What happened
On the morning of an unspecified date in 2002, a de Havilland DHC-3 Otter, registration C-FLGA, departed from Lake de l'Avion, Quebec, destined for a hunting camp along the Aguanish River. The aircraft, operated by Derpass Aviation Inc., was carrying the pilot and three passengers. While navigating the river toward the destination, the pilot encountered low cloud ceilings that obscured the tops of the nearby mountains.
Upon reaching the destination area, the pilot attempted a 360-degree turn to survey the landing site. During this maneuver, the aircraft drifted toward a steep mountainside. The aircraft struck the treetops, and the left wing was subsequently torn from the fuselage, causing the plane to flip and crash upside down on the rugged terrain. The impact resulted in three fatalities among the passengers, while the pilot survived the crash and was rescued the following morning.
The investigation
Investigators examined the aircraft's mechanical condition and the pilot's flight history. The aircraft was found to be well-maintained and operated within weight limits. Technical analysis of the wreckage showed the engine was producing high power at the time of impact, and the control cables remained intact despite the loss of the left wing. Data from the onboard GPS confirmed the flight path followed the Aguanish River and recorded the bank angles during the final turn.
While the pilot reported feeling vibrations during the turn which he attributed to wake turbulence, manufacturer experts determined that crossing one's own wake turbulence in such a manner would have had a negligible effect on the flight. Investigators also reviewed the weather conditions, noting that while visibility was good, the low cloud base in the mountainous terrain likely hindered the pilot's ability to maintain adequate clearance from the slope.