Flight and Crew
On the afternoon of 13 October 2011, an Airlines PNG Bombardier DHC-8-103, registered P2-MCJ, operated a regular public transport flight from Nadzab to Madang under Instrument Flight Rules. The flight crew consisted of two pilots and a flight attendant, with 29 passengers on board. Earlier that day, the same crew had flown the aircraft from Port Moresby to Nadzab. The autopilot was inoperative due to an unserviceable yaw damper, requiring manual flight.
Sequence of Events
The aircraft departed Nadzab at 1647 local time with the Pilot-in-Command as handling pilot, climbing to 16,000 ft. En route, the crew diverted right of the planned track to avoid thunderstorms. The Pilot-in-Command reported that communications with Madang Tower indicated a storm approaching the aerodrome. Intending to descend below cloud for visual reference, the pilot focused outside the cockpit. The descent to Madang was steep to remain above the Finisterre Ranges. Neither pilot noticed the airspeed increasing toward VMO. When the aircraft reached VMO at 10,500 ft with a descent rate of 3,500–4,200 ft/min and propellers at 900 RPM, the VMO overspeed warning sounded. The Pilot-in-Command raised the nose, reducing descent to about 2,000 ft/min, but the warning continued. The First Officer recalled the Pilot-in-Command moving the power levers back quickly. Shortly after, both propellers oversped simultaneously, exceeding 1,200 RPM by over 60%, seriously damaging the left engine and rendering both engines unusable.
Emergency and Forced Landing
The emergency caught the pilots by surprise, with confusion and shock on the flight deck. The left propeller overspeed lasted about 10 seconds, governed for 5 seconds, then oversped again for 15 seconds, severely damaging the left engine. About 3 seconds into the second overspeed, the right propeller feathered due to a beta switch malfunction. The Pilot-in-Command shouted questions, and the First Officer reported a double propeller overspeed and right engine shutdown. After about 40 seconds, the left propeller windmilled, producing no power. The First Officer made a mayday call to Madang Tower, providing GPS position. The crew did not perform emergency checklists. The aircraft descended at high rates, with the windmilling left propeller creating drag and asymmetry with the feathered right propeller. The average descent rate was 2,500 ft/min, exceeding 6,000 ft/min at one point. The crew initially considered ditching but decided to make a forced landing in the mouth of the Guabe River. At about 800 ft AGL, the left propeller was feathered and both engines shut down. The Pilot-in-Command aimed for an area beside the river to avoid boulders in the riverbed, but overshot his intended spot. The aircraft impacted terrain at 114 knots with flaps and gear retracted. The tail struck first, and during impact the left wing and tail detached. The wreckage came to rest 300 m from initial impact and was consumed by a fuel-fed fire. The front section fractured and rotated 180 degrees, coming to rest inverted.
Aftermath
Of the 32 occupants, only the two pilots, the flight attendant, and one passenger escaped the wreckage before it was destroyed by fire.