What happened
A military transport flight traveling from Clark Air Force Base in the Philippines to McChord Air Force Base was scheduled to stop at Kadena Air Force Base and Yokota Air Force Base. The C-141 was carrying 16 individuals, including six Marines. During the night portion of the flight, the crew communicated with air traffic control and received instructions to descend through various flight levels, moving from FL370 down toward FL100.
While the aircraft was descending, an air traffic controller misidentified the C-141 as a different Navy aircraft. Consequently, the controller issued a clearance to descend to 5,000 feet, which was below the minimum required altitude for that specific airspace. While flying at approximately 7,000 feet in conditions of low visibility, the four-engine aircraft collided with the slope of Mt. Constance, a peak measuring 7,756 feet, located within Olympic National Park. The impact occurred roughly 150 feet below the mountain's summit and triggered an avalanche. The crash resulted in 16 fatalities and no survivors.
Findings
The investigation determined that the primary factor was a controller error involving aircraft misidentification, which led to an unsafe descent clearance. Additionally, the crew faced significant challenges due to nighttime operations, cloud cover, and a lack of visual ground references, making it impossible to detect the terrain before impact.