Satellite imagery of volcanic ash is used to verify the Air Resources Laboratory (ARL) time dependent three-dimensional Volcanic Ash Forecast Transport And Dispersion (VAFTAD) model. VAFTAD forecasts are included in volcano hazards alert messages issued as an aid to aircraft operations for ash clouds that reach flight levels of 6 km or higher and may drift hundreds to thousands of kilometers from an explosive volcanic eruption. VAFTAD is run by users connected through Internet to a workstation at ARL using screen-prompted input, and is applicable globally. Model output gives charts of the forecast ash cloud which are phone-faxed back to the user and made available for public distribution over various weather information distribution systems and Internet. Volcanic ash model verification is essential for interpreting ash cloud forecasts and applying them for decision-making. The VAFTAD model verification is detailed using a September 1994 eruption of the Klyuchevskoi Volcano on Kamchatka Peninsula in eastern Russia. Both the downwind extent of the ash cloud along the main flow axis and the ash cloud width perpendicular to the main flow axis, seen on satellite imagery, compared remarkably well with the VAFTAD calculations that used eruption source information and archived meteorological analyses as model input.