An investigation into a light plane crash that killed two people has failed to determine what caused the pilot to lose control.
Wayne Matthews, 62, and his passenger Brent Baldwin died when their two-seater light aircraft hit the ground at Whenuapai air base in 2008.
A Civil Aviation Authority report says several eyewitnesses watched the plane bank to the right and descend rapidly before it hit the ground and burst into flames.
The report has determined that either a mishandled manoeuvre or a significant distraction caused the pilot to lose control of the plane.
But the investigation did not establish with any certainty what this may have been or why it happened.
It says the pilot had extensive experience and there was no evidence of engine failure.