Accident Details
A Wildlife Observation Services Inc. Cessna 337 (registration C-GGDW, serial number 337-0153) was on an aerial fire patrol and wildlife survey with a pilot and a biologist on board. The aircraft was based in Grande Prairie, Alberta. At 1437 mountain daylight time, the pilot lost control of the aircraft during a low-level turn approximately 15 nautical miles west of Beaverlodge, Alberta. The aircraft descended steeply through trees, skidded, and came to rest at the edge of a beaver pond.
The aircraft was substantially damaged. The pilot was fatally injured, and the biologist, seated in the front right seat, sustained serious injuries. The emergency locator transmitter (ELT) did not activate; however, locating the aircraft and survivor was facilitated by global positioning system tracking equipment installed in the aircraft and monitoring software used by Alberta Sustainable Resource Development (ASRD) flight following personnel.
Flight Information
The primary mission was a fire patrol, with a secondary objective to conduct a Trumpeter Swan cygnet survey if circumstances permitted. The pilot arrived at Grande Prairie airport at 1300 for pre-flight inspection. They departed at 1347. The pilot had not communicated to the chief pilot that the flight would involve a low-level wildlife survey.
The aircraft first appeared on NAV CANADA radar at 1347:46 and remained on radar until the accident. It was not receiving control services. The last radar return with altitude readout was at 1437:05, showing an altitude of 2900 feet asl, approximately 1500 feet horizontally from the accident site, on a heading of 078° magnetic with a ground speed of 80 knots.
The wreckage trail indicated the aircraft struck trees in an approximately 40° left-wing-low attitude, about 40 feet above ground. The trees were 35 to 50 feet tall. The descending flight path angle was approximately 45°. The aircraft skidded and tumbled approximately 80 feet across the shoreline after initial ground impact, coming to rest on a small peninsula jutting into the pond. The total wreckage trail length was approximately 136 feet. Impact forces were primarily to the left side.
Pilot and Occupants
The pilot was licensed, certified, and qualified in accordance with regulations. He had approximately 580 hours total time, with 105 hours on the Cessna 337. He was hired by Wildlife Observation Services Inc. in May 2008 and completed training and a pilot proficiency check on 17 July 2008. He had completed seven wildlife survey flights after starting the ASRD contract.
Both occupants were wearing three-point lap and shoulder harnesses. Neither wore a helmet. The autopsy report identified blunt cranial trauma as the immediate cause of death, consistent with ground impact on the left side. The cabin space in the front right area was not compromised, but impact forces caused multiple fractures and lacerations to the biologist.
Rescue and Search
Aircraft under contract to ASRD are required to check in every 30 minutes. The pilot made a check-in call at 1419. At 1454, ASRD attempted to call C-GGDW after a missed check-in. At approximately 1525, ASRD commenced emergency procedures. By approximately 1650, flight followers disseminated the last recorded position from resource tracking software (RTS), which used GPS coordinates broadcast via satellite from a portable unit the biologist had brought. By 1715, RCMP and Rescue Coordination Centre were advised. No ELT signals were received. The aircraft was located at 1925, and aeromedical evacuation occurred at 2035.
The ELT antenna was mounted on the top surface of the inboard end of the right wing. The antenna cable had pulled out of connectors at both ends during impact, preventing signal transmission. The ELT unit itself functioned properly when tested.
Weather and Aircraft
Weather at Grande Prairie: few clouds at 7000 feet agl, light wind from southwest, temperature 30°C, altimeter 29.75 inches of mercury. Density altitude was 5509 feet for an altitude of 2850 feet asl (average aircraft altitude just before impact).
The aircraft was a 1967 Cessna 337 with a Horton STOL kit installed in 1994 (STC SA937CE), consisting of leading edge cuffs, stall fences, droop wing tips, and vortex generators. The STC did not require amendments to the flight manual for stall speeds. Records indicated the aircraft was certified, equipped, and maintained in accordance with regulations, and was within load and center of gravity limits. No airframe failure or system malfunction was found. The aircraft was configured with flaps at 1/3 and gear up at impact.
Flight Path Analysis
Track log data from the handheld GPS recovered showed the last 10 minutes of flight. The last two turns before loss of control exceeded 50° angle of bank, with a maximum of 55° on the final turn. Ground speed during the final turn was approximately 83 knots at 2850 feet asl (150 feet agl).
The aircraft flight manual indicated a stall speed of 84 knots calibrated airspeed at 60° angle of bank, gear down, power off, flaps 1/3, maximum gross weight. Based on GPS groundspeed and density altitude, the average calibrated airspeed during the final turn was 76 knots.
Operational Context
Wildlife Observation Services Inc. had valid operations certificates under Subparts 702 and 703 of Canadian Air Regulations. The company operations manual required flight authorization by the operations manager or chief pilot before departure. Operational control was delegated to the pilot-in-command. The pilot had authority to release the aircraft when away from base but did not inform the chief pilot of the low-level survey.
ASRD’s contract specified pilot qualifications: 1200 hours total time, 100 hours multi-engine, 200 hours PIC, and six months operational experience. The occurrence pilot met multi-engine and PIC requirements but not total time or operational experience. ASRD combined wildlife missions with fire patrols in June 2008; forest protection duties were primary. Wildlife surveys required lower altitudes and slower speeds. The company operations manual did not specify training or procedures for low-altitude wildlife surveys, only that training not be conducted below 500 feet agl or near wildlife.