In heavy fog and with no radio connection to the controller, likely blocked by the mountains in low altitude, the helicopter crashed into a hillside in Calabasas, California. “This was totally avoidable, and on the part of some people I can go as far as to say irresponsible,’’ said Robert Ditchey, a longtime airplane pilot, aeronautical engineer and former airline executive who lives in Los Angeles. “Here’s one of the most important people in the world who comes to a tragic end like this and you say, ‘Why? What the hell happened?’