CEN23FA270 · Icon A5

The flight of two airplanes was in cruise flight on a north heading about 50 ft above a lake when the pilots agreed to fly closer to the west shore of the lake. The pilot of the second (non-accident) airplane initiated a climb and turned toward the west. In his peripheral vision, he noticed a splash and thought the pilot of the amphibious light sport airplane had landed on the water. He made several radio calls to the accident pilot with no response. A witness reported seeing both airplanes fly about 30–40 ft above the surface of the water; however, they did not see the accident. The airplane was destroyed when it impacted the water and became submerged in about 26 ft of water. Examination of the wreckage indicated that the airplane impacted water in a left-wing-low attitude. Further examination revealed no evidence of preimpact failures or malfunctions that would have precluded normal operation. Damage to the propeller indicated that the engine was likely under power at the time of the accident. The pilot’s autopsy revealed cardiovascular disease that would have increased his risk of experiencing a sudden impairing or incapacitating cardiac event, such as arrhythmia, chest pain, or heart attack. There was no autopsy evidence that such an event occurred; however, such an event does not leave reliable autopsy evidence if it occurs shortly before death. Toxicology results indicated that the pilot had used a cannabis product. However, the precise timing of his last cannabis use, and whether it caused significant impairing effects at the time of the accident, could not be determined from the measured levels of delta-9-THC and its metabolites.

Verbatim NTSB analysis and probable cause from the NTSB dataset