Aviation Investigation Report A17W0024 - Transportation Safety Board of Canada
Findings as to causes and contributing factors
These are findings related to the unsafe acts, unsafe conditions, or safety deficiencies that are associated with the safety significant events that played a role in causing and/or contributing to the occurrence.
1. For unknown reasons, the aircraft entered a spin from a stall exercise.
2. The instructor and trainee recovered the aircraft from the spin, but insufficient altitude remained to recover from the ensuing dive.
Findings as to risk
These findings are not causal or contributory to the occurrence. They identify a risk that was found during the investigation that has the potential to degrade safety. They may describe a condition that is systemic in nature that applies to an audience beyond those involved in the immediate occurrence.
1. If flight training units do not emphasize that the most important reaction to a stall or approach to stall is a reduction in the angle of attack, a loss of aircraft control may occur.
2. If organizational safety processes do not identify and mitigate non-standard practices, manoeuvres that are outside of the aircraft limitations defined in the aircraft flight manual may be conducted, increasing the risk of aircraft accidents.
3. If full-stall demonstrations are required as part of a multi-engine rating test, there is an increased risk that, due to unknown spin characteristics, pilots may not be able to regain aircraft control if the stall progresses into a spin.
Other findings
These findings are not causal or contributory to the occurrence and are not systemic in nature. They identify an element or contain a message that has the potential to enhance safety. They can resolve an issue of controversy or provide a data point for future safety studies or analyses.
1. It could not be determined whether the instructor or the trainee involved in the occurrence had been exposed to the non-standard practice in use for stall-recovery training or whether the instructor had used it on the accident flight or on previous flights.
2. Given that the aircraft was almost entirely destroyed by the crash and subsequent post-impact fire, it could not be determined whether any pre-impact system failure or malfunction contributed to the accident; however, the components that were examined showed no signs of malfunction.
3. The information contained in Advisory Circular 700-031, Prevention and Recovery from Aeroplane Stalls, was not incorporated into TP 11575, Instructor Guide—Multi-Engine Class Rating.