Sweep Width Determination for HU-25B Airborne Radars: Life Raft and Recreational Boat Targets

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Sweep Width Determination for HU-25B Airborne Radars: Life Raft and Recreational Boat Targets

M. J. Lewandowski / R. Q. Robe / A. A. Allen / W. H. Reynolds / G. L. Hover

During October and December 1988 the U.S. Coast Guard R&D Center conducted two experiments to determine sweep widths for airborne radar search by Coast Guard HU-25B aircraft. Search objects were 4- to 10-person life rafts and 23- to 42-foot recreational-type boats. Two radar systems were evaluated: the AN/APS-127 forward-looking airborne radar (FLAR) and the AN/APS-131 side-looking airborne radar (SLAR). Realistic radar searches were conducted in Block Island Sound off the CT/RI/NY coast and in the Atlantic Ocean off Nova Scotia, Canada, to collect data using unalerted sensor operators and standard search patterns. Aircraft and target positions were recorded by a precision microwave tracking system. Target detections and environmental conditions were recorded by observers onboard the search aircraft and the target vessels. Sea conditions represented in the data analysis included 0- to 4-foot significant wave heights and 0- to 28-knot winds. Data from the 1988 experiments were combined with data collected during 1987 where appropriate. Analysis of the data confirmed that sweep widths varied with significant wave height and target size. Recommended sweep width values and HU-25 electronic search guidance are presented, along with a recommendation for computer simulation to develop POD versus coverage factor curves for HU-25 electronic search planning. Keywords: Search and rescue; Airborne radar; Side looking airborne-radar; Sweep width; Electronic search; Probability of detection. (JHD)