Search and rescue crews will spend four days looking for the remains of a German tramper who disappeared in the Nelson Lakes National Park nine years ago.

West Coast search and rescue leader Senior Sergeant Mark Kirkwood said every year, LandSAR, the police and partner agencies did a search and rescue exercise (SAREX) where they picked an area with a missing party or parties.

He hoped the search this month in the rugged Travers Saddle alpine area of the Nelson Lakes National Park would help bring Christian Prehn home to his family in Germany.

Christian Ulf Erik Prehn disappeared while tramping in the area in February 2014. His pack was found by a Department of Conservation worker on the Travers Saddle, but an extensive Search and Rescue operation found no sign of the 19-year-old.

The search was called off in March that year, and police said at the time it would only continue if new information came to light.

The Travers Saddle is 1787m above sea level, and subject to extreme weather conditions.

In 2015, Prehn’s family helped fund another search for their son using donations they had received online.

The search included the use of a helicopter. At the time, the search coordinator described the environment as “terribly bloody torturous terrain”.

The team for the search this month, including LandSAR, CanyonSAR, and the Alpine Cliff Rescue team, had been working on the exercise, dubbed Operation Prehn, for months to identify search areas, mainly in their own time, Kirkwood said.

A police drone team would also be taking part, and the Royal New Zealand Air Force would be flying an NH90 helicopter to transport the teams in and out.

Around 50 to 60 people will be coming for the operation in the area of Travers Saddle, beginning on Feburary 10, though this was weather dependent.

Kirkwood said the incident control point would be in St Arnaud and there would be “a lot of large helicopter activity” for four days.

The exercise was a good chance to use new technology such as the Starlink satellite internet, which would allow them to share information live from the field, including photographs and videos.

“The drone will allow us to look to areas that were previously unable to be searched, because they’re too dangerous – unless there’s something down there you wouldn’t send people down there on a rope.”

Dogs would not be used in the search.

“That area chews dogs up,” Kirkwood said.

“On the last search dogs become injured quite quickly in that environment because there are scree slides and sharp rocks and it rips dogs up pretty quick.”

Kirkwood said he chose for the team to head to the saddle because he was aware of the search in the past, and cold case searches were one of his passions.

He led the search for Martin O'Brien, who was found safe in January, and the search for Marni Sheppeard, whose remains were found in the Rolleston River area on the West Coast in March last year.

“I thought it was a good chance for everyone to work together in the hope that we actually find Christian to bring him home to his family.”