What happened
On November 14, 2001, a Robinson R22 helicopter, registration PT-YNH, was performing a local flight from Campo de Marte, São Paulo, to the Helicentro Tamboré helipad in Barueri. The flight involved a pilot and a passenger, both of whom were experienced fixed-wing airline pilots.
During a high-angle approach to the helipad, the aircraft encountered a tailwind. The pilot reported that as the aircraft reached the final approach phase, the sink rate increased significantly to approximately 1,000 feet per minute while the airspeed dropped to nearly zero. In an attempt to arrest the descent, the pilot applied collective pitch; however, this resulted in a loss of engine RPM because the power required exceeded the power available. The aircraft subsequently lost control, with the tail rotor striking the ground followed by the skids, resulting in severe damage to the airframe, including the main rotor, engine, and tail boom. Both occupants were uninjured.
The investigation
CENIPA's investigation focused on the flight parameters and the decision-making process during the approach. The investigation established that the aircraft was airworthy, with all maintenance inspections up to date, and was within weight and center of gravity limits.
Investigators examined the meteorological conditions, noting unstable winds and gusts of 10 knots. The analysis highlighted that the pilot's decision to continue the approach despite the tailwind and high sink rate deviated from the manufacturer's operating manual, which advises against tailwind landings and warns against allowing airspeed to drop below 30 knots when the sink rate is high. Furthermore, the investigation considered the possibility that the flight was an unannounced transition or training flight for the passenger, who had not flown this helicopter type in over a year.
Findings
- The pilot's decision to continue the approach rather than performing a go-around was a primary contributing factor.
- Improper use of controls led to a loss of engine RPM when attempting to correct the sink rate with excessive collective input.
- The presence of a tailwind reduced lift and increased the difficulty of maintaining a controlled approach.
- A potential atmosphere of complacency, stemming from the friendship between the two pilots, may have reduced situational awareness and allowed errors to go uncorrected.
- Inadequate flight planning contributed to the unsafe approach parameters.