The Value of Searching by Voice in LandSAR

Costigan, R


This study is concerned with off-track foot searching for a missing person (MP) who is presumed wanting to be found and who is by nature responsive.
Such searching is done predominantly by sight, calling and listening. Search methods that maximise emphasis on detection by sight are usually called Line or Grid Searching. Normally, detection by sound would be considered a windfall to such searching. Any method that seeks to optimise the use of sound, leaving detection by sight to good fortune, can be thought of as being at the other end of a spectrum of methods. Many methods have been devised that fall between. It would assist a search organiser to know where on this scale lies the optimal search method, or combination of methods, at any point of time in a search operation.
Spreadsheet modelling has been used to calculate the comparative probabilities of success (POS) of various strategies, combining three common search methods either exclusively or in combinations.
Results strongly favour searching by calling and listening exclusively, that is, targeting a responsive MP, regardless that the MP’s responsiveness might reasonably be expected to be in decline or extinguished.
A confronting corollary of this result is that in most such circumstances the probability of saving the MPs life will be substantially improved by ignoring the possibility that the MP is in the state that is regarded as the most distressing and most urgent of possible states – surviving but no longer responsive.

KEY WORDS: landSAR, missing person, search strategy, voice searching, Probability of Area

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