Drones may be the next step in the search for missing German tourist Christian Prehn.
His father Jens Prehn said the family planned to have drones or unmanned aerial vehicles searching Nelson Lakes National Park, while they remained at home in Krefeld, Germany. Christian, 19, was last seen on February 25.
Police began searching for him after a Department of Conservation worker discovered his pack lying beside the track in the Travers Saddle area at the beginning of this month.
Search teams spent several days searching for Christian in unforgiving alpine territory, aided by a helicopter, but search co-ordinator Senior Constable Dave Colville announced on March 7 that further ground searches would be carried out only when new information came to light.