Helicopter operators have been put through their paces in Central Otago, learning how to deal with a natural phenomenon that's responsible for a number of fatal crashes.
World-leading helicopter expert Claude Vuichard has perfected a technique to get out of the so-called 'vortex ring state', and he's now he's passing on his knowledge others.
Practising for the worst-case scenario, helicopter pilots have been schooling up on the technique that could save their lives.
- Flying farewell for Wanaka helicopter pilot Nick Wallis
- Conservation Minister Eugenie Sage confirms DoC staff on-board helicopter in fatal crash
- Family heartbroken after Kiwi helicopter pilot killed fighting Australian bushfires
Helicopter pilot Bill Day says there's no question that he is a safer pilot today then he was yesterday as a result of the new technique.
The vortex ring state is when a helicopter gets caught in its own downwash and loses altitude rapidly. The phenomenon is blamed for bringing down the helicopter that crashed during the raid on Osama Bin Laden's compound.
Mr Vuichard says between 5-10 percent of fatal helicopter crashes are due to the vortex ring state.
For the last 30 years, Mr Vuichard has been perfecting a technique of flying sideways out of the vortex rather than forward, which was considered best practise for 70 years.
"When you're pushing forward and you have a tail wind, you fly to the accident place - and you're flying to your death because you have no way to go out, you're trapped in your bubble."
Queenstown's Helicopter Line Company, who brought Mr Vuichard out for the training, found during in an investigation that a vortex ring was potentially the cause of a crash of one of their own machines that killed a passenger on Mount Alta in 2014.
The company adopted Mr Vuichard's vortex ring state recovery technique after that accident.
"Everybody goes out there to fly safely, and everybody goes out there to bring everybody home," says pilot Troy Feck. "Unfortunately, in the alpine environment we operate in, there are additional risks - and we need to train towards that to mitigate them."
The technique represents a new tool in the toolbox for these pilots, should the worst occur.