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The increasing demand for the use of unmanned aerial systems (UAS) in various social and economic applications have pressed aviation authorities to draw up rules and regulations that permit the release of such aircraft in nonsegregated airspace. However, issues related to the safety of air traffic operations arise when considering the possibility of coexistence of manned and unmanned aircraft simultaneously. Thus, surveillance plays a key role in monitoring and controlling air traffic in new scenarios. The positional information provided by the Automatic Dependent Surveillance -Broadcast (ADS-B), originally designed to improve situational awareness for pilots and support controllers in air traffic management, interacts with the Sense and Avoid Systems (S&AS) of the UAS in order to avoid exposure to events of loss of separation (AIRPROX) andcollisions. This paper presents a qualitative approach to assess safety when using ADS-B systems integrated with UASs in aeronautical operations. In addition, the possibility of using a methodology previously applied on manned systems for assessing safety on UASs is discussed. A new testing platform (PIpE-SEC) is presented as a possible solution for this safety evaluation.

The demand for increasing air traffic volume has pressed aviation authorities to densify the global airspace through separation reduction between aircraft, allowing operations that are more efficient in the Air Traffic Management (ATM). However, issues related to the safety of air traffic operations arise when considering the possibility of reducing the separation of aircraft. Objectively, for greater efficiency and separation reduction, without significantly affecting safety, surveillance positions of the aircraft must appear not only more accurate and precise to the air traffic controller (ATCo), it should be more trustworthy, which concerns the integrity of that information. This research proposes to assess the impacts of these parameters on the safety levels of air traffic control system (ATC) inserted in the new concept of Global ATM (CNS/ATM). To achieve it, an analysis of the data related to error in positioning of the Global Navigation Satellite System (GNSS) was made to establish its behavior. This behavior analysis is used to model a complete traffic control system for simulation purposes and, adopting the safety analysis methodology developed by Vismari (2007), evaluate the effects that these new parameters had on the safety levels found in the research developed by Vismari (2007) for air traffic environments based on Automatic Dependent Surveillance -Broadcast (ADS-B). They are compared to various scenarios in which there was a GNSS system performance degradation. For each studied scenario, it was found that GNSS behavior's degradation was not sufficient to create risk events in aspects related to integrity of the aircraft position data. Thus, within the simulated conditions, the system kept the safety levels regarding to the integrity of the aircraft position informed on screen to the air traffic controller in conflict resolution operations. The computational model developed has several features, which, although not totally applied in this research, constitute a legacy for future research and for integration with the Integrated Platform for Testing Critical Embedded Systems (PIpE-SEC) developed within the Safety Analysis Group (GAS) of EPUSP.