One might think that thermo imaging technology might be a vital tool while searching for warm bodies in snow, but you would be wrong.
While infrared cameras are very useful in some wilderness rescue operations they rely on surface temperatures to locate victims. The cameras work by using special lens that only allow in infrared light and a sensor that can detect the infrared spectrum. Presumably the victims of an avalanche would be buried and their thermo register would be hidden from the lens of the camera, but if they had even a finger poking out the cameras might be able to provide a location.
With that said, this BBC article points out that they would be effective in searching avalanche prone areas for missing persons at night avoiding risk to rescuers. It should also be noted that these cameras work in some low visibility conditions including mist and rain so if someone was stranded on a mountain and not visible to the naked eye they might be of use. For this reason alone if you consider the cost of a helicopter search and rescue operation in the mountains, the addition of an infrared camera seems like a justified purchase.