What happened
On February 11, 2004, at approximately 15:30 local time, a Schweizer 269C-1 helicopter, registration PT-YVE, was conducting a local flight training mission near Itirapina, São Paulo. The flight was part of the second pre-solo mission for a student pilot under the instruction of an experienced instructor.
While flying at a low altitude of approximately 100 feet over a plateau area, the aircraft struck a low-voltage power line. The impact caused the wire to become entangled in both the main rotor head and the tail rotor. Following the collision, the aircraft performed a sharp maneuver before crashing vertically into a wooded area. The impact resulted in the total destruction of the aircraft and the two fatalities of the crew members.
The investigation
CENIPA investigators examined the wreckage and found approximately 15 meters of low-voltage wire entangled in the rotor systems. Technical analysis of the engine and transmission revealed that the engine was producing power at the moment of impact, as evidenced by damage to the engine adapter splines and the torsion fracture of the drive shaft. \nThe investigation also reviewed the operational environment and the flight school's procedures. It was noted that the power line had been recently installed and was not marked, and dense vegetation obscured the visibility of the utility poles. Furthermore, the investigation looked into the instructor's physiological state, noting he had received only about four hours of sleep the previous night, and evaluated the flight school's lack of standardized instruction areas or written flight orders.
Findings
- Inadvertent low-altitude flight: The instructor performed a low-altitude flight that was not required for the student's current training stage.
- Lack of operational oversight: The flight school lacked written instruction orders (OI) and had not formally defined specific geographic boundaries for training areas, leaving flight profiles to the discretion of individual instructors.
- Obstacle visibility: The low-voltage wire was unmarked and difficult to detect due to the surrounding vegetation.
- Human factors: The instructor's excessive self-confidence and potential fatigue from insufficient sleep may have reduced situational awareness and led to poor judgment regarding terrain and obstacles.
- Regulatory non-compliance: The flight did not adhere to standard minimum altitude requirements for flying over non-built-up areas.