Robert J. Koester MS Center for Earth and Environmental Science Research, Kingston University London
Ross Gordon QSO Search and Rescue Institute of New Zealand
Tony Wells Search and Rescue Institute of New Zealand
Russell Tucker New Zealand Police
Primary Contact: Robert J. Koester, P.O. Box 94, Charlottesville, VA 22903 USA Email: R.Koester@Kingston.ac.uk
Search theory is completely dependent upon an accurate assessment of how well a search area was covered by a team or the Probability of Detection (POD). Determining the POD for auditory whistle blasts and a response to sighting lights at night (sound-light line technique) involves a two-way detection problem. Two experiments were carried out at Nelson Lakes along the Porika Road track in New Zealand. The first experiment was conducted during the day with six subjects and fourteen two-person teams conducting a sound line tactic. The detection index for a search team hearing a shout was 332 meters. The detection index for a subject hearing a whistle was 401 meters. Searchers were able to detect 99% of high-visibility clues (orange gloves) and 52% of low-visibility clues (gray gloves) on the track. The night experiment was conducted at the same location, but with different search subjects placed in different locations. Search teams used a sound-light line tactic in two-person teams. The detection index for a search team hearing a shout was 306 meters. The detection index for a subject hearing a whistle was 395 meters and seeing a light 277 meters. The detection index for a subject detecting either signal was 460 meters.
This is the first report in the land search literature of both elements (searcher and subject) of a two-way detection problem.
Keywords: Detection index, Sweep Width, two-way detection, Probability of Detection, POD, whistle, shout, sound-light line.