What happened
The pilot departed from Butte, Montana, without obtaining a preflight weather briefing. While en route at flight level 180 toward Salmon, Idaho, the aircraft encountered instrument meteorological conditions and icing. The pilot attempted to avoid these conditions by climbing to flight level 200.
During the climb, the pilot reported encountering severe turbulence associated with developing cumulonimbus activity. Control of the aircraft was subsequently lost, resulting in a descent and ground impact.
Findings
The investigation highlighted several critical factors contributing to the accident:
- The pilot failed to obtain a preflight weather briefing prior to departing both Butte, Montana, and Salmon, Idaho.
- The decision to fly into known icing and instrument conditions without adequate preparation.
- Encountering severe turbulence associated with cumulonimbus activity during the climb.
Safety message
Pilots are reminded of the importance of obtaining a comprehensive preflight weather briefing before departure. Understanding weather patterns, particularly regarding icing and thunderstorm development, is essential for safe flight planning and execution. Avoiding known hazardous weather conditions through proper planning and real-time decision-making can prevent loss of control incidents.