Aircraft Stall and Terrain Impact During Return to Departure Airport (N4765G)

Incident Overview and Radio Issue After takeoff, the pilot was instructed to switch from the airport tower frequency to the departure control frequency. Radio transmissions indicated the aircraft's radio was operating normally on the tower frequency, but the pilot could not change to the departure control frequency as directed. The pilot requested and received approval to return to the departure airport. During the return flight, the pilot continued to troubleshoot the radio problems, as indicated by radio transmissions. ## Flight Path and Stall The aircraft's flight track showed the pilot flew directly toward the runway aimpoint about 1,000 feet from, and perpendicular to, the runway during the left base turn to final. The aircraft descended as low as 200 feet pressure altitude. The pilot then made a right turn about 0.5 miles from the runway, followed by a left turn toward the runway. A pilot witness near the accident location observed the aircraft maneuvering and predicted it was going to stall. The aircraft's airspeed decreased to about 53 knots during the left turn, and video showed the bank angle increased before the aircraft aerodynamically stalled and impacted terrain. ## Post-Accident Findings Post-accident examination of the airframe, engines, and review of recorded engine monitoring data revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. Toxicology testing showed the pilot had diphenhydramine, a sedating antihistamine, in his liver and muscle tissue. While therapeutic levels could not be determined, side effects such as diminished psychomotor performance from his use of diphenhydramine were not evident from operational evidence. Thus, the effects of the pilot's use of diphenhydramine was not a factor in this accident. The accident is consistent with the pilot becoming distracted by the reported non-critical radio anomaly and turning the base leg of the traffic pattern too early during his return to the airport. The pilot then failed to maintain adequate airspeed and proper bank angle while maneuvering from base leg to final approach, resulting in an aerodynamic stall and impact with terrain.