Overview
A Sikorsky S-76A medevac helicopter, registration C-GIMR, operated by Canadian Helicopters Limited, departed Sudbury for Temagami, Ontario, on a short flight to meet a land ambulance. At approximately 2202 eastern standard time, while on final approach to the Temagami Snake Lake Helipad in night visual meteorological conditions, the helicopter crashed in a forested area at the edge of the lake. The helicopter came to rest on its left side and was substantially damaged. Three of the four occupants received serious injuries and were transported to hospital.
Flight Crew
The crew consisted of a captain (pilot flying, PF), a first officer (pilot not flying, PNF), and two paramedics. The captain held a valid airline transport pilot license-helicopter with approximately 3107 hours total flying time, including 2267 hours on the Sikorsky S-76A. He had completed required training, including night VFR/IFR and controlled flight into terrain training with specific training for black hole approaches. He had visited the location once before on a day VFR flight. The first officer held a valid commercial pilot license-helicopter with approximately 1967 hours total flying time, 147 hours on type. He was certified and qualified for the flight and had all required training, but was new to EMS operations and had never been to the location.
Weather and Approach
The closest reporting weather station was in North Bay, Ontario, about 50 nautical miles south. The 2200 METAR reported wind 140° True at 3 knots, visibility 12 statute miles, light snow, scattered cloud at 1600 feet agl, broken at 3000 feet agl, temperature 6°C, dew point -7°C, altimeter 29.85 inHg. The region experienced localized light to moderate snowfall, and it was uncertain if the flight could land in Temagami. The helicopter departed Sudbury at approximately 2140, climbed to 2500 feet, and proceeded to Temagami. Visibility was no less than four to five statute miles and improved during the flight.
Helipad and Hazards
The Snake Lake Helipad is located on the northeast edge of Temagami with a field elevation of 997 feet asl, a 100 by 100-foot asphalt pad with retro-reflective cones and lead-in cones at 220° magnetic. Four perimeter cones could be equipped with e-flares upon request, but were not requested. The directory cautions of wires under and along the east and north sides, large hills south, east, and north, a tower west, a fire tower south, and a ball park east. A single house beside the ball park has typical door entrance lights. Approaches and departures are conducted in the southwest quadrant (210°M–260°M). The approach requires flying over the town and a small hill starting approximately 2430 feet horizontally from the helipad, rising to about 1017 feet asl (20 feet above helipad elevation), then sloping down to the lake shore 723 feet from the pad.
Accident Sequence
The helicopter approached from the southwest on a heading of approximately 048°M, entering the trees near the lake edge about 814 feet horizontally from the helipad. Trees on the approach averaged 40 feet in height. The helicopter impacted trees on the downward slope of the hill, about 70 feet from the shore, where the hill height was about 10 feet above the helipad. The descent was near vertical with very little horizontal momentum; the nose came to rest about 15 feet from the shore. The rotor diameter was 44 feet; tree damage was mostly within this diameter. Rotor blades were completely destroyed. A tree passed through the left landing gear bay, main battery, and continued through the engine deck and exhaust collector of the right engine. There was evidence of heat but no post-crash fire. No anomalies were found with the helicopter.
Crew Actions and Findings
During the last 1.5 minutes of approach, the PF was explaining procedures to the PNF, including black hole illusions. The PNF was monitoring airspeed, altitude, and distance, relaying information. The PF was flying a visual approach and utilized this information. However, the PF's radar altimeter was not set to 150 feet as per operations manual. The helicopter was on a stabilized approach with an 8° descent profile. The PF acknowledged a 0.5 nm and 500 foot call but visually perceived the helicopter as too high, increased the rate of descent (evidenced by rotor rpm changes). The PNF did not question the deviation or make further calls. The descent from 500 feet to impact in less than 21.5 seconds equated to a descent rate over 1400 feet per minute, exceeding the recommended maximum of 750 feet per minute.
Seat Belt Failure
The lap belt seat attachment for the paramedic in the starboard aft-facing seat failed. The belt had a clip-on steel hook attached to an aluminum barrel nut threaded onto seat-back pivot bolts. The barrel nut failed due to thinning from wear and the bolt not passing completely through, creating a weak point. Under side impact loads, the barrel nut failed at its weakest point.
Findings
The Transportation Safety Board found that the pilot flying was likely affected by visual spatial disorientation and perceived the approach height to be too high. While correcting for this misconception, the helicopter descended into trees 814 feet short of the helipad. The pilots were likely distracted during the critical phase of the approach and did not identify the deviation.