The commission that investigates air accidents has declined to give evidence on a fatal midair collision that killed three men over Paraparaumu.
Wellington coroner Ian Smith, who concluded his inquest into the deaths yesterday, asked the Transport Accident Investigation Commission to present its findings on the crash and to answer questions.
During the inquest, Smith mentioned that one of the reasons for holding the inquiry was that the families of the dead men had pointed out deficiencies in the commission's report.
He wrote to the commission in September 2011, asking for a representative to discuss the report at this week's inquest.
However, the commission replied that it could not be compelled by law to give evidence and would not do so. It sent an observer to the inquest most days but did not take part.
The commission's report, released in 2009, has been criticised at the three hearings of the inquest, along with a Civil Aviation Authority report into the crash that killed Cessna pilot Bevan Hookway, 17, helicopter pilot James Taylor, 19, and examiner David Fielding, 30, on February 17, 2008.
Taylor was doing a final test flight with Fielding when the aircraft collided as Hookway was performing a manoeuvre called a joining procedure.
The men were killed when the helicopter crashed into the Paraparaumu Placemakers store and the plane into a residential street.
The commission report said there was a well-recognised risk with the joining procedure.
However, the brother of one of men killed believes the aircraft were going faster than the reports suggest.
Michael Fielding, who works for Crown entity Callaghan Innovation and has a PhD in mechanical engineering, made his own calculations of the air speeds.
He challenged the CAA report, which he felt had not used correct data.