ACAS installation on unmanned aerial vehicles: effectiveness and safety issues

Purpose The paper aims to investigate the compatibility of manned-aircraft airborne collision avoidance systems (ACAS) for use on unmanned aerial vehicles (UAV). Design/methodology/approach The paper uses the Fault Tree method for defining ACAS model adapted for the UAV operations, with the aim of showing the presence of certain factors that configure in such ACAS system, and whose failure can lead to an adverse event - mid-air collision. Findings Based on the effectiveness analysis of ACAS solution adapted for the UAV operations, for given inputs, it can be concluded that the probability of ACAS failure is on the order of 10-4, as well as that in the case of autonomous ACAS solution for the UAV, the probability is reduced to 10-5. The most influential factors for the failure of the UAV's ACAS are as follows: technical implications on the UAV, human factor, sensor error, communication and C2 link issue. Practical implications The established model could be used both in the UAV's ACAS design and application phases, with the aim of assessing the effectiveness of the adopted solution. The model outputs not only highlight the critical points of the system but also provide the basis for defining the Target Level of Safety (TLOS) for the UAV operations. Originality/value The developed model can be expected to speed up the design and adoption process of ACAS solutions for the UAVs. Also, the paper presents one of the first attempts to quantify TLOS for the UAV operations in the context of collision avoidance systems.