QUICKSILVER Sport 2S — Henderson, LA

What happened

The pilot was conducting a personal flight with a passenger when the airplane impacted trees and terrain. There were no witnesses to the accident. During the final 27 seconds of recorded GPS track data, the pilot maintained a north course, descended from 816 to 778 ft mean sea level, and decelerated to 43 mph calibrated airspeed. The aerodynamic stall speed at maximum gross weight was 38 mph. The final recorded position was about 0.5 miles south of the accident site. Although there was no GPS track data for the final portion of the flight, based on the last recorded data point and the accident location, the airplane descended about 761 ft during the final 0.5 mile of the flight. In addition to the steep descent path, the airplane impacted terrain in a nose down pitch attitude consistent with an aerodynamic stall. Postaccident examination revealed no evidence of a mechanical malfunction or failure that would have precluded normal operation of the airplane before it collided with trees and terrain.

The pilot’s autopsy did not identify any natural disease that would have contributed to the accident; however, toxicology testing detected the presence of the inactive metabolite of clonazepam in heart blood and liver tissue. Considering the half-life of clonazepam, the detected level of the inactive metabolite suggests the pilot’s use of the medication likely occurred several days before the accident; thus, it is unlikely that his use of clonazepam was a factor in the accident.

Toxicology testing also identified the sedating antihistamine diphenhydramine at a level above its therapeutic range in the pilot’s blood. Considering that postmortem redistribution of diphenhydramine may result in central levels being two-to-three times higher than peripheral levels, the circulating level was likely in the therapeutic range at the time of the accident. Diphenhydramine causes marked sedation and carries the warning that use may impair mental or physical ability required to perform potentially hazardous tasks. Thus, it is reasonable to consider diminished reaction times and flying performance attributable to the use of sedating medication. It is therefore likely that the impairing effects of diphenhydramine contributed to the accident.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.