What happened
On May 19, 1999, at approximately 16:53 local time, a Robinson R-44 helicopter, registration PT-YLF, was performing a transport flight from Fazenda Leda to Holambra, São Paulo. The flight was operated by the pilot, who was accompanied by two passengers.
During the takeoff roll from an uncertified landing site, the aircraft traveled approximately 200 meters before striking a lightning protection wire connected to two high-voltage towers. The impact caused a loss of control, leading the helicopter to strike the ground and subsequently crash into a nearby lake. The pilot sustained fatal injuries at the scene, while the two passengers suffered serious injuries.
The investigation
CENIPA's investigation focused on the operational decisions and environmental factors present during the takeoff. The investigation established that the pilot was flying under Visual Flight Rules (VFR) but lacked the necessary Instrument Flight Rules (IFR) rating required for the planned night portion of the flight. The flight plan estimated an arrival time that would have placed the aircraft in night operations, which was non-compliant with the pilot's qualifications and the aircraft's certification.
Investigators examined the takeoff profile, noting that the aircraft maintained an altitude of approximately 25 feet during the initial acceleration. This altitude placed the helicopter within a high-risk zone of the manufacturer's recommended height/velocity diagram. Additionally, the investigation looked into the visibility of the power lines, noting that while the towers were visible, the wires themselves lacked the necessary marking spheres required by certain standards for such crossings.
Findings
- Deficient planning: The pilot chose a takeoff heading of 270 degrees, which was perpendicular to the high-voltage lines, despite having the option to use a different heading given the calm wind conditions.
- Deficient judgment: The pilot operated at a low altitude (25 ft) during the takeoff roll, increasing the risk of obstacle collision.
- Environmental factors: The sun was positioned near the horizon, approximately 10 degrees to the right of the takeoff axis. The reflection of sunlight off the aircraft's plexiglass may have caused glare, obscuring the pilot's view of the wires and impairing altitude perception.
- Regulatory non-compliance: The flight was intended to transition into night VFR operations without the pilot possessing an IFR rating or the aircraft being IFR-certified.
- Lack of obstacle marking: The high-voltage wires lacked the necessary visual signaling to aid in detection.