What happened
On the afternoon of the accident, a Cessna 172M, registration C-GRGW, was conducting a routine pipeline patrol in the foothills of Alberta. The flight, operated by Alta Flights Limited, had been modified to include additional fuel tanks for extended-range operations. While performing low-level reconnaissance near the Chain Lakes Reservoir, the aircraft was circling a stream crossing at Chaffen Creek.
During these maneuvers, which involved low-altitude left-hand turns, the aircraft entered a spin and began a rapid descent. The aircraft struck the terrain at 1734 Mountain Daylight Time. The pilot, the sole occupant, sustained fatal injuries. The impact destroyed the aircraft, though no post-impact fire occurred. Witnesses on the ground observed the event and were able to reach the site on foot shortly after the crash.
The investigation
Investigators examined the wreckage and analyzed flight data from the aircraft's SkyTrac GPS-based flight-following system. The investigation focused on the aircraft's handling during the period when the pilot was performing photography. Digital photos recovered from a handheld camera showed the aircraft was banking at approximately 45 degrees at an altitude of about 350 feet above ground level just before the accident.
Technical analysis of the engine and airframe showed no mechanical failures in the flight controls. While the engine's power setting was difficult to determine during the descent, evidence suggested the engine was producing significant power at the moment of impact. The aircraft's center of gravity was noted to be near the aft limit due to the configuration of the auxiliary fuel tanks.
Findings
- The aircraft entered an aerodynamic stall and spin for undetermined reasons while maneuvering at low altitude.
- The pilot managed to stop the rotation of the spin, but the low altitude left insufficient height to recover from the resulting descent.
- The task of performing detailed photography while flying at low altitudes increased the risk of pilot distraction from primary flight controls.
- The use of real-time GPS flight-following data was instrumental in accurately locating the accident site when the emergency locator transmitter signal was initially obscured by terrain.