Search and rescue (SAR) has always been one of the best known of the U.S. Coast Guard’s 11 congressionally mandated missions, officially beginning with its 1848-created predecessor, the U.S. Life-Saving Service.

“Coordinating SAR operations across such a vast area of responsibility is an enormous task and, when coupled with an inherently dynamic maritime environment, the Coast Guard is constantly challenged to sustain mission excellence,” Lt. Cmdr. James O’Mara of the Office of Performance Management and Assessment wrote in a fall 2014 U.S. Coast Guard Proceedings article, “Future SAR: Evolving Search and Rescue Improvements.”

“The number of ships, boats, and planes we have to meet our overall SAR mission ebbs and flows, but we can always meet the requirement. …

“Looking forward, the public will expect the Coast Guard to not merely maintain current levels of service, but also to improve SAR effectiveness. On the horizon during the next 10 to 20 years, we will see exciting opportunities to refine existing capabilities and leverage new technologies to improve SAR operational effectiveness and provide the most cost-effective service to the American public.”

Among the tools now being incorporated into SAR is the Search and Rescue Optimal Planning System (SAROPS), which uses robust sensor and detection capabilities to create patterns enabling responding crews to find victims more effectively and efficiently. Another, Rescue 21, is a VHF radio distress safety net to maintain maritime domain awareness, distress monitoring, and communications at least 20 miles offshore. Unmanned aerial vehicles, incorporated into offshore law enforcement operations, also are proving a game-changer for SAR concepts of operations (CONOPS).

At the same time, larger and more numerous ships – from cargo to cruise to private recreational vessels – have increased the number of people at sea, as are more underwater commercial drilling activities and increasingly popular new commercial and recreational subsurface activities. Also increasing the potential for humans at risk is the continuing human predilection to live along coasts, lakes, and rivers, where natural disasters such as hurricanes and floods are an ever-present threat to densely populated areas.

“In terms of capabilities, we have the Rescue Swimmer Program and a chain of VHF/FM radio stations around the coasts we call Rescue 21 [R-21], which not only monitor Channel 16 – the international call and distress band – but also have direction-finding capability. R-21 is fully deployed in the Lower 48, Hawaii, and Guam. Alaska is coming online soon, with some differences,” J.R. Frost, program manager for SAROPS, said.

The idea is to minimize the time required to find distressed persons because, in the marine environment, time is always of the essence.”

“For a long time, we’ve had emergency position-indicating radio beacons [EPIRBs] that operate on 406 megahertz [MHz] that a mariner can purchase – carriage is mandated on all safety and life-at-sea vessels. They emit a signal that is picked up by, presently, LEO [low Earth orbit] satellites orbiting specifically for this purpose. The beacons are sequentially numbered and are supposed to be registered with the country in which it was purchased. When the signal is received from the satellite, it is automatically transmitted to the appropriate rescue centers and countries.

“EPIRB is the marine version of these beacons, floating. There also are the emergency locator transmitters, designed as a replacement for older analog 121.5-MHz emergency locator transmitters. There are still a lot of those in aircraft around the world. When the 406 transmits, it includes the serial number and, if it has an embedded GPS chip, position as well. The third is the personal locator beacon, which is intended to be carried by hikers or hunters to alert the SAR system if they get in trouble. Their positions can be determined by a process called doppler that can determine an approximate position of the beacon.”

The latest development in the 406-MHz range is MEOSAR (Medium Earth Orbit SAR), which is being coordinated with the U.S. Air Force, the National Oceanic and Atmospheric Administration (NOAA), NASA, and the international community.

“That capability is going on GNSS [global navigation satellite systems] internationally, all of which will carry SAR repeaters that receive the signal, then send it back down to the ground. From there it is parsed out by computer to the appropriate place, depending on location and country code,” Frost said. “Those will use a different method for locating the beacons that will be significantly more accurate and will provide continuous coverage. Russia, Canada, France, and the U.S. put up the original SARSAT [SAR Search and Tracking] system, but there are only a few of those still in operation. Once the full GNSS constellation is up, there won’t be any breaks in coverage.

“SAROPS helps us plan efficient searches, using intelligent resource allocation of our assets, which is a fairly complex process. It basically gives us a probability grid of the most likely and less likely locations based on the information we have. SAR is always done in an information-sparse environment, otherwise it wouldn’t be a search. That information includes whatever we can find out about the incident; when and where it happened, which often is vague; winds and currents, using sophisticated environmental data from NOAA, the U.S. Navy, and other sources. The idea is to minimize the time required to find distressed persons because, in the marine environment, time is always of the essence.”