Two men and the pilot died when the Cessna C-185E plane crashed into a small island in Potts Lagoon, just east of Port McNeill, B.C.
The investigation found that several modifications to the aircraft — though approved — meant that the plane reacted differently than the pilot would have normally experienced.
"While manoeuvring for landing on water, the aircraft experienced an accelerated aerodynamic stall while being flown at an altitude from which recovery was not possible," the TSB said in a statement released on Wednesday.
“Pilots need accurate information on how an aircraft will fly after modifications have been made to it,” said Joseph Hincke, a TSB board member.
“We are concerned that this information is not available consistently and that accidents will continue to occur as a consequence.”
Air Cab, the company that operated the plane that crashed, will be explaining what modifications have been made to their planes and their effect on aircraft handling during any initial and recurrent pilot training.