Incorporation of Ambient Sound Levels into UAS Flight Path Optimisation

quietdrones2026 Tracking Number 48

Research on the environmental noise impacts of unmanned aircraft systems (UAS) remains limited, and their effects within cities and urban areas are not yet fully understood. This study investigates how existing ambient sound levels can be incorporated into the calculation of UAS flight paths with the specific objective of reducing observable sound exposure at street level. Three approaches to flight-path optimisation are compared. The first approach incentivises routing over areas predicted to have relatively high broadband ambient noise levels, derived from Strategic Noise Mapping. The second compares the broadband ambient sound levels with the predicted broadband sound level of a UAS in flight. The third incorporates both ambient and predicted UAS sound levels but additionally examines their spectral content to calculate a detectability likelihood factor (d’). All methods were implemented in Geospatial Information Systems (GIS) software to generate friction layers for least-cost path analysis, enabling the identification of “optimum” routes. Although this research does not propose a single preferred methodology, it highlights key differences among the resulting flight paths, explains where and why deviations occur, and illustrates how these outcomes depend on the initial input parameters. The findings also raise important questions regarding future methodologies for assessing the environmental noise impacts of UAS operations and decision making for route optimisation.