VT-BHS Accident - Probable Causes and Contributing Factors.
3.2. Probable Causes and Contributing Factors.
3.2.1. The cause of the accident was loss of Situational Awareness wherein the crew got Spatially Disoriented during a turn for returning to base in response to an emergency warning. In the process, the helicopter went beyond the flight envelope exceeding its structural limits and thereby leading to failure of the rotor system.
3.2.2. The contributory factors to the loss of Situational Awareness were:
3.2.2.1. Spatial Disorientation. In response to the TGB Hot Warning, the crew was required to reduce speed to 60 to 70 Kts and land as soon as possible. The Pilot initiated a manual turn without using the AFCS upper modes or reducing speed, in flight conditions below VMC. These actions coupled with inadvertent entry into clouds, led to the helicopter reaching steep nose down attitude with bank angle in excess of 90.
3.2.2.2. Pilot Training and Experience. The crew had limited type experience and inadequate exposure to IFR operations. They had also not undergone simulator training for IF or handling of critical emergencies. The crew knowledge of the helicopter systems was inadequate.
3.2.2.3. Cockpit Resource Management. Crew coordination was found lacking during handling of the emergency. The Co-Pilot did not render any assistance during the critical phase of flight. The AFCS and available avionics on board were not appropriately utilized for negotiating the marginal weather.
3.2.2.4. Piloting. The large and sudden control applications by the Pilot at the time when the helicopter was beyond its cleared flight envelope led to exceedance of structural limits and subsequent failure of the rotor system.
3.2.2.5. Additional Factors. The situation was compounded by continuous activation of MW during the period.
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