What happened
On December 15, 1999, an AS350 B2 helicopter, registration PP-EOY, was deployed by the São Paulo Military Police Air Group to provide emergency medical evacuation following a traffic accident. The aircraft arrived at a street intersection in São Paulo to transport a medical team.
Upon arrival, the pilot initially landed on an inclined section of the road to allow the medical crew to disembark. Due to the slope of the terrain and the presence of a large crowd of bystanders behind the aircraft, the pilot attempted to reposition the helicopter further forward to a more stable location. During this maneuvering, the aircraft taxied approximately 13 meters along the ground. As the pilot attempted a subsequent landing, the aircraft experienced a lateral oscillation, causing the main rotor blades to strike the exposed rebar of a nearby construction wall. The impact caused severe damage to the engine and main rotor assembly and triggered a small engine fire, which was quickly extinguished. While the pilot and passenger escaped without injury, a bystander working at the construction site sustained serious injuries from rotor debris.
The investigation
CENIPA's investigation focused on the decision-making process and the environmental constraints at the landing site. Investigators examined the aircraft's maintenance records, noting the AS350 B2 was nearly new with only 36 flight hours. The pilot was found to be highly experienced and properly licensed.
The investigation analyzed the landing site, which had been demarcated by ground personnel (police and rescue teams). Investigators determined that the pilot's attempt to move the aircraft forward placed the helicopter in a highly restricted area, positioned directly beneath low-voltage power lines and a public street lamp, with limited lateral clearance due to nearby buildings.
Findings
- Inadequate landing site assessment: The pilot attempted to land in a restricted area with significant physical obstructions and overhead hazards.
- Loss of situational awareness: It is possible that high motivation to provide urgent medical aid led the pilot to overlook the risks of the chosen landing zone.
- Deficient ground support: The personnel responsible for signaling and marking the landing area lacked sufficient experience to identify a safe landing zone.
- Improper command application: The investigation noted a possible conflict in the use of flight controls, which allowed the lateral oscillation that led to the rotor strike.