Federal investigators have concluded that the December 1st crash of a private plane in the central mountains of Idaho that killed a San Jose man and four members of his family was caused by icy conditions that led to engine failure. According to the San Francisco Chronicle, a National Transportation Safety Board report that says the single-engine Beechcraft Bonanza piloted by Dale Smith was not suited for the weather conditions. Investigators could not determine whether Smith had obtained weather information before the flight. The crash near Johnson Creek airstrip killed the 51-year-old Smith, his son Daniel, his daughter-in-law Sheree, daughter Amber and her fiancé, Jonathan Norton. The flight had taken off from Baker City and was headed to Butte Montana.