What happened
On 5 August 2014, a charter aircraft engaged in a sightseeing flight around New Zealand's lower South Island crashed near the Poolburn Reservoir. The aircraft was performing a low-level maneuver intended to clear cattle from a remote farmland airstrip. While attempting to turn the plane around to perform a second pass over the strip, the aircraft entered an aerodynamic stall. Due to the low altitude at which the maneuver was being conducted, there was insufficient height to recover before the plane impacted the ground. The accident resulted in one fatality and two serious injuries.
The investigation
Investigators examined the circumstances surrounding the flight and the operational procedures of the operator. The inquiry established that the pilot was attempting to move livestock away from the landing area before touchdown. The investigation ruled out mechanical failure or engine malfunction as contributing factors, and found no evidence that pilot incapacitation played a role in the crash. Furthermore, the investigation looked into the legality and safety of the specific maneuver being performed, noting that while the operator believed stock clearing was a permitted activity, there were no formal written guidelines or specific flight training provided to pilots for such tasks. There was also noted ambiguity regarding whether such maneuvers are explicitly permitted under Civil Aviation Rules.
Findings
Several environmental and operational factors contributed to the loss of control. A northwesterly wind was blowing directly across the airstrip, which complicated low-level flight and necessitated a larger turning radius than usual. The pilot chose to execute a downwind turn toward rising terrain without increasing altitude, which significantly reduced the margin for error and terrain clearance. Ultimately, the decision to increase the bank angle at a low airspeed while turning toward higher ground led to the aerodynamic stall.
Safety action
Following the investigation, the Commission recommended that the Director of Civil Aviation issue a clear statement to the aviation industry regarding the legality of stock-clearing maneuvers. If such activities are deemed permitted under Civil Aviation Rules, the Director should provide specific guidance on how they must be conducted safely. The inquiry also highlighted the necessity for operators to implement clear procedures and ensure pilots are regularly trained and proficient in all specialized maneuvers.