What happened
On 3 February 2016, a Bell 206L-4 helicopter, registration PK-UAG, was performing a charter flight in the Siriwo area of Papua, Indonesia. The flight, operated by PT. Amur Aviation Indonesia, was part of a multi-sector mission traveling from Timika to Enarotali, Bayabiru, and finally to the Spot 99 helipad.
As the aircraft approached the Spot 99 helipad, it descended to approximately 150 feet above ground level. During the final approach, at an altitude of roughly 50 feet and a low airspeed of 10 to 15 knots, the helicopter entered an uncommanded right-hand spin. The pilot attempted to recover the aircraft by applying left rudder and pushing the cyclic to increase airspeed. However, the proximity of a 15-meter cliff prevented a successful recovery. The pilot eventually reduced engine power to idle, but the aircraft struck the roof of a local house. The impact resulted in serious injuries to the pilot, while the three passengers on board escaped without injury.
The investigation
The investigation conducted by the KNKT focused on the flight dynamics and the operational decisions leading to the accident. Because the aircraft was not equipped with flight recorders, investigators relied on GPS data and witness accounts.
Investigators examined the pilot's approach pattern, noting that the aircraft did not perform a reconnaissance of the area prior to the landing attempt. Furthermore, the investigation looked into the operator's management practices, specifically regarding how the pilot was prepared for a flight to an unfamiliar landing site. It was noted that the pilot was flying to this specific helipad for the first time and was not accompanied by a qualified pilot to assist with navigation or terrain awareness.
Findings
- The primary cause of the accident was a loss of tail rotor effectiveness (LTE), which triggered the right-hand spin.
- The aircraft was flying at an altitude too low to allow for a successful recovery from the spin due to the nearby terrain.
- The pilot lacked sufficient situational awareness regarding the surrounding obstacles and terrain because no prior reconnaissance was conducted.
- The operator's decision to rely on a passenger's local knowledge, rather than providing a qualified pilot or conducting a proper briefing, resulted in inadequate information for the flight.
Safety action
Following the investigation, the KNKT issued safety recommendations to PT. Amur Aviation Indonesia. The committee emphasized the need for stricter adherence to company SOPs regarding operations in unfamiliar areas, specifically requiring proper risk assessments and ensuring that pilots are accompanied by qualified personnel or adequately briefed when navigating new routes.