Search Areas

Category: Segmenting the Map
Published on Thursday, 27 September 2012 04:51
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The Search Area is an area which encompasses the entire search and rescue effort.  This includes all areas which are searched or intended to be searched.  It does not necessarily include areas through which resources travel for logistics purposes, such as deployment routes for searchers.  There are several methods for determining the search area.

Theoretical

The theoretical search area is a circle drawn around the Initial Planning Point (IPP), with a radius equal to the maximum distance the subject could have traveled in the time allotted.  If a subject is lost in rugged terrain he may have been able to hike only 2 miles per hour.  If that subject has been lost for 24 hours, the maximum distance traveled is,

$$2 \frac{miles}{hour} \times 24 hours = 48 miles.$$

Thus, for the scenario of a subject who can travel 2 mph and is missing for 24 hours, the search area would be 48 miles in radius, or 96 miles in diameter. Searching an area this large would be a daunting task.  If we assume the subject spent half of that time resting, we would have a search area 48 miles in diameter, which is slightly better, but still a very large search area.

Statistical

The statistical search area is a circle drawn around the IPP for which there is historical data to suggest there is some probability of the subject being within.  This data can be obtained from sources such as the Syrotuck or the more recent, and extensive, Koester books.  The best data, statistical or otherwise, is locally gathered, so start a database of search results if you haven't already.  Statistical areas are often described by there probability.  As an example, a "25% area" would be the area within which 25% of subjects are found.  The map below shows the statistical areas for a Dementia subject in temperate, mountainous terrain from the data in Koester's book: