Weather can really do people in quickly. For the high-angle incidents that we respond to, it's usually someone who will climb up a mountain but cannot get down, or they may not have the proper mountaineering training and they either get stuck or fall. No mountain is too high. However, weather and environmental conditions often present obstacles. For example, if we cannot get a helicopter into the site, we may have to enter on foot, which may mean 6 hours to reach a scene.
Access is really the only problem.
Other than that, there is no place that we cannot go. We're trained to be specialists in high angle, vertical and high altitude situations, deal with the most severe weather conditions and be self-sufficient for a minimum of two days without any resources. Unfortunately, rescue helicopters in the United States are underpowered and small. They tend to be either Bell 500s or 206L Rangers, which are quite small. Often, they are loaded down with medical and other equipment, with usually one to two people inside with their personal gear.