On April 17, 2001, about 1500 Alaska daylight time, a Cessna 207 airplane, N6476H, sustained substantial damage when it collided with snow-covered terrain about 8 miles west of Mountain Village, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country government flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the State of Alaska, Department of Public Safety. The private certificated pilot, the sole occupant, received minor injuries. Instrument meteorological conditions prevailed in the area of the accident. VFR flight following procedures were in effect. The flight originated at the Kotlik Airport, Kotlik, Alaska, about 1430. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on April 20, 2001, the supervisor for the State of Alaska's aircraft section reported that the pilot was returning to Bethel, Alaska, from Kotlik, after conducting a death investigation. The supervisor reported the pilot said he was flying along the north side of the Yukon River, and decided to cross to the south side due to concerns of colliding with any potential opposite direction aircraft. The frozen river was about one mile wide, and snow showers were present. The pilot told the supervisor that during the turn, he lost visual contact with the snow-covered terrain, and collided with the ground at a shallow angle. After the collision, the pilot was able to begin walking toward Mountain Village, and was met by rescue personnel traveling on snow machines. The airplane received damage to the fuselage, wings, and engine. In the Pilot/Operator report (NTSB form 6120.1/2) submitted by the pilot, the pilot indicated the weather conditions at the accident site were less than 1/4 mile visibility in blowing snow, with scattered clouds at 300 to 400 feet above the ground. In the narrative portion of the report, the pilot reported he entered a "whiteout" and lost all ground reference. He also indicated that about 0900, he attempted to fly to Kotlik, but returned to Bethel, Alaska, due to poor weather conditions. He departed for Kotlik again about 1300. The pilot indicated he checked the reported weather conditions in the area of his flight by monitoring the automated weather observation system (AWOS) at Bethel, St. Mary's, Alaska, and Emmonak, Alaska. He telephoned village residents at Kotlik, and St. Mary's, and also talked via radio to a pilot in the area of Emmonak. The closest official weather observation station is St. Mary's, Alaska, which is located 19 nautical miles east of the accident site. On April 17, 2001, at 1455, an Aviation Routine Weather Report (METAR) was reporting in part: Wind, 220 degrees (true) at 7 knots; visibility, 9 statute miles; clouds and sky condition, few at 1,200 feet, 3,900 feet scattered; temperature, 36 degrees F; dew point, -13 degrees F; altimeter, 29.88 inHg. A METAR at 1455 from Emmonak, Alaska, which is located 41 nautical miles northwest of the accident site, was reporting in part: Wind, 010 degrees (true) at 7 knots; visibility, 5 statute miles; clouds and sky condition, few at 100 feet, 1,600 feet overcast; temperature, 32 degrees F; dew point, 29 degrees F; altimeter, 29.85 inHg.