Amateur-built Odyssey accident near Arlington, Washington, November 20, 2020

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

The pilot departed from the airport with moderate-to-heavy storms over the departure area. He flew a path through the storms on a north-northeast track for about 50 nautical miles (nm). Automatic dependent surveillance-broadcast (ADS-B) radar track data discontinued briefly and when the track data were reacquired, they showed the airplane in a tight 360° right turn. The airplane then continued southwest for about 5 nm before turning to the west and then north in the vicinity of a small area of rain showers. The airplane entered a right spiral turn until track data were lost. A postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Toxicology testing indicated that the pilot used two sedating drugs at some point before the flight but the specimens available for testing were insufficient to readily reflect the antemortem peripheral blood levels. Whether impairment by the pilot’s use of a combination of sedating drugs contributed to the circumstances of this accident could not be determined from the available information. The ADS-B radar data and damage to the airplane were consistent with a loss of control; however, the reason for the loss of control could not be determined.

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.