The flight was a non-scheduled charter carrying eleven passengers, including three children, from Tekin in West Sepik Province to Kiunga. Sunbird Aviation, a small charter company based in Goroka, operated the twin-engine turboprop under visual flight rules. Picard radioed air traffic service to report he was entering the left-hand traffic pattern for landing. The weather at Kiunga was good, with clear conditions and no reported wind issues. He configured the aircraft for approach. What happened next took only seconds. Witnesses on the ground reported a change in engine sound as the aircraft suddenly rolled over and dove into the ground. Three people were pulled alive from the wreckage and transported to Kiunga Hospital, but all three were pronounced dead on arrival.

Papua New Guinea's Accident Investigation Commission sent two investigators to the crash site, joined by a representative from manufacturer Britten-Norman. Bad weather and flooding delayed examination of the wreckage for five days. When investigators finally reached the aircraft, they found the right engine had failed, but they could not determine precisely when. Damage to the engine suggested it was still hot and slowly spinning down at impact, pointing to a recent shutdown. Yet Picard had set the rudder trim tab fully to the left to compensate for asymmetric thrust, and the right propeller had automatically feathered, both actions requiring time. The right fuel tank was empty. Evidence suggested Picard had attempted to cross-feed fuel from the left tank, though impact forces had distorted the controls beyond certainty. No definitive mechanical cause for the engine failure was ever established.

The investigation identified the primary cause as an excessively aft center of gravity. Aircraft naturally pitch up when flaps are extended on approach, and pilots compensate with elevator trim. But the Mamutu's loading placed the CG so far aft that when Picard deployed full flaps, the pitch-up became uncontrollable. The wreckage showed full nose-down elevator trim applied, meaning Picard had used every tool available to push the nose down. It was not enough. At the aircraft's low altitude, stall recovery was impossible. Investigators found no evidence that Picard had calculated the CG for this flight, or for any recent flights, despite routinely signing paperwork attesting that he had. Worse, the Weight and Balance Computation Sheet itself was wrong. Major repairs from a previous crash had reduced the permissible baggage load, but the calculation form was never updated to reflect the change.

The investigation painted a picture of systemic neglect. The aircraft's emergency locator transmitter had passed its mandatory replacement date and did not activate on impact. The incorrect weight-and-balance sheet had been in use for years without correction. The pilot had been signing off on CG calculations without performing them. Investigators concluded the aircraft was not technically airworthy at the time of the flight and that Sunbird Aviation had violated regulations in operating it. The ATS radio system in the Kiunga area also suffered from static interference, garbling some of Picard's transmissions, though this did not directly cause the crash. In Papua New Guinea's remote highlands, where small aircraft are the primary link between communities, the margin between routine flight and disaster can be measured in a few miscalculated pounds placed a few inches too far aft.