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Underwater Positioning Study of Flight Recorder

A flight recorder is installed on each airplane, which is also called “black box”, and it records the process of every flight. Thus if the airplane crashes and plumps into water, the underwater locater beacon (ULB) will be activated and emit supersonic sound at 37.5 kHz for 30 days. The rescue team will do their best to plot tracks, use directional hydrophone to detect the signal emitted from ULB, and derive the possible location of ULB with the acoustic reception of ULB and other flight information prior crash. When possible locations of ULB are determined, chartered vessel would go around these locations with ROV to confirm the site and start to salvage the ULB. This salvage process is very costly and time consuming. We propose using underwater acoustic detection simulation (Gaussian Beam Model, GBM[1]) to enhance the search process, which is to identify the location with acoustic data assimilation and transmission loss simulation. The ULB of NA-706 Black Hawk Helicopter in the tragedy in February, 2018 was salvaged successfully and the location is close to the estimated location based on the scheme of the acoustic data assimilation and transmission loss simulation proposed in this paper.