What happened
On the night of 11 January 1995, a Learjet 35, registered as C-GPUN, departed Vancouver International Airport on a medical evacuation mission. The flight was intended to transport a patient from the Masset aerodrome in the Queen Charlotte Islands to Prince Rupert for medical treatment. The aircraft was carrying a flight crew of two pilots and a medical team of three.
While performing an instrument approach to runway 12 at Masset, the aircraft descended into the ocean approximately 8.8 nautical miles northwest of the aerodrome. The impact resulted in the destruction of the aircraft and five fatalities, with two bodies recovered by search and rescue teams and three others presumed lost. There were no signs of mechanical failure or emergency communications prior to the crash.
The investigation
The investigation focused on the aircraft's descent profile and the possibility of an altimeter error. While flight data recorder (FDR) analysis confirmed the aircraft was under positive control and following the approach procedure, the cockpit voice recorder (CVR) was unserviceable due to a failure that occurred 12 days prior to the accident. This lack of audio data prevented investigators from analyzing the crew's decision-making or identifying specific distractions.
Investigators examined several scenarios regarding the aircraft's altitude. They ruled out a setting of 29.17 in. Hg, as the aircraft's flight profile did not match the behavior of professional pilots flying with a correct setting. They also found the theory of a 29.92 in. Hg setting unlikely, as it would have required multiple significant errors in altitude management and a failure to notice a massive discrepancy between the two altimeters.
Findings
- The crew likely performed the instrument approach using an unintentionally mis-set altimeter of 30.17 in. Hg.
- This error caused the aircraft to fly at a much lower altitude than intended, leading to controlled flight into water.
- The investigators could not determine the specific cause of the incorrect setting or why the crew failed to detect the error during their scans.
- The aircraft was not equipped with a Ground Proximity Warning System (GPWS).