Issue

In seeking to improve the Coast Guard’s Search and Rescue Optimal Planning System (SAROPS), the Research and Development Center (RDC) conducted a review to ensure over-ice search patterns for persons and objects were optimized by Coast Guard Search and Rescue (SAR) personnel. SAROPS is a Monte-Carlo based computational algorithm software program for maritime search planning. RDC personnel believed that SAROPS for ice searches might be improved by validating that optimal lateral range curves were being used for all search scenarios. Any updates would be based on the probability of detection as a function of range at the closest point of approach. The curves contribute to SAR sweep width tables, which are incorporated into SAROPS as an indicator of the probability of success of a particular search pattern. The probability is based on the variables involved in the search, of which the most important are the search platform and sensors being used .

Background

The Office of Search and Rescue and Coast Guard 9th District are the primary stakeholders, as the greatest number of ice rescues are conducted within the district’s area of responsibility on the Great Lakes. The existing SAR patterns have rescuers apply the same lateral width tables over water to SAR situations over-ice. SAR planners typically use helicopters and surface search assets, including airboats, for over-ice operations. The project included the participation of a team from the RDC, as well as aviators from Coast Guard Air Station Traverse City, Mich., and several Coast Guard small boats from Sturgeon Bay and Bayfield, Wis. Additional boat crews from St. Ignace, Mich. and Duluth, Minn. Participated. The team developed test plans based on ice coverage and asset availability, collecting data in two stages: an initial test in March 2012, and several follow-on tests in February 2013. The 2012 test provided detection range data for search targets on ice, to evaluate the airboats’ SAR abilities and limitations. While the unusually warm 2012 winter weather only resulted in a single day of on-ice testing, the team obtained sufficient data to properly define and prepare for the follow-up testing in the winter of 2013 .

PROJECT FIELD TESTING

The RDC-led team conducted extensive over-ice testing between Feb. 8–22, 2013, with MH-65 helicopters and airboats. The tests covered a target field measuring 8 miles by 8 miles, with 20 search objects simulating persons and snowmobiles on the ice near Green Bay, Wis. The team collected data from various search patterns used by the helicopters and airboats, and in various lighting conditions to test visual acuity and night-vision capabilities against the 20 search objects. Airboat testing included the use of a “sprint and stop” search pattern methodology, to more quickly cover the target field. The team captured data while the airboat was both in motion and stopped, as personnel conducted visual searches with and without binoculars. Both airboat and helicopter searches used standard parallel search and creeping line search patterns.

Outcome

The testing resulted in new lateral range curves based on the better-understood probability of over-ice detections, versus the standard over-water lateral ranges. The results supported a larger sweep width, and resultant track spacing for search objects on-ice versus those in the water. The resultant increase in track spacing will substantially increase the expected area that a helicopter can cover in support of a SAR mission over-ice, and assist SAROPs planners significantly in decision-making during the SAR case. By leveraging the radial ranges of detections made, and the subsequent radial range curves, the sprint and stop search method will have immediate utility in searches of specific locations. Results thus far suggest greater effectiveness in employing SAR assets for higher probability of detection for searches on ice.