Pegasus QUANTUM accident near Fort Atkinson, Wisconsin, August 9, 2017

The NTSB's narrative final · quoted from the NTSB record

The sport pilot (who was not an instructor) and the student-pilot-rated passenger were making a local personal flight in the weight-shift-control (WSC) aircraft. The pilot was seated in the front seat, and the passenger was seated in the rear seat. A flight instructor observed the WSC aircraft make several stable visual approaches to a grass runway. The last approach was unstable, which the flight instructor attributed to the passenger attempting to fly the approach. A go-around was initiated, which transitioned to a diving left turn that continued to impact with a river. Postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The aircraft's two "training bars," which were designed for use by a flight instructor flying from the rear seat, were each deformed to the left, consistent with the passenger gripping them as the aircraft impacted the river.  The passenger had recently accomplished a solo flight in a fixed-wing airplane, which has reverse control inputs from a WSC aircraft. The passenger likely made incorrect control inputs during the go-around, due to negative transfer of learning from his fixed-wing airplane training. Because of the position of the training bars, the front-seat pilot would have been unable to see the inputs being made by the person in the rear seat. Although toxicological testing indicated that the pilot had used diphenhydramine at some point before the accident, the blood levels of this drug can change postmortem, and the pilot's blood levels at the time of the accident may have been significantly lower than the therapeutic range. Based on the accident scenario and available information, the pilot's use of diphenhydramine most likely did not contribute to the accident.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.