Horrified onlookers on the ground could do nothing for the four tourists and five Skydive NZ staff onboard the Walter Fletcher FU24 which crashed into a paddock near the Fox Glacier airstrip shortly after taking off on September 4, 2010.
It was one of the country's worst aviation disasters.
Coroner Richard McElrea today released his findings into the tragedy. He concluded the aircraft was overloaded and off-balance.
This, coupled with some unknown factor - possible engine malfunction, control column failure, or inadvertent pilot error - probably accounted for the aircraft's loss of control, he said.
However, it was unlikely the cause of the crash would ever be fully understood.
Killed in the crash were Patrick Michael Byrne (26), of Ireland; Glenn James Bourke (18), of Australia; Annika Charlotte Kirsten (23), of Germany; Bradley Victor Coker (24), of England; skydive masters Adam Bennett (47), Michael John Suter (32), Christopher McDonald (62), Rod Clifford Miller (55), of Greymouth; and the pilot Chaminda Nalin Senadhira (33), of Queenstown.
Mr McElrea found all nine on board died from from blunt force injuries.
Witnesses to the crash included David Baldwin, a commercial pilot and aviation examiner.
He described seeing the aircraft in a ''near vertical climb'' about 25m to 30m followed by a stall turn to the left and a brief vertical descent.
It briefly managed to pull its wings level before crashing.
Helicopter pilot Andrew Gutsell described the aircraft gaining altitude with the nose lifting in a ''text book stall'' about 60m when it plummeted, without sufficient airspeed, and crashed, left wing first.
None of the passengers were restrained, which probably resulted in ''load-shift'' as passengers slid to the rear of the aircraft during the ascent, throwing it off its centre of gravity.
The Greymouth inquest was told that eight of the bodies had been found in the tail section of the plane.
Mr McElrea made a recommendation, directed at Transport Minister Gerry Brownlee, that passenger restraints for tandem parachuting operations be ''urgently considered'' for implementation across the industry.
He also recommended all similar aircraft used for parachute operations be restricted to six people and the pilot.
Mr McElrea said it was likely the aircraft was above its allowable weight limit by some 67kg.
The aircraft operator had also been unaware that, following its conversion from an agricultural plane, the centre of gravity had moved backwards by two inches.
''It is clear on the evidence that load-shift forces that occurred when the aircraft was in operation were an essential element in the crash. The more aft [behind] the centre of gravity, the less the stability of the aircraft.''
It was also possible the pilot's control column had been broken, or else a loose object in the cockpit had jammed the pitch control mechanism, although both of these would be rare events.
Mr McElrea said Mr Senadhira had a good reputation as a pilot, but a pilot-related factor, including possible distraction or ''an intentional early rotation of the aircraft, for whatever reason, without sufficient flying speed'' could not be ruled out.
''Weight and balance issues in themselves cannot be ruled out as causative of the dangerously nose-high attitude of the aircraft at take-off, but it is likely some other factor has also occurred.''
The regulatory regime in place at the time of the accident did not require parachuting operators to be subject to ongoing Civil Aviation Authority (CAA) monitoring and audits, but that was changed last year.
''Had commercial tandem parachuting operations been required to be certificated and subject to CAA audit ... there is more likelihood that weight and balance problems in carrying the eight unrestrained passengers in a Walter Fletcher aircraft would have been identified and acted upon,'' Mr McElrea said.
By Matthew Theunissen.
Crash inquest
Findings
• Nose lifted in ''text-book stall''.
• Plane over weight limit and off-balance.
• Unknown factor also involved in crash.
• ''Load-shift'' with unrestrained passengers an essential element of crash.
• Eight bodies found in tail section.
• Certification and audit requirements likely to have identified weight and balance problems.
• RecommendationsSimilar aircraft limited to six passengers and pilot.
• Passenger restraints be ''urgently considered''.
