I spied an interesting image in a recent issue of Backcountry magazine. Professional skier Nina Hance wore both a Backcountry Access Float avalanche airbag backpack and a Black Diamond Equipment Avalung II artificial air pocket sling. Although wearing both probably lessens risk of injury and death compared with wearing just one, the practice of doubling up has not been widely adopted. Enter the new Black Diamond JetForce avalanche airbag backpack: it is inflated and deflated with a battery-powered fan, which may obviate the need for wearing both devices. The JetForce works to prevent avalanche trauma and snow burial like all airbag backpacks. In addition, great potential exists to delay carbon dioxide displacement asphyxia by creating an artificial air pocket.
Trauma and Burial
Avalanche airbag backpacks have been around in Europe for a three decades. However, adoption in North America has been fraught with difficulties. The packs are costly and heavy. Compressed gas canister has been cuffed with import regulations. US airlines prohibit flying with full canisters: replacing and refilling canisters is costly and time consuming. Multiday trips may obligate a backup canister in case of multiple deployments.
Avalanche airbag backpacks work by two mechanism. First, given the large volume of cushioning surrounding the head and neck, airbag backpacks help minimize trauma, which accounts for 25% of avalanche deaths. Second, more to the point, the inflated airbag increases the volume of a person wearing it. This employs the principal of particle segregation called sifting, often referred to as inverse segregation, when larger particles rising to the top of a collection of moving particles.
Whereas all airbags help prevent trauma and burial, the new JetForce also potentially creates an air pocket. The JetForce uses a fan powered from a rechargeable lithium ion battery to inflate the airbag; after three minutes, the fan reverses to deflate the bag. Until recently, the Avalung was the only commercially-available artificial air pocket device, made in a sling worn over clothing or incorporated into a backpack. For those who survive avalanche from immediate trauma and abrupt suffocation by airway compromise (from snow obstruction or ice mask formation), buried people die from carbon dioxide displacement asphyxia, rebreathing expired air. The Avalung works shunting expired carbon-dioxide-rich air to the back, and drawing in oxygen-rich air through a chest port. Wearing both an Avalung and airbag backpack is a bit laborious: travel in tight or technical terrain can be problematic with a larger, heavier pack and donning and doffing both can be laborious. Thus in addition to helping to prevent trauma and full or partial burial, the Jetforce may—a big unproven hypothesis—help prevent asphyxia.
Compared to similar canister packs, the JetForce weighs a scosh more (the JetForce Halo 28 clocks in at 7.5 pounds) and cost on the upper end ($1250-$1300). But JetForce backpacks can be taken on an airplane. The lithium-ion battery allows at least 4 deployments or 120 hours of standby with a single charge. Practice is free: I deployed the JetForce multiple times in my living room and at a Mount Hood Sno-park.
Canister airbag backpacks are still a great option. Fortunately, cost is decreasing, availability is increasing, and refilling and replacing canisters is easier. I’ve refilled and exchanged canisters in Chamonix, Davos, and Portland, Oregon. Moreover, Scott Alpride system uses carbon dioxide and argon in small, inexpensive, airline-friendly cartridges similar to those used in personal flotation devices.
It is too early to tell if the JetForce will become standard issue. But the added function of a potential air pocket, may dramatically increase safety. Aside from avalanches, a possibility exists that air pocket created by the JetForce might help delay non-avalanche deep snow and tree well submersion asphyxia.