THC was the prime factor.
Rather than issue a “probable cause,” Canada's Transportation Safety Board issues “Findings as to Causes and Contributing Factors,” “Findings as to Risk” and “Safety Actions.”
In this case, the TSB issued the following:
Findings as to Causes and Contributing Factors:
(1) The aircraft was flown at low altitude into an area of low forward visibility during a day VFR flight, which prevented the pilot from seeing and avoiding terrain.
(2) The concentrations of cannabinoids were sufficient to have caused impairment in pilot performance and decision-making on the accident flight.
Findings as to Risk:
(1) Installation instructions for the ELT did not provide a means of determining the necessary degree of strap tightness to prevent the ELT from being ejected from its mount during an accident. Resultant damages to the ELT and antenna connections could preclude transmission of an effective signal, affecting search and rescue of the aircraft and occupants.
(2) Flying beyond gliding distance of land without personal floatation devices on board exposes the occupants to hypothermia and/or drowning in the event of a ditching.
(1) Earlier on the day of the accident, the pilot flew the route from Fort Simpson to Yellowknife in cloud on a VFR flight plan in controlled airspace.
(2) With the ELT unable to transmit a usable signal, the SkyTrac system in C-GATV was instrumental in locating the accident site. This reduced the search time and allowed for timely rescue of the seriously injured survivors.