History of the Flight
On January 11, 1995, at 0035 Pacific Standard Time, a twin-engine Learjet 35 (registration C-GPUN) departed Vancouver International Airport, British Columbia, on a one-hour medical evacuation flight to the Masset aerodrome in the Queen Charlotte Islands. On board were two pilots and a medical team of three. The flight was conducted under instrument flight rules at night. After routine communications with air traffic services, the aircraft reported outbound from the Masset non-directional beacon on the published NDB "A" instrument approach to runway 12. Radar data showed the aircraft began a descent about 10 seconds after completing the procedure turn and establishing on the final inbound track. Forty-three seconds later, at a point 8.8 nautical miles from the runway threshold, the aircraft disappeared from radar and crashed into the ocean. Intense search and rescue operations recovered the aircraft wreckage and the bodies of two occupants; the other three are presumed to have perished. The aircraft was destroyed.
Investigation Findings
The investigation found no evidence of mechanical defects or systems malfunctions before impact, and no direct implications from aviation systems or services. Weather was not considered a causal factor. The flight data recorder showed the aircraft maintained controlled altitudes, indicating the pilot was flying the approach according to procedures. The cockpit voice recorder was not available, preventing in-depth analysis of crew performance. The Board determined that the crew most likely conducted the instrument approach with reference to an unintentionally mis-set altimeter of 30.17 in. Hg, and unknowingly flew the aircraft into the water. The circumstances leading to the incorrect altimeter setting could not be determined, nor was it determined why the crew did not detect the error.
Analysis of the Approach Profile
Radar and flight data recorder information revealed that the aircraft flew a consistent, lower-than-required altitude profile during the entire instrument approach. The aircraft held definite altitudes, demonstrating positive control. The lack of any emergency communication supports the premise of normal circumstances until impact. Three possible scenarios were considered, including altimeter settings of 29.17 in. Hg (the correct local setting) and 29.92 in. Hg (standard pressure). The scenario involving the 29.92 setting was deemed unlikely because it would have required the crew to overlook multiple standard procedures and altitude deviations. However, the Board concluded that the mis-set altimeter of 30.17 in. Hg was the most probable explanation.
Conclusion
The probable cause of the accident was the crew's unintentional mis-setting of the altimeter to 30.17 in. Hg, which led to controlled flight into the water. The investigation could not determine how the incorrect setting occurred or why it went undetected.