Airlines PNG Flight 4684

The aircraft departed Jacksons International Airport at 10:50 am local time and reported to Jacksons Tower that they were climbing to 9,000 ft via the Kokoda Gap, with an estimated time of arrival at 11:20 am. At 11:11 am, while en route to Kokoda and on descent in the Kokoda Gap, the crew of Flight 4684 conversed with the crew of an aircraft, registered P2-KST, which was departing from Kokoda. There was no indication that the crew of Flight 4684 had any problems with their aircraft. On the ATC recording, the crew was heard saying "Thank you very much, morning long you". This was the last communication from Flight 4684. ==Aircraft==

The aircraft involved in the accident was a De Havilland Canada Twin Otter, registered in Papua New Guinea as P2-MCB. It had a serial number of PCE-PG0073. The aircraft was configured to carry 19 passengers and two crew, with a maximum take-off weight of 5,670 kg. The aircraft was fitted with the required equipment for two-pilot Instrument Flight Rules. An autopilot system was not fitted in the aircraft. The aircraft had accumulated a total flying time of 46,700 hours. The aircraft was built in 1974. ==Passengers==

The aircraft was carrying 11 passengers and two crew. The passengers included eight Australian tourists on their way to trek the Kokoda Track, two tour guides (one Australian and one Papua New Guinean) from No Roads Expeditions tour company, and a Japanese tourist. Seven of the nine Australian passengers on board came from Victoria, and two from Queensland. Aboard the flight was a part-time tour guide Matthew Leonard, who was the son of Western Australia police inspector Bill Leonard. The Captain was Jannie Moala from Papua New Guinea. She had accumulated 2,177 flying hours, of which 1,836 of them were on the Twin Otter. AIC found no evidence that she had been trained by Airlines PNG for use of the Global Positioning System (GPS). However, training records that were provided by the operator showed that items identified within the operator's training syllabus that included the introduction to, and use of the GPS for en route navigation had been marked by the training captain as complete. No evidence as to the extent of that training, or level of understanding attained by Moala, was provided by the operator. The operator stated that at about the time of the accident, a GPS training package specific to the conduct of GPS non-precision approaches was being introduced. The co-pilot was First Officer Rodney Souka from Papua New Guinea. He had accumulated 2,150 flying hours, of which 1,940 were on the Twin Otter. AIC did not find any evidence that Souka had been trained by Airlines PNG for using the Global Positioning System (GPS) on the aircraft. ==Investigation==

The accident was investigated by the Accident Investigation Commission (AIC), assisted by the Australian Transport Safety Bureau (ATSB). The AIC could only determine the cause of the crash without access to a Cockpit Voice recorder or Flight Data Recorder, as neither recorder were required on a Twin Otter. The lack of both flight data and cockpit voice recorders adversely affected a full understanding of the accident investigation. Alternatively, on board the aircraft was a small electronic GPS tracking and data telemetry device. Using the device's Non-Volatile memory, the ATSB was able to piece together portions of the flight path. The weather in Kokoda Gap at the time was poor. Based on eyewitnesses accounts and photographic evidence retrieved by ATSB, Kokoda Gap was obscured by clouds at the time of the accident, making it difficult for the pilots to know if they were in close to terrain. Given the surrounding mountainous terrain, the evident cloud in the Kokoda Gap, had the potential to severely limit the crew's escape options, increase their workload, and test their situational awareness. A reduction in situational awareness and the presence of mountainous terrain during an approach are known risk factors in instances of controlled flight into terrain (CFIT). Later investigation found that only one pilot had an IFR rating, while the other did not. The co-pilot, First Officer Rodney Souka, had been assessed for instrument approach procedures; however, he was not qualified for flight under the IFR. Although the crew had planned the flight under Instrument flight rules, the forecast cloud in the area should have alerted the crew that under the actual conditions, visual flight in the Kokoda Gap would prove problematic. The visual descent into the Kokoda Gap required 5 km visibility, while at the time of the accident, the visibility was less than 5 km. The Australian ATSB then turned their attentions to Souka. They examined his postmortem and medical history. Investigators found that Souka had critical coronary artery heart disease, and the examining pathologist considered that Souka could have had a medical emergency at any time. Souka's relatives reported that they were not aware of any significant medical condition affecting him. If an emergency occurred in mid-air as the aircraft approached the cloud to the north of the Kokoda Gap would have instantly increased Moala's workload and distracted her from the primary task of flying the aircraft. Both those factors are known to increase the risk of CFIT. Investigators noted that Kokoda Airport was lacking in basic navigation infrastructure. The lack of ground-based navigation aids at Kokoda Airport meant that the only potential navigation assistance for the crew during their approach to Kokoda was from a GPS, or via the ground-based non-directional beacon/distance measuring equipment (NDB/DME) located at Girua Airport. The investigation concluded that the accident was probably a controlled flight into terrain: that is, an otherwise airworthy aircraft was unintentionally flown into terrain, with little or no awareness by the crew of the impending collision. ==See also==