What happened
On April 29, 1998, a Robinson R-22 helicopter, registration PT-HVM, was conducting an instructional flight near Parque Ecológico do Tietê in São Paulo, Brazil. The flight, operated by Master Escola de Pilotagem, was performing autorotation training exercises. During a 180-degree autorotation maneuver, the low RPM warning alarm sounded.
The instructor attempted to instruct the student to correct the situation, but receiving no response, the instructor attempted to take control of the aircraft. However, the instructor noted that the flight controls felt heavy. Despite attempts to execute a recovery and a subsequent flare, the aircraft maintained a high rate of descent. The helicopter struck the ground in a running landing condition. One of the skids collided with low vegetation on the irregular terrain, causing the aircraft to overturn and resulting in the main rotor striking the ground. The aircraft sustained severe damage to its structure, engine, landing gear, rotors, and tail cone. Both occupants, the instructor and the student, were uninjured.
The investigation
CENIPA's investigation examined the operational, human, and material factors involved in the accident. The investigation established that the flight was being conducted in an unauthorized area, as the terrain was unsuitable for the maneuvers being performed, contrary to the manufacturer's manual recommendations.
Investigators also analyzed the psychological profiles and cockpit dynamics. The investigation found a significant lack of Crew Resource Management (CRM) between the two pilots. There was evidence of a hierarchy inversion in the cockpit due to the disparity in age and flight experience between the student (a highly experienced fixed-wing pilot) and the instructor. Furthermore, the investigation noted that the flight school lacked clear rules regarding designated instruction areas, leading to operational complacency.
Findings
- Inadequate Flight Planning: The training was conducted in an area not suitable for autorotation maneuvers, violating the aircraft's operating manual which requires a landing area to be available if necessary.
- Deficient Crew Coordination: A lack of effective communication and coordination between the instructor and student prevented a timely recovery. The instructor's attempt to assume control was hindered by the student's failure to release the controls.
- Human Factors: The combination of the student's aggressive personality and the instructor's tendency toward complacency, exacerbated by the student's superior flight hours in fixed-wing aircraft, led to a breakdown in cockpit hierarchy.
- Deficient Instruction: The pre-flight briefing was insufficient to ensure the student could effectively correct a low RPM condition or follow commands during an emergency.
- Deficient Supervision: The flight school demonstrated a lack of oversight regarding the use of unauthorized instruction areas.