What happened
On the night of the occurrence, a Sikorsky S-7COA medivac helicopter, registration C-GIMR, departed Sudbury, Ontario, to perform a medical transport mission. The flight was intended to meet a land ambulance at the Snake Lake Helipad in Temagami. The crew, consisting of a captain, a first officer, and two paramedics, flew the mission under night visual meteorological conditions amidst localized light snowfall.
As the helicopter approached the helipad from the southwest, the pilot flying began explaining the mechanics of night approaches and potential illusions to the first officer. During this final phase of the approach, the aircraft's descent rate increased significantly. The helicopter struck a line of trees located approximately 814 feet short of the landing site. The impact caused substantial damage to the aircraft, including the destruction of the rotor blades, and the helicopter came to rest on its left side. Of the four people on board, three individuals sustained serious injuries.
The investigation
Investigators examined the aircraft's mechanical condition and the flight crew's performance. The investigation found no mechanical anomalies in the engines or flight controls that contributed to the crash. However, the team analyzed the cockpit configuration, noting that the radar altimeter had not been set to the 150-foot setting required by the company's operations manual.
The investigation also scrutinized the seat restraint systems following the failure of a lap belt attachment. It was determined that the barrel nut for the aft-facing paramedic seat had been weakened by wear and an improperly seated attachment bolt. The lateral forces of the crash caused this weakened component to fail during the impact.
Findings
- The pilot flying was likely experiencing visual spatial disorientation, leading to the false perception that the aircraft was too high.
- While attempting to correct this perceived error, the pilot initiated a descent rate exceeding 1400 feet per minute, far surpassing the recommended 750 feet per minute limit.
- The flight crew was likely distracted by instructional conversation during the critical approach phase, which prevented them from recognizing the deviation from the established descent profile.
- The first officer failed to identify or call out the deviation from the intended approach path.