A new investigation report from the Transportation Safety Board of Canada (TSB) has concluded that a loss of directional control led to a tragic helicopter accident near Sept-Îles, Que. more than a year and a half ago. Two of the four passengers, who had been assigned to inspect a salmon pass, were killed in the crash.

The incident occurred at about 9:40 a.m. local time on Sept. 2, 2015, according to the report, which was published on April 3 of this year. The Héli-Nord chopper was approaching a landing site at a river camp near the salmon pass, about 20 nautical miles north of Sept-Îles, when the aircraft made a sudden clockwise turn and crashed into a rock.

Two passengers, one in the front left seat and one in the rear central seat, sustained fatal injuries, while the pilot and the two other passengers in the back seat were seriously injured, but survived. A fire was triggered in the helicopter’s emergency tailpipe, but people at the site extinguished the flames.

The TSB investigated the crash and discovered that the helicopter’s weight and the flight regime had caused the loss of directional control, while the altitude – only a metre or two from the ground – was too low for recovery. The aircraft rotated when the engine torque exceeded its limits. The pilot tried to counteract the rotation by reducing the torque while turning left; when this failed, the pilot increased the torque and tried to speed up the aircraft to increase the altitude, but this also did not work.

The investigation also found that the pilot had been inexperienced with a Bell 206B helicopter with a short tail rotor. This was why he could not recognize the loss of tail-rotor effectiveness, nor counteract sufficiently.

“No in-flight training on loss of tail-rotor effectiveness is provided on account of the risks this would entail,” the report stated.

In addition, the TSB noted that the passenger in the front seat had not been wearing her seatbelt correctly at the time of impact. Investigators speculated that this had probably caused her fatal abdominal injuries. “If occupants do not wear safety belts correctly during a flight,” the TSB warned, “there is an increased risk of serious injuries or death in the event of an accident.”

Conversely, the pilot’s survival of the crash was likely because he was wearing head protection at the time.

“The fact that the pilot was wearing a helmet significantly reduced the severity of his head injuries,” wrote the TSB.