What happened
On 23rd August 2019, a Bell 407 helicopter, registration VT-SVK, was conducting non-scheduled rescue and relief operations in the Uttarkashi district of Uttarakhand. The aircraft, operated by M/s Aryan Aviation Pvt. Ltd., was flying between Aarakot and Chiva to deliver essential food and medical supplies following severe flooding in the region.
During the third flight sortie of the day, while descending at approximately 6,500 feet, the helicopter struck an overhead cable. The impact caused the right skid to sever from the front cross tube, which then struck the cockpit's Perspex. The resulting debris injured the pilot, causing facial bleeding. The impact also triggered an abrupt and uncontrollable change in the aircraft's flight attitude, characterized by intense pitching and rolling.
With no suitable landing fields available due to the steep mountainous terrain and the presence of a flooded river below, the pilot attempted an emergency landing on a riverbed covered in boulders. The helicopter struck a large rock on its belly before coming to a rest. The pilot sustained serious injuries, while the aircraft engineer escaped with minor injuries.
The investigation
AAIB India investigators examined the wreckage and flight history to determine the sequence of events. The investigation confirmed that the aircraft had successfully completed two previous sorties that day without incident. The pilot had been actively scanning the flight path for obstructions during those earlier flights.
Technical examination of the wreckage revealed extensive damage to the Bell 407 structure. The right skid assembly was severely compromised, and the impact of the severed skid caused significant distortion to the cockpit and cabin doors. The fuselage, tail boom, and horizontal stabilizer sustained substantial damage, and the main rotor blades were also impacted. The investigation also reviewed the operational environment, noting the challenging terrain and the necessity of the relief mission.
Findings
- The primary cause of the accident was the collision with an overhead cable during the descent phase of the flight.
- The impact of the cable strike caused structural failure of the right skid assembly and secondary damage to the cockpit glazing.
- The loss of control was exacerbated by the sudden mechanical damage and the resulting debris hitting the pilot.
- The pilot'1s decision to perform a forced landing on the riverbed boulders was a response to the lack of alternative landing sites in the narrow valley.