Air-scent K-9's are most commonly used to search large, uninhabited sections of land, including woods, fields, swamps and heavy brush.  These dogs are taught to range out ahead of the handler and to "alert" whenever they detect the scent of a human; they then follow this air-borne odor to the source of the scent.  Air-scent dogs may be "generic" (following any human scent) or "scent-specific" (following only one specific human's scent).  Although the term air-scent is generally used to refer to K-9's that are searching for live humans, these dogs will also locate deceased victims- many are cross-trained specifically for cadaver search.