A significant need exists for automatic obstacle detection systems on-board rotorcraft due to the heavy work load demands that are imposed upon the pilot and crew. Such systems must augment the pilot's ability to detect and avoid obstacles for the sake of improving flight safety. The most important requirements of obstacle detection systems include a large field-of-view, a high update/frame rate, and high spatial resolution. In military systems the requirement of covertness is also present. To satisfy the requirement of covertness Honeywell, in conjunction with NASA Ames, has developed and demonstrated through simulation the feasibility of maximally passive systems for obstacle detection and avoidance. Such systems rely on techniques of passive ranging such as motion analysis and binocular stereo to perform their function through the use of passive sensor imagery. Honeywell's current efforts in passive ranging-based obstacle detection systems involves the real-time implementation of the motion analysis component of such systems. The real-time implementation within a Honeywell flexible testbed environment is the subject of this paper. An overview of the motion analysis algorithm is provided and the issues involved in its real-time implementation are addressed.