Mooney M20M N40KA accident near Snoqualmie, Washington

Probable cause

The pilot’s decision to fly the airplane into known icing conditions, which resulted in a loss of airplane control and collision with terrain.

NTSB analysis

After a 6-year hiatus from flying, the pilot had just purchased the airplane. The morning of the accident flight, he filed an instrument flight rules (IFR) flight plan and received a weather briefing that identified icing conditions along the planned flight route. The pilot departed the airport about 0842 and planned to climb to an altitude of 17,000 ft mean sea level (msl). About 0901, the controller cleared the pilot to depart 14,000 ft msl and climb to 17,000 ft msl. Subsequently, the controller informed the pilot of multiple PIREPs for icing conditions from 12,000 ft msl to 18,000 ft msl and offered the pilot an altitude of 19,000 ft msl to get above the icing, which the pilot accepted.

About 0904, after climbing to an altitude of 16,300 ft msl, the airplane began a rapid descent with a series of tight spiral turns. Communication between the controller and the pilot became broken and unreadable. An airplane operating in the area relayed to the controller that the pilot reported being out of control. Shortly after 0910 radar contact was lost, and the airplane impacted terrain. It is likely that the accident airplane encountered structural icing and that the erratic turns coupled with a rapid descent rate were indicative of the pilot’s loss of airplane control, which resulted in a collision with terrain.

Postaccident examination of the engine and airframe revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The supplement to the pilot’s operating handbook and the airplane flight manual contained a warning that stated, “INTENTIONAL FLIGHT INTO KNOWN ICING IS PROHIBITED.” The pilot’s logbook contained no record of a recent instrument proficiency check.

Text from the NTSB. Open the NTSB docket for WPR22FA023 for the full record.