Cessna 337 N337V accident near Ennis, Montana

Probable cause

The pilot-in-command’s failure to maintain sufficient airspeed while attempting an evasive maneuver from a boxed canyon, which resulted in an aerodynamic stall/spin and impact with mountainous terrain. Contributing to the accident was the pilot-in-command’s failure to monitor the environment before flying into mountainous terrain.

NTSB analysis

The left seat pilot-in-command (PIC) reported that, he passed the controls to the right seat student pilot once they were en route on the accident flight. The rear seat passenger’s postaccident statement indicated that the left seat pilot was at the controls for the duration of the flight; however, he may not have seen the exchange of the flight controls as he was seated behind both pilots at the time. As they were flying southbound on the cross-country flight over a valley about 3,000 ft above ground level, they agreed that they wanted to view a resort in the area. The student pilot then turned the airplane to the southeast towards higher mountainous terrain. After the airplane had entered a boxed canyon, and with a ridge in the airplane’s flightpath that it could not clear, the PIC took control of the airplane and attempted an evasive maneuver to reverse course to exit the canyon. However, during the maneuver, the PIC likely did not maintain sufficient airspeed, which resulted in an aerodynamic stall/spin and subsequent impact with remote mountainous terrain. The PIC reported no mechanical anomalies with the airplane that would have precluded normal operation.

Toxicology results indicated that the student pilot had used cannabis, but likely had metabolized it such that no detectable psychoactive chemicals remained in his blood. The toxicology results and the student pilot’s limited role in the accident flight suggest that the effects of cannabis use were unlikely to have contributed to the accident.

Text from the NTSB. Open the NTSB docket for WPR20LA245 for the full record.