Recent advances in software and artificial intelligence technologies have led to the increasing need to support the collaboration between humans and systems in various application domains. The growing capacity for systems has leveraged the power of building applications that have higher autonomy. However, a proper understanding of allocating tasks to either humans or machines is still lacking, and no suggestions are provided to support this allocation. Current approaches do not consider knowledge about the appropriate level of automation (LOA) in this collaboration and do not support adaptive automation, especially task assignments during the system’s operation. The knowledge about which factors affect the variability in human-system interaction LOA has not been explicitly captured. This paper presents a preliminary study that identifies the factors that influence levels of automation in autonomous systems and present the identified factors as a list. Identifying the factors that influence the level of autonomy of systems advances research in the design of autonomous systems by introducing an adaptive automation approach that can recommend levels of automation to support human-computer interactions. Modern systems must be prepared to identify, capture and process the significant volume and variety of data related to the factors that might influence the variability of systems’ behaviours.