VICTORIA -- Moments before a small plane crashed into the northern tip of B.C.'s Gabriola Island in December, killing all three people on board, the pilot radioed to a controller on the ground complaining of instrument failure.
Pilot Alex Bahlsen struggled to regain control of his twin-engine Piper Aerostar on approach to Nanaimo, telling a controller he "just had a fail" as the aircraft veered wildly off its flight path and the pilot repeatedly radioed for new landing coordinates.
The details are part of a Transportation Safety Board of Canada investigation report released Monday, examining the flight's final moments and the pilot's struggle to land on the evening of Dec. 10, 2019.
The aircraft was so badly damaged in the crash that investigators can't say with certainty what caused the plane to go down in calm winds and light drizzle. Investigators couldn't even say for certain who was flying the aircraft at the time of the crash, but noted "both occupants seated in the front of the aircraft held valid pilot licences."
At approximately 6:04 p.m., the doomed plane made a pair of tight, circular turns despite contrary instructions from the controller on the ground.
The plane's speed and altitude also began to vary erratically, dropping to 1,800 feet at speeds of approximately 300 kilometres per hour, then climbing to 2,700 feet at 110 kilometres per hour.
Less than a minute later, the controller advised the pilot to regain altitude if possible, however the pilot did not acknowledge the instruction. At 6:05 p.m., the aircraft was last seen on radar travelling at over 220 kilometres an hour, just 300 feet from the ground.
The TSB's flight coordinates show the plane making two circlular turns over the water before crashing on Gabriola Island. (TSB)
One factor investigators are pointing to as a potential contributor to the crash is the failure aircraft's attitude indicator, which the pilot reported just seconds before radar contact was lost.
TSB engineers, however, have been unable to determine if the instrument was malfunctioning at the time, or if it was damaged only after the aircraft hit the ground and burst into flames.
"During the occurrence, the pilot informed air traffic control that the [attitude indicator] had failed," according to the TSB report. "The aircraft was not equipped with a 2nd attitude indicator nor was it required to be by regulation."
The plane was also equipped with a horizontal situation indicator (HSI), which TSB investigators say had twice failed in the weeks prior to the crash, first on Nov. 22 and again on Nov. 26. Bahlsen, the pilot and owner of the aircraft, had an appointment to have the indicator fixed on Dec. 11, the day after the crash.
"In total, 13 flights had been conducted after the 1st failure of the HSI," investigators noted. "There were no journey log entries for defects with the HSI or evidence of maintenance completed. Regulations require that defects that become apparent during flight operations be entered in the aircraft journey logbook."
The TSB report notes that pilots are at increased risk of spatial disorientation when coping with the stress of primary instrument failure.
"When pilots do not have reliable external or internal cues to alert them to the aircraft’s orientation, they can become susceptible to vestibular illusions," the report notes. "These illusions can cause pilots to sense that the aircraft is level even though it is in a bank or pitched up or down. This illusion may continue unrecognized until the aircraft impacts terrain."
Alongside Bahlsen, Vancouver Island residents Allan and Katheryn Boudreau, both 53 years old, were killed in the crash.
Witnesses on Gabriola Island reported seeing the airplane spiralling out of control in its final moments before nosediving into the ground and exploding on impact.
The pilot and his passengers were on a two-day trip from Cabo San Lucas, Mexico, to Nanaimo, after making an overnight stop at an airport in Chino, Calif.
Gabriola Island, which has a population of about 4,000 people, is a 20-minute ferry ride east of Nanaimo.
