News release

The Transportation Safety Board of Canada (TSB) released its investigation report (A23W0158) into a controlled flight into terrain involving a de Havilland DHC-6 Twin Otter aircraft, operated by Air Tindi Ltd., at Lac de Gras, Northwest Territories.

On December 27, 2023, the aircraft departed Margaret Lake for the Lac de Gras road camp under visual flight rules with two crew members and eight passengers on board. On arrival, the flight crew were unable to determine their position visually in relation to the road camp due to poor weather conditions and conducted four improvised instrument approaches to the landing site. During the last attempt to land, the aircraft descended to below 50 feet above ground level and lost visual contact with the terrain. Shortly after, it impacted a hill close to the desired landing site. Given the poor visibility, the crew only observed the hill approximately two seconds before impact. Two passengers were seriously injured, and the other occupants sustained minor injuries.

The investigation found that the flight crew continued into deteriorating weather due to prior success in similar conditions and a plan-continuation bias, which led to a reduced perception of the risks associated with continuing the flight.

The investigation also found that over time, deviations from standard operating procedures had become common practice with Air Tindi Ltd. flight crews on the DHC-6, including the use of improvised approaches in instrument meteorological conditions. The oversight mechanisms used by Air Tindi Ltd. did not effectively detect or respond to these deviations, allowing them to continue.

This accident also reflects a broader challenge with Transport Canada’s oversight, which has a limited ability to identify gaps between documented procedures and actual day-to-day flying operations, making it difficult to detect drifts from current regulations. Regulatory Surveillance is a TSB Watchlist issue.

Following this occurrence, Air Tindi Ltd. conducted an internal safety investigation and identified opportunities to improve its processes and procedures. Actions taken include increased weather limits, enhanced pilot monitoring requirements, expanded crew resource management and simulator training, and upgraded aircraft instrumentation to improve situational awareness.

See the investigation page for more information.