Loss of instrumentation and spatial disorientation contributed to the plane crash on Gabriola Island that killed three people in December.
A twin-engine aircraft crashed on the northwest part of the island the evening of Dec. 10. Alex Bahlsen of Mill Bay and Allan and Katheryn Boudreau of Chemainus died in the crash.
The concluded report, that included the circumstances leading to the crash and communications between air traffic controllers in the moments before the aircraft disappeared from radar, were made public by the Transportation Safety Board of Canada on Monday, July 27.
According to the report, the crash of a private Piper Aerostar was due to the possible loss of function in the aircraft’s altitude indicator and spatial disorientation because of weather conditions as it was attempting to line up to land at Nanaimo Airport.
The three people aboard the Piper Aerostar were making their way home on a two-day long trip that departed from Cabo San Lucas International Airport, Mexico, Dec. 9, and had stopped overnight at China Airport, Calif., before departing shortly after 11:40 a.m., Dec. 10., for Bishop, Calif., to stop for fuel. The aircraft departed Bishop for Nanaimo Airport at about 2:25 p.m. on an instrument-flight-rules flight for Nanaimo.
At about 5:40 p.m. the Vancouver-area control centre air traffic controller advised the pilot a weather advisory had been issued for Nanaimo Airport that said visibility was 2.5 statute miles with light drizzle and mist an a overcast ceiling of 400 feet above the ground. Seven minutes later, with the aircraft about 32 nautical miles south of Nanaimo Airport, the pilot asked the controller about weather conditions at Victoria International Aiport. Weather conditions there were visibilty of five nautical miles in mist, with a broken ceiling at 600 feet and an overcast layer at 1,200 feet. The controller also included observations made by a pilot who’d landed at Nanaimo Airport 15 minutes earlier who reported being able to see the runway approach lights at 373 feet above ground level. The controller provided vectors to the Piper Aerostar’s pilot to intercept Nanaimo Airport’s instrument landing system localizer – a part of the instrument landing system that sends a signal to an aircraft’s on-board instrument landing system receiver to help line it up with the runway.
Moments later the air traffic controller noticed the aircraft hadn’t intercepted the localizer signal and contacted the pilot who confirmed he intended to intercept the signal. The aircraft lined up with the localizer momentarily, but then turned to the west. The pilot asked for a new heading and reported he’d “just had a fail,” according to the TSB report.
The controller gave new heading instructions, the pilot acknowledged, but the aircraft continued to turn beyond the new heading, climbed and slowed. At 6:04 p.m., the pilot reported the aircraft’s altitude indicator had stopped functioning and requested a new heading from the air traffic controller. Seconds later the aircraft had reach an altitude of about 2,700, at a ground speed of 60 knots, continued its right turn and started losing altitude.
The last radar contact, just after 6:05 p.m., showed the aircraft at 300 feet and a ground speed of 120 knots, shortly before it crashed.
The investigation revealed the aircraft’s altitude indicator had been overhauled in Dec. 2015. The plane’s horizontal situation indicator, the investigation found, had failed briefly Nov. 22 and again on Nov. 26. The aircraft’s owner had made an appointment with an aircraft maintenance facility to troubleshoot the malfunctions Dec. 11, the day following the crash.
Investigators could not determine, because of damage sustained in the crash, if either the horizontal situation indicator or altitude indicators were functioning at the time of the crash, but did determine that the pump, which provide pneumatic pressure to the instruments, was able to produce pressure.
The aircraft was not equipped with – nor was it required to by regulation – a flight data recorder or cockpit voice recorder.
Investigators could also not determine who was flying the aircraft at the time as both front-seat occupants were pilots.
The TSB report concluded there was a possible loss of spatial orientation caused by suspected malfunction of flight orientation instrumentation combined with limited visibility, making the pilot unable to accurately determine the aircraft’s flight altitude.
“Aircraft owners must ensure that aircraft deficiencies are recorded and rectified before flight,” the report noted.
“The lack of external visual cues, the loss of instruments, and the onset of acute stress with perceptual bias or narrowing of attention are all factors that increase the risk of spatial disorientation. In such situations, pilots may become reliant on their perceptions of motion and orientation, which would make them susceptible to disorientation.”
To read the full TSB report, visit https://bit.ly/39EZNfe.