Locating a drowning victim in a body of water is a difficult and time-consuming process. Even if witnesses can accurately report where they saw a person go into the water, subsurface currents and other factors can move a submerged body a significant distance. Dragging with a hook rig often isn’t usually effective because of underwater obstructions, and unless the body of water is very small recovery diving becomes a tedious and often dangerous operation. Poor to zero visibility is often the case, and the water is usually cold once a diver goes a few feet down.
SONAR, which stands for SOnic Navigation And Ranging, uses high-frequency sound pulses that are reflected back to the system where the on-board computer produces an image of the underwater environment. (It is the “ping” that is often depicted in submarine movies.) Many SAR teams and related emergency services now incorporate a SONAR capability to their practices. BSARD has a Humminbird Helix 12 G4N system and an expert operator/analysis team available at no charge to the requesting agency.
Our best practice protocol uses dogs, SONAR, and divers in a specific process designed to minimize the risks and increase the probability of success.
- The entirety of the body of still or moving water presents the greatest challenge. Witness interviews, if available, can narrow the search area somewhat.
- Open-water certified human remains detection dogs further define the areas of probability, based on current, depth, and surface air movement. This becomes the general area to be scanned by SONAR.
- The SONAR operator performs a grid search by boat and the analyst looks for any “Targets of Interest” (TOI). The team will drop a sound-reflective cage as close to the TOI as possible. The cage has a buoyed line attached with a surface float.
- The diver goes down the buoyed line to investigate the TOI. If the target is the victim then the diver team can initiate the recovery.