Contrail formation in the exhaust plume of the ATTAS aircraft engine burning fuels with 2 ppmm and 266 ppmm sulfur has been studied using an aerosol dynamics model coupled to a 2-dimensional, axisymmetric flow code. For both the low and high sulfur fuels, the model predicted approximately 35% of the available water condenses within 200 m downstream of the exhaust exit. However, particle size distributions for the low sulfur plume are broader and extend to larger sizes. Model results indicate that, for the engine and flight conditions treated, sulfuric acid is a viable soot activating agent when the fuel sulfur mass loading is reduced to 2 ppmm and that differences in the contrail particle size distribution for sulfur mass loadings between 2 ppmm and 266 ppmm would be difficult to detect.¿ 1997 American Geophysical Union