Slope Angles — Do you measure 'em? How important are they?

Just curious about common practice for slope angle measurements in avy terrain.

If you're willing to answer a short survey (~3min total), follow this link...

Backcountry Slope Angles Survey

...and you'll get 20% off a PoleClinometer kit (or few) for your time.

Hope you'll share your thoughts on the subject in this thread too:

• How important is slope angle in your everyday avalanche safety practice?
• What are your favorite inclinometer devices/methods?
• How good is your "eye" for slope angle, and do you occasionally verify your estimates against actual measurements?

FWIW, my favorite devices are PoleClinometer and the Avalanche Inclinometer app. I don't measure slope angles a lot here in VT, but when I travel into more avalanche-prone terrain I take a lot of quick "line-of-sight" readings as I move through the mountains just to remind myself of what could slide, especially when avy forecasts are anything other than "low".

Looking forward to hearing from those of you who spend more of your days in exposed avy terrain to learn about how you incorporate slope angle into your regular practice. Thanks for anything you care to share!

Nope dont measure shit. Why? Because all of Alpental is avalanche prone terrain.

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theodolite app ftw

it's always steeper than any measurement

I don't measure slope now, cuz I'm super conservative on my recon missions. If I did some sort of hut trip or something w/ no guide, etc. Sure, I'd take a look to reconfirm my pussiness.

If I do, pole method w/emergency duct tape wrapped 2/3 up my pole. If horizontal pole is under tape, slope is <34*.

Cheaper than a fancy sticker, and the duct tape can be used if you need it. Not that it isn't a cool idea.

absolutely, all the time, even during the summer. I don't necessarily make go/no-go decisions in the moment based on a slope angle measurement (I try to leave myself more margin of error than that) but it's always useful to know the angle for future reference. alpha angle too. plus it helps me hone in my ability to visually estimate slope angle.

I have both a BCA clinometer and a couple of phone apps; I like the one built into the camera on the UAC app.

How do you all typically measure the slope when standing above it?

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Originally Posted by The SnowShow

How do you all typically measure the slope when standing above it?

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sight down it with a clinometer or one of the apps

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Originally Posted by The SnowShow

How do you all typically measure the slope when standing above it?

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I use an app called Dioptra.

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I used to use the BCA app with that capability, but they did away with it, so I assumed it may have not been a reliable technique.

@isbd - thanks for pointing out Dioptra. Awesome app. I had previously been using "Clinometer" also an Android app.

OP - this thread should be in the slide zone.

... Thom



Sent from my LM-G710VM using Tapatalk

I use a GPMS machine.

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Originally Posted by The SnowShow

How do you all typically measure the slope when standing above it?

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Watch this video...
https://vimeo.com/289213914
...skip to around the 32-second mark for the down-slope sighting method.

Note that this video shows using the PoleClinometer slope meter specifically. But the first part of the sighting down-slope method ("first move yourself around 'til your line-of-sight matches the angle of the slope") is the same regardless of which device you're using. Note too that not all inclinometer devices are compatible with down-slope sighting (eg. the BCA one can't be used for sighting down slope unless you have a buddy to read the thing while you sight down the edge of it).

As for phone apps, some use the camera for sighting down-slope, but I've never been a fan of that for a couple reasons (difficult to use in sun glare, and sometimes dubious accuracy). The best app I've seen is the Avalanche Inclinometer app, which speaks the slope reading while you sight down the edge of your phone ("like a gun sight") when measuring in down-slope mode. Or you can tap the screen to lock the reading while sighting the same way. Really slick.

those using a clinometer, do you take extra steps to account for the height of your eye, especially on shorter slopes?

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Originally Posted by grayson

Watch this video...
https://vimeo.com/289213914
...skip to around the 32-second mark for the down-slope sighting method.

Note that this video shows using the PoleClinometer slope meter specifically. But the first part of the sighting down-slope method ("first move yourself around 'til your line-of-sight matches the angle of the slope") is the same regardless of which device you're using. Note too that not all inclinometer devices are compatible with down-slope sighting (eg. the BCA one can't be used for sighting down slope unless you have a buddy to read the thing while you sight down the edge of it).

As for phone apps, some use the camera for sighting down-slope, but I've never been a fan of that for a couple reasons (difficult to use in sun glare, and sometimes dubious accuracy). The best app I've seen is the Avalanche Inclinometer app, which speaks the slope reading while you sight down the edge of your phone ("like a gun sight") when measuring in down-slope mode. Or you can tap the screen to lock the reading while sighting the same way. Really slick.

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Have you tried Theodolite of Dioptra? Doesn't sound like it.

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Originally Posted by nickel

those using a clinometer, do you take extra steps to account for the height of your eye, especially on shorter slopes?

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Yeah. The above video actually shows this well.

I have used and owned a Suunto Pm-5 for many years surveying and skiing. One year a ski partner and I had a competition going guessing slope angles. After a couple hundred challenges over a few years we found that we became very good at estimating slope angles. Then we quit because we both had the same answer. The Suunto is still in my ski bag, I'll have to re-start the competition to see how much our skills have degraded with non-use. Den

So you guys who use your phones for slope angle: I now keep my phone off because it can interfere with your transceiver even in airplane mode, so you guys pull out your phone, wait for it to boot up then hit the app for the inclinometer?

Seems to me you guys keep your phones on, and if you do, why do you need slope angle? Because I only keep my phone on when I know there’s absolutely no danger of getting caught in an avalanche.

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Originally Posted by plugboots

So you guys who use your phones for slope angle: I now keep my phone off because it can interfere with your transceiver even in airplane mode, so you guys pull out your phone, wait for it to boot up then hit the app for the inclinometer?

Seems to me you guys keep your phones on, and if you do, why do you need slope angle? Because I only keep my phone on when I know there’s absolutely no danger of getting caught in an avalanche.

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Thanks for the virtue signaling. Best example I’ve seen here in a while.

I knew I’d get a response like that, and I thought about not posting it, but I have been keeping my phone in airplane mode until recently and now I keep it off.

Then I also thought, I don’t give a fuck, maybe somebody didn’t know this and now they’ll rethink it.

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Originally Posted by plugboots

I knew I’d get a response like that, and I thought about not posting it, but I have been keeping my phone in airplane mode until recently and now I keep it off.

Then I also thought, I don’t give a fuck, maybe somebody didn’t know this and now they’ll rethink it.

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I'm not saying you're wrong, I'm saying that delivery is everything ;)

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Originally Posted by zion zig zag

I'm not saying you're wrong, I'm saying that delivery is everything ;)

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Yes, I know.

Hey everybody! I'm not going to edit my post, but I didn't mean anything other than: "Hey, remember to keep your phones off when using a tranceiver!"

From what I have read and been told, phone interference with beacons occurs primarily with the beacon in search mode and is HIGHLY related to how close the devices are physically; at 10cm distance this interference may be significant, by ~50cm it's negligible. I suppose this could bite you if you were holding your phone and beacon in the same hand during a search but my arm is longer than 50cm and my phone stays in airplane mode in my pocket. I have practiced and do practice searching using my beacon with my phone off, fully on, and on but airplane mode; I have not seen a discernible difference in search effectiveness. So on the one hand, I've read some things about some devices interfering with some beacons in some circumstances; on the other hand, I have plenty of actual experience effectively performing beacon searches with my real every day bc kit, which includes my phone. Anecdotally, of all the people I've ever toured with, not one powers off their phone completely or has ever asked me to do so (or even mentioned doing so). So I don't worry too much about it, and phone app clinometers are nice.

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Originally Posted by plugboots

Yes, I know.

Hey everybody! I'm not going to edit my post, but I didn't mean anything other than: "Hey, remember to keep your phones off when using a tranceiver!"

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AFAIK, the research indicates the beacon interference is primarily a concern if you are searching for a victim (turn it off if you go to search in a situation where low SNR is plausible). Best practice has phone 20 cm+ from beacon. Easily achieved with beacon in secure pant pocket, phone in chest pocket. Not faulting you for being more conservative, just pointing out the current understanding. I also think arguments could be made for a phone being on and accessible (e.g. GPS nav, slope meas, emergency phone calls, locating, etc).

https://backcountryaccess.com/electr...your-beacon-2/

OK, OK.
And yes, with my wife and I and our transceivers and phones we could not find interference. Scared us a little though.
I apologize.

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Originally Posted by galibier_numero_un

@isbd - thanks for pointing out Dioptra. Awesome app. I had previously been using "Clinometer" also an Android app.

OP - this thread should be in the slide zone.

... Thom



Sent from my LM-G710VM using Tapatalk

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Same here. The Dioptra app is pretty cool. Just downloaded it and played around with it around our shop area. Thanks isbd.

I always tell folks to take their inclinometer out a measure a lot of slopes to develope their terrain angle eyeballs. It's a good preseason training thing. Measure your garage roof. Every time you pull your car out take a second a memorize that angle in your brain.

Walking out on a slope convexities to measure looking down slope can be tricky and dangerous. Be VERY careful when you do this, since you'll likely be on the major stress point of the slope.

Back to the original question, I'll check slope if it's an area that is steep enough to be concerned. With us, we're generally meadow-skipping on 25-30 slopes that we know well and, aside from some smaller terrain traps we are aware of and avoid, have never been a problem. As I tell my wife, we choose slopes that are historically documented as never having slid in the history of mankind. Obviously, not always the case and when we do venture into unfamiliar territory with steeper pitches, it's in low conditions and I do take a slope as much from curiosity as anything. Rarely are we in the 35-40 range.

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Originally Posted by mall walker

From what I have read and been told, phone interference with beacons occurs primarily with the beacon in search mode and is HIGHLY related to how close the devices are physically; at 10cm distance this interference may be significant, by ~50cm it's negligible. I suppose this could bite you if you were holding your phone and beacon in the same hand during a search but my arm is longer than 50cm and my phone stays in airplane mode in my pocket. I have practiced and do practice searching using my beacon with my phone off, fully on, and on but airplane mode; I have not seen a discernible difference in search effectiveness. So on the one hand, I've read some things about some devices interfering with some beacons in some circumstances; on the other hand, I have plenty of actual experience effectively performing beacon searches with my real every day bc kit, which includes my phone. Anecdotally, of all the people I've ever toured with, not one powers off their phone completely or has ever asked me to do so (or even mentioned doing so). So I don't worry too much about it, and phone app clinometers are nice.

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Yup. Definitely do your beacon check with how your phone will be running on your tour. I do airplane mode and if there are any search issues, it's powered off. A buddy's phone halves his search distance when it's powered up, sending/receiving (non airplane mode).

I run both Dioptra and Clinometer. It's good to train your eyes from both perspectives.

... Thom

Sent from my LM-G710VM using Tapatalk

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Originally Posted by GoldMember

Back to the original question, I'll check slope if it's an area that is steep enough to be concerned. With us, we're generally meadow-skipping on 25-30 slopes that we know well and, aside from some smaller terrain traps we are aware of and avoid, have never been a problem. As I tell my wife, we choose slopes that are historically documented as never having slid in the history of mankind. Obviously, not always the case and when we do venture into unfamiliar territory with steeper pitches, it's in low conditions and I do take a slope as much from curiosity as anything. Rarely are we in the 35-40 range.

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One of the Sheep Creek avalanche accident guys told his wife the same thing...

Could somebody please do a refresher post on current info related to phones and transceiver interference, preferably in a standalone thread? I have some ignorant confusion. I believe tremper spoke about it and addresses in his new book. I used to do airplane mode. Lately, I’ve kept it off. I like using it for quick pictures.

I have a suunto compass with a slope meter that I carry in a pants pocket. I pull it out frequently. It has helped me and has been a clear component of me backing off an objective.

Don't, but probably should to at least train the eyes to be better at guessing slope.

What i do pay very much attention to, is run outs and traps.

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Originally Posted by Hacksaw

One of the Sheep Creek avalanche accident guys told his wife the same thing...

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Wow, I didn’t know that, and I didn’t read that in the reports/articles I read.

My kid gave me one of them angle/thermometers that straps to your pole so did a tour on boxing day hit the button and its dead

it wasn't really dead they just don't work when its colder than -20C

i gotta dig that thing out and try it again

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Originally Posted by plugboots

Wow, I didn’t know that, and I didn’t read that in the reports/articles I read.

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She said it at a "survivors/PTSD" clinic this past summer.

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Originally Posted by Hacksaw

She said it at a "survivors/PTSD" clinic this past summer.

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Drift: Are those clinics common?

A friend of a friend was a survivor (and first responder) of the Durrand glacier incident. Seems this person had been (and still may) want to participate in such a clinic.

I measure slope angles habitually. It’s a fun and easy game to play to see how well my eyes gauge reality. Any and all tools that get backcountry skiers to slow down and pay attention to the snowpack, weather and terrain help create a safer experience for all.

It matters.

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Originally Posted by bodywhomper

Drift: Are those clinics common?

A friend of a friend was a survivor (and first responder) of the Durrand glacier incident. Seems this person had been (and still may) want to participate in such a clinic.

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No, their not comman. This was a panel discussion at an event not for survivors, but for patrollers/s&r/CAIC types.

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Originally Posted by Hacksaw

No, their not comman. This was a panel discussion at an event not for survivors, but for patrollers/s&r/CAIC types.

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Thanks for the additional info.

Looks like dioptra is android only. Are you iPhone users using clinometer or something else?