What happened
On June 5, 2022, a Bell 206B helicopter, registration PP-MCJ, was performing a low-altitude inspection of 138-kV electrical transmission lines near Currais Novos, Rio Grande do Norte. The flight, operated by Companhia Hidro El entanto do São Francisco (CHESF), was traveling from Natal to Mossoró with a crew of three. During the mission, the aircraft struck a 230-kV transmission line belonging to TAESA. Following the impact, the helicopter fell into a nearby dam and sank. The collision resulted in three fatalities, and the aircraft was destroyed.
The investigation
CENIPA's investigation focused on the circumstances surrounding the low-altitude operation and the visibility conditions at the time of the accident. Investigators examined the aircraft's maintenance records, which were up to date, and confirmed the presence of a Wire-Strike Protection System. The inquiry also reviewed the crew's experience, noting that while the pilot in command was highly experienced, the inspectors on board had relatively limited experience in aerial inspections. The investigation scrutinized the adequacy of flight planning, the accuracy of navigational aids, and the visibility of the transmission line infrastructure.
Findings
- Inadequate signage: The 138-kV transmission towers were not painted red as required by technical standards, making them difficult to identify.
- Outdated navigational data: The aircraft was equipped with a 2004 aeronautical chart, which lacked information regarding the intersection of the CHESF and TAESA transmission lines. Additionally, the onboard GPS and tablet did not contain updated intersection data.
- Flawed decision-making: Despite deteriorating meteorological conditions, the decision was made to continue the mission, which may have been influenced by self-imposed pressure to maintain the inspection schedule.
- Inadequate flight planning: There was a lack of prior knowledge regarding the specific operational hazards, such as the unmarked intersection of the two power line networks.
- Reduced situational awareness: The low flight speed of approximately 80 knots may have hindered the crew's ability to detect the obstacle in time.