Auto Revert - Pain or Life Saver?

A short clip from the Glencoe Anatom/BCA park when covered with snow.  A group of well trained guys in the park when I skied in to see how they were doing.  They seemed to have a problem locating one of the sending units which was 2m down.  As there are 8 other beacons buried its quite a challenge if more than 3 are on.  However the problem was apparent after a while as one of the Pulse beacons had auto reverted to send which is its default setting.  The Trackers default is no auto revert unless you press SP mode when switching on.  There is a good reason for this.  The tip itself is often the safest place to be, and the T2 has a big button you can just bump of yourself to get back into transmit.  False signals from auto revert is a major issue at avalanche sites and costs time and lives. Another issue here because of the problem is that some of the group had "marked" either the beacon on auto revert or the buried one so there was some confusion.  The T2's simplicity showed it's worth being so accurate down to cm's.  That's why these beacon parks are so good as real situations occur and have to be sorted out and its a learning experience for all concerned especially me!

BCA Training Park Glencoe

Awesome snow cover up at Glencoe. Possibly the best early conditions in decades.  Wide complete cover all the way from the summit back to the car.  A few medium slabs were triggered this morning by ski patrol but overall conditions are tremendous.  I installed the BCA training park today.  Some pictures of what greeted me below.  Next year I will take the kit home for maintenance as the weather has taken its tole on the wires and the control box and it really needs a bit of care.  Take care if using the park as although I have buried the beacons 50/100cm down into the snowpack I was unable to get the wires down below 12cm due to a hard crust and being knackered from all the digging.  I believe an MRT will be using the site tomorrow and many folk came to me wanting advice and future training today.

2m of snow over the park

The tin probe strike covers dug out

100m of wire to unravel!

Two kite boarders who had a ball!

All buried and ready to be used - me? knackered!

Avalanche Danger Scale Re Post

As it's near the ski season I will re post some stuff  just to give a heads up for folk on interpreting the forecast.  This post was from when the SAIS forecast first changed to the wheel type view and was to help folk understand how it related to the European scale which is identical to the one below now.

Click for a larger size

The new scale is the result of collaboration between avalanche professionals in Canada, the USA and Europe. It is a North American Danger Scale with Icons standardized internationally (recognizable by Europeans visiting Noth America.)

Key changes:

• The danger levels have been reversed — Extreme is now on top.
• Extreme and High have been grouped as backcountry travel is not reccommended at either level.
• Icons have been added to give an at-a-glance indication of the risk of travel.
• Travel advice is given for each danger level.
• The likelyhood of avalanches information has been retained from the previous scale.
• The last column gives the potential size and extent of avalanches.

The Avalanche Danger Scale uses five progressively increasing danger levels: Low, Moderate, Considerable, High and Extreme. It indicates the likelihood of avalanches, how they might be triggered and recommended actions in the backcountry. However, the wording is very brief and does not include a meaningful indication of risk. Below is an explanation of each danger level, including the transitions between levels, signs of instability at each level and the implications of slope angle, aspect and elevation.

Low

Travel is generally safe. The snowpack is well bonded and natural avalanches will not be seen except for small sluffs on extremely steep slopes. Human-triggered avalanches are unlikely except in isolated locations in extreme terrain. The danger will usually be from wind-driven snow in gullies and chutes or deposited across very steep open slopes near ridge lines. Ski or board one by one as smoothly as possible without falling if you suspect the formation of wind slab. Be aware of shaded, north to east aspects where the danger may be transitioning to Moderate. There are few fatalities at this danger level.

Moderate
This is the most difficult danger level for backcountry skiers and boarders to assess snow stability. Many of the usual indicators such as cracks, settling, whumpfing and signs of recent avalanche are absent, especially at the lower end of the moderate level. Key indicators are any recent snowfall, and wind deposition. Snowpack tests may help assess stability.

Conditions are generally favourable for travel providing routes are chosen carefully. The snowpack is only moderately bonded on some steep slopes. Areas of danger are usually restricted to certain types of terrain such as bowls and gullies. The altitude, aspect and type of terrain where danger can be expected are usually detailed in the Avalanche Forecast. Remote triggering is unlikely, so you only need to be concerned about the steepness of nearby terrain features.

Human-triggered avalanches are possible. Ski or board carefully, one by one, in suspect terrain and avoid high loading of the snowpack by spreading people out on the uphill track. Carefully evaluate the stability of very steep slopes (steeper than 35°) and aspects identified as potentially dangerous in the Avalanche Forecast.

Be especially careful if the higher elevation band in the forecast, or the danger on other aspects, is Considerable. There is a significant difference in instability between Moderate and Considerable. Don’t get sucked onto higher, steeper and more dangerous slopes. Although naturally triggered avalanches are not expected, ice climbers should watch out for the sun warming steep collection zones above their climbs.

If deep-slab instability due to a persistent weak layer is mentioned in the Avalanche Forecast, you need to pay careful attention to the terrain. Avalanches from such a layer are not only likely to be large and extensive, they are completely unpredictable. Unless you have specific local knowledge, keep off large open slopes at this danger level if the forecast warns of a persistent weak layer.

Considerable
Conditions have become much less favourable. The snowpack is only moderately or poorly bonded over a much larger area of the terrain. Human triggering is possible by a single skier on steep slopes and aspects mentioned in the Avalanche Forecast. Remote triggering of avalanches is possible, so the maximum steepness of the slope above you should be used when deciding if you want to continue.

Instability indicators mentioned in Moderate danger above will likely be present. Backcountry touring at this danger level requires good routefinding skills, and experience in recognizing dangerous terrain and evaluating slope stability.

Keep to slopes of less than 35°, especially slopes at the altitude and aspect indicated in the Avalanche Forecast. Remember that remote triggering is possible. Typically the talus fans at the bottom of gullies starts out at around 30° and the slope steepens as it gets higher. Keep off such slopes at this hazard level. The remarks about persistent weak layers in the previous section on Moderate danger level also apply to this danger level.

High
Conditions have become dangerous, most often as a result of significant amounts of new snow, snowfall accompanied by wind or the snowpack becoming isothermal and threatening wet-snow avalanches. The snowpack is poorly bonded over large areas and human triggering is likely on steep slopes (steeper than 30°). Remote triggering is likely and large natural avalanches are to be expected.

Stay on slopes that are flatter than 30° for any part of the slope and be aware of the potential for avalanches from slopes above. If you do decide to ski or board on less steep slopes, be very aware of the surrounding terrain to avoid inadvertently crossing the bottom of steeper slopes or cutting down a steep convex rollover.

Usually this level of hazard is only present for a few days at a time. The smart backcountry traveller will stay in simple terrain until conditions improve. If you are caught out on a multi-day trip you may have to dig in and wait for travel conditions to improve and the avalanche danger to lessen.

Extreme
Extreme danger levels are rare and usually the result of unusually large amounts of new snow. The snowpack is weakly bonded and unstable. Numerous large avalanches are likely. The weight of the new snow can trigger avalanches on layers buried deep in the snowpack. Natural avalanches can release on slopes of less than 30°

Backcountry touring is not recommended and often impossible. Avoid all avalanche terrain and keep well away from avalanche path runouts.

As Lucky as you can get!

Here's a nice bit of filming that's still a bit disturbing to watch but well worth seeing through to the end.  They do say in the alps that there are two often used types of avalanche control "Gazex & "Swedex" this film being the Swedex.

Not sure what to take from this film.  Who rescues the last man if he takes a line that pops.  Its often long hard hoof back up if buddies go down which costs time.  Maybe someone had stayed on a safer line.  He obviously had a good air pocket otherwise he was panned!  Anyway watch it and learn.

A Guide to the SAIS Forecast Re Post

A re post from last year, pre the SAIS site update to help interpret the forecast.  Maybe not as good as the SAIS but another take on the subject to help lay persons get a handle on the forecast and look at it in more depth. Knowledge in depth as well as breadth.

SAIS Forecasters "Spring Run" Glencoe

First questions I would ask most folk generally who own a Transceiver/Beacon is: do you regard yourself as "situationaly aware" ie, do you observe the weather and what's around you and what the snows doing under your feet. Do you read the SAIS area forecast and understand it and can you relate it to the part of the area and slope aspects you will ski. If the answer is yes to all of these, then a beacon is a vital part of your overall approach to ski safety and practice is vital. Also, a Beacon is no use if you can't pinpoint a victim so you need a probe, and a shovel, as without a good shovel for you to dig them out the victim is royally screwed. First things first - avoid getting avalanched, it isn't pretty so have a look at this and feel scared:

It aint pretty so don't kid yourself you can breath out your arse

Avalanche Risk Scale

Old Forecast for Glencoe

You will see on the snow pit data below a lot of information from the name of the observer to the OS Grid that you can apply on a map to the aspect and elevation.  The is also a code on the bottom corner.  The first figure is any observed avalanche activity that day and the first figure is 5 which shows 5 avalanches were observed. The others relate to wind and overhead conditions. These are entered into a computer model.

F = crystal type - the classifications are:

E = grain size in mm
R = hardness - a symbolic representation of the F, 4f... scale.

e = the water content. The number of vertical lines goes from 0 to 4 as the snow wetness goes through dry, moist, wet, very wet and slush.

 

Each shaded block represents the hardness of a separate layer of the snowpack

TEST PITS

The SAIS forecast covers an area. To be more specific we need to lots of smaller tests as we go to test aspects within the forecast area. These are easy compression and shear tests. Remember that they are only valid for where they have been done - 10m away it might be different and for that reason use your eyes and look around you, and make judgements using all the information your senses bring you.  If it looks iffy, feels iffy then its probably staring you in the face that its a good day to go somewhere else and ski something less risky.

Test compression & shear by pulling on a column

Shear tests can be quick and easy to interpret for where you have done one and work for most kinds of weak layers given the caveat about there usefulness above. 


Start by isolating a column about the same size as the blade of your shovel, in other words, about one foot by one foot (30 x 30 cm). Be sure to completely isolate the column. Then take the blade of the shovel and lay it flat on top. Finally start tapping progressively harder on the shovel blade until the column fails. Start with ten taps by articulating from your wrist, then ten more taps by articulating from your elbow, then ten more from your shoulder using the full weight of your arm. Don’t push your arm into the snow, but let it fall with its own weight. In this way, the test is somewhat quantifiable. In other words it doesn't depend on “feel” or the opinion of the tester, but it has a reproducible number which is more or less same for most people and can easily be communicated to others. For instance, it failed on an easy tap from the elbow, or it failed on a moderate tap from the elbow or perhaps a hard tap from the shoulder. Since snow stability is dependent on the size of the trigger required to make it fail, this test is especially easy to interpret. Of course, if you have an unusually light arm or an unusually heavy one, you need to take that into account.

Green zone does not mean NO RISK it just means less risk

Practice - Duncan Gunn, in case he needs to rescue his Dad