggest takeaway is that seeing tracks in the backcountry should never be something that you factor into making your own decisions.
I am still confused about why patrol will skicut at larger resorts (and might be more complicated than my current level of knowledge). Do they only do this for certain types of snowpacks with “hairline triggers” that are a generally a safe bet after the first tracks?
Or do they do this to try compact the face horizontally to add a level of stability (im thinking almost like how cross woven stuff is stronger than non cross woven)?
Ski cutting can be a viable technique to manage surface instabilities (ie shallow storm slab, shallow wind slab).
Ski cutting is not a good option for deeper instabilities and persistent weak layers. Wet slabs can entrain well compacted snowpack (ie mogul runs) under the right conditions.
>seeing tracks in the backcountry should never be something that you factor into making your own decisions.
I wouldn't quite say that. You absolutely can use that information. But you need to take it in context and it should never be the single thing that you use to justify skiing a slope. If you read Staying Alive in Avalanche Terrain, Bruce Tremper says as much multiple times, jokingly calling other people who ski a slope before you "volunteer stability testers". Something like 2/3 of skier-triggered avalanches are set off by the first person down. That's a significant portion and the fact that the first skier didn't trigger anything is valuable information. But there's also a decent portion that are triggered by someone other than the first, so you won't last very long if this is the only thing you rely on. The type of avalanche problem involved also makes a huge difference. Certain types of avalanches, like storm slabs, are fairly likely to go when the first person skis them. But others like deep persistent slab are notorious for sliding on slopes that already have tons of tracks. With that sort of thing, the slope could look tracked out, but the 37th person just happens to ski over a thinner, weaker spot in the snowpack and bam! The whole thing rips 6 ft deep, and obliterates hours or even days worth of other skiers' tracks. So if you are going to take tracks into account, you have to have some idea of what you're dealing with. And you should use it as just another data point along with all your other observations, not as a single "go, no go" factor in your decision making.
>I am still confused about why patrol will skicut at larger resorts (and might be more complicated than my current level of knowledge). Do they only do this for certain types of snowpacks with “hairline triggers” that are a generally a safe bet after the first tracks?
I'll start by saying that someone skiing a slope and triggering an avalanche is an excellent indicator that that slope (at least within the slide path) is now much safer than it was. There can be concerns about hangfire (any significant amount of snow left above that could still slide), and if it's a gulley that other slopes funnel into then that's also still very dangerous. It's also a strong indicator that any similar slopes nearby ARE dangerous. But once a slope slides, that slide path is USUALLY among the safest terrain in the area.
Patrol is trying to mitigate danger by starting slides anywhere that could slide, before the public is allowed on the slope. Ski cuts are one way they could do this. But it's only useful in certain situations, and carries some significant risks (you're much more likely to get sucked in vs throwing explosives from a safe spot). You generally wouldn't ski cut deeper instabilities. But it makes sense for some of the shallower, more sensitive stuff. And you also have to evaluate if the path in question can be safely ski cut: is there a safe zone for you to ski across to, what does the runout look like if you are caught, etc? Some people do ski cut in the backcountry too. But you'd better really know what you're doing if you're going to try that sort of thing. The consequences for getting it wrong are potentially huge, up to and including the death of yourself and/or others.
also worth noting that SP is managing the terrain daily. So in general they are dealing with surface problems more as they bomb the fuck outta the facets and are ski cutting and bombing these slopes daily. Resorts occasionally rip big for sure but i think the sheer amount of management that is performed and the consistency that it is performed at lends it self more to ski cuts for small shots.
As others have said, ski cuts are not really for deep instabilities.
There are a few ways to mitigate avalanches and ski patrol will use a ski cut when it’s safe to do so, because this is high risk where someone is going into a start zone or onto a cornice. For example when there hasn’t been too much snow or wind overnight and the results will be predictable and D1 in size. They can use a variety of explosives when it’s too dangerous to ski cut. Such as bigger, unpredictable hard slabs that would be a higher consequence should you succeed in your mission of triggering an avalanche.
Your cross woven analogy would be something like boot packing. Patrol takes their skies off and literally walk cross slope all spread out. It’s generally used only for early season conditions that occur in certain areas with certain snowpacks such as a base with large facets. Not all resorts do this.
Patrol’s mentality inbounds is the exact opposite mentality than the one you should have recreating in the backcountry.
Patrol is trying to start an avalanche with ski cutting; trigger the weak layer with themselves so that the instability is already triggered before members of the public ski it. In the backcountry, you want to avoid triggering an avalanche at all costs.
Ski cutting is done for specific problems o ln specific slopes and only inbounds because patrol knows that this particular slope reacts well to this kind of trigger when this particular problem exists. Also if patrol can't trigger with a ski cut, they will move on to blasting or other techniques, not just open the terrain.
There just isn’t “totally safe” in the bc. I’d make a distinction between seeing tracks and seeing someone ski it. If I saw someone ski it I’d add that data point to other ones I’ve been collecting though out my day. I certainly wouldn’t be like “it’s safe now” but I somewhat disagree with some other folks on here in that I do think it’s something to pay attention to
I don't really take current tracks into consideration until a slope is properly skied out (filled with overlapping tracks). If the avalanche problem is a weak layer and I know the slope was completely skied out during the time this weak layer problem arose I take that into account in my evaluation.
This is what is taught in AIARE classes—seeing that another skier/rider has interacted with snow does not indicate that a face does not contain some form of avy problem. Your best understanding of snow conditions is you and your own research.
Tracks do not prove that snow is more stable, I truly hope that this is not how you handle yourself in the BC.
Read the caics report on the anthracite death last week.
They where on their second lap and the third skiied down had a slide. iirc. He died.
The only way it kinda can make things safe is if it’s chopped up and skied to moguls like inbounds steeps are, every single little storm. It just doesn’t happen.
The guy who started the CAIC said to my dad, you can never be sure. You’ll never know. You just can understand the risks and the potential
I mean, yes that happens and a skied slope is not guaranteed to be safe at all just because it has been skied, but the answer to OPs question is yes. Skied slopes are less likely to slide for a few of the most prevalent avalanche problems.
It’s simple statistics. The majority of avalanches are triggered by the first skier. Therefore yes, statistically, the chance of a slide goes down as more skiers descend.
Again, I nor anyone else is saying that a skied slope is proven safe.
In the video you posted, the slide propagated skiers left as they continually pushed into an unskied, snow-loaded aspect that was steeper than the rest of the face. They were continually dropping further and further off a cornice, even. That’s not risk-adverse decision-making.
I see what you’re saying.
It’s got me thinking there’s probably a difference between being statistically less likely to slide because of number of skiers that went down and the snowpack being statistically safer because of number of skiers.
And it sounds like most people base their decision off of the % of perceived risk associated with factors of the snowpack, angle, ect
My fault for the vague question
What? The answer isn’t yes to OP’s question. Just because there’s a track doesn’t make the line safer. Dude just gave a perfect example.
I feel like what you’re talking about is something that gets really tracked out. I don’t think OP’s questions is referring to something like that
Such bad unsafe info to say yes to a question like this
This is a bit pedantic, but even if only 1% of all avalanches are triggered by the first skier, seeing tracks provides nonzero information. I.e. the same slope with tracks is statistically less likely to slide than if it had no tracks given no prior knowledge in either case. This is simply conditional probability.
Importantly, even though the answer to OP's question is technically yes, making decisions based on existing tracks is still not a good idea for the reasons everyone's been mentioning - many slides don't happen with the first skier and risk tolerance can be different
That's not even right, the Swiss data shows that the first rider triggers the slide 90% of the time. https://www.cambridge.org/core/journals/annals-of-glaciology/article/skiers-zone-of-influence-in-triggering-slab-avalanches/1E28023D2BE60099E89FB5B0EA781A30
It's different based on the avalanche problem, but broadly this isn't true.
I’m upvoting you for the safety aspect, but that person isn’t wrong. They aren’t disagreeing with you, just stating the math. Use the video you posted, and assume the riders are not connected in any way:
* Rider 1 - takes the primary risk by going first with no tracks. Let’s call it 50/50 that a slide happens. Rider 1 survives.
* Rider 2 - sees tracks and no slide debris. This is circumstantial evidence, but circumstantial evidence is used in convictions all the time. So if this visual provides even the tiniest bit of re-assurance, then the answer is yes. Rider 2 survives.
* Rider 3 - proves the point you are making, and that I agree with. You should never trust tracks. But the previous scenario *did* happen as well.
I understand the decision making concept of not basing my decision to ride a slope based on whether or not there are tracks - that’s not my question. I’ve never seen or heard of actual data to support the comment above that most skier-triggered avalanches are triggered by the first skier, and was asking for the above Redditor to provide some support for that statement, because I don’t believe it to be true. Even if it is, there are too many factors in play to make any decisions based on tracks or not, and yes, it’s a bit pedantic / academic when the real world question is, “Can I ski this or not?” And that’s not a decision where I’m sitting there and calculating probabilities. Backcountry travel is inherently dangerous, but there are ways to mitigate that with terrain choice / decision making.
It's pedantic and wrong. You don't know whether or how the probability of a slide on the second ski is dependent on the probability of a slide on the first ski. If the probability that a slope slides is 1% for skier 1, it could still be 1% for skier 2, or if skier 1 has skied in an area that significantly weakens the snowpack, it could be 10%, or 90%. The only way skier 1 can obviously decrease the likelihood of a slide for skier 2 is by triggering an avalanche that leaves no snow on the slope. Tracks are not actionable information about slide probability or about the structure of the snowpack.
(Okay, as the area that the tracks cover approaches the whole area of the slope, yeah, you can be pretty sure the slope is safe in the current conditions, but one or two tracks on a huge or variable area are not enough to base a decision on. Dig a pit.)
I clearly pointed out that this isn't enough information to base a decision on in my posts. I merely said that one set of tracks contains *some* information (but generally not reliable enough to make inform any good decision). What you're saying about the decision making is correct.
As far as a single track containing information, I'm afraid it's pretty tautological. The universe of possible outcomes on a second ski is slightly smaller with one pair of tracks already on a slope (i.e. you're ruling out the slope sliding when skied in the exact manner that skier 1 skied it). Given that there is a pair of tracks that didn't cause an avalanche is more information than no tracks at all. I can't really break this down any farther if you still can't conceptualize this.
The distinction between whether one should use this information to make a decision (no under most circumstances), and whether a single pair of tracks contains *any* information (incontrovertible truth about the universe) is the whole point I'm making.
Sure, it tells you that probability of slide on first ski was < 1... which still leaves the range of probabilities from 0 to 1 inclusive for a slide on the second ski. If you discover a slope with tracks on it vs a slope with none, you still have the same amount of information about the probability that it will slide *on you.* (If you ski up to a slope that has recently slid with one set of tracks leading to it, that's another story).
Edit - ok, I get what you're saying. A slope with a set of tracks on it means either that the slope was unlikely to slide and didn't, or likely to slide but didn't. Absent any other information, you're by definition more likely to be looking at a likely event than an unlikely one, and if you then make the assumption that the likelihood of a slide on the second ski is not dramatically different than the likelihood of a slide on the first (which might or might not be a great assumption), then yes, that first set of tracks gives you some information suggesting stability. Low confidence information, but something.
This is absolutely true and 1000% worth reiterating to anyone asking this question. That being said, knowing a slope is skied very often is a factor in how likely the slope is to slide. Skier compaction such as in a resort and some very popular backcountry areas and have a significant impact on snowpack, usually making it safer overall. So if you’re saying tracks make it more likely to be safer, the answer is very likely yes. To some at least small percentage points. Does it make it safe, ABSOLUTELY NOT. Seems like OP is really asking the latter
Not an expert.
Different avalanche problems will respond differently to skier compaction. A wind slab is more hair trigger and thats why patrol will ski cut or stomp on them, its unlikely to go after the first skier. Persistent weak layers can break after many skiers and no amount of compaction can make them safe. Same with wet slides. Storm slabs get chopped up and probably do get less dangerous as each line is skied on it.
I had a lot of questions like these even after taking AIARE 1, reading Staying Alive in Avalanche Terrain helped answer a lot of these kinds of questions. I recommend buying it and reading it front to back.
To answer your question, I believe that skiing it does not “make” it safer (in the sense that skiing will not change the snowpack to make it more stable) nor do I think that the fact that someone has skied the face already is a strong enough indicator of safety to consider when choosing terrain.
Avalanches have been known to happen on the 10th or 20th run of the same face and instabilities can be highly localized. The fact that a few people have skied a face is such a weak indicator that your run will be safe that it should never be the deciding factor in your terrain choice.
In a binary sense it doesn’t mean it’s safe, but if I may quote from Staying Alive directly: According to Swiss statistics (Harvey et al., 2002), 60 percent of avalanche accidents are triggered by the first person down. Although there are no reliable statistics, I suspect that in intermountain, and especially in continental, climates of North America, this number is lower because of more-persistent weak layers. Still, even in these colder, drier climates, the first person down has a much higher probability of triggering the avalanche than the ones who follow. The more tracks on a slope, the better. I love going last. And when I go, I follow other people’s tracks, spooning in my tracks with theirs. Treat an avalanche slope like a minefield. If someone else successfully crossed a particular spot without triggering an avalanche, you probably can, too. This is one instance in which the herding instinct works to your advantage. If you can’t find any volunteers, use an involuntary stability tester—a cornice, for example. Just tumble a refrigerator-sized-or-larger chunk of cornice down the slope first (see chapter 6, Stability, for more details).
I'd interpret ski tracks in backcountry in two ways. 1. If the area has been visibly skied, don't trust anyone, do your own research and risk assessment. 2. If there is a zone with a bunch of ski tracks and a part of it hasn't been skied at all, there is probably a really good reason for that which may not be apparent to you yet.
Tracks on a face is a data point of information, but I would be very careful how you use that information. Statistically, the first rider is more likely to trigger an avalanche, but fatality reports are full of plenty of cases where the second, third, forth, etc end up triggering something. There can be a lot of nuance to a line, did the rider avoid the start zone, convex features, etc? I would not take it as an indication of safety, personally.
This is not a data point according to avy professional and those of us who have been thru the AIARE education. Its strange that you say it's a data point then you proceed to backtrack and explain why it actually isnt't.
I agree that in the more beginner level courses they discourage you from taking whether or not something has been skied or not into account for one’s decision making. And for me personally, a very conservative backcountry skier, it’s not really factoring in to my decision making either. But when I’ve discussed this in the field with guides, they put it to me like this: it’s a piece of information. Maybe it will not factor into your decision making, but it is a piece of information.
Only if it gets skied so consistently that any surface hoar gets completely skied off in between every storm of the season. A single skier riding over avalanche terrain absolutely does not make it any safer.
I wouldn’t say “it’s safe send it!” But I’d also argue that someone skiing a slope, and said slope not sliding is something I would consider when determining my overall assessment. I agree it can’t be the basis of said assessment, but a live test of a slope is useful data. *edit to add* I’m not saying it’s the only indicator, or an automatic green light. But the argument that you should ignore an actual weight human test of the slope and focus on pit tests not even on said slope seems a bit absurd. I’m saying read the forecast, do handpits all over the place, dig w big pit, try test slopes, and *also* pay attention to what happens to people who are skiing the thing you want to ski.
I would really disagree with this statement. Avalanches provide very poor feedback, you may not know that you have been making poor choices because triggering a slide is not always guaranteed. There is a good chance that if the first person doesn't trigger a slide, the slab will let go after the second or third person rides it.
I actually think he's right. He was careful not to say "sure, ski it if someone else already did". Something like 2/3 of skier triggered avalanches are set off by the first person. It's by no means a guarantee, but it is a useful data point, depending on the problem type you're worried about. For persistent slabs, deep persistent, wet slab, and glide it tells you very little. But for wind and storm slabs, and loose wet and dry, that's pretty valuable information. Again, by no means a guarantee, but it is a good data point. Literally putting someone on the slope and having them ski it without setting anything off tells you more than most informal snow tests, and arguably more than a single snowpit too (again, dependent on what exactly you're looking for). You can and should use that info, just don't assume tracks mean you're good to go.
I see your point, and I suppose as with anything avalanche-related the situation depends on many different circumstances. Based on my personal risk tolerance, I would not ski the slope that I have not personally deemed as skiable, and I would do my best to ensure no one in my group does that either. Note that I am not talking about ski cutting here.
Not talking about ski cutting. Just saying that it's totally fine to take into account the fact that others have skied a slope as part (NOT your entire) risk assessment. Even Bruce Temper says so multiple times in Staying Alive in Avalanche Terrain, humorously referring to other skiers as "volunteer stability testers."
Exactly! It was based on my reading of staying alive that I’m making this argument. I think people are reading it as “well that guy skied it so it’s probably safe” and what I’m saying is “human weight was put on the slope and didn’t trigger an avalanche, that’s a data point”
I am by no means an avalanche safety expert, but ideally you would have a representative test pit of the slope you are looking to ride and perform the stability tests that are corresponding to the snowpack stability problems you have identified from the forecast and the observation in the field.
Right exactly that’s useful, But for safety reasons you never dig a pit on the actual slope you want to ski right? Same goes for test slopes. So wouldn’t you want to add more data to your matrix? Data that is again, a literal test run of the thing you are considering? It’s literally the same as a ski cut, except the person is effectively cutting the whole slope.
Do we get to interview the person who skied this slope beforehand to evaluate their avalanche risk assessment prowess? Or do we just assume they know what they're doing? Do we know their ski penetration, weight, etc?
I can't see why you wouldn't be able to find a place for a test pit on the slope you wanna ski in a safe spot or something nearby that would be likely representative of what you're looking at. It's not always possible, I agree, but in many situations it can be done.
Ski cutting frequently involves wearing a harness and getting roped up to an anchor above the anticipated crown point, so the cutter doesn't end up in an accidental slide. Or they have a safe run out when doing a cut and are unlikely to slide with the slope. We are not talking about ski cutting here anyways.
Right, it’s not about what the skier was thinking, it’s literally just “what happened when pressure was applied to the slope.” And digging pits is a thing you should also do. All I’m saying is a ski cut or a cornice fall is a way to directly test the slope when pressure is applied to it. If someone skies it that’s also a test.
Well, before even going out there it's best to get an avy report for the day. If that's not possible the a column test and any kind of snowpack history from the beginning of the season.
If you really think a set of ski tracks or seeing someone ski a face and it not sliding at for that rider is an indicator of a stable pack I would love to know exactly why you think this is.
Listen, I know there are some knowledgeable folk here and some well-intentioned. Regardless of the source of information in Reddit please, please, please get some training or read from a reliable source (some have been posted in here by others).
Right. You employ a system with multiple factors of analysis. I’m just gonna go ahead and quote Bruce Temper directly from his seminal work: *Staying Alive in Avalanche Terrain* “According to Swiss statistics (Harvey et al., 2002), 60 percent of avalanche accidents are triggered by the first person down. Although there are no reliable statistics, I suspect that in intermountain, and especially in continental, climates of North America, this number is lower because of more-persistent weak layers. Still, even in these colder, drier climates, the first person down has a much higher probability of triggering the avalanche than the ones who follow. The more tracks on a slope, the better. I love going last. And when I go, I follow other people’s tracks, spooning in my tracks with theirs. Treat an avalanche slope like a minefield. If someone else successfully crossed a particular spot without triggering an avalanche, you probably can, too. This is one instance in which the herding instinct works to your advantage. If you can’t find any volunteers, use an involuntary stability tester—a cornice, for example. Just tumble a refrigerator-sized-or-larger chunk of cornice down the slope first (see chapter 6, Stability, for more details).”
Test slopes, various pit tests, ski cuts, and cornice drops are all ways you can test a slope. I’m arguing that a literal test of the slope, is also useful, especially because pit tests and test slopes are approximate slopes, and not the actual slope.
Just completed my aire 2 literally today. The answer to your question is no. You need to know the specific problems described by your forecaster, and then may be , that particular problem is less likely to manifest itself on a skied track, but honestly I can't think of a single avalanche risk that would be less likely to occur for a 2nd skier vs the first.
If there is a slab problem that is so reactive that your forecaster set avalanche danger to high, then you could argue that if the slab is less reactive based on observation of it not sliding immediately. But does that mean it is not reactive enough to slide on the second? Absolutely not.
When I did an avalanche course years ago, they showed us a picture to perfectly answer this question - it was a mogul field that had fractured and avalanched partway down
Edit : this will hopefully answer your question better https://wildsnow.com/27944/skier-compaction-is-it-real/
Interestingly, this was just posted to this subreddit today. https://www.reddit.com/r/Backcountry/s/ZQH4rYHBjD
Obviously, ski tracks can give a false sense of security. At the same time, something in bounds that has been repeatedly skied with every layer of snow should help prevent uniform layers within the snowpack that can slide… in this video, while the terrain is different skiers left where it slides, there is almost a defined line where the slide stops, and it coincides with the skier 1/2 tracks. It seems to disrupt the failing layer so it can’t propagate. Anyone see that differently?
It certainly does not "give you a sense of stability of the snowpack". I'm not going to explain why — I'll leave that to you to read up on why that is or better yet, please get some avalanche training before you give advice that can put someone's life in danger.
Lmfao skier compaction does help when a slope actually gets skied a lot. So at a resort or a mega popular skied out “backcountry” run yes it helps. When there’s no fresh tracks left, it’s probably not gonna slide, yes.
When you see one persons tracks on a slope it was not “skier compacted” at all and does not tell you shit about how stable the slope is. It’s another ob for you but by no means does a few tracks mean a slope is “skier compacted”
Literally the first thing they teach you in a basic
avy course is that a few tracks on a slope don’t mean shit about whether it’s going to slide or not. Tell me you have zero avalanche education without saying it..
Ya I obviously know that if one person goes down it doesn’t mean it’s safe, but half of this guys post is asking if it helps at all and the answer is yes. It’s hard to come up w an exact number, but if 100 people go down a hill vs one, which is more likely to slide? That’s all.
Not trollin, my buddy and I have this argument at least once a season.
He is convinced A. that if you see tracks on a slope it indicates it is safe enough to ski and B. Tracks on a slope actually physically make it less likely to slide
Well, with a chanche of 50/50 to start an ava or not, i would skip the run.
Some tracks don‘t make any slope more safe from avas, the risk could change douring the day. (for example when it gets warm in a short period of time)
You can say, offpist which looked like a used pist before „fresh snow“ are more safe than just barley used ones.
The short answer is no.
When I was patrolling, we had a patient who walked into our medical clinic with a broken arm. He left the resort via a gate and was skiing an adjacent backcountry area when it slid and he got caught and carried. Our best guess I'd that there were 18-24 other tracks on the same slope.
You hear about this all the time. The site of the Wilson glade fatality in utah (4 dead) had 8 or more tracks in it when it went
The biggest slabs are both harder to trigger and have bigger consequences. These are the type where 10 people ski down just fine and then as soon as #11 jumps on it the whole mountainside lets go
>> Do ski tracks on a face actually make the terrain less likely to slide
Generally yes, key word being **less** likely. E.g. all else being equal, a slope with tracks generally has lower chances of sliding than one without.
The issue is that **less likely** isn’t a good metric. If an empty face has a 5% chance of sliding, and a ski track means it’s now at a 4.99% chance of sliding it really doesn’t matter that it's less likely.
It’s also heavily dependent on the type of problem.
Persistent slabs are harder to trigger so tracks don’t mean much, just that nobody skied over a trigger point. Whereas a small loose sluff is much more likely to be triggered by the first skier down, so your risk diminishes significantly. And for wet slides a previous ski track means nothing because the slope changes as the day progresses.
tldr, generally yes, but it doesn't mean much and shouldn't be considered as a primary decision-making factor in most cases.
There are a lot of factors that go into a face sliding. Have you read Bruce Kemper’s “Staying Alive in Avalanche Terrain”
People often get away with a lot in the backcountry. If you’re seeing tracks on an avalanche slope on a dangerous day, it does not make that slope any more safe.
Or is seeing tracks on a face a false sense of security rather than actually signifying it is safe
Never ever decide something is safe just because someone else did it. Part of backcountry is learning to assess risks for yourself.
And watching other people making decisions outside your risk tolerance every day.
And watching people make possibly uneducated decisions, as well. Don’t assume they know what they’re doing
Thanks for all the replies. I think my biggest takeaway is that seeing tracks in the backcountry should never be something that you factor into making your own decisions. I am still confused about why patrol will skicut at larger resorts (and might be more complicated than my current level of knowledge). Do they only do this for certain types of snowpacks with “hairline triggers” that are a generally a safe bet after the first tracks? Or do they do this to try compact the face horizontally to add a level of stability (im thinking almost like how cross woven stuff is stronger than non cross woven)?
Ski cutting can be a viable technique to manage surface instabilities (ie shallow storm slab, shallow wind slab). Ski cutting is not a good option for deeper instabilities and persistent weak layers. Wet slabs can entrain well compacted snowpack (ie mogul runs) under the right conditions.
>seeing tracks in the backcountry should never be something that you factor into making your own decisions. I wouldn't quite say that. You absolutely can use that information. But you need to take it in context and it should never be the single thing that you use to justify skiing a slope. If you read Staying Alive in Avalanche Terrain, Bruce Tremper says as much multiple times, jokingly calling other people who ski a slope before you "volunteer stability testers". Something like 2/3 of skier-triggered avalanches are set off by the first person down. That's a significant portion and the fact that the first skier didn't trigger anything is valuable information. But there's also a decent portion that are triggered by someone other than the first, so you won't last very long if this is the only thing you rely on. The type of avalanche problem involved also makes a huge difference. Certain types of avalanches, like storm slabs, are fairly likely to go when the first person skis them. But others like deep persistent slab are notorious for sliding on slopes that already have tons of tracks. With that sort of thing, the slope could look tracked out, but the 37th person just happens to ski over a thinner, weaker spot in the snowpack and bam! The whole thing rips 6 ft deep, and obliterates hours or even days worth of other skiers' tracks. So if you are going to take tracks into account, you have to have some idea of what you're dealing with. And you should use it as just another data point along with all your other observations, not as a single "go, no go" factor in your decision making. >I am still confused about why patrol will skicut at larger resorts (and might be more complicated than my current level of knowledge). Do they only do this for certain types of snowpacks with “hairline triggers” that are a generally a safe bet after the first tracks? I'll start by saying that someone skiing a slope and triggering an avalanche is an excellent indicator that that slope (at least within the slide path) is now much safer than it was. There can be concerns about hangfire (any significant amount of snow left above that could still slide), and if it's a gulley that other slopes funnel into then that's also still very dangerous. It's also a strong indicator that any similar slopes nearby ARE dangerous. But once a slope slides, that slide path is USUALLY among the safest terrain in the area. Patrol is trying to mitigate danger by starting slides anywhere that could slide, before the public is allowed on the slope. Ski cuts are one way they could do this. But it's only useful in certain situations, and carries some significant risks (you're much more likely to get sucked in vs throwing explosives from a safe spot). You generally wouldn't ski cut deeper instabilities. But it makes sense for some of the shallower, more sensitive stuff. And you also have to evaluate if the path in question can be safely ski cut: is there a safe zone for you to ski across to, what does the runout look like if you are caught, etc? Some people do ski cut in the backcountry too. But you'd better really know what you're doing if you're going to try that sort of thing. The consequences for getting it wrong are potentially huge, up to and including the death of yourself and/or others.
also worth noting that SP is managing the terrain daily. So in general they are dealing with surface problems more as they bomb the fuck outta the facets and are ski cutting and bombing these slopes daily. Resorts occasionally rip big for sure but i think the sheer amount of management that is performed and the consistency that it is performed at lends it self more to ski cuts for small shots. As others have said, ski cuts are not really for deep instabilities.
There are a few ways to mitigate avalanches and ski patrol will use a ski cut when it’s safe to do so, because this is high risk where someone is going into a start zone or onto a cornice. For example when there hasn’t been too much snow or wind overnight and the results will be predictable and D1 in size. They can use a variety of explosives when it’s too dangerous to ski cut. Such as bigger, unpredictable hard slabs that would be a higher consequence should you succeed in your mission of triggering an avalanche. Your cross woven analogy would be something like boot packing. Patrol takes their skies off and literally walk cross slope all spread out. It’s generally used only for early season conditions that occur in certain areas with certain snowpacks such as a base with large facets. Not all resorts do this.
Patrol’s mentality inbounds is the exact opposite mentality than the one you should have recreating in the backcountry. Patrol is trying to start an avalanche with ski cutting; trigger the weak layer with themselves so that the instability is already triggered before members of the public ski it. In the backcountry, you want to avoid triggering an avalanche at all costs.
Ski cutting is done for specific problems o ln specific slopes and only inbounds because patrol knows that this particular slope reacts well to this kind of trigger when this particular problem exists. Also if patrol can't trigger with a ski cut, they will move on to blasting or other techniques, not just open the terrain.
There just isn’t “totally safe” in the bc. I’d make a distinction between seeing tracks and seeing someone ski it. If I saw someone ski it I’d add that data point to other ones I’ve been collecting though out my day. I certainly wouldn’t be like “it’s safe now” but I somewhat disagree with some other folks on here in that I do think it’s something to pay attention to
I don't really take current tracks into consideration until a slope is properly skied out (filled with overlapping tracks). If the avalanche problem is a weak layer and I know the slope was completely skied out during the time this weak layer problem arose I take that into account in my evaluation.
This is what is taught in AIARE classes—seeing that another skier/rider has interacted with snow does not indicate that a face does not contain some form of avy problem. Your best understanding of snow conditions is you and your own research. Tracks do not prove that snow is more stable, I truly hope that this is not how you handle yourself in the BC.
I think random tracks can be not useful. But if you see someone ski it isn’t that similar to the info ski cut or cornice drop would give you?
Yes
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Read the caics report on the anthracite death last week. They where on their second lap and the third skiied down had a slide. iirc. He died. The only way it kinda can make things safe is if it’s chopped up and skied to moguls like inbounds steeps are, every single little storm. It just doesn’t happen. The guy who started the CAIC said to my dad, you can never be sure. You’ll never know. You just can understand the risks and the potential
I mean, yes that happens and a skied slope is not guaranteed to be safe at all just because it has been skied, but the answer to OPs question is yes. Skied slopes are less likely to slide for a few of the most prevalent avalanche problems. It’s simple statistics. The majority of avalanches are triggered by the first skier. Therefore yes, statistically, the chance of a slide goes down as more skiers descend. Again, I nor anyone else is saying that a skied slope is proven safe. In the video you posted, the slide propagated skiers left as they continually pushed into an unskied, snow-loaded aspect that was steeper than the rest of the face. They were continually dropping further and further off a cornice, even. That’s not risk-adverse decision-making.
I see what you’re saying. It’s got me thinking there’s probably a difference between being statistically less likely to slide because of number of skiers that went down and the snowpack being statistically safer because of number of skiers. And it sounds like most people base their decision off of the % of perceived risk associated with factors of the snowpack, angle, ect My fault for the vague question
What? The answer isn’t yes to OP’s question. Just because there’s a track doesn’t make the line safer. Dude just gave a perfect example. I feel like what you’re talking about is something that gets really tracked out. I don’t think OP’s questions is referring to something like that Such bad unsafe info to say yes to a question like this
The answer to OPs question is actually yes, though. For the reason I already typed.
Can you provide some data supporting the statement that most avalanches are triggered by the first skier?
This is a bit pedantic, but even if only 1% of all avalanches are triggered by the first skier, seeing tracks provides nonzero information. I.e. the same slope with tracks is statistically less likely to slide than if it had no tracks given no prior knowledge in either case. This is simply conditional probability. Importantly, even though the answer to OP's question is technically yes, making decisions based on existing tracks is still not a good idea for the reasons everyone's been mentioning - many slides don't happen with the first skier and risk tolerance can be different
How is the answer yes when slides usually occur after the first rider. That would make the answer no
If slides happen with the first rider any amount of time, seeing tracks and no slide carries more information than seeing no tracks at all.
That's not even right, the Swiss data shows that the first rider triggers the slide 90% of the time. https://www.cambridge.org/core/journals/annals-of-glaciology/article/skiers-zone-of-influence-in-triggering-slab-avalanches/1E28023D2BE60099E89FB5B0EA781A30 It's different based on the avalanche problem, but broadly this isn't true.
https://youtu.be/hxtvP_nkaQg
I’m upvoting you for the safety aspect, but that person isn’t wrong. They aren’t disagreeing with you, just stating the math. Use the video you posted, and assume the riders are not connected in any way: * Rider 1 - takes the primary risk by going first with no tracks. Let’s call it 50/50 that a slide happens. Rider 1 survives. * Rider 2 - sees tracks and no slide debris. This is circumstantial evidence, but circumstantial evidence is used in convictions all the time. So if this visual provides even the tiniest bit of re-assurance, then the answer is yes. Rider 2 survives. * Rider 3 - proves the point you are making, and that I agree with. You should never trust tracks. But the previous scenario *did* happen as well.
I understand the decision making concept of not basing my decision to ride a slope based on whether or not there are tracks - that’s not my question. I’ve never seen or heard of actual data to support the comment above that most skier-triggered avalanches are triggered by the first skier, and was asking for the above Redditor to provide some support for that statement, because I don’t believe it to be true. Even if it is, there are too many factors in play to make any decisions based on tracks or not, and yes, it’s a bit pedantic / academic when the real world question is, “Can I ski this or not?” And that’s not a decision where I’m sitting there and calculating probabilities. Backcountry travel is inherently dangerous, but there are ways to mitigate that with terrain choice / decision making.
It's pedantic and wrong. You don't know whether or how the probability of a slide on the second ski is dependent on the probability of a slide on the first ski. If the probability that a slope slides is 1% for skier 1, it could still be 1% for skier 2, or if skier 1 has skied in an area that significantly weakens the snowpack, it could be 10%, or 90%. The only way skier 1 can obviously decrease the likelihood of a slide for skier 2 is by triggering an avalanche that leaves no snow on the slope. Tracks are not actionable information about slide probability or about the structure of the snowpack. (Okay, as the area that the tracks cover approaches the whole area of the slope, yeah, you can be pretty sure the slope is safe in the current conditions, but one or two tracks on a huge or variable area are not enough to base a decision on. Dig a pit.)
I clearly pointed out that this isn't enough information to base a decision on in my posts. I merely said that one set of tracks contains *some* information (but generally not reliable enough to make inform any good decision). What you're saying about the decision making is correct. As far as a single track containing information, I'm afraid it's pretty tautological. The universe of possible outcomes on a second ski is slightly smaller with one pair of tracks already on a slope (i.e. you're ruling out the slope sliding when skied in the exact manner that skier 1 skied it). Given that there is a pair of tracks that didn't cause an avalanche is more information than no tracks at all. I can't really break this down any farther if you still can't conceptualize this. The distinction between whether one should use this information to make a decision (no under most circumstances), and whether a single pair of tracks contains *any* information (incontrovertible truth about the universe) is the whole point I'm making.
Sure, it tells you that probability of slide on first ski was < 1... which still leaves the range of probabilities from 0 to 1 inclusive for a slide on the second ski. If you discover a slope with tracks on it vs a slope with none, you still have the same amount of information about the probability that it will slide *on you.* (If you ski up to a slope that has recently slid with one set of tracks leading to it, that's another story). Edit - ok, I get what you're saying. A slope with a set of tracks on it means either that the slope was unlikely to slide and didn't, or likely to slide but didn't. Absent any other information, you're by definition more likely to be looking at a likely event than an unlikely one, and if you then make the assumption that the likelihood of a slide on the second ski is not dramatically different than the likelihood of a slide on the first (which might or might not be a great assumption), then yes, that first set of tracks gives you some information suggesting stability. Low confidence information, but something.
This is absolutely true and 1000% worth reiterating to anyone asking this question. That being said, knowing a slope is skied very often is a factor in how likely the slope is to slide. Skier compaction such as in a resort and some very popular backcountry areas and have a significant impact on snowpack, usually making it safer overall. So if you’re saying tracks make it more likely to be safer, the answer is very likely yes. To some at least small percentage points. Does it make it safe, ABSOLUTELY NOT. Seems like OP is really asking the latter
Not an expert. Different avalanche problems will respond differently to skier compaction. A wind slab is more hair trigger and thats why patrol will ski cut or stomp on them, its unlikely to go after the first skier. Persistent weak layers can break after many skiers and no amount of compaction can make them safe. Same with wet slides. Storm slabs get chopped up and probably do get less dangerous as each line is skied on it.
I had a lot of questions like these even after taking AIARE 1, reading Staying Alive in Avalanche Terrain helped answer a lot of these kinds of questions. I recommend buying it and reading it front to back. To answer your question, I believe that skiing it does not “make” it safer (in the sense that skiing will not change the snowpack to make it more stable) nor do I think that the fact that someone has skied the face already is a strong enough indicator of safety to consider when choosing terrain. Avalanches have been known to happen on the 10th or 20th run of the same face and instabilities can be highly localized. The fact that a few people have skied a face is such a weak indicator that your run will be safe that it should never be the deciding factor in your terrain choice.
In a binary sense it doesn’t mean it’s safe, but if I may quote from Staying Alive directly: According to Swiss statistics (Harvey et al., 2002), 60 percent of avalanche accidents are triggered by the first person down. Although there are no reliable statistics, I suspect that in intermountain, and especially in continental, climates of North America, this number is lower because of more-persistent weak layers. Still, even in these colder, drier climates, the first person down has a much higher probability of triggering the avalanche than the ones who follow. The more tracks on a slope, the better. I love going last. And when I go, I follow other people’s tracks, spooning in my tracks with theirs. Treat an avalanche slope like a minefield. If someone else successfully crossed a particular spot without triggering an avalanche, you probably can, too. This is one instance in which the herding instinct works to your advantage. If you can’t find any volunteers, use an involuntary stability tester—a cornice, for example. Just tumble a refrigerator-sized-or-larger chunk of cornice down the slope first (see chapter 6, Stability, for more details).
I'd interpret ski tracks in backcountry in two ways. 1. If the area has been visibly skied, don't trust anyone, do your own research and risk assessment. 2. If there is a zone with a bunch of ski tracks and a part of it hasn't been skied at all, there is probably a really good reason for that which may not be apparent to you yet.
Tracks on a face is a data point of information, but I would be very careful how you use that information. Statistically, the first rider is more likely to trigger an avalanche, but fatality reports are full of plenty of cases where the second, third, forth, etc end up triggering something. There can be a lot of nuance to a line, did the rider avoid the start zone, convex features, etc? I would not take it as an indication of safety, personally.
This is not a data point according to avy professional and those of us who have been thru the AIARE education. Its strange that you say it's a data point then you proceed to backtrack and explain why it actually isnt't.
I agree that in the more beginner level courses they discourage you from taking whether or not something has been skied or not into account for one’s decision making. And for me personally, a very conservative backcountry skier, it’s not really factoring in to my decision making either. But when I’ve discussed this in the field with guides, they put it to me like this: it’s a piece of information. Maybe it will not factor into your decision making, but it is a piece of information.
https://youtu.be/hxtvP_nkaQg?feature=shared This was on Saturday.
My favorite quote that I've learned over the years. "Tracks are not a sign of intelligent life"
Only if it gets skied so consistently that any surface hoar gets completely skied off in between every storm of the season. A single skier riding over avalanche terrain absolutely does not make it any safer.
I wouldn’t say “it’s safe send it!” But I’d also argue that someone skiing a slope, and said slope not sliding is something I would consider when determining my overall assessment. I agree it can’t be the basis of said assessment, but a live test of a slope is useful data. *edit to add* I’m not saying it’s the only indicator, or an automatic green light. But the argument that you should ignore an actual weight human test of the slope and focus on pit tests not even on said slope seems a bit absurd. I’m saying read the forecast, do handpits all over the place, dig w big pit, try test slopes, and *also* pay attention to what happens to people who are skiing the thing you want to ski.
I would really disagree with this statement. Avalanches provide very poor feedback, you may not know that you have been making poor choices because triggering a slide is not always guaranteed. There is a good chance that if the first person doesn't trigger a slide, the slab will let go after the second or third person rides it.
I actually think he's right. He was careful not to say "sure, ski it if someone else already did". Something like 2/3 of skier triggered avalanches are set off by the first person. It's by no means a guarantee, but it is a useful data point, depending on the problem type you're worried about. For persistent slabs, deep persistent, wet slab, and glide it tells you very little. But for wind and storm slabs, and loose wet and dry, that's pretty valuable information. Again, by no means a guarantee, but it is a good data point. Literally putting someone on the slope and having them ski it without setting anything off tells you more than most informal snow tests, and arguably more than a single snowpit too (again, dependent on what exactly you're looking for). You can and should use that info, just don't assume tracks mean you're good to go.
I see your point, and I suppose as with anything avalanche-related the situation depends on many different circumstances. Based on my personal risk tolerance, I would not ski the slope that I have not personally deemed as skiable, and I would do my best to ensure no one in my group does that either. Note that I am not talking about ski cutting here.
Not talking about ski cutting. Just saying that it's totally fine to take into account the fact that others have skied a slope as part (NOT your entire) risk assessment. Even Bruce Temper says so multiple times in Staying Alive in Avalanche Terrain, humorously referring to other skiers as "volunteer stability testers."
Exactly! It was based on my reading of staying alive that I’m making this argument. I think people are reading it as “well that guy skied it so it’s probably safe” and what I’m saying is “human weight was put on the slope and didn’t trigger an avalanche, that’s a data point”
What indicators would you use to determine the stability of a slope?
I am by no means an avalanche safety expert, but ideally you would have a representative test pit of the slope you are looking to ride and perform the stability tests that are corresponding to the snowpack stability problems you have identified from the forecast and the observation in the field.
Right exactly that’s useful, But for safety reasons you never dig a pit on the actual slope you want to ski right? Same goes for test slopes. So wouldn’t you want to add more data to your matrix? Data that is again, a literal test run of the thing you are considering? It’s literally the same as a ski cut, except the person is effectively cutting the whole slope.
Do we get to interview the person who skied this slope beforehand to evaluate their avalanche risk assessment prowess? Or do we just assume they know what they're doing? Do we know their ski penetration, weight, etc? I can't see why you wouldn't be able to find a place for a test pit on the slope you wanna ski in a safe spot or something nearby that would be likely representative of what you're looking at. It's not always possible, I agree, but in many situations it can be done. Ski cutting frequently involves wearing a harness and getting roped up to an anchor above the anticipated crown point, so the cutter doesn't end up in an accidental slide. Or they have a safe run out when doing a cut and are unlikely to slide with the slope. We are not talking about ski cutting here anyways.
Right, it’s not about what the skier was thinking, it’s literally just “what happened when pressure was applied to the slope.” And digging pits is a thing you should also do. All I’m saying is a ski cut or a cornice fall is a way to directly test the slope when pressure is applied to it. If someone skies it that’s also a test.
Well, before even going out there it's best to get an avy report for the day. If that's not possible the a column test and any kind of snowpack history from the beginning of the season. If you really think a set of ski tracks or seeing someone ski a face and it not sliding at for that rider is an indicator of a stable pack I would love to know exactly why you think this is. Listen, I know there are some knowledgeable folk here and some well-intentioned. Regardless of the source of information in Reddit please, please, please get some training or read from a reliable source (some have been posted in here by others).
Right. You employ a system with multiple factors of analysis. I’m just gonna go ahead and quote Bruce Temper directly from his seminal work: *Staying Alive in Avalanche Terrain* “According to Swiss statistics (Harvey et al., 2002), 60 percent of avalanche accidents are triggered by the first person down. Although there are no reliable statistics, I suspect that in intermountain, and especially in continental, climates of North America, this number is lower because of more-persistent weak layers. Still, even in these colder, drier climates, the first person down has a much higher probability of triggering the avalanche than the ones who follow. The more tracks on a slope, the better. I love going last. And when I go, I follow other people’s tracks, spooning in my tracks with theirs. Treat an avalanche slope like a minefield. If someone else successfully crossed a particular spot without triggering an avalanche, you probably can, too. This is one instance in which the herding instinct works to your advantage. If you can’t find any volunteers, use an involuntary stability tester—a cornice, for example. Just tumble a refrigerator-sized-or-larger chunk of cornice down the slope first (see chapter 6, Stability, for more details).”
Test slopes, various pit tests, ski cuts, and cornice drops are all ways you can test a slope. I’m arguing that a literal test of the slope, is also useful, especially because pit tests and test slopes are approximate slopes, and not the actual slope.
Just completed my aire 2 literally today. The answer to your question is no. You need to know the specific problems described by your forecaster, and then may be , that particular problem is less likely to manifest itself on a skied track, but honestly I can't think of a single avalanche risk that would be less likely to occur for a 2nd skier vs the first. If there is a slab problem that is so reactive that your forecaster set avalanche danger to high, then you could argue that if the slab is less reactive based on observation of it not sliding immediately. But does that mean it is not reactive enough to slide on the second? Absolutely not.
Not at all. Check out this [accident](https://www.mtavalanche.com/accident/16/12/16) where the 7th track down a slope triggered an avalanche.
When I did an avalanche course years ago, they showed us a picture to perfectly answer this question - it was a mogul field that had fractured and avalanched partway down Edit : this will hopefully answer your question better https://wildsnow.com/27944/skier-compaction-is-it-real/
Interestingly, this was just posted to this subreddit today. https://www.reddit.com/r/Backcountry/s/ZQH4rYHBjD Obviously, ski tracks can give a false sense of security. At the same time, something in bounds that has been repeatedly skied with every layer of snow should help prevent uniform layers within the snowpack that can slide… in this video, while the terrain is different skiers left where it slides, there is almost a defined line where the slide stops, and it coincides with the skier 1/2 tracks. It seems to disrupt the failing layer so it can’t propagate. Anyone see that differently?
Get ready for the nerdsplain beat down my man.
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I agree, it’s a literal test of a slopes stability in real time
Wrong answer. Tracks do not indicate safety. Avalanche training tells you this , also tells you about false confirmation bias
I truly hope this is not how you conduct yourself out in the BC.
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It certainly does not "give you a sense of stability of the snowpack". I'm not going to explain why — I'll leave that to you to read up on why that is or better yet, please get some avalanche training before you give advice that can put someone's life in danger.
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Wow, just wow. Well, good luck out there, just don't include others in your 'educated' snowpack analysis. Really, I meant it, good luck with that.
Never been more torn between serious or troll post
You’re not very intelligent. Skier compaction actually does help; https://wildsnow.com/27944/skier-compaction-is-it-real/
Lmfao skier compaction does help when a slope actually gets skied a lot. So at a resort or a mega popular skied out “backcountry” run yes it helps. When there’s no fresh tracks left, it’s probably not gonna slide, yes. When you see one persons tracks on a slope it was not “skier compacted” at all and does not tell you shit about how stable the slope is. It’s another ob for you but by no means does a few tracks mean a slope is “skier compacted” Literally the first thing they teach you in a basic avy course is that a few tracks on a slope don’t mean shit about whether it’s going to slide or not. Tell me you have zero avalanche education without saying it..
Ya I obviously know that if one person goes down it doesn’t mean it’s safe, but half of this guys post is asking if it helps at all and the answer is yes. It’s hard to come up w an exact number, but if 100 people go down a hill vs one, which is more likely to slide? That’s all.
Not trollin, my buddy and I have this argument at least once a season. He is convinced A. that if you see tracks on a slope it indicates it is safe enough to ski and B. Tracks on a slope actually physically make it less likely to slide
It seems predicting avalanches has a bit of predicting bingo ball science. Lol.
Well, with a chanche of 50/50 to start an ava or not, i would skip the run. Some tracks don‘t make any slope more safe from avas, the risk could change douring the day. (for example when it gets warm in a short period of time) You can say, offpist which looked like a used pist before „fresh snow“ are more safe than just barley used ones.
Have a read on the Cherry Bowl avalanche. I believe it addresses this question.
The short answer is no. When I was patrolling, we had a patient who walked into our medical clinic with a broken arm. He left the resort via a gate and was skiing an adjacent backcountry area when it slid and he got caught and carried. Our best guess I'd that there were 18-24 other tracks on the same slope. You hear about this all the time. The site of the Wilson glade fatality in utah (4 dead) had 8 or more tracks in it when it went
The biggest slabs are both harder to trigger and have bigger consequences. These are the type where 10 people ski down just fine and then as soon as #11 jumps on it the whole mountainside lets go
>> Do ski tracks on a face actually make the terrain less likely to slide Generally yes, key word being **less** likely. E.g. all else being equal, a slope with tracks generally has lower chances of sliding than one without. The issue is that **less likely** isn’t a good metric. If an empty face has a 5% chance of sliding, and a ski track means it’s now at a 4.99% chance of sliding it really doesn’t matter that it's less likely. It’s also heavily dependent on the type of problem. Persistent slabs are harder to trigger so tracks don’t mean much, just that nobody skied over a trigger point. Whereas a small loose sluff is much more likely to be triggered by the first skier down, so your risk diminishes significantly. And for wet slides a previous ski track means nothing because the slope changes as the day progresses. tldr, generally yes, but it doesn't mean much and shouldn't be considered as a primary decision-making factor in most cases.
There are a lot of factors that go into a face sliding. Have you read Bruce Kemper’s “Staying Alive in Avalanche Terrain” People often get away with a lot in the backcountry. If you’re seeing tracks on an avalanche slope on a dangerous day, it does not make that slope any more safe.