The concept of a bio-inspired navigation system using acoustic sensors is presented and various possible approaches for its effective integration in Remotely Piloted Aircraft Systems (UAS) are investigated. Acoustic sensors can have useful applications in UAS obstacle detection and localization, especially in Global Navigation Satellite System (GNSS) denied environments. Taking inspiration from echolocating mammals, especially bats, novel navigation techniques are presented employing both multistatic and monostatic acoustic sensors. Laboratory experiments are presented in which a small array of transmitters provides input data to a multilateration receiver. Based on the positive results of these initial experiments, various possible approaches are investigated for integration of the proposed echolocation techniques in a multi-sensor UAS Navigation and Guidance System (NGS) and in an Acoustic Laser Obstacle Avoidance (ALOA) system for Separation Assurance and Collision Avoidance (SA&CA).