Accident
On 11 August 2009, a de Havilland Canada DHC-6 Twin Otter aircraft, registered P2-MCB, was being operated on a scheduled regular public transport service from Port Moresby to Kokoda Airstrip, Papua New Guinea. The aircraft carried two pilots and 11 passengers. At about 1113 local time, the aircraft impacted terrain on the eastern slope of the Kokoda Gap at an elevation of approximately 5,780 ft above mean sea level. The site was in heavily-timbered jungle, about 11 km south-east of Kokoda Airstrip. The aircraft was destroyed by impact forces, and there were no survivors.
Investigation
The investigation determined that prior to the accident, the crew were manoeuvring the aircraft within the Kokoda Gap, probably in an attempt to maintain visual flight in reported cloudy conditions. The investigation concluded that the accident was probably the result of controlled flight into terrain: an otherwise airworthy aircraft was unintentionally flown into terrain, with little or no awareness by the crew of the impending collision.
Contributing Safety Factors
The official findings identified several contributing safety factors. Visual flight in the Kokoda Gap was made difficult by extensive cloud coverage in the area. The crew attempted to continue the descent visually within the gap despite weather conditions not conducive to visual flight. It was probable that while manoeuvring at low level near the junction of the Kokoda Gap and Kokoda Valley, the aircraft entered instrument meteorological conditions. The aircraft collided with terrain in controlled flight.
Other Safety Factors
Additional safety factors were noted. The copilot was assessed during normal proficiency checks for instrument approach procedures but was not qualified for flight in instrument meteorological conditions. The operator did not have a published emergency recovery procedure for inadvertent flight into instrument meteorological conditions. The Civil Aviation Safety Authority Papua New Guinea surveillance of the operator did not identify operations in contravention of Rule 91.112. The lack of a reliable mandatory occurrence reporting arrangement minimized the likelihood of an informed response to Papua New Guinea-specific safety risks. There was no qualified Director (or similar) of Aviation Medicine in Papua New Guinea. The absence of both flight data and cockpit voice recorders adversely affected a full understanding of the accident.
Other Key Findings
The investigation was unable to discount possible incapacitation of the copilot as a factor in the accident. Although not required by aviation rules at the time, the adoption of threat and error management training for flight crews and by operators was noted as a potential tool to identify and mitigate operational risk.