Airplane Subsequently Climbed To 16,300 Ft, Then Began A Rapid Descent To 11,300 Ft With Erratic Turns

Location: North Bend, WA Accident Number: WPR22FA023
Date & Time: October 28, 2021, 09:10 Local Registration: N40KA
Aircraft: Mooney M20M Injuries: 1 Fatal
Flight Conducted Under: Part 91: General aviation – Personal

On October 28, 2021, about 0911 Pacific daylight time, a Mooney M20M, N40KA, sustained substantial damage when it was involved in an accident near, North Bend, Washington. The private pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot filed an instrument flight rules (IFR) flight plan with a planned route from Arlington Municipal Airport (AWO), Arlington, Washington, to Magic Valley Regional Airport (TWC) Twin Falls, Idaho. A review of preliminary air traffic control (ATC) communications and radar data provided by the Federal Aviation Administration (FAA) revealed that the airplane departed AWO about 0842.

The airplane subsequently climbed to 16,300 ft, then began a rapid descent to 11,300 ft with erratic turns. The airplane was over mountainous terrain approximately 47 miles southeast of the departure airport and descended through 5,400 ft when a simultaneous loss of radar and communication occurred, shortly after 0910. ATC services were provided by Seattle Air Route Traffic Control Center (ARTCC) and Seattle Terminal Radar Airport Control (TRACON). This aircraft was the subject of an ALNOT. The airplane wreckage was located in densely wooded mountainous terrain. The wreckage debris was about 21 ft in length and 15 ft wide. The northwest most point of the wreckage consisted of the engine, and propeller sections, which sustained impact and thermal damage. All three propeller blades were liberated from the hub and revealed signatures consistent with engine power during impact. The cabin and fuselage were consumed by post-impact fire. The vertical and horizontal stabilizer, rudder and elevator sections were present and formed the southwestern perimeter of the wreckage. The TKS system affixed to the leading edges of the vertical and horizontal stabilizer were present.

A review of the meteorological conditions that existed the day of the accident revealed instrument meteorological conditions. AIRMET Z was active for light to moderate rime icing, and clear ice conditions. PIREPS confirmed the icing conditions and low-level turbulence in the vicinity of the accident site.

The supplement to the pilot’s operating handbook and FAA approved airplane flight manual contained a warning that stated, “INTENTIONAL FLIGHT INTO KNOWN ICING IS PROHIBITED.”