Passive, Long-Range Detection of Aircraft: Towards a Field Deployable Sense and Avoid System

Unmanned Aerial Vehicles (UAVs) typically fly blind with operators in distant locations. Most UAVs are too small to carry a traffic collision avoidance system (TCAS) payload or transponder. Collision avoidance is currently done by flight planning, use of ground or air based human observers and segregated air spaces. US lawmakers propose commercial unmanned aerial systems access to national airspace (NAS) by 30th September 2013. UAVs must not degrade the existing safety of the NAS, but the metrics that determine this have to be fully determined yet. It is still possible to state functional requirements and determine some performance minimums. For both manned and unmanned aircraft to fly safely in the same airspace UAVs will need to detect other aircraft and follow the same rules as human pilots. Key specifications of the international committee F38 on UAS systems standard F2411-04 (1) proposed requirements which include a field of regard of 220◦(horizontal) × 30◦(vertical), minimum detection range of 3 statute miles under visual flight rules and a required miss distance of 500 ft. Without this capability, widespread utilization of UAVs will not be possible. This paper focuses on the sensing of aircraft with passive vision. Small size, low weight and power requirement make cameras attractive for this application. Multiple