The preliminary finding of the tri-service investigation into the fatal crash of the Mi-17V5, which led to the death of all 14 who were on board, including Chief of Defence Staff General Bipin Rawat, has ruled out mechanical failure, sabotage or negligence as the cause of the accident. The inquiry team said the accident was a result of the helicopter entering into the clouds due to an unexpected change in the weather conditions in the valley in Tamil Nadu, where it crashed. The change of weather led to spatial disorientation of the pilot resulting in a controlled flight into terrain (CFIT), a statement issued by the defence ministry has said.