What happened
On Good Friday, 2 April 1999, an Aerospatiale AS 350B helicopter, registration ZK-HBH, crashed in the Rowallan Forest near Tuatapere. The aircraft was conducting a routine charter flight for a hunting party, traveling from Clifden toward Lake Poteriteri and eventually Preservation Inlet. After a routine radio check at 12:59 hours, the helicopter disappeared from communications. At 13:01 hours, the aircraft struck the forest canopy, colliding with multiple trees before impacting the ground at an elevation of 600 feet. The crash resulted in 5 fatalities, including the pilot and four passengers.
The investigation
Investigators examined the flight history, the pilot's medical background, and the aircraft's maintenance records. The pilot was highly experienced, with over 5,000 hours on the type. While the aircraft had been properly maintained, evidence suggested the helicopter may have been overloaded by approximately 5% due to the weight of supplies and equipment. The investigation also looked into the possibility of cargo shifting within the cabin, as items such as rifles and camping gear were found scattered at the site. Furthermore, the search and rescue efforts were complicated by the lack of a passenger list, which meant the exact number of people to be recovered was initially unknown.
Findings
While the exact cause of the loss of control was not definitively proven, the investigation identified several contributing factors. The pilot's ability to maintain control of the aircraft may have been medically impaired by the sudden onset of a cardiac event. Although the pilot's known ECG abnormalities were within acceptable regulatory limits, they presented an increased risk of sudden incapacitation. Additionally, the lack of cargo restraint in the rear cabin meant that shifting supplies could have potentially interfered with flight controls or distracted the pilot. The investigation also noted that the aircraft was likely operating slightly above its maximum permitted weight.
Safety action
Following the inquiry, recommendations were made to the operator to implement practical systems for securing cargo and maintaining passenger lists. The operator subsequently adopted the use of nets and tie-downs for cabin cargo and updated flight-following procedures to ensure passenger manifests are accurately recorded.