What happened
On May 24, 2001, a Schweizer (Hughes) H-269C, registration I-PIGA, was performing agricultural spraying operations over a rice paddy in Borgo San Martino, Italy. The mission involved flying at an extremely low altitude of approximately 2 meters to disperse biological pesticides using an external spray kit.
While flying an east-west pattern at speeds between 55 and 60 knots, the helicopter's skids inadvertently entered the water and struck the submerged floor of the paddy. The pilot attempted an immediate full-power climb to recover; however, the impact caused the skids to break approximately one-third of their length. The force of the impact caused the main rotor blades to strike the tail boom, severing it. The aircraft subsequently rolled onto its right side and slid approximately 30 to 40 meters across the paddy bed before coming to a halt. The pilot sustained minor injuries and was able to egress the aircraft without assistance.
The investigation
The ANSV investigation examined the aircraft's maintenance history, the pilot's experience, and the environmental conditions at the time of the accident. The investigation confirmed that the aircraft was airworthy and had undergone recent inspections. The pilot was an experienced commercial operator with significant flight hours on the specific type.
Investigators analyzed the physical evidence at the crash site, noting that the water depth in the paddy was between 10 and 15 centimeters. The investigation also looked into the visual conditions, specifically the lack of rice vegetation and the presence of a film on the cockpit windows caused by the spraying process.
Findings
- The primary cause of the accident was the pilot's incorrect assessment of the altitude above the rice paddy and a delayed perception of the aircraft's attitude and trajectory.
- The lack of rice vegetation and the reflection of sunlight off the water created a "mirror effect," making it difficult for the pilot to accurately judge the height above the surface.
- A residue of the biological pesticide had formed a film on the exterior of the cockpit canopy, which further hindered the pilot's ability to perceive the distance to the ground.
- The repetitive nature of the low-altitude flight tasks may have led to a decrease in the pilot's level of concentration.