Judge Cecil Margo , one of the original investigators , later stated in his memoir Final Postponement , that he believed the plane crashed due to separation of the wing . At the time of the crash , Margo said that four Vickers Viscounts had been lost in crashes , two due to structural failure , and two over water with unknown cause . Margo continues saying that just after this crash , another Vickers Viscount was lost over the sea on its way to Ireland , and yet another was lost over land in Australia . The crash in Australia allowed investigators to find the cause of in-flight disintegration , a failed wing spar . Later on , Margo connected the dots with the other crashes at sea , and as of writing his memoirs , he believed that the Rietbok crash was due to a failed wing spar as well . Subsequently , both Australian Viscount crashes were found to be due to maintenance errors
over water with unknown cause
Ansett-ANA Flight 149
South African Airways Flight 406