Debrief


"Show and Stall" Usually Fatal

On August 19, 2006, a Cessna 177B Cardinal departed the pilot's farm airstrip, 5 NM east of Manning, Alta., at about 21:25 Mountain Daylight Time (MDT). The flight was a local sightseeing trip with three passengers. At 21:35, the aircraft was observed approaching a community centre 5 NM south of the take-off point, where a sporting event was underway. The aircraft approached from the northeast and made a slow-speed pass at a height estimated at between 150 and 500 ft above ground level (AGL). It then made a steep turn to the left, followed by a steep climbing right turn. The nose then dropped sharply and the aircraft entered a spin of two turns. The rate of spin slowed before the aircraft impacted the ground in a near-vertical, nose-down attitude in light brush. There was no post-impact fire, and all four occupants sustained fatal injuries. The nature of the damage and ground scars indicated a very rapid deceleration and high-impact forces.

On-site inspection of the wreckage by investigators from the Transportation Safety Board of Canada (TSB) revealed no pre-impact malfunction that would have contributed to the accident. The engine was heard to operate all the way to the ground, and examination of the wreckage confirmed that the engine was likely developing power on impact. Allflight controls were continuous, and the flaps were in the retracted position. The left-wing tank contained fuel, andthe right-wing tank, which was heavily damaged, held no fuel. Fuel was observed leaking from the wreckage shortly after the accident. The aircraft weight and centre of gravity were estimated to be within certified limits.

The aircraft was powered by a four-cylinder Lycoming O-360-A1F6D piston engine. It was manufactured in1972 and owned by the pilot since 1997. The most recent maintenance recorded in Transport Canada files was in February2000, when repairs were completed following an accident at the pilot's farm strip in August1999. Nosubsequent maintenance activity, including required annual inspections or annual reports to Transport Canada, could be confirmed by documentation or by inquiries made of regional maintenance organizations.

The pilot held a Canadian private pilot licence, issued in 1993. His most recent medical examination was conducted on May 22, 2003, and his medical certificate was valid until June 1, 2005. The pilot's total flying time declared on his last medical examination form was 218hr, and his recent experience could not be determined. At the time of the occurrence, the sky was clear, winds were calm, and twilight conditions existed. Weather conditions were not considered to have been a factor in the accident.

The observed behaviour of the aircraft and the impact angle were consistent with those of an aerodynamic stall followed by a spin. If a spin is allowed to develop following a stall, a considerable amount of height can be lost by the aircraft before recovery. Several other accidents have been documented in the 10 years prior to the accident, which had occurred during low-altitude manoeuvring. In these occurrences, the low altitude of the aircraft precluded recovery from a stall/spin before impact with the ground. Due to the forces involved in this type of accident, fatalities are common.

Low-speed handling characteristics are part of the Canadian private pilot training curriculum. Additionally, safety promotion material advising of the hazards of low flying is provided by Transport Canada. TheCanadian Aviation Regulations (CARs) prohibit the operation of an aircraft at heights less than 1 000 ft over assemblies of people. Publication in the Aviation Safety Letter of this factual information gathered by the TSB will hopefully raise awareness of the importance of maintaining effective energy management at low altitudes.

Thank you to the TSB Western Regional Office forproviding this account. -Ed.


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