What happened
During the initial climb phase of flight, the airplane experienced an abnormal pitch-up attitude accompanied by significant wing rocking. The aircraft subsequently settled back toward the ground and impacted a snowbank, resulting in a nose-over position. The pilot reported that frost was present on the wings prior to departure but stated that he had brushed it off before starting the engine.
The investigation
A post-accident examination of the wing's upper surface revealed that frost remained on the wings despite the pilot's claims. Analysis of the cargo and fuel load indicated that the airplane weighed 3,700 pounds at the time of the accident. This weight exceeded the certified gross weight limit of 3,600 pounds by 10 percent.
Findings
The combination of excess weight and frost on the wings critically degraded aerodynamic performance. The residual frost disrupted airflow over the wing surfaces, reducing lift generation capacity at a time when the aircraft was already operating beyond its maximum certified limits. These factors contributed to the inability to maintain controlled flight during the critical takeoff phase.
Safety message
Pilots must ensure that wings are completely free of frost, ice, or snow before flight. Additionally, accurate weight and balance calculations are essential to ensure the aircraft remains within certified operating limits during all phases of flight.