Investigation of remote sensing distances of aircrafts with underwater passive acoustic system

The seas, which covers approximately 2/3 of our world, contain many living species as well as many human-made structures. Today, passive acoustic listening in underwater environment is used in many applications such as detection/positioning of leaks in underwater pipelines, detection of ships, monitoring of marine animals. Another acoustic source that can be detected with these already installed systems is aircraft. The acoustic sound levels produced by aircraft flying at certain distances above the sea are at a level that cannot be neglected. In addition, the amplitude of the sound pressure doubles as the sound signal passes from the air environment to the water environment. This allows aircraft to be detected more easily under water. Thus, aircraft that violate the borders of other countries over the sea without permission can be detected and located. In this study, an investigation was made on the detection distances of four different aircraft, a helicopter (Bell 212) and three various fixed wing propeller aircraft (B-N Islander, Twin Otter, P-3 Orion) from underwater. Thus, a preliminary study has been made for an aircraft positioning system that can be used in the underwater environment. According to this study, it has been shown that the relevant aircraft can be detected underwater from distances between 219-790 m