A Method for Eliciting Safety Requirements for Military Unmanned Aircraft Systems Related to Critical Scenarios

The expansion of unmanned aircraft systems (UAS) usage has highlighted the need for robust safety mechanisms to mitigate operational risks in critical scenarios. In this context, it is envisioned that the potential of the critical decision method (CDM), a semi-structured interview technique that utilizes non-routine incidents to capture the decision-making processes employed in these situations and explore how different actions might have influenced the outcome, can be used to elicit knowledge that will contribute to safe UAS operation. However, there is a gap in the literature concerning the proposals and guidance for utilizing CDM in the systems development requirements elicitation process. This study aims to address this gap by applying CDM combined with model-based systems engineering to systematically elicit the safety requirements for UAS in critical operational scenarios. The methodology involves stakeholder interviews, scenario analysis, and requirements elicitation that reflect both operational insights and situational hazards. Sixty-eight safety requirements were identified for the UA and 51 for their ground control stations, providing a comprehensive framework for enhancing safety. The study concludes that CDM is an effective tool for eliciting requirements, offering significant contributions to the early design phases of UAS projects and supporting the development of safer and more resilient systems.