What happened
On May 13, 2016, a Bell 206L-4 helicopter, registration PT-YEL, was performing an interdiction mission to monitor deforestation in an indigenous area near Cacoal, Rondônia. The aircraft was transporting two crewmembers and three passengers to an open pasture chosen as a landing site.
During the final approach to the landing area, the helicopter struck a single-phase power line positioned approximately 15 meters above the ground. The impact was mitigated by the aircraft's wire cutter, which successfully severed the line. Despite the collision, the pilot maintained control of the aircraft and completed the landing safely. The aircraft sustained minor damage to the main rotor blades, drift, windshield, and control panel. All five occupants were unharmed.
Following the incident, the pilot attempted a restart and takeoff; however, due to excessive vibrations caused by the impact, the pilot elected to shut down the engine and abandon the aircraft once the rotors stopped.
The investigation
CENIPA's investigation focused on the circumstances leading to the collision and the operational environment of the mission. The investigation examined the pilot's flight planning, the adequacy of the landing site survey, and the organizational oversight provided by the operator, IBAMA.
Investigators noted that the landing site was an unapproved area and that the crew had only performed a single overflight of the area prior to landing. The investigation also reviewed the pilot's previous involvement in a serious incident in 2015 and found that the operator lacked a formal program for monitoring crew members returning to flight duties after such events. Furthermore, the investigation identified a lack of standardized mission briefings and insufficient dissemination of the General Operations Manual (MGO) to the crew.
Findings
- Inadequate obstacle identification: The crew failed to perceive the power line during the approach due to an insufficient survey of the landing area.
- Deficient flight planning: The pilot did not adequately account for terrain obstacles, such as power lines, during the planning phase.
- Inadequate landing site evaluation: The approach relied on a single overflight, which did not allow for a comprehensive assessment of the terrain or potential hazards.
- Organizational vulnerabilities: There was a lack of managerial oversight regarding mission briefings and a failure to ensure that all crew members were fully aware of the procedures outlined in the operator's manual.
- Lack of crew follow-up: The operator lacked a structured process for the reintegration and monitoring of pilots following previous aeronautical incidents.