We propose to use MODIS Airborne Simulator data acquired during the SCAR-A experiment, that took place in July 1993 in the Eastern US, to validate the MODIS operational atmospheric correction algorithm. The first step is to calibrate the visible, near-infrared and middle- infrared channels using Rayleigh scattering in the visible for the absolute calibration, high clouds or sun glint views for the inter calibration. Calibrated data are compared with simultaneous observations from AVIRIS. The second step is to investigate an aerosol retrieval method using the 2.14 μm band. The split window technique applied to thermal channels at 11 and 12 microns is also used to derive the water vapor content over land. After applying atmospheric corrections, we present some of the directional features exhibited by selected targets.