Mid-Air Collision Avoidance Principles

Unmanned Aircraft Systems are about to replace human pilots not only in dangerous, dull or tedious missions but generally where the human being is the limiting factor including size and economic issues. There is a wide range of applications for which UAVs have to be operated in non-segregated airspace in general and uncontrolled airspace in particular, regardless of civil, governmental or military usage, such as disaster and incident management, border patrol, or construction site prospection or inspection (/2/, /3/, /4/, /5/, /11/, /12/). However, all airspace users – manned or unmanned – shall adhere to the same standards, rules and laws. Depending on the airspace and its usage – in particular by anyone other than the UAS – functional and technical requirements for the operation of unmanned aerial vehicles can be derived aiming on the minimisation of hazards to third parties in the air or on the ground. A reliable aircraft collision avoidance system is the key enabler for providing access to unsegregated airspace. However, the procedures preventing mid air collision start well before any close encounter itself and cover in a holistic approach the topics airspace definition and usage, flight planning, provision of seperation and finally sense and avoid.