The continuous increase of accident and incident reports has indicated the potential of drones to threaten public safety. The published regulatory framework for small drones is not visibly based on a comprehensive hazard analysis. Also, a variety in the constraints imposed by different regulatory frameworks across the globe might impede market growth and render small-drone operations even more complicated since light drones might be easily transferred and operated in various regions with diverse restrictions. In our study we applied the Systems-Theoretic Process Analysis (STPA) method to small-drone operations and we generated a first set of Safety Requirements (SR) for the authority, manufacturer, end-user and automation levels. Under the scope of this paper, we reviewed 56 drone regulations published by different authorities, and performed (1) a gap analysis against the 57 SRs derived by STPA for the authority level, and (2) Intra-Class Correlations in order to examine the extent of their harmonization. The results suggest that the regulations studied satisfy 5.3% to 66.7% of the SRs, and they are moderately similar. The harmonization is even lower when considering the range of values of various SRs addressed by the authorities. The findings from the drones’ case show that regulators might not similarly and completely address hazards introduced by new technology; such a condition might affect safety and impede the distribution and use of products in the international market. A timely and harmonized standardization based on a systematic hazard analysis seems crucial for tackling the challenges stemmed from technological advancements, especially the ones available to the public.
Literature and industry standards do not mention inclusive guidelines to generate safety recommendations. Following a literature review, we suggest nine design criteria as well as the classification of safety recommendations according to their scope (i.e. organisational context, stakeholders addressed and degree of change) and their focus, the latter corresponding to the type of risk barrier introduced. The design and classification criteria were applied to 625 recommendations published by four aviation investigation agencies. The analysis results suggested sufficient implementation of most of the design criteria. Concerning their scope, the findings showed an emphasis on processes and structures (i.e. lower organisational contexts), adaptations that correspond to medium degree of changes, and local stakeholders. Regarding the focus of the recommendations, non-technical barriers that rely mostly on employees’ interpretation were introduced by the vast majority of safety recommendations. Also, statistically significant differences were detected across investigation authorities and time periods. This study demonstrated how the application of the suggested design and classification frameworks could reveal valuable information about the quality, scope and focus of recommendations. Especially the design criteria could function as a starting point towards the introduction of a common standard to be used at local, national and international levels.
