AO-2014-004 Piper PA32-300, ZK-DOJ, Collision with terrain, Near Poolburn Reservoir, Central Otago, 5 August 2014

On 5 August 2014 an aeroplane on a sightseeing flight charter around the lower South Island crashed near the Poolburn Reservoir, killing the pilot and seriously injuring the two passengers.

The aeroplane aerodynamically stalled while being manoeuvred at low level in the vicinity of an airstrip located on remote farmland. The stall occurred at a height that was insufficient to enable recovery before the aircraft struck the ground.

The pilot was carrying out a stock-clearing manoeuvre to move cattle that were on the airstrip, and was in the process of turning the aeroplane around at low level to perform a second pass over the airstrip to scare the livestock away before landing, when the accident occurred.

The following factors were found to have contributed to the accident:
- a northwesterly wind directly across the airstrip made low-level flying difficult, and required more space than normal for the pilot to turn the aeroplane around
- the pilot's decision to turn downwind at low level, and towards higher ground without climbing, reduced terrain clearance and safety margins
- the pilot's decision to continue the turn despite low terrain ahead, and to increase the angle of bank at a low airspeed, led to the aerodynamic stall.

The Transport Accident Investigation Commission made the following findings:
- pilot incapacitation was very unlikely to have been a contributing factor
- a mechanical or engine failure was very unlikely to have been a contributing factor
- the aeroplane stalled in a turn performed at low level during a stock-clearing manoeuvre
- 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.

The Commission made the following recommendation to the Director of Civil Aviation:
- he provide a clear statement to relevant sectors of the aviation industry on whether stock clearing is a permitted activity. 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 identified from the inquiry into this occurrence are:
- flying at close proximity to the ground requires a high degree of accuracy as there is little margin for error. 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.