Heavy rain creating an optical illusion on the windshield of a helicopter could have played a role in a fatal crash in northwestern British Columbia last summer, but the Transportation Safety Board says without onboard recording devices it's impossible to determine the exact cause. The board released its investigation report Tuesday into the August crash of an Aberdeen Helicopters Ltd. aircraft that was under full power when it hit the upper part of a mountain northwest of Stewart, killing the pilot. Investigators point to sudden heavy rain as one possible reason for the crash, noting that rain, especially on sloping windshields, can create a "refraction error'' that makes either the horizon or oncoming objects appear lower. Transport Canada is making "positive'' progress on that recommendation, the board report says. "However, until the regulations are finalized, the risks associated with the safety deficiency ... will continue to exist.''

Source: CBC News March 09, 2021 23:37 UTC