The co-owner of the plane that crashed at Fox Glacier, with the loss of all nine people on board, has disputed an official finding that the plane being overweight and out of balance caused the accident.
John Kerr, a pilot and director of Glacier Skydive Air Services, told an inquest on Wednesday he believed "jammed controls or controls failure" were the likely cause.
The Transport Accident Investigation Commission's report found the converted Fletcher FU24 crop-duster was overloaded with too much weight towards the back when it crashed soon after taking off on September 4, 2010.
During cross-examination at the inquest in Greymouth, Mr Kerr was quizzed on the company's understanding of Civil Aviation Authority (CAA) manual and procedures.
He admitted that the recommended CAA weight and balance calculations had never been implemented.
He also accepted that before the plane crashed, it exceeded weight expectations recommended in the CAA manual.
He said, however, that the skydive company was aware of the discrepancy with weight and balance obligations, and was due to check with the CAA after it had completed a 100 hours of flying.
At the time of crash, the company still had 10 hours of flying time left.
Aviation expert Barry Payne told the inquest he believed the aircraft crashed due to its centre of gravity being compromised by a load shift during its climb.
Pilot Chaminda Senadhira, dive-masters Adam Bennett, Michael Suter, Christopher McDonald and Rod Miller, and overseas tourists Glenn Bourke, Patrick Byrne, Annita Kirsten, and Brad Coker died in the crash.
Skydive dive-master Dean Thomas, a veteran of over 7500 jumps, said there was nothing unusual about the day of September 4, 2010.
While the Christchurch earthquake that day had affected power at the aerodrome, the company had already undertaken five jumps in the morning.
Mr Thomas, who witnessed the fatal crash, said the weather was good.
He described Mr Senadhira as someone "who instilled a lot of confidence, and was very safe".
He recalled "there was no mechanical issues, it was a brand new plane which had been stripped out for skydiving".
He also said the Skydive company "never cut corners on safety or quality of equipment".