TheSnowpit.com News Blog

While Colorado skiers celebrated an August dusting of snow, the other side of the world remains locked in a recently unruly winter.

All heli-skiing operations use experienced judgement to continue operations
despite rising avalanche hazard. However, the "Considerable" conditions in the Richardson mountain range of New Zealand and continued heli operations there combined on August 17th to result in a 2m-deep burial of a client, who was promptly and successfully dug out alive. With three guides digging on scene and beacons available for locating the buried subject, the response seemed to be a best-case scenario for such a deep burial.

Not all deep burials are so lucky. Two brothers and their friend, all expert skiers, were skiing in Southeast Austraila (New South Wales) in Kosciuszko National Park also on August 17th, and one triggered and fell with a cornice collapse, which subsequently triggered a large avalanche. It is unclear whether the brothers carried beacons or other safety equipment, but it appears from the three-hour-plus search response that beacons did not play a helpful role even if they were worn.

This incident is rather interesting since the unburied brother, who witnessed the slide and burial, started digging in the location he felt his brother had been buried. The news points to some clues that he noticed, including skis (not attached to the subject) found sticking up out of the snow. However, he later abandoned his individual digging efforts to help the searchers who arrived on scene. Three hours later, his brother's body was recovered in the spot he had initially been digging at. The burial depth (3m) possibly would have prevented successful recovery even if he pursued first digging effort, but in this case the intuition of an on-site witness was spot-on.

Tragically, two other skiers died from collisions with trees in-bounds at Mount Blue Cow and Sun Valley ski resorts in that same area of Australia also on August 17th. The news has given much press to the unfortunate and unlikely event lineup.

Alta's Ski Lift solution; A brief history of artillery and avalanche control; Current alternates

With Mount Hood Meadows making a new request for leasing a howitzer and Alta proposing a new ski lift on the south side of Flagstaff Mountain - whilst billing it as a new method of avalanche control via 'skier compaction' - this topic seems a good one for the summer. Enjoy.

A Brief History of Artillery Use in Avalanche Control

This indeed will be brief. After all, I cannot possibly describe the scope and culture of artillery use in avalanche control here. However, a great place to start is Doug Abromeit's paper (PDF) entitled United States Military Artillery For Avalanche Control Program: A Short History In Time. He gives a great overview, complete with some awesome historic photos.

But beyond the history, the idea of shooting down avalanches with large military weapons actually seems somewhat romantic, in the classic sense of the word. It is not only attractively powerful, but it also probably feeds off of the original
myths and tall tales about yodeling and other noises setting off avalanches. Quite interesting, as the concussive force of the shells sets off the avalanches, so perhaps all we need is a really strong yodeler?

Of course, the real attraction to artillery and avalanches seems to be the efficiency: for around $50 a shot and a lease from the military, you can reach all the visible areas of a ski resort - areas that would not be inside of a pedestrian bombing run even with an early morning patrol snowmobile and ski. And you can even reach them when you can't see them in a storm. Hence the prevalence of military artillery used in snow control around the USA, mainly in the form of howitzers, but also some recoilless rifles, and - as Doug's paper mentions - even an armored tank at Stevens Pass. These armaments are used at ski resorts, transportation corridors, and some backcountry venues.

Issues With Artillery

There are many disadvantages of using artillery in avalanche control. They range from area to area. For example, issues currently under investigation from the BNSF / Glacier National Park dispute include concerns such as danger to wildlife as well as who will actually foot the bill for the shells. Whereas, scrutiny for the up and coming artillery plan for Hood Meadows includes concerns for danger to mountaineers!

Specific disadvantages of the howitzer and other military-based artillery include:

• Trained marksmanship is needed to operate the weapons, and with the power behind them, mis-aiming can be extremely hazardous.
• Duds, or fired but unexploded shells, still contain the chemicals to explode and must be carefully tracked and logged to be taken care of later. In addition, mis-manufacturing of the shells can create very dangerous shrapnel and explosive situations for the gunner and attending people while the shell is being fired but is still in the gun.
• And, as the motivation for this overview, all howitzers and recoilless rifles are designated surplus by the US military. That is, both weapons and shells can be hard to come by and may eventually run out.

Which means eventually, no more shells will be available. (At least not at the attractive surplus-type price tag.) And, as the military has stopped producing such weapon types en masse, commercially manufacturing such shells for the lesser demand of avalanche control would be much more expensive.
Of course, one could assume that, as time passes, another weapon currently in military use and fit for avalanche control will be designated as surplus by the military, and folks could use that (whatever that weapon might be) instead. However, there are a few flaws with that theory.

First, it assumes that the weapons released in the future would serve the same purpose as howitzers, that is, the new weapons would actually be useful for avalanche control. And with the prevalence of Stinger missiles and other small, more technological devices in current warfare, howitzers will probably be the last military option for avalanche control.

And secondly, with new, more powerful weapons to hypothetically be had, that new weapon would only solve the lack-of-inexpensive shells issue, not the other issues above. In fact, with greater range and more explosive power, the issues with wildlife, duds, misfires, potential danger to the gunner, confirming the area is clear, and so on would only be exacerbated.

Other Control Plans

Some areas have developed other plans to accomplish avalanche control without artillery, or with reduced artillery. In fact, Doug states in his paper that:

From the beginning, Monty Atwater and other Forest Service Snow Rangers continued perfecting the use of hand delivered explosives and looking for methods to supplement and perhaps replace military artillery.

The alternatives that Doug describes in his paper include:

• Avalauncher or other artillery based on the Parsoneault Valve, and Locat projectile devices
• Gas exploders for snow compression in starting zones (such as the Gaz-Ex Exploder)
• Bomb trams
• Bomb deployment towers (such as the Wyssen Tower)

Of course, as mentioned in Avalanche Mitigation Services' history paper for the Avalauncher (PDF), the compressed gas and Parsoneault valve devices are still not only dealing with explosives, but also highly compressed gas. Plus, some quote the dud rate of the Avalauncher at much higher percentages than howitzers, often higher than 10%. Thus, Avalauncher accidents are not only possible, they've happened in the past, as outlined in in the history paper.

Canada, dealing with the fact that not all areas needing control are accessible by artillery, have long since turned to helicopter deployment as an alternative method of delivering explosives. In addition, even for more accessible areas, the parks turned from artillery early on due to the shell-availability issue. From Brad White's paper entitled Development of Avalanche Safety and Control Programs In the Canadian Rocky Mountain National Parks (PDF Original):

After the Granduc mining disaster in the same year, the technique of helicopter bombing was developed and in the late 1960's Alpine Specialist Peter Fuhrman and local helicopter pilot Jim Davies began to experiment with the helicopter for road control in the Parks. The helicopter proved to be an effective tool and by the end of the decade most of the major avalanche paths effecting roadways were being controlled on a sporadic basis...... In the late 1990's the use of artillery was discontinued due to lack of reliable ammunition and today teams of forecasters based at Sunwapta, Banff and Lake Louise do daily analysis and use a combination of heli-bombing, avalunchers, pre-placed explosives and closures for road control methods in the mountain parks.

In addition, Canada has done some work on short-range projectile delivery, through a multi-target explosive launcher known as ACES positioned at the top and center of the paths. However, according to Brad White's paper, the system has not yet hit the big-time:

In the initial tests the launcher worked very well, but after exposure to the weather the charges froze onto the launcher and eventually the idea was shelved. Work continued on the pre-placed explosive system and a third generation of the Avalanche Control Electronic System (ACES) is still in use today.

The Yellowstone program of 22 years has gone a similar way with helicopters, as stated in their Sylvan Pass Mitigation Plan (PDF):

The program has relied upon military weapons (recoilless rifles or howitzers) since it started. These weapons fire explosive rounds into avalanche starting zones from a gun mount located on the south side of the pass. The artillery enables the crew to test the stability of the snow and attempts to reduce the hazard by triggering frequent small avalanches. This methodology is common among crews who manage highways and ski areas in avalanche prone areas. In 2004 a helicopter was introduced as a method to deploy explosives to avalanche starting zones.

Helicopters reduce the risk of vaulting explosives into someone's backyard, and usually allow for better examination of the area before actually deploying the explosives. Disadvantages of helicopter-based deployment, however, includes the somewhat critical fact that helicopters are limited by weather (Yellowstone allows artillery in case of emergencies). Also, the skill needed for the system is not reduced, just changed - from firing to flying.

Of course the old standbys that don't involve shooting or exploding always exist: sheds, concrete diverters, earthen walls, or simply moving the structure or activity away from hazard, (though of course that's not always an option). After all, as I covered in previous blogs, if BNSF repaired their sheds then shelling wouldn't even be an issue, and if Juneau had built concrete diverters around their powerlines then, well... as I also said earlier, hindsight is always an easier 20-20.

But all in all, it seems that the available options have come a long way since Ed LaChapelle's control and forecasting article from 1960, where he outlines the options for avalanche controls as: Artillery fire, Defense structures, Avalanche signal installation, Weather telemetering, Hazard forecasting, and Research. I wonder what the next 48 years will bring.

• Italian Alps Avalanche
• Economics of the Juneau Avalanche
• Global Warming Lawsuit
• Pro Skier Returns after back injury
• Two Snowflakes Alike?

Although winter seems to be over here in Southern California, events continue in the rest of the world. Perhaps the most tragic recent event was the recent fatality of five mountaineers in the Italian Alps. The avalanche apparently descended from a loaded slope above them. Their guide survived, though badly hurt.

Then, returning to the Juneau avalanche aftermath, people are beginning to realize what benefits there might be in analyzing the return period for a climax avalanche. David McClung contributed to the after-analysis at Juneau, pointing out that a bit of money spent on a concrete diverter upslope of the power lines would have saved quite a lot later. Hindsight is 20-20.

In other news, CNN released an article in February describing how the Alaska Native village of Kivalina is suing two dozen oil companies for causing global warming and destroying their native way of life. Much damage has been caused by fall and winter waves coming all the way in to the village where previously ice formed as protection. Reports from the Army Corps of Engineers confirm the damage, and oil, power, and other companies who emit greenhouse gases in Alaska are named in the suit.

The Tahoe Daily ran an article about Roy Tuscany, who burst-fractured his vertebra in 2006 and, with exceptional determination and patience, returned to the slopes this year to ski again. Congratulations - that sure seems to be an unbelievably hard road and something for Roy to be proud of.

And finally, since I'm still moping that summer is ahead of us and not behind, I revisited one of my favorite Slashdot posts on why, by probability theory, two (small) snowflakes out there are probably alike. As the referenced article on Slashdot has since expired, you can read this one from Kenneth Libbrecht on how nano-flakes (the familiar six-sided plate) are actually very much alike, but that once they form more complex structures the probability greatly decreases (and probably disappears).