D 13/15 SUN DANCER N588V accident near Boulder City, Nevada

Probable cause

The pilot’s failure to maintain clearance from powerlines while maneuvering, which resulted in a wire strike and impact with terrain. Contributing to the accident was the pilot’s impairment from alcohol consumption and his use of diphenhydramine before the flight.

NTSB analysis

The pilot departed in the motorglider and impacted powerlines and terrain near the airport shortly thereafter. An individual who interacted with the pilot before the accident flight reported that “something was off” and that the pilot “seemed a little woozy.” A witness near the accident site reported seeing a low-flying airplane and stated that the engine sounded normal; however, she did not see the accident. Postaccident examination of the glider revealed no evidence of mechanical malfunctions or anomalies that would have precluded normal operation.

Toxicological testing of the pilot detected impairing levels of ethanol and diphenhydramine consistent with the pilot having recently consumed alcohol before the flight. Therefore, it is likely that the pilot’s impairment from consuming alcohol contributed to his failure to maintain clearance from power lines.

Diphenhydramine is available over-the-counter in many products used to treat colds, allergies, as well as insomnia because of its strong sedating effects. Patients are advised not to use diphenhydramine with ethanol because that increases drowsiness. Diphenhydramine alone would have caused drowsiness and diminished reaction time and performance; in combination with ethanol, these effects would be enhanced. Thus, the effects from the pilot’s use of diphenhydramine contributed to this accident.

Text from the NTSB. Open the NTSB docket for WPR22FA109 for the full record.