What happened
During the final approach to runway 23, the crew was at an altitude of 500 meters and an indicated airspeed of 160 km/h while approximately 500 meters from the threshold. The flight engineer informed the captain that the flaps were set to three-quarters position and noted that the airspeed was slightly low. The captain did not adjust the configuration or speed, continuing the approach in this state.
After passing over the perimeter road, the captain commanded full flap extension and a reduction in throttle. As the flight engineer extended the flaps fully and slowed the power levers, the aircraft began to lose altitude rapidly. It struck treetops before impacting the ground 175 meters short of the runway threshold. The airframe rolled for a short distance and came to rest after colliding with a ditch.
All 27 occupants evacuated the aircraft safely without injury. However, the severe structural damage sustained during the impact rendered the airframe beyond repair.
Findings
The investigation concluded that the accident resulted from the captain adopting an incorrect approach configuration. By maintaining an insufficient approach speed while full flaps were selected, the aircraft stalled and impacted the terrain short of the runway.