Wayne Stevens got involved in Land Search and Rescue in 1984, while a student in the tramping club at Wellington's Victoria University.
Back then it was all about manpower to find missing people, but these days it is far more scientific, he says.
"Today the police rely on us to use a lot more behavioural analysis, like the age of the person and the circumstances of the person.
"It helps determine where to put in effort."
There have been memorable missions over three decades, including a two-night rescue on the Tararua Range. "The tent blew in and it was an absolutely brutal night."