On January 9, 2002, a Cessna 210L (registration N1713X) was involved in an aviation accident near Great Falls, MT. Investigators recorded the probable cause as: The pilot's intentional continuation of a visual flight rules (VFR) flight into instrument meteorological conditions (IMC), and his failure to maintain clearance from the terrain. Factors include low ceilings, snow, mountainous/hilly terrain, and trees. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
While flying in mountainous terrain, a pilot encountered lowering ceilings and snow, deviated from course, and struck trees during a course-reversal turn after entering clouds.
Background
A pilot attempted to fly through an area of mountainous or hilly terrain. Prior to departure, the pilot received two weather briefings. The earlier briefing indicated that the planned route would be VFR at the time of departure. A second briefing, received approximately 90 minutes before departure, stated that the route would be mostly VFR, but an update showed areas of possible mountain obscuration.
Flight Events
During the flight, the pilot encountered lowering ceilings and snow. As he continued, he deviated from his planned course. Initially, he was able to remain below the clouds, but eventually entered an area where his attempts to maintain clearance from the terrain resulted in the aircraft entering the bottom portion of the cloud layer. Because he was having difficulty keeping visual contact with the terrain, he initiated a course-reversal turn. During the turn, the aircraft clipped a tree top and then impacted a number of other trees.