I. Introduction
"Did you know that over 70% of aviation accidents are attributed to human error? Exploring the unpredictable element in human reliability is not just an academic exercise; it's a matter of life and death in critical industries." Human reliability plays a pivotal role in the functioning and safety of complex systems, where the unpredictable element introduces a layer of challenge that demands profound investigation. As technological advancements continue to shape our world, the reliability of human performance in intricate and interconnected systems becomes increasingly critical [1]. This paper review delves into the multifaceted aspects of human reliability within complex systems [2], aiming to provide a comprehensive understanding of the unpredictable elements that influence performance.