Colorado mountain flying: Crashes and weather

Almost half of all crashes in a mountainous area within 50 nautical miles of Aspen, Colorado involved one or more weather-related factors. The weather factor most commonly mentioned (48 of 113 weather-related cases) in reports provided by the National Transportation Safety Board was high density altitude. A rarely recognized phenomenon that appeared to be a factor in five crashes was downslope or gravity winds flowing downhill against prevailing winds aloft, when pilots were flying in an easterly direction and anticipating updrafts on the western slopes of the Continental Divide. Pilots generally have inadequate training in understanding mountain weather and its many implications for flying. Moreover, they are provided with too little information on the limitations of their aircraft in relation to density altitude. Pilots need specific knowledge and their own local weather forecasting techniques in order to travel safely among mountains. Pilot training should include more sophisticated weather instruction that reflects current knowledge. In-depth research must be undertaken into local mountain weather systems and their interaction with wider atmospheric patterns.