I'm not posting here with the intention of offending anyone or denegrating the incident pilot but this exert from the ATSB report makes sobering reading. I would suggest there is a lesson for all professional pilots here. If you disagree with the ATSB's findings in this case fine, but the message is still valid.
My condolences to those who lost an experienced and valued friend.
"In the context of this accident, specialist medical opinion was obtained regarding the significance of the toxicology results. That advice included that the presence of THC was consistent with the ingestion of cannabis by the pilot in the 24-hour period prior to the accident. On the basis of that evidence, the specialist commented that:
…the adverse effects on pilot performance of recent cannabis use must be considered a significant factor in the fatal accident involving VH-NIT.
In March 2004, the Australian Transport Safety Bureau (ATSB) released a research report titled ‘Cannabis and its Effects on Pilot Performance and Flight Safety: A Review’ (available at www.atsb.gov.au). That report reviewed the scientific research on the use of cannabis and examined the manner in which the use of cannabis could affect the ability of a pilot to operate an aircraft.
The pharmacological effects of cannabis use include effects on cognitive and psychomotor function that can significantly impair the ability to perform complex tasks that require attention and mental coordination. Complex tasks requiring rapid responses and discriminations, such as the management of in-flight emergencies, are especially sensitive to cannabis impairment. "