Blockchain applications in UAV-towards Aviation 4.0 Reza Vatankhah Barenji 1 and Mazyar Ghadiri Nejad 2 1 Hacettepe University, Department of Industrial Engineering, 06800, Ankara, Turkey 2 Department of Industrial Engineering, Girne American University, 99428, Kyrenia, TRNC, Turkey reza.vatankhah@hacettepe.edu.tr, mazyarghadirinejad@gau.edu.tr Abstract. Aviation 4.0 is one of the most important contexts that started to attract many researchers in recent years. The main element of Aviation 4.0 is to employ and manage unmanned aircraft vehicles (UAVs). Employing UAVs in the Aviation 4.0 era will minimize the human dependency level of the aviation management systems. Embedding UAVs with Blockchain tech- nology (BCT) might become an increasing phenomenon since the UAVs should be operated in an environment with many obstacles and possibilities of cyber-attacks. Therefore, using BCT, regulators in the whole world will be able to track the identities of UAVs flying in their territories. This chapter first, provides detailed information about the BCT and explains its imple- mentation architecture, and then the potential applications of this technology in the UAV in the Aviation 4.0 era are stated. Keywords. Aviation 4.0; Blockchain technology; Cyber-physical system; Unmanned aircraft vehicles (UAVs); Applications. 1 Introduction Industry 4.0 is a newly merged paradigm for employing a cyber-physical technol- ogy in embedded devices (all the devices that hold a processor for decision-making) aiming to boost the smartness level of the device or system. One of the manifesta- tions of Industry 4.0 in the aircraft industry is Aviation 4.0. Generally, aviation is the activity surrounding mechanical flights and the aircrafts industry. The aircraft includes fixed-wing and rotary-wing types, morphable wings, wing-less lifting bod- ies, as well as and lighter than aircraft such as hot air balloons and unmanned aerial vehicles (UAVs). The main object in the Aviation 4.0 era is boosting the smartness level of UAVs and improving the humanness decision-making level of the aircraft [1]. Besides that from a system point of view, Aviation 4.0 attempts to provide a platform and approach to good mange the included UAVs with a minimum level of