Coast Guard Search & Rescue Metrics and Definitions Slides 2-6 Courtesy of: R.J. Koester, D.C. Cooper, J.R. Frost, R.Q. Robe Presented by Dave Larson

Effective Sweep Width (Koopman) Cannot be measured directly Is an objective measure of detectability Large value => detection is easy Small value => detection is hard Depends on the characteristics of Searcher/Sensor (What we are searching with.) Search Object (What we are searching for.) Environment (What we are searching in.) Terrain, Vegetation, Weather, etc. Has units of length (feet, meters, miles, etc.)

A Uniform Random Distribution

Effective Sweep Width Number detected = 40. Number missed within sweep width = 0. Number detected outside sweep width = 0. Effective Sweep Width (Unrealistic Perfect Detection Making a Clean Sweep)

Effective Sweep Width Number detected = 40. Number missed within sweep width = 16. Number detected outside sweep width = 16. Effective Sweep Width Max Detection Range (More Typical Detection Pattern)

Effective Sweep Width Notes In both of the previous examples, there were The same object density (# of objects/unit of area), The same length of searcher track, and The same number of objects detected (40) Therefore, The effective sweep widths are also the same. “Effective” means “has the same effect as” Effective sweep width represents the expected amount of detection.

Distance to right or left of sensor at the closest point of approach (CPA) is Lateral Range Lateral range curve (Koopman) – Pd vs. Lateral Range

Effective Sweep Width Key to Improved Search Planning and Evaluation Improves POD Estimation Allows us to Objectively Relate POD to Effort Expenditure Has both Predictive and Retrospective Value More Accurate and Reliable than Subjective Estimates Based on Observable Factors Improves Effort Allocation Makes known, proven (mathematical) techniques available Improves conceptualization of the search problem

High-Altitude Visual Search LRC

Low-Altitude Visual Search LRC