What happened
On June 20, 2020, at approximately 11:52 local time, an AS350B3 helicopter, registration I-MLTA, was engaged in aerial work near Collesano, Sicily. The mission involved external sling load operations (HESLO) to transport netting for the purpose of reinforcing a rocky cliffside. After completing approximately 40 successful rotations of transporting material, the pilot attempted a final maneuver to recover ground personnel from the cliff.
While performing a hover near the rock face to pick up the crew, the helicopter approached too closely to the left side of the aircraft. The main rotor blades struck the rock wall, causing an immediate loss of control. The helicopter plummeted down the slope, eventually coming to rest against a metal guardrail of a retaining wall. The impact caused damage to nearby residential windows and vehicles. The pilot sustained minor injuries, while the personnel on the ground remained uninjured.
The investigation
The ANSV investigation examined the flight data and operational procedures. Although the aircraft was not equipped with a Flight Data Recorder (FDR) or Cockpit Voice Recorder (CVR), investigators reviewed data from the Engine Data Recorder (EDR) and a cockpit camera (Vision 1000). The camera, which views the cockpit from the right side, showed no mechanical anomalies prior to the impact; the aircraft was flying at a very low altitude in a stable hover with only minor oscillations. The EDR also confirmed no engine power issues.
Investigators also reviewed the operator's Manual of Operations (MO). While the MO permits personnel pick-up via hovering when landing is not feasible, it requires a specialist to be on board to assist with visual cues and safety. In this instance, the specialist was not present during the maneuver. Furthermore, the pilot's seating position (right side) created a blind spot regarding the obstacle on the left.
Findings
- The primary cause of the accident was the contact between the main rotor blades and the rock face during a low-altitude hover.
- Operational fatigue may have contributed to the event, as the pilot had just completed 40 repetitive load-and-unload cycles.
- The absence of a required specialist to assist the pilot during the personnel embarkation maneuver hindered situational awareness.
- The pilot's position in the right-hand seat made it difficult to monitor the proximity of the obstacle located on the left side of the aircraft.