Abstract
The aviation industry is a significant contributor to global carbon emissions. Hydrogen is a clean jet fuel alternative being explored by aircraft manufacturers, though the design considerations of aviation hydrogen refuelling systems remain underexplored. Hydrogen’s properties would necessitate significant changes to infrastructure, the refuelling procedure, and ground support activities, which could impact the behaviour of personnel across the refuelling system. Thus, new safety and operational challenges for workers should be proactively identified and mitigated during system design. Systems thinking methods are increasingly being used to inform safer system design. These methods demonstrate how system safety influences interactions between components across multiple system levels, including regulators, companies, and individuals. Although most studies apply a single systems thinking analysis in isolation, the advantages of applying multiple systems thinking methods to a single system are under increasing investigation. Two systems thinking methods, Cognitive Work Analysis (CWA) and Systems Theoretic Process Analysis (STPA), were applied to the emerging aviation hydrogen refuelling system with the aim of identifying challenges and solutions for system design, including training requirements, insights regarding equipment design, hazards, and risk controls, and to understand the benefits of applying CWA and STAMP-STPA to the same system. Following a Delphi process eliciting feedback from international subject matter experts on three resulting models, the outputs were analysed in accordance with the study aims. System-wide challenges were identified with implications for design, training, and procedures. Changes to the refuelling task may impact refueller workload and introduce opportunities for error. However, performance can be supported by enhancing user interface functionality to optimise human-machine interaction. Additionally, the CWA and STPA outputs were consistent and complementary; combined use may deepen system knowledge and facilitate risk control identification. This research demonstrates the application of multiple systems thinking methods to an emerging system, providing insight into how safety and efficiency can be maintained during the hydrogen transition.