While on a visual approach, Trigana Air Flight 267, an ATR 42 turboprop with 54 people on board, contacts air traffic control and disappears into a cloud. Repeated calls to the aircraft go unanswered. A pilot departing Oksibil reports seeing smoke on a nearby mountainside. The plane has impacted a mountain, killing all on board. Why would a relatively modern plane with a qualified crew and safety equipment collide with a mountain? Find out what happened on this episode of Black Box Down.