Ercoupe 415 N3956H accident near Rogersville, Tennessee

Probable cause

The pilot's failure to maintain a proper glidepath on approach, which resulted in an inflight collision with trees and terrain. Contributing to the accident was the pilot’s use of an impairing medication.

NTSB analysis

During a short local flight, the pilot was maneuvering the airplane in the vicinity of the airport at an altitude lower than was typical, and a bank that was steeper, than a witness who was used to seeing the airplane had viewed in the past. Two pilot-rated witnesses described that later when returning to the airport, the airplane's engine sounded normal as the airplane entered the airport traffic pattern to land, but that its altitude was too low on final approach. The airplane then suddenly banked right when it struck the tops of trees before impacting terrain.

While the wreckage was partially consumed by a post-impact fire, postaccident examination of what remained from the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Additionally, damage signatures observed on the propeller and the witness accounts indicated that the engine was likely operating normally at the time of the accident. Given the available information, it is likely that the airplane struck trees after the pilot descended too low while on final approach to the runway. Toxicological testing identified the sedating antihistamine diphenhydramine at therapeutic levels in samples from the pilot. This medication is known to cause psychomotor slowing, sedation, and impaired cognition. It is possible that the pilot’s performance was impaired, which could have contributed to his failure to maintain a proper glidepath while approaching the runway.

Text from the NTSB. Open the NTSB docket for ERA20LA183 for the full record.