Safety and reliability in aviation – A systematic scoping review of normal accident theory, high-reliability theory, and resilience engineering in aviation

Aviation is a complex system with different interconnected and interdependent subsystems that rely on each other to ensure safety and reliability. The technological progress in the sector has increased safety, but incidents and accidents still happen. However, accident analyses and safety research have not paid equal attention to all aviation subsystems resulting in possibly undetected or underestimated risks. This study systematically investigates the literature on aviation safety from 1984 to 2021 with a particular focus on Normal Accident Theory (NAT), High-reliability Theory (HRT), and Resilience Engineering (RE) as their underpinning theoretical perspectives. The analysis of the 77 records that were screened as most relevant shows that the studies underpinned by these theories were mainly looking at the ‘primary operational aviation subsystems' such as air traffic control (ATC) and flight operations and significantly less at the 'secondary operational subsystems' such as ground operations and aircraft maintenance. In addition, the analysis showed that research building on RE has increased in recent years and is now the predominant theoretical framework in studies of this type. Nevertheless, NAT and HRT are still relevant and are often employed in conjunction with RE. Future research should pay more attention to the role of secondary subsystems and their impact on the safety, reliability, and efficiency of the aviation system. Moreover, there is perhaps a need for researchers to develop a more integrative framework that includes valuable components of all three theories and to create a set of safety and reliability strategies suitable for both primary and secondary aviation subsystems, hence, benefiting the entire aviation system.