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Last updated: 29 November 2021
Date:Sunday 9 November 1997
Type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Twin Otter 300
Operator:Royal Australian Army
Registration: VH-HPY
MSN: 706
First flight: 1980
Total airframe hrs:18208
Engines: 2 Pratt & Whitney Canada PT6A-27
Crew:Fatalities: 0 / Occupants: 4
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 0 / Occupants: 4
Aircraft damage: Damaged beyond repair
Location:9 km (5.6 mls) SW of Simbai (   Papua New Guinea)
Phase: En route (ENR)
Departure airport:Koinambe Airport (KMB), Papua New Guinea
Destination airport:Simbai Airport, Papua New Guinea
On the third day of flying operations in Papua New Guinea, the crew of the Darwin-based Twin Otter were conducting a flight from Madang and return via a number of airstrips in the central highlands. When haze and cloud prevented them flying the flight-planned direct track between the Koinambe and Simbai airstrips, they decided to fly north-west via the Jimi River valley and one of its tributaries. Two of the trainees were occupying the cockpit seats, one as flying pilot and the other as navigating pilot using a 1:1,000,000-scale chart. When the crew turned the aircraft to follow a tributary off the Jimi River, the training pilot was in the aircraft cabin. A few minutes later, their discussion regarding the progress of the flight attracted the attention of the training pilot. By this time, however, the position of the aircraft in the valley, and its available performance, were such that an escape from the valley was not possible. The aircraft collided with trees before impacting steeply sloping ground.

Probable Cause:

1. There had been a significant loss of corporate knowledge, experience and risk appreciation within the Army concerning the operation of Twin Otter type aircraft in tropical mountainous areas.
2. No training needs analysis for the exercise had been conducted.
3. The tasking and briefing of the training pilot were incomplete.
4. The training pilot did not adequately assess the skill development needs of the trainees.
5. The supervision of the flight by the training pilot was inadequate.
6. The scale of chart used by the crew was not appropriate for the route they intended to fly.

Accident investigation:
Investigating agency: BASI
Status: Investigation completed
Duration: 1 year and 9 months
Accident number: BASI report 9703719
Download report: Final report

Follow-up / safety actions

ATSB issued 5 Safety Recommendations

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This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Koinambe Airport to Simbai Airport as the crow flies is 24 km (15 miles).

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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