One of the main objectives of the “Ash dispersal forecast and civil aviation” workshop was to investigate the state of existing Volcanic Ash Transport and Dispersal Models (VATDM) in order to identify potential new improved strategies of dispersal forecasting, e.g. probability/ensemble forecasting. In this context, a benchmark case (26 Feb. 2000 Hekla eruption) was run using different state-of-the-art Volcanic Ash Transport and Dispersion Models (VATDM) to understand better the variability associated with different modelling approaches when using the same (or very similar) input dataset.