What happened
At a non-towered airport operating under visual meteorological conditions, two aircraft were departing from intersecting runways. A Cessna 3ally 340A was performing an instrument flight rules cross-country departure from runway 4, while a Cessna 172M was conducting a visual flight rules repositioning flight from runway 36. The two runways converged near their departure ends.
While both pilots had reportedly announced their intentions on the common traffic advisory frequency, the occupants of the Cessna 172M stated they did not hear the transmission from the Cessna 340A. Airport surveillance footage showed the Cessna 172M had just lifted off and was approaching the runway intersection when the Cessna 340A was positioned just above runway 4. As the Cessna 340A began a left climbing turn with an increasing bank angle, the aircraft rolled inverted and struck the ground in a nose-low and left-wing-low attitude. The Cessna 172M sustained no damage and completed its flight safely. The accident resulted in 2 fatalities.
Findings
Investigation of the Cessna 340A wreckage showed no evidence of mechanical failures that would have prevented normal flight. It is believed the aircraft was flying at its published takeoff and climb speed of 93 knots. As the pilot increased the bank angle, the aircraft likely reached a critical angle of attack, leading to an aerodynamic stall.
While toxicological analysis of the pilot's liver revealed the presence of atorvastatin, naproxen, and diphenhydramine, the levels of the latter could not be quantified to determine if impairment was a factor. No issues were identified with the airport's radio equipment or the communication between the Cessna 340A and air traffic control.