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Bipin Rawat chopper crash | How a military aviation accident investigation unfolds

The probe into the Mi-17V5 that killed Chief of Defence Staff General Bipin Rawat will examine everything from the machinery, flight path, communications, flight data, maintenance records, and possibly information from the OEM to arrive at the most plausible analysis

December 09, 2021 / 08:40 PM IST

The Indian Air Force’s probe into the Mi-17V5 that killed 12 passengers, including Chief of Defence Staff General Bipin Rawat and his wife Madhulika along with 10 other military personnel will be exhaustive in its scope to determine the cause — whether human error, material failure, weather, or sabotage.

It would examine everything from the machinery, flight path, communications, flight data, maintenance records, and possibly even information from the Original Equipment Manufacturer (OEM) to arrive at the most plausible analysis. With the Mi-17V5 forming the backbone of the IAF’s Medium Lift Helicopter (MLH) capability, and has seen five previous crashes, the findings of the probe will be most avidly watched.

The crash of the Russian-origin helicopter has only one survivor, Group Captain Varun Singh, who has been shifted to Bengaluru after being initially treated at the Military Hospital, Wellington. Singh, a fighter pilot who was receiving the VVIP as a liaison officer, himself is a skilled pilot as he saved his LCA Tejas from crashing in 2020 when its Flight Control System malfunctioned — a feat for which he was awarded the Shaurya Chakra this Independence Day.

The Aircraft Accident Investigation Bureau (AAIB) from the Directorate of Flight Safety that comes under the air headquarters reached the spot on December 9 morning, and are in the process of submitting an interim assessment of the crash. This doesn’t necessarily form a part of the final findings of the Court of Inquiry (CoI). It takes into account the type of wreckage, its spread, and type of burning in around two to four days.

The CoI that might last at least three months would examine its maintenance records with the 109 Helicopter Unit (HU) in Sulur, going into when, how, and the personnel assigned with its servicing. These records are currently being collected to be handed over to the AAIB that will briefly go over them to come out with the ‘most probable cause’. The AAIB will not, however, examine the Flight Data Recorder (FDR), and the Cockpit Voice Recorder (CVR) — the former has been located — which the CoI would assess.

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The CoI, which has been ordered by Air Chief Marshal VR Chaudhari given the gravity of the accident, is being headed by Air Marshal Manavendra Singh, himself a helicopter pilot, and who is currently heading the Training Command in Bengaluru as its Air Officer Commanding-in-Chief. He is likely to be assisted by a technical and flying member.

Beginning with putting out the entire wreckage on a flat surface on a floor area, it will study the CVR, FDR, and fully examine the maintenance records. Spot analysis is key. For instance, in case of a mid-air blast, the wreckage is spread out over a larger area.

At the Defence Services Staff College (DSSC) where Rawat was heading, Varun Singh was posted as an instructor. His account would be key for investigators in ascertaining the cause behind the crash, said pilots who have been part of Boards of Inquiry. Besides matching it with the findings of the FDR, and his account of what transpired in the helicopter, it will particularly be compared to new mobile phone footage that surfaced on social media.

The clip showed fuzzy footage of the helicopter in what is initially believed to be moments before its crash in The Nilgiris. To interview civilian witnesses, the CoI would write to the District Magistrate to produce such persons. During the October 1989 aerobatics tragedy of a Mirage 2000 jet at Delhi’s Palam Air Force Station (AFS), of the multiple video recordings of the crash, only two were found to correctly capture the plane’s descent during a ‘roll’ until it crashed.

All the Tamil Nadu-based Southern Air Command’s assets will be simultaneously checked for airworthiness. The CoI will last until each component (fuel pump rotor blades, engine parts, etc.) are checked and matched with other site, documentary, survivor, and eyewitness examination to ascertain everything from a technical snag to a Foreign Object Damage (FOD). Sky visibility (called OCTA in air force parlance) given by the Meteorological Officer (Met Officer) before every flight will be taken into account. One OCTA denotes good visibility and means that only an eighth of the sky is covered with clouds.

The CoI will eventually conclude ‘material failure’, or ‘human error’ as the cause, and in case of the latter, ‘apportion blame’, besides recommending how to prevent such an incident. In case professional culpability is determined, the CoI orders a Summary of Evidence (SoE), where the personnel can produce witness and documentary evidence to make their case, with ‘censure’ or ‘administrative action’ being ordered at the SoE stage itself in case of a minor professional dereliction.It might otherwise progress to a General Court Martial, a stage still very off in the latest crash.
Parth Satam is a journalist who has been covering India’s defence sector for more than a decade. Twitter: @ParthSatam. Views are personal.
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