What happened
On 1 November 2008, a Robinson R22 helicopter, registered ZK-HXR, failed to reach the Wanaka aerodrome during a flight from Haast. The aircraft was being operated as a single-pilot flight intended for a refueling stop. Following the disappearance, search efforts identified debris floating in Lake Wanaka, approximately 22 kilometres northwest of the aerodrome. Four days after the incident, the fuselage and the pilot were recovered from the lake bed, though several critical components remained missing.
While no witnesses observed the impact, the pilot had been seen flying past a barge operated by an acquaintance roughly six minutes before the crash. Telecommunications data indicated that the pilot was actively sending and receiving text messages in the minutes leading up to the accident, including a message sent very close to the estimated time of the crash.
The investigation
Investigators examined the wreckage and determined that the aircraft experienced a mast bump before hitting the water. This mechanical event is often triggered by low-G conditions, which may have been induced by turbulence or other unidentified factors. The investigation also looked into the pilot's flight profile and recent communications. Evidence suggested a tendency toward high-speed flight, which can intensify the helicopter's response to low-G maneuvers. Furthermore, the timing of the pilot's cellular activity was analyzed to determine if distraction played a role in the inability to recover the aircraft.
Findings
- The primary cause of the accident was a mast bump occurring prior to the water impact.
- The mast bump was likely precipitated by a low-G condition, potentially caused by turbulence.
- The pilot's preference for high-speed flight may have increased the severity of the aircraft's reaction to low-G conditions.
- The use of a cellphone for text messaging near the time of the accident may have reduced the time available for necessary recovery maneuvers.