Evidence shows that those who are heavy, chronic users remain impaired even when they are not intoxicated. These impairments (attention and memory related) can last for many weeks, months, or even years after stopping use.
It has been proven in several studies that cannabis seriously impairs aircraft piloting skills.
In one study, (Cannabis and its Effects on Pilot Performance and Flight Safety: A Review. ATSB, 2004) the subjects were nine licensed pilots, highly trained in a flight simulator task, who were current cannabis users. They received a cannabis cigarette containing 20 mg THC (a moderate dose). This dose caused a significant impairment in performance which lasted over 24 hours after use.
So how do you think that went?
Most of the pilots were unaware that their performance was still impaired at 24 hours. Additionally, several pilots reported that they had actually flown while high on cannabis.
Cannabis is almost certainly the number two recreational drug of concern, after alcohol, but the synthetic cannabinoids are probably in the number three position.
These drugs, often not-illegal, are manufactured usually by steeping vegetable material in an oil containing high concentrations of a manufactured synthetic drug that is similar to the active ingredients in cannabis, yet different enough to not be included in the listing of illegal drugs. These drugs can be much stronger than normal cannabis and also present detection and monitoring problems to safety regulators.
The New Zealand Drug Foundation believes usage is on the rise.
“Very little research data is available on the use of synthetic cannabinoids in New Zealand. However, high demand for products, rising presentations to emergency departments, increasing reports from health providers, and increased marketing and media attention suggest usage rates are increasing.
“We don’t know much about the health effects… they have not been approved for human consumption and there is very limited information available regarding their short and long-term effects.”
Carterton Fatal Accident
In January 2012, a hot air balloon flight collided with a power line while attempting to land just north of Carterton, in the Wairarapa. Eleven people were killed (ten passengers and the pilot). This accident is New Zealand’s worst aviation tragedy since Erebus in 1979.
The Transport Accident Investigation Commission (TAIC) investigated the causes and circumstances of the accident.
According to the TAIC report, it was "highly likely'' that the pilot smoked cannabis on the morning of the flight, with two witnesses saying they saw him smoking something only about 25 minutes before the flight.
Toxicology results found he had 2 micrograms of cannabis per litre of blood, which was consistent with smoking cannabis four to six hours prior, and that he was unlikely to have been smoking tobacco.
The TAIC report specifically says, “It has not been possible to determine with any certainty how often the pilot used cannabis. It is possible that he used it more than “occasionally” as described by those two witnesses who were close to him.”
“The Institute of Environmental Science and Research Limited noted that symptoms of cannabis intoxication usually peak 10-15 minutes after smoking cannabis and last one and a half to four hours. The degree of cognitive impairment cannot be determined as the effects vary from person to person. Nevertheless, cognitive impairment of the pilot could not be excluded given the carry-over effect of cannabis from both recent and longer-term use. The extent to which longer-term use could cause cognitive impairment would depend on the frequency of use.
“Studies have shown that the greater the judgement and skills required in performing a task, the greater would be the impairment. Flying low level across the paddock; replying to a radio call; preparing to land in variable wind conditions; and dealing with a sudden change in flight path would have all combined to put the pilot under some pressure to make quick and correct decisions.”
“Cognitive impairment could typically contribute to these types of error. Although it cannot be concluded definitively that the cause of the accident was the pilot smoking cannabis, the possibility that it did contribute to the accident could not be excluded.”