Pilot was trying to clear cattle before fatal crash

The Glenorchy Air Piper PA-32-300 Cherokee Six B crashed near Poolburn in Central Otago. Photo / NZ POLICE

A Central Otago plane crash that killed the pilot and seriously injured two passengers was caused by the aircraft stalling during a low-flying stock-clearing manoeuvre, the Transport Accident Investigation Commission says.

The commission today released its report into the 2014 crash, which killed Queenstown pilot Ray Crow and injured American tourists Sarah, 31, and Erik Hoffmann, 35, during a Lord of the Rings sightseeing flight on August 5, 2014.

It said the pilot of the Glenorchy Air Piper Cherokee was trying to move cattle off the airstrip, near the Poolburn Reservoir.

The aircraft stalled while he was turning the plane around at a low level to perform a second pass over the airstrip to scare the livestock away before landing, it said.

Glenorchy Air pilot Ray Crow. Photo / Queenstown.net.nz

But he was too low to enable recovery before the aircraft hit the ground, it said.

The report said a contributing factor was a north-westerly wind directly across the airstrip, which made low-level flying difficult.

The pilot's decision to turn downwind at low level, turn towards higher ground without climbing reduced terrain clearance and safety margins. Continuing the turn despite low terrain ahead, and increasing the angle of bank at a low airspeed, also contributed to the crash, it said.

"The operator believed that stock clearing was permitted, but had no written guidelines and had not given its pilots flight training in the manoeuvre. There was a lack of clarity on whether stock clearing was a permitted activity under the Civil Aviation Rules."

Pilot incapacitation and mechanical failure were "very unlikely" to have been contributing factors, it said.

The commission recommended Director of Civil Aviation Graeme Harris provide a clear statement to relevant sectors of the aviation industry on whether stock clearing was permitted.

"If the director decides it is a permitted activity under a particular Civil Aviation Rule part, he should provide clear guidance on the conduct of the activity."

The key lessons to be learned from the crash were flying at close proximity to the ground required a high degree of accuracy as there was little margin for error, it said.

"It is important that pilots are fully aware of the stall characteristics of their aircraft, in particular how they are affected by manoeuvres such as steep turns. Pilots should also be aware of the effects of wind on the amount of ground covered during a turn.

"Operators must issue clear guidelines and procedures for their pilots to follow, and ensure that they are being complied with. Pilots should be required to regularly demonstrate proficiency in carrying out the types of manoeuvres and operations they perform for the operator."