High-visibility paint could have prevented a mid-air collision in which two women were killed, a coroner says.
Flight instructor Jessica Rose Neeson and flight student Patricia Smallman were killed in the incident near Feilding Aerodrome in July 2010.
The other plane's pilot, Manoj Kumar Kadam, made a controlled crash landing and survived. Both aircraft were Cessna 152s.
Coroner Tim Scott released his findings into the tragedy today and despite making no recommendations, highlighted a number of possible reasons for the accident.
On July 26, a sunny day with blue skies and a few high clouds, both planes were flying in uncontrolled airspace.
They operated under visual flight rules, restricted to flying to 1500ft (457m) above sea level, above which was controlled airspace.
Mr Kadam took off from Feilding and climbed towards 1500ft. About the same time, Ms Smallman began returning to the airfield from a similar height.
At 3.27pm, at about 1300ft, the planes collided.
Coroner Scott said if Mr Kadam had been restricted to climbing to a lower ceiling, say 1100ft, the crash would have been avoided.
He said it was problematic that civil aviation rules had limited the maximum height allowed at Feilding for the Cessnas to 1500ft, and if the women were allowed higher, there likely would have been no crash.
He said for reasons unexplained, but possibly due to distraction, it was "obvious" none of the three people in the air heard or appreciated the full significance of radio communications, which if correctly interpreted, would have revealed how close they were before the crash.
Coroner Scott said if both planes had high-visibility paint, the crash could have been avoided.
"No one saw the other aircraft and therefore the other aircraft was not avoided." Alternatively, he said if the women saw Mr Kadam's plane, they saw it too late.
Coroner Scott said it was sensible for people re-painting aircraft to now consider using high-visibility paint.
The findings noted that Mr Kadam had rescheduled his flight on the day. This was allowed, and both parties had some idea of the change in timing, but the coroner called the consequences catastrophic.
"Tragically had Manoj kept to his original schedule, the times would have been significantly different and almost certainly the collision would not have happened."
Coroner Scott said he need not make recommendations, as Feilding Aerodrome had already changed rules about flight paths and separation distances between planes.
It also had a new automated system updated regularly with information about wind and weather conditions.
This was the second coronial hearing into the crash. The first, in 2011, was held to record Mr Kadam's evidence before he left New Zealand.
The Transport Accident Investigation Commission also investigated the crash, publishing a report in February 2013. Its findings informed part of Coroner Scott's decision.
Mrs Smallman, who had retired before becoming a flight student, was 64. Jessica Neeson was 27.