Accident Overview
On March 11, 2008, about 1050 Alaska daylight time, a wheel ski-equipped Cessna 180 airplane, registration N66036, sustained substantial damage when it collided with snow-covered terrain approximately 16 miles east-northeast of White Mountain, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91. The airline transport certificated pilot reported no injuries, while the two passengers received minor injuries.
Flight Details
The flight originated at Koyuk Airport, Koyuk, Alaska, about 1020, en route to White Mountain. No flight plan was filed. The pilot was volunteering his airplane in support of the annual Iditarod sled dog race. According to the pilot, he departed from Koyuk with several other airplanes. The weather conditions at departure were reported as having a ceiling of about 3,000 feet and visibility of 10 miles.
Weather and Environmental Factors
As the flight progressed toward White Mountain, the pilot was in cruise flight at 2,500 feet mean sea level (msl). The route crossed low hills east of the airport, and the pilot reported that visibility began to deteriorate. He descended to about 2,000 feet msl and suddenly flew into whiteout conditions. The airplane collided with a mountain ridge at an elevation of about 2,000 feet msl and overturned.
A pilot who flew to the site shortly after the accident reported difficulty seeing the ridge line. He stated that visibility was good, about 5 miles, but the ridge line was relatively horizontal without contrasting features, making it difficult to identify against the sky. The Federal Aviation Administration’s Aeronautical Information Manual (AIM), Section 7-5-13, notes that whiteout occurs when a person becomes engulfed in a uniformly white glow, often due to blowing snow, dust, sand, mud, or water. The AIM further describes flat light as an optical illusion that can obscure terrain features and lead to a whiteout environment rapidly.
Wreckage and Damage
The airplane received structural damage to the wings, landing gear, and fuselage.