OCR Text |
Show TABLE I Small avalanches ( coarse probe time about 15 minutes for s ingle pass). Number of coarse probes before makinq fine probe 0 1 2 3 4 Relative chance of finding the vict im alive 18% 31% 39% 45% 49% Larger avalanches ( coarse probe time about one hour for s ingle pass) . Number of coarse probes before making fine probe 0 1 2 3 4 Relative chance of finding the v'rct im al ive 8% 18% 20% 21% 21% Comparison of increased speed resulting from decreased probing depth with the reduced probability of finding the victim when less volume is searched gives the following guideline: The probing depth should not be reduced to less than 10 feet in the interest of speed, except when strong evidence indicates a shallower burial depth. Strongest of the latter evidence is shallow deposition of avalanche debris recognizable by presence of ground or undisturbed snow underneath. Finally, consider the question raised in Section 2.1. What is the basis for justifying initial probes in regions of presumed high priority ( most likely burial sites)? The answer, again from mathematical analysis ( Reference No. 8), confirms intuition. An initial search of a region is justified if the percent of search time required for the region is less than the probability of finding the victim in the region. For example, consider the hypothetical accident which is diagrammed in Figure 18. Which region should be searched first: The stand of firs, the bend, or the final deposition area? Ideally, a table of " relative search time" versus " probability of location" should be constructed ( see Table II). The final deposition area is chosen for the first search area since the probability of locating the victim in this region exceeds the relative time required to search the region. 43 |