A view of site where an Indian Air Force helicopter crashed at Coonoor area of Nilgiris district, about 538 km southwest of Chennai, the capital city of India's Tamil Nadu state, Dec. 8, 2021.Photo:Xinhua

Preliminary findings of an inquiry team investigating a chopper crash that killed India's Chief of Defense Staff  General Bipin Rawat, his wife and 12 others has found a pilot error in the cloudy weather a reason for the accident, defense officials said Saturday.

The inquiry has ruled out mechanical failure or sabotage for the crash.

"The tri-services court of inquiry into the Mi-17 V5 accident on Dec. 8, 2021 has submitted its preliminary findings. The inquiry team analyzed the Flight Data Recorder and Cockpit Voice Recorder besides questioning all available witnesses to determine the most probable cause of the accident," a statement issued by defense ministry said.

A view of site where an Indian Air Force helicopter crashed at Coonoor area of Nilgiris district, about 538 km southwest of Chennai, the capital city of India's Tamil Nadu state, Dec. 8, 2021.Photo:Xinhua

"The court of inquiry has ruled out mechanical failure, sabotage or negligence as a cause of the accident. The accident was a result of entry into clouds due to unexpected change in weather conditions in the valley," the statement added.

"This led to spatial disorientation of the pilot resulting in Controlled Flight into Terrain. Based on its findings, the Court of Inquiry has made certain recommendations which are being reviewed," said the statement.

The probe was called last month by the Indian Air Force immediately after the deadly crash.

The helicopter with 14 people on board crashed at Coonoor area of Nilgiris district, about 538 km southwest of Chennai, the capital city of Tamil Nadu.