Think of it as a "glorified spud gun", that's how the "avalauncher" is described by those who use it on Tūroa, Mt Ruapehu to keep skiers safe.

The cannon is used to trigger avalanches from a distance and to control the snowpack prior to opening ski fields to the public.

A projectile is fired from the avalauncher after inert compressed nitrogen gas is released into a chamber, forcing the payload to fly out.

The Nitro Express avalauncher, a 'glorified spud gun'. Photo / Supplied
The Nitro Express avalauncher, a 'glorified spud gun'. Photo / Supplied

Mt Ruapehu hopes to open both the Whakapapa and Tūroa ski areas on July 1.

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Designed to explode on impact with the surface of the snow, the avalauncher projectile is used to trigger the weaknesses in the snowpack.

Managing the avalanche work on the slopes is challenging but necessary, Mt Ruapehu general manager of safety and the environment Andy Hoyle said.

"It will come as no surprise to anyone that the last two winters have proven to be very challenging in terms of avalanche risk management on Mt Ruapehu, specifically the upper start zones of Tūroa," Hoyle said.

Brendon Nesbit and Dan Struder assemble a projectile prior to firing. Photo / Supplied
Brendon Nesbit and Dan Struder assemble a projectile prior to firing. Photo / Supplied

"With names like 'Upper Big Bowl', 'Gliding Gladys' and 'Joe's Slider', these immense start zones dominate the skyline above the ski area and demand utmost respect (and some fear) from those that must work with them intimately throughout the winter seasons."

In 2018, a routine avalanche control mission resulted in a moderate-sized avalanche cascading over the return station of the High Noon Express.

And last year, conditions lined up to produce a number of large avalanches after a storm dumped metres of snow on top of a weak layer of older snow.

The avalauncher has been used in the industry for many years and specifically on Mt Ruapehu since the early 1980s.

This year, a newer version of the device was being trialled for Tūroa, the Nitro Express.

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A Kiwi-made adaptation of the avalauncher, the Nitro Express was originally located at Whakapapa, where it controlled the Te Heu Heu Valley Headwall.

It has a range which can reach around 1.4km from the launch point to start zone, with a 300m elevation gained, Hoyle said.

Ethan Mickleson approaches the avalaucnher hut on Turoa. Photo / Supplied
Ethan Mickleson approaches the avalaucnher hut on Turoa. Photo / Supplied

Testing of the avalauncher was undertaken at Tūroa earlier this week and was successful, with new projectiles to be tested with larger payloads.

"Until then, we are excited about the success of the day and hopeful that we can use this tool effectively from this point on to help mitigate the avalanche risk above Turoa," Hoyle said.

"Successful avalanche risk management requires a range of strategies and the skill is in knowing when to apply which option.

"We will always rely on our customers respecting closures to ensure we can work efficiently, keep everyone safe and get the ski area open as soon as possible each day."

Not every lift at the ski areas will be able to open this season due to the inability to bring in overseas expertise to work due to Covid-19.

The lower ski area boundary at Turoa, Mt Ruapehu in August 2019. Photo / Supplied
The lower ski area boundary at Turoa, Mt Ruapehu in August 2019. Photo / Supplied

However, Ruapehu Alpine Lifts (RAL) chief executive Jon Dean was looking forward to opening the mountain for a few weeks this year, dependent on snowfall.

"The winter 2020 season at Mt Ruapehu will be unlike any other and the team is striving to offer the best possible ski season for everyone," Dean said.

"Our focus is offering top-to-bottom skiing at both ski areas, with a beginner focus at Whakapapa's Happy Valley."

There won't be any night skiing at Whakapapa this year or First Tracks, and RAL would not operate any transport shuttles due to Covid-19.

One of the avalanches which travelled through the Turoa, Mt Ruapehu ski area in August 2019. Photo / Supplied
One of the avalanches which travelled through the Turoa, Mt Ruapehu ski area in August 2019. Photo / Supplied

The exact details in relations to Covid-19 restrictions and how they apply to visitors is not known but would be clearer on June 22 when the Government announces changes to alert levels.

"Fortunately, we have been able to retain all of our permanent and summer staff through the lockdown, and we have a great bunch of returning locals who will be able to fill some vacancies," Dean said.

"There will still be some jobs available, and those will be advertised on the Mt Ruapehu website once we have our 2020 team confirmed."