The sinking of the Titanic was far more than a simple accident. It was a tragedy that could have been prevented. It was the result of a long chain of mistakes: a fatal series of avoidable human errors that sent the Titanic and more than half of her passengers to their water graves. Based around the official inquiry held immediately after the event, plus evidence that's come to light since the wreck of the Titanic was discovered in 1985, National Geographic, in this drama-documentary special explores "Titanic: How It Really Sank".