What happened
At approximately 0830 CST, a McDonnell Douglas Hughes 369E helicopter, registration C-FHMF, was performing a transport flight near Davy Lake, Saskatchewan. The aircraft was moving a crew of two line-cutters from a base camp to a nearby work site. While flying at altitudes between 300 and 500 feet, the pilot observed a caribou swimming across a small, unnamed lake.
In an attempt to observe the animal, the pilot initiated a right turn and descended toward the water. During this maneuver, the aircraft entered a steep descent over a treeline. Although the pilot attempted to recover the aircraft, the helicopter continued over the water and struck the surface at approximately 100 knots. The impact caused the helicopter to sink rapidly. While the pilot and one passenger managed to exit the submerged wreckage and swim to shore, a second passenger was unable to be rescued and subsequently drowned.
The investigation
Investigators examined the wreckage, which had been recovered from the lake by the operator. Although the wreckage suffered a secondary impact during transport to an airstrip, engineers were able to confirm that the engine was at high power at the time of the accident and that all controls were functional.
Technical analysis of the tail rotor assembly revealed a fatigue fracture in the bell crank support arm. However, photographic evidence confirmed this component was still intact at the time of the initial crash, meaning the fracture did not contribute to the accident. The fracture likely went unnoticed during a recent 100-hour inspection because the tail rotor area was inspected in darkness using only a flashlight.
Medical examinations determined that the non-surviving passenger's death was caused by drowning, noting that injuries sustained during the impact, heavy work clothing, and cold water temperatures made physical exertion difficult. The pilot's recent medical treatment for a minor infection was found to have no impact on flight capabilities, and the pilot was well-rested and within all regulatory flight time limitations.
Findings
- The pilot experienced target fixation on the caribou, leading to a loss of situational awareness and a high rate of descent at low altitude.
- The pilot's ability to recover the aircraft was likely hindered by the glassy water phenomenon, which made accurate height judgment over the lake surface nearly impossible.
- The lack of personal flotation devices for the passengers, as they were not required by regulations for this specific flight path, may have impeded the rescue of the second passenger.