onboard visual sense and avoid system for small aircraft

The sense and avoid (SAA) capability is a key issue in the integration of Unmanned Aircraft Systems (UAS) into the common airspace [1]. Besides the lack of a regulatory framework in most countries, some technological challenges are still not resolved which holds back routine UAS applications. Most UAS or Remotely Piloted Aircraft Systems (RPAS) have no SAA capability. The separation for these aircrafts must be done solely by the Air Traffic Control (ATC) which is not cost effective. Furthermore, in the case of a lost link, there should be some kind of collision avoidance capability onboard; otherwise, if we want to maintain the current safety level of the air traffic system, a single unmanned airplane would block a significant sector of the airspace.