What happened
During a night personal flight, the pilot and a passenger departed the airport, after which the passenger noted the cabin temperature was high. In response to this, the pilot contacted air traffic control to request a return to the airfield. The controller authorized the landing and offered assistance, which the pilot declined without declaring an emergency.
As the aircraft type was maneuvering on the downwind leg of the traffic pattern, the cockpit voice recorder captured 11 separate warnings from the enhanced ground proximity warning system (EGPWS), covering terrain, obstacles, and stalls. The aircraft eventually struck trees and the ground, resulting in a post-impact fire. There were 2 fatalities resulting from the accident. Post-accident inspections of the aircraft showed no mechanical failures or malfunctions that would have prevented standard operation.
Findings
The investigation identified several contributing factors to the loss of control. The pilot was managing a high workload while flying at a low altitude at night, which included navigating the traffic pattern, monitoring inbound traffic, and addressing the cabin heat issue.
Toxicological analysis of the pilot's blood revealed the presence of methylone, a stimulant. Given the concentration of 0.34 ug/ml detected, investigators determined that the pilot was likely impaired by methylone, which can negatively impact cognitive performance and information processing. While the pilot had a history of heart disease and had used marijuana at an unspecified time prior to the flight, there was no evidence of a recent cardiac event or impairment from prescription medications or prior cannabis use. There was also no evidence that the passenger interfered with the flight controls.