This book provides a solution to “rare event” problems without using the classical theory of reliability and theory of probability. This solution is based on the methodology of risk assessment as “measure of danger” (in keeping with the ICS RAS) and an expert approach to determining systems’ safety indications using Fuzzy Sets methods. Further, the book puts forward a new concept: “Reliability, Risks, and Safety” (RRS). The book’s main goal is to generalize present results and underscore the need to develop an alternative approach to safety level assessment and risk management for technical (aviation) systems in terms of Fuzzy Sets objects, in addition to traditional probabilistic safety analysis (PSA). The concept it proposes incorporates ICAO recommendations regarding proactive system control and the system’s responses to various internal and external disturbances.