Pilot error has been blamed for the crash of a skydive airplane at Fox Glacier in which nine people died.
Giving evidence on Monday at an inquest into the accident, aviation expert Barry Payne - who investigated the September 2010 crash on behalf of the coroner - laid the blame at the feet of the Queenstown-based pilot, Chaminda Senadhira.
Mr Payne told the inquest in Greymouth the pilot lost control of the aircraft because he failed to correctly adjust, or trim, part of the tail, known as the stabilator, before takeoff.
He said the pilot was used to an airplane that trimmed the aircraft electronically and lacked experience with the one he was flying on the day of the crash.
"The probable critical trim omission prior to takeoff was probably compounded by the pilot's limited experience on the FU24 aircraft type and transition from flying the Pilatus Porter PC6 aircraft that is equipped with an electric trim and warning system."