An investigator from the Civil Aviation Authority has told an inquest into a Fox Glacier skydiver crash the behaviour of the pilot needs to be looked at further.
The converted top dressing plane crashed on 4 September 2010 killing all nine on board. An inquest is being held in Greymouth.
The CAA's Alan Daley flew to Fox Glacier in the days following the crash to help look through the wreckage in the search for clues.
Mr Daley said the pilot, Chaminda Senadhira, had a history of performing illegal stunts and this showed a lack of professionalism.
He said a possible explanation for the crash is that Mr Senadhira intentionally tried to lift off before he had enough speed, something that needs further investigation.
Mr Daley, said the fact the crash happened directly after the lunch break was important because pilots often became distracted when they broke from their normal routines.
Mother baffled by aviation designer's evidence
The mother of a man who died when the plane crashed says she does not understand why the person who modified it did not know the aircraft was going to carry passengers.
The inquest heard on Thursday from the aviation designer, Donald McGill, who oversaw the plane's modification from a top dressing plane to a skydiving plane.
He said the flight manual, which he revised, did not take into account the modified plane would carry passengers, because this was only a possibility.
Outside the hearing, Pamela Bennett, whose son died in the crash, said this statement did not make sense.
She said the aircraft was converted precisely so it could carry passengers.
Mr Gill told the inquest on Thursday that while he wrote a revised flight manual,any deficiencieswere the fault of the Civil Aviation Authority.
Mr Gill says the Aviation Authority was responsible for approving the manual.
The inquest has already heard from the co-owner, who said it was difficult to work out whether it was being overloaded because the flight manual only applied to the plane's use as a top dresser.