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New Delhi: The helicopter crash that killed Chief of Defence Staff (CDS) Bipin Rawat and 13 others near Coonoor in Tamil Nadu on December 8 last year was caused by a pilot error in cloudy weather, the tri-service investigation into the incident has found, according to media reports.
Chief of Air Staff Air Chief Marshal V.R. Chaudhari and Air Marshal Manvendra Singh, who headed the tri-service investigation into the crash, apprised defence minister Rajnath Singh on the findings of the probe on Wednesday.
According to news agency PTI, the inquiry did not find any technical snag or sabotage that could have caused the crash. Instead, bad weather led to a phenomenon called Controlled Flight Into Terrain (CFIT), which is believed to be the prime reason for the crash of the Indian Air Force (IAF) Mi-17V5 helicopter that was flying from Sulur airbase to Wellington.
However, there has not yet been an official comment on the probe report, either by the IAF or by the defence ministry.
According to experts, CFIT refers to a phenomenon when an aircraft under control is piloted into the ground, water or other terrains largely due to bad weather or pilot error. CFIT generally takes place in bad weather conditions or when a flight is landing.
According to the International Air Transport Association (IATA), CFIT refers to accidents in which there was a collision with terrain, water, or obstacle, without indication of loss of control of the aircraft. “The critical distinction in these types of accidents is the fact that the aircraft is under the control of the flight crew,” it said.
The Federal Aviation Administration of the US government described CFIT as an unintentional collision with terrain (the ground, a mountain, a body of water, or an obstacle) while an aircraft is under “positive control”.
“Most often, the pilot or crew is unaware of the looming disaster until it is too late,” it said.
According to PTI, people familiar with the investigation report said that sudden cloud cover could have resulted in CFIT.
“At times, a pilot may lose situational awareness when there is a visual disruption,” said an aviation expert.
Visuals of the helicopter captured by locals, probably moments before the crash, had shown that the chopper was flying at a low altitude.
The chopper had crashed around eight minutes before its scheduled landing at Wellington.
According to The Hindu, Air Vice Marshal (Retd) Manmohan Bahadur, a former helicopter pilot, said that CFIT means that the pilot is in “full control of the aircraft but due to faulty situational awareness the aircraft strikes the terrain”.
CFIT also implies that the helicopter was fully serviceable and the instruments were in order. The crash was likely caused by “loss of situational awareness and disorientation”, which in most cases is due to poor weather, a senior Army pilot told the newspaper.
According to PTI, the probe team examined all likely scenarios for the crash including possible human error or whether it was a case of disorientation by the crew when the helicopter was preparing for landing.
General Rawat’s wife Madhulika, his defence advisor Brigadier L.S. Lidder, staff officer to the Chief of Defence Staff Lt Col Harjinder Singh were among the 12 others who were killed immediately after the crash near Coonoor in Tamil Nadu. Decorated pilot Group Captain Varun Singh was rescued but died a week later due to the injuries he sustained.
Air Marshal Manvendra Singh, who headed the probe team, is currently serving as Air Officer Commanding-in-Chief of the Bengaluru-headquartered Training Command of the IAF. He is known to be one of the best air crash investigators in the country.
Defence secretary Ajay Kumar and a number of senior officials of the ministry were present when the IAF officials briefed the defence minister, according to PTI.
(With PTI inputs)