What happened
On November 8, 1999, a Hughes 269 C helicopter, registration ZS-HFB, was conducting a private survey flight in the lower Drakensberg region between Mount Fletcher and Matatiele. The aircraft was ascending a valley when the crew encountered sudden and violent atmospheric conditions.
During the ascent, the aircraft was struck by a severe downdraft. In an attempt to maneuver away from the descending air, the helicopter was forced into the side of a mountain. The impact resulted in a heavy landing on sloping terrain, which caused the aircraft to roll over the edge of a cliff approximately four to five meters in height. The helicopter ultimately came to rest in an inverted position.
The investigation
Investigators examined the circumstances of the flight and the physical evidence at the crash site. The investigation established that the aircraft was operating under clear weather conditions, though winds were recorded at 110 degrees at 25 knots.
Following the impact, the pilot was able to extricate himself from the wreckage and subsequently assisted the passenger. As the occupants moved away from the downed aircraft, the wreckage ignited. Despite efforts to suppress the flames, the fire consumed the helicopter, leaving only the wreckage behind. There were no fatalities in the accident, though one person sustained injuries.
Findings
- The primary cause of the accident was the encounter with a sudden and severe downdraft while the aircraft was climbing through a valley.
- The force of the downdraft prevented the pilot from maintaining altitude or maneuvering effectively, leading to the collision with the mountainside.
- The terrain and the momentum of the heavy landing caused the aircraft to roll over a cliff edge.