OHS Canada Magazine

Cannabis use a factor in 2011 Northwest Territories plane crash

April 1, 2013

Health & Safety Transportation Workplace accident -- fatality Workplace accident -- injury

EDMONTON (Canadian OH&S News)

EDMONTON (Canadian OH&S News)

Though the plane kept below cloud cover, the Transportation Safety Board of Canada (TSB) found the pilot in a deadly October, 2011 crash was flying high.

On March 20, the board released its investigation report into the accident that killed the pilot and a passenger and left the two other passengers with serious injuries, finding that toxicology reports showed there were high levels of THC — the principal psychoactive in marijuana — in the pilot of the Air Tindi Ltd. flight from Yellowknife to Lutsel K’e, N.W.T.

“Even allowing for a reasonable margin of error in the toxicology results, the amount of THC present in this occurrence is considerably greater than the threshold that resulted in degraded pilot performance in studies on the impairing effects of THC,” the report said, noting that the amount in the pilot’s blood was well over the amount that studies show could be detected within six hours of smoking marijuana.

Complex tasks such as flying, the report added, can be impacted by marijuana use up to 24 hours after smoking.


“With what we call a class two investigation — a major, where there’s a very high level of public interest, a lot of resources put into the investigation — then we would always have toxicology carried out. If there’s a fatal, the coroner would always have toxicology carried out,” explained Jon Stuart, manager of human performance and macro analysis at the TSB.

“The TSB has the power to require [those involved in an incident] to undergo a medical investigation, but that cannot be an invasive test — it could be a urine sample or a tongue swab, but not a blood test. We can’t compel them to do that,” he added, though an investigator must have reasonable grounds to believe the test would be useful in an investigation.

The TSB labelled the crash as a controlled flight into terrain, one of the issues that have been on its watchlist since the list was introduced in 2010. From 2000 to 2009, controlled flight into terrain incidents represented seven per cent of all accidents and 35 per cent of all fatalities for air taxi operators like Air Tindi.

Terrain warning system could have prevented crash

“Because no effective evasive manoeuvres were made before impact, it is likely that the crest of the Pehtei Peninsula was obscured in fog, and not visible to the pilot. The application of increased engine power immediately before impact was likely made when the terrain in front of the aircraft suddenly became visible,” the report noted, adding that a terrain awareness warning system could have warned of the impending crash soon enough for the plane to pull up and avoid the terrain.

Other contributing factors to the incident, the report said, was that the pilot made the decision to fly closer to the ground — using visual contact with the ground to navigate — despite being trained to fly relying on the instruments, which would have given the pilot safer clearance from the landscape.

“It is possible that the pilot, under the influence of cannabis, avoided the higher workload” of using instrument-based flying and instead chose to remain under visual flight rules, the TSB said. “Aspects of the pilot’s planning, flying technique and decision making were inconsistent with regulatory and administrative requirements, the company operations manual policy and safe flying practices.”

Since the incident, Air Tindi has introduced random drug testing for its pilots, maintenance engineers and dispatch personnel, amongst other changes to its flight procedures.

This is the fifth time the TSB has investigated an incident in which the operator(s) have tested positive for cannabis use — a Manitoba flight in 2001 that resulted in the death of the pilot and first officer, the B.C. ferry that sank in 2006 where two passengers were killed, a main-track rail collision in March of 2010 where a crew member was taken to hospital in serious collision, and a second marine accident.

The board is developing a policy to run toxicology tests for most investigations, Stuart said.

Transport Canada can suspend a pilot’s license or issue a $5,000 fine to pilots found to be under the influence, and corporations can be fined up to $25,000 for the offence.



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