Helicopter Noise Modelling in an Urban Setting: A NORAH2 Demonstration for Cannes, France

Abstract

Urban helicopter activity is intermittent and route-focused, yet most strategic mapping tools were developed for fixed-wing traffic and long-term averages, leaving urban rotorcraft noise under-represented. In the EU, the Environmental Noise Directive (2002/49/EC) and its CNOSSOS-EU methods require Member States to measure, map, and report aviation noise at major airports (using indicators such as Lden and Lnight), covering helicopter operations as part of overall aviation noise; yet current practice and tooling remain largely fixed-wing oriented. To the authors’ knowledge, no peer-reviewed real-case applications of NORAH2 to urban helicopter operations have yet been published. Therefore, this study demonstrates an end-to-end NORAH2 workflow using Cannes, France, as an urban case study, modelling 556 helicopter operations recorded between 12 and 25 May 2025 over an 8.3 km × 2.5 km analysis grid, and utilising openly available ADS-B/Mode-S trajectories to generate noise-related maps that can be used to support policy-making. Radar trajectories were conditioned to retain sampling while ensuring kinematic plausibility; environmental layers (terrain, land cover, basic meteorology) and rotorcraft representations were configured in NORAH2. Standard indicators were produced on a uniform grid, Lden (day–evening–night) and LAeq, 16 h, alongside event-count metrics (N60/N65/N70) and single-event LAmax footprints. Over a two-week window, outputs exhibited coherent corridor-level structure and event footprints consistent with observed operations, indicating that ADS-B-derived trajectories, after light conditioning, are suitable inputs for urban NORAH2 mapping. The period analysed is short; results are demonstrative for that window and not intended as statutory exposure assessments. The contribution is twofold: (i) the first published demonstration that connects open radar-like data to NORAH2 outputs in a dense urban setting, and (ii) evidence that NORAH2 can provide both energy-average and frequency-of-occurrence views useful for city noise management.