LAUSR

Structured search strategies have been well studied, but consequences of frequently made assumptions can lead to “optimum” recommendations that are far from optimum in that they ignore risks of failure. Common assumptions are many targets that have average sizes and shapes, and are randomly orientated. The effects of common assumptions are examined for parallel and grid line searches. Equations are provided for estimating probabilities of hitting elliptical targets with parallel and square grid lines along with new simplified equations when orientations are random. In a large portion of searches, the probability of missing the largest, most valuable target, dangerous ordnance, or key target is critical to the decision-maker. The risk of missing a target is frequently central to the decision. Where the target is elliptical in shape and has unknown orientation, square grid line search should be considered over line search. Square grid line search has a slightly lower expected probability of detecting an elliptical target with one or more hits than an equal-cost parallel line search, but the probability of missing regardless of orientation in square grid search is significantly lower. Where two or more hits are required, the square grid has a significantly higher probability of hitting and a slightly lower standard deviation than an equal-cost line search. For elliptical targets, the use of a square grid significantly reduces the chances of search failure.