Accident Overview
On 26 April, a Bell 206B helicopter (serial number 647) departed Mould Bay Airport, Northwest Territories, at 0729 mountain standard time on a visual flight rules (VFR) flight to Sachs Harbour and Inuvik. The pilot was scheduled to meet a Twin Otter aircraft at a fuel cache near Mercy Bay, approximately 140 statute miles south of Mould Bay, around 0900. When the helicopter did not arrive, the Twin Otter crew initiated an air search along the direct track from Mould Bay at about 1000. They located burned and scattered wreckage on sea ice about nine miles south of the Mould Bay weather station. A ground party from the weather station reached the site at approximately 1500 and confirmed the wreckage belonged to the missing helicopter. The pilot sustained fatal injuries.
Location and Environment
Mould Bay is an Arctic sea bay on the east coast of Prince Patrick Island, oriented north-south and surrounded by barren hills up to 900 feet high. The bay is roughly 20 miles long and 8 miles wide at its southern end, where it opens into Crozier Channel. The accident site was near the southern end on the direct track between Mould Bay Airport and the Mercy Bay fuel cache. The Mould Bay weather station, a remote high Arctic facility, is situated on the north shore of the bay.
Flight and Pilot Information
The helicopter had been chartered by a polar research company to retrieve sea buoys and relocate an ice camp approximately 300 miles northwest of Mould Bay. The pilot flew from Inuvik to Mould Bay on 18 April and reached the ice camp on 19 April. He operated from the camp for four days and returned to Mould Bay on 23 April. The helicopter was released by the client for the return flight to Inuvik on the morning of 26 April. The pilot obtained his commercial helicopter licence in 1993 and had about 1,500 hours of flight experience. He was raised in Sachs Harbour and was reportedly very familiar with Arctic terrain and climate. He had frequently hunted and snowmobiled in Arctic whiteout conditions. He had been employed seasonally for several years herding reindeer near Tuktoyaktuk, Northwest Territories, with a Robinson R-22 helicopter. Training records show he received 10.6 hours of dual instrument training before obtaining his commercial licence. He was not endorsed for night or instrument flight, and there was no evidence of additional instrument training after licensing. Post-mortem examination and medical record review found no evidence of incapacitation or physiological or psychological factors that could have adversely affected his performance. Tests for common drugs were negative.
Weather Conditions
The area forecast for the Mould region, issued at 0430 MST on 26 April, indicated VFR conditions would generally prevail during the planned flight. Sky conditions were forecast as scattered cloud at 2,000 to 3,000 feet above sea level (asl) with tops at 5,000 feet, visibilities greater than six statute miles, and occasional visibilities of four to six miles in light snow. Local stratus ceilings of 300 to 800 feet above ground level (agl) and visibilities of half to four miles in fog and light snow were anticipated in areas of on-shore upslope flow. The pilot spoke with Sachs Harbour Community Aerodrome Radio Station (CARS) before departure and determined that good VFR weather existed there.
The Mould Bay 1400 UTC (0700 MST) AUTO5 SA reported sky clear below 10,000 feet, visibility greater than 9 statute miles, temperature -18°C, dew point -21°C, and winds 360 degrees true at 4 knots. Similar conditions were reported one hour later. However, weather station personnel estimated the sky condition as 500 to 1,000 feet overcast and visibility 1 to 4 miles when the helicopter left. The Twin Otter, which departed Mould Bay for Mercy Bay at 0900 MST, reported 500 feet overcast and visibility 1 to 4 miles on departure. The differences between eyewitness reports and the AWOS suggest the AWOS was not accurately recording actual conditions at the time of the accident.
Aircraft and Equipment
The helicopter was certified, equipped, and maintained in accordance with regulations. It had basic flight instrumentation for instrument flight, mounted in the centre of the instrument panel, left of the pilot's position and above the radio console. It was fitted with a global positioning system (GPS) receiver, which was operating at impact. A high frequency (HF) radio was installed; the vernier HF antenna tuner was mounted on the left wall of the instrument centre console. The research company provided flight following on 5680 KHz, and the pilot advised a Mould Bay operator he would contact them on that frequency about five minutes after takeoff. Approximately five minutes after departure, a three- to five-second HF carrier-only transmission was heard, possibly indicating the pilot was tuning the antenna. No further communication occurred. The accident site was about five minutes (air time) from Mould Bay Airport. The helicopter was equipped with a Pointer Sentry C-4000 emergency locator transmitter (ELT) mounted on the right side of the vertical control tube tunnel. The ELT was torn from its mount and antenna lead at impact; the case was penetrated and the switch circuitry damaged, preventing signal transmission.
Wreckage and Crash Dynamics
The wreckage trail indicated the helicopter was travelling south when it struck the ice, in an approximately 40-degree nose-down and 45-degree left-bank attitude. The airframe was extensively disintegrated. The fuel cell and three 10-gallon kegs of jet fuel (presumed in the cabin) ruptured during the accident. The ice surface was scorched and sooted along most of the wreckage trail. Due to the near-complete destruction by impact and fire, no pre-impact failure or system malfunction could be identified, though none was found.
Probable Cause
It is probable that the pilot lost visual reference because of the whiteout conditions, became disoriented, and lost control of the helicopter. It is possible that the pilot was tuning the radio at the time of the occurrence, which would have contributed to his disorientation.