Avalanche rescue is the time-critical process of locating and extracting people buried by an avalanche, almost always carried out by the victims' own companions because professional rescue is too slow. The standard sequence is beacon search, probe to pinpoint, and strategic shoveling, all done within minutes — survival odds fall sharply after about 15 minutes of burial, so speed, gear, and practiced skill are vital.
An avalanche shovel is a compact, collapsible shovel with a sturdy metal (usually aluminum) blade, carried by every backcountry traveler to dig out a buried victim quickly and to dig snow pits for snowpack assessment. Avalanche debris sets up dense and hard, so a strong metal blade is essential — plastic shovels are inadequate. It's the third piece of the beacon-shovel-probe rescue kit.
An avalanche probe is a long, collapsible pole (typically 240–320 cm) that a rescuer assembles and pushes into the snow to pinpoint a buried victim's exact location and depth after a beacon search has narrowed it down. Probing confirms the precise spot and depth so the team can dig efficiently, making the probe an essential part of the beacon-shovel-probe rescue kit.
An avalanche airbag is a backpack with a large inflatable balloon that the user deploys by pulling a trigger when caught in an avalanche. By increasing the wearer's volume, it uses the 'inverse segregation' effect to help keep them nearer the surface of the moving debris, reducing the chance of deep burial. It improves survival odds but does not guarantee safety and is no substitute for avoiding avalanches.
An avalanche beacon (transceiver) is a body-worn device that normally transmits a radio signal and can switch to receive mode to locate a buried victim's beacon during a rescue. Together with a probe and shovel, it's essential safety gear for backcountry travel: everyone in the party wears one, and fast, practiced use is critical because buried victims' survival odds drop sharply after about 15 minutes.
Depth hoar is a weak layer of large, faceted, sugary snow crystals that forms near the base of the snowpack, created by strong temperature gradients in shallow, cold snow. These poorly bonded grains can persist for much of the season and act as a stubborn weak layer for deep, destructive persistent-slab avalanches, making depth hoar one of the most dangerous structures in the snowpack.
The snowpack is the total accumulation of snow on the ground, built up in layers from successive snowfalls and weather events. Its internal structure — strong and weak layers and the bonds between them — determines avalanche danger, because a cohesive slab over a buried weak layer is what produces slab avalanches. Understanding the snowpack through observation and testing is central to avalanche forecasting and safe travel.
A wind slab is a dense, cohesive layer of snow formed when wind transports and deposits snow onto leeward (downwind) slopes, packing it into a stiff slab over softer or weaker snow. Wind slabs are a common avalanche problem, especially near ridgelines and in gullies, and can be very reactive soon after forming. Signs include smooth, pillowy, chalky, or drum-like snow and visible wind drifting.
A persistent slab avalanche releases on a persistent weak layer — such as buried surface hoar, facets, or depth hoar — that can linger in the snowpack for days, weeks, or even months. These are especially dangerous and hard to predict because the weak layer is buried and stubborn, slides can be triggered remotely or from a distance, and they can propagate far and break large. They are a leading cause of avalanche fatalities.
A wet avalanche occurs when liquid water from melting (warm temperatures, strong sun) or rain saturates and weakens the snowpack, causing wet, heavy snow to release. Wet avalanches move slower than dry slides but are dense and destructive, and their timing is often predictable — rising with daytime warming and spring melt — making timing and observation key to avoiding them.