The unexpected opening of a rear door that led to overalls flying out and striking the tail rotor is the likely cause of a triple-fatal helicopter crash near Wānaka Airport nearly six years ago, according to a new report which also makes industry safety recommendations.  

A final report into the tragic accident, which killed two Department of Conservation workers and pilot Nick Wallis less than three months after brother and fellow pilot Matthew Wallis died in a helicopter crash at nearby Lake Wānaka, has been released by the Transport Accident Investigation Commission (TAIC). 

On October 18, 2018, an MD Helicopters Incorporated MD 500D, registered as ZK-HOJ, crashed shortly after takeoff from Wānaka Aerodrome, the report said. 

Emergency services at the scene of the fatal helicopter crash, next to Clutha River, near Wānaka Airport where Nick Wallis and two DoC workers died. Photo / NZME 

Crewed by pilot Wallis and two passengers, Department of Conservation workers Paul Hondelink and Scott Theobold, the helicopter was engaged in an airborne wildlife-culling operation in the Landsborough River area when it broke up mid-flight, spun while descending, and caught fire upon impact. 

All three occupants were killed. 

The helicopter was part of the first flight of the day for the wildlife control mission, and the two DoC workers, along with their equipment, were being flown to a remote staging point. 

At 10.53am, the helicopter took off with the pilot in the front-left seat, one DoC worker in the front-right seat, and the other on the right side of the rear bench seat. 

The helicopter had been refuelled to full capacity and carried significant cargo, including rifles, ammunition, recording equipment and extra aviation fuel. 

Shortly after take-off, the helicopter ascended to about 150m before several witnesses noticed unusual behaviour. 

One witness saw the helicopter descend nearly vertically with items trailing behind, while another saw the tail section separate from the helicopter, causing it to spin and eventually crash and catch fire. 

TAIC has concluded that the likely cause was the unexpected opening of the left-rear door, leading to unsecured overalls exiting the cabin and striking the tail rotor. 

This caused the tail rotor assembly to detach, hitting the main rotor blades and breaking them. 

The tail boom was also struck and failed, rendering the helicopter uncontrollable. 

Ranger and rural fire officer Paul Hondelink was one of three people killed when a helicopter crashed near Wānaka Airport. Photo / Otago Daily Times 

Key findings indicate wear in the door-latch mechanism and inadequate maintenance as contributors to the door opening. Additionally, the cargo was not properly secured, exacerbating the situation. 

The report emphasised the importance of reporting in-flight door openings and securing cargo, while also highlighting the need for clear maintenance guidelines and unambiguous Civil Aviation Authority (CAA) rules. 

In response, TAIC has made safety recommendations, including urging the CAA to reinforce incident reporting and addressing rule ambiguities. 

In 2022, the company that owned the helicopter, The Alpine Group, was fined $315,000 on two charges of failing to comply with its duties under the Health and Safety at Work Act. 

Ben Tomsett is a Multimedia Journalist for the New Zealand Herald, based in Dunedin.