ICAO Annex 3 Amdt 82 and PANS-MET requires that quantitative volcanic ash (QVA) concentration information is provided by designated Volcanic Ash Advisory Centres (VAAC) as part of the International Airways Volcano Watch (IAVW) framework overseen by the International Civil Aviation Organization (ICAO). The quantitative volcanic ash (QVA) concentration information is provided per volcano in the form of a high-resolution four-dimensional representation of a volcanic ash cloud based on 3-hourly timesteps. New information is provided when there is a significant change in the erupting characteristics or at 6 hourly intervals until the ash is no longer present. The information is intended for use in operator's flight planning and decision support systems allowing, e.g., more efficient routes in accordance with their safety management programme during significant volcanic ash cloud events.