Operational space weather for aviation under ICAO: Lessons for improved nowcasting and forecasting from 6 years of service

Since November 2019, ICAO Space Weather Centres have issued operational advisories to support civil aviation decision making for HF communications, GNSS, and radiation. We present a consolidated analysis of the ICAO advisory record from November 2019 to September 2025, using the advisories as an operational “space weather climate” dataset to identify where current products perform well, where they are biased, and which post event lessons translate into concrete service improvements.Across the period, we identify 2,350 advisories grouped into 867 advisory series, dominated by GNSS (1,472) and HF communications (872). Moderate advisories prevail (1,592) over Severe (758). Advisory occurrence scales with Solar Cycle 25 activity and exhibits both strong storm driven clustering (notably May and October 2024) and a clear equinox season enhancement. Geographic footprints are distinct: HF advisories concentrate in the auroral oval and polar cap, while GNSS advisories preferentially populate a low latitude belt with pronounced activity in the South Atlantic sector.We use these results, supported by targeted event case studies and an impact oriented illustration from HF quality reporting, to propose operational priorities: harmonised cross centre event definitions and closure criteria, better constrained model to observation chains (especially for SEP driven absorption and GNSS impacts), and routine post event analysis with outcome based logging that links advisories to observed operational effects. This bridges research and operations by turning long term advisory statistics into actionable requirements for next generation nowcasting and forecasting services.