The brother of a helicopter instructor killed in a mid-air crash over Paraparaumu has told an inquest he does not believe the pilots involved had time to avoid each other.
Trainee helicopter pilot James Taylor and his examiner David Fielding died when their aircraft collided with a Cessna flown by Bevan Hookway in 2008.
Mr Fielding's brother Michael Fielding, who has a doctorate in mechanical engineering, told the court on Wednesday he had done his own calculations of the aircrafts' speeds leading up to the crash.
He said that he did not believe some issues relating to the crash had been adequately dealt with in other reports before the court.
Dr Fielding said his calculations showed that the combined speeds of the aircraft as they approached each other was too high to allow the pilots time to see each other and take evasive action.
In reply to a question from the Civil Aviation Authority's lawyer, Dr Fielding agreed that he was not trained to conduct accident investigations.
The inquest has previously been told Mr Hookway was doing an overhead rejoining manoeuvre shortly before the crash.
On Tuesday former Civil Aviation Authority safety investigator Peter Kirker told the court that 12 years before the crash, the authority had identified the potential for collision at Paraparaumu Airport.
Mr Kirker said if earlier safety recommendations for the airport had been followed, the mid-air crash in 2008 may never have occurred.