What happened
On July 9, 2013, a Eurocopter Germany BK117 A-4, registration HK4866, was performing a non-scheduled commercial transport flight from Ocaña to the San Pablo district in Teorama, Colombia. The mission involved transporting two passengers for an oil company to a site where a pipeline had recently been sabotaged. The flight was being escorted by a Colombian Army helicopter due to the presence of subversive groups in the area.
As the aircraft was descending toward a landing zone marked by smoke, it performed a 180-degree turn for the final approach. During this maneuver, the helicopter struck high-voltage power lines. The electrical lines became entangled in the tail boom, horizontal stabilizers, and the main rotor mast. This contact immediately destroyed the aircraft's aerodynamic lift and control, causing the helicopter to plummet vertically to the ground from approximately 100 feet. The impact resulted in the five fatalities on board, including the pilot, co-pilot, flight technician, and two passengers.
The investigation
The GRIAA investigation, which was reopened in 2014 following the discovery of new evidence, examined the flight path, the aircraft's mechanical condition, and the environmental threats present at the time. Investigators analyzed the aircraft's wreckage, noting that the tail boom had separated and components of the rotor system were scattered within a 150-meter radius.
While the aircraft's engines showed signs of functioning at the time of impact, the investigation focused on the sequence of events during the final approach. Investigators also reviewed the meteorological conditions, which were clear with high visibility, and determined that the sun's position did not significantly hinder the crew's ability to identify the power lines. Furthermore, the investigation looked into evidence of gunfire from the western hillside during the approach.
Findings
- The primary cause of the accident was the collision with high-voltage power lines during the final approach.
- This collision was likely the result of an operational evasive maneuver performed by the crew in response to suspected gunfire from illegal groups on the adjacent mountainside.
- The entanglement of the electrical lines with the main rotor mast and tail boom caused an instantaneous loss of aerodynamic stability and control.
- The high-velocity vertical impact and extreme deceleration led to the immediate deaths of all five occupants.
- The crew was fully qualified, with valid licenses and medical certificates, and no evidence of fatigue or operational deviation was found.