Search and Recovery
“Sending a police officer underwater in zero visibility without scanning sonar is like sending an officer on patrol without a bulletproof vest” (Sgt Rob Riffle, Dive Team Supervisor, Winnipeg Police Services).
Police, fire, and military first responders are often called for the unenviable task of underwater body recovery with the victim being the result of drowning, marine accident, suicide or homicide.
This sonar application focuses on three phases of operation:
Search
Locate
Recover
Side-scan sonar is conventionally used for the Search and Locate components of the program; this instrument works best when towed from a vessel at a fixed speed and in a straight line with the sensor at a constant height above a relatively flat bottom. It is often described as a wide-area search tool. However, side-scan search is limited by irregular shoreline, the presence of man-made structures, current flow, and sudden changes in water depth. It is not the tool to direct divers to target in real time. Tripod-deployed scanning sonar is most often used in areas where side-scan cannot be deployed and is ideally suited to guide divers in real time to targets of interest—even in low or zero in-water visibility. Besides target detection, Kongsberg high-resolution scanning sonar is used to identify potential diver hazards. This increases diver safety and ultimately reduces bottom time as the supervisor can direct the diver to target(s) more efficiently.
Where water depth exceeds diver limits, ROV-deployed Kongsberg scanning or multibeam imaging systems are used to identify and assist recovery.
Rescue diver supervision
Divers deploy during operations in any conditions – summer or winter, clear visibility or no visibility. Being a rescue diver can be dangerous work – many divers lose their lives not during actual operations, but during diver training. Therefore, Kongsberg believes that sensor technology can keep divers out of the water until absolutely necessary. The supervisor can then keep their dive time to a minimum by guiding the diver to the target quickly and while avoiding potential threats from debris or obstacles.
Underwater crime scene investigation
Investigating underwater crime scenes has its own unique challenges. Weapons are often discarded from bridges, bodies are typically weighted, wrapped in blankets or sleeping bags, stuffed into barrels…. Not only does the does the target sought after have to be found and documented, but other evidentiary material associated with the crime scene must be located. Combine all of this with potentially high current flow, zero visibility and other man-made junk on bottom in the search area and the challenges are daunting even to the most experienced police dive teams. Kongsberg side-scan, imaging multibeam, and scanning sonars are routinely used for investigating U/W crime scenes. Even if the target sought after is not visible acoustically, the diver’s position can be monitored in real time to ensure the area in question has been 100% searched. When a target is located, using the Kongsberg scanning sonar allows the operator to calculate its exact geographic position and measure distances and angles to other features of interest. This additional information is critical when presenting recorded sonar data as reliable evidence at trial. The police must not only find the evidence, but accurately record the exact time and location of the discovery, and present images showing that the site or evidence was not tampered with. This strengthens the prosecution’s case while denying the defense an easy out by discrediting the evidence.
Marine accidents
Marine accidents involve vessels that sink or ram each other, crash into docks or structures, aircraft that hit the water, vehicles that fall from bridges or run off the highway, trains falling from trestles, heavy equipment getting dragged underwater or falling off of barges: it is almost an endless list. Investigating these accidents is critical to establishing the root cause and determining whether it was due to an equipment failure, operator error, environment conditions or a criminal act. In marine accidents, the challenge is to not only search for and locate the target interest, but to identify surrounding evidentiary debris associated with the incident. High-resolution acoustic imaging is critical in viewing what Kongsberg calls the “Full Picture” – that which is beyond the range of the human eye or what underwater cameras are able to detail. Kongsberg has a variety of sensors that can be mounted on surface vessels, ROVs, AUVs and USVs to hasten the location of the target and detail surrounding areas.
Related products
Contact
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Colin SmithProduct Manager MultiBeam Sonars