Twin Otter C-FAIV Crash into Vancouver Harbour

Flight Details and Approach Sequence A Twin Otter registered C-FAIV departed Victoria Harbour at 1718LT for a scheduled VFR flight to Vancouver Harbour water-aerodrome. The estimated en route time was 20 minutes, and the flight proceeded normally. The aircraft reported by Active Pass at 2,000 feet, an altitude maintained to cross the Vancouver Control Zone per standard procedure. After exiting the control zone, a slow descent began toward Vancouver Harbour. Normal radio procedures were followed as the flight reported by standard visual reporting points. ## Accident Sequence Just before joining final approach, the aircraft transmitted “AIV, Third Beach,” and landing clearance was issued by Harbour Tower. As the approach continued, the aircraft reached approximately 175 feet above the surface when nine ground witnesses heard a loud noise from the aircraft. Two surviving witnesses also heard a noise. Power was subsequently applied, and C-FAIV yawed left, rolled in the same direction, and plunged into the harbour in a left-wing and nose-down attitude, 2,500 feet from the intended landing area. ## Emergency Response and Casualties An ELT tone was heard by the tower controller 54 seconds after the radio call at Third Beach. The controller called the aircraft several times but received no response. The flight had lasted 24 minutes. Both pilots and nine passengers were killed, while two others were injured. The aircraft was destroyed. ## Official Findings The final approach was normal until an unusual noise occurred, followed by loss of control. The aircraft dived into the water with left wing down, nose down, and some sideslip; the exact roll, pitch, and yaw at impact could not be estimated with useful accuracy. At impact, the complete left flap system was retracted. The inboard span-wise push-pull flap control rod (inboard bell-crank to inboard rod, PT # C6CW-1029-1) was severely stress-corroded and had at least three longitudinal cracks; it had separated from its inboard fitting. It was deduced that in-flight failure of the left-hand inboard flap control rod caused sudden retraction of the complete left-hand flap system and sudden loss of control. Passengers had not been briefed in evacuation procedures. The crew was qualified for the type of operation under Transport Canada regulations. After the left flap control rod failure, no action by the pilot could have averted the accident.