Preliminary investigation into the Air Niugini ATR 42-300 freighter overrun at Madang indicates that the cargo on board the turboprop was substantially heavier than the loadsheet data showed.
The aircraft had been loaded with 330 boxes of cigarettes. While the operator’s cargo supervisor said that each box had been assumed to weigh 12kg, none had been weighed before loading.
Papua New Guinea’s accident investigation commission says the commanding pilot had determined that the maximum cargo to be loaded was 3,710kg.
Using a 12kg assumption, the total weight of the boxes reached 3,960kg. But the average weight was actually higher and the inquiry calculates the true load at 4,303kg – an excess of 593kg compared with the pilot’s figure.
“It was not possible to determine the actual distribution of cargo in the aircraft after the accident, because of the large number of cartons removed by local people before the investigation began,” the commission adds.
Around a third of the cargo was taken, it believes.
But based on recollections from one of the personnel assisting with the loading, the inquiry estimates that 87 cartons – weighing over 1,100kg – had been loaded in a single compartment, for which the loadsheet showed just 350kg.
The aircraft, bound for Tabubil and then Port Moresby, had also been loaded with 2,650kg of fuel in order to fly both sectors, owing to fuel uplift limitations at Tabubil.
As the ATR (P2-PXY) perfomed its take-off roll from Madang’s runway 25 on 19 October, the pilot found he could not pull the control column back as the aircraft reached rotation speed, calculated at 102kt.
“He reported afterwards that the controls felt very heavy in pitch,” says the inquiry. He immediately aborted the take-off but could not stop the aircraft before it overran the end of the runway, travelled down an embankment, hit the perimeter fence and sank into a creek.
Its outer starboard wing, damaged in the collision, caught fire and all three occupants – the two ATR pilots plus a captain acting as operational support – escaped through a roof hatch.
Investigators state that there is no evidence of any pre-existing discontinuity in the flight-control systems. The probe has yet to reach conclusions on the accident but will analyse the operator’s cargo-loading procedures and the aircraft’s weight and balance status.