Unfortunately there is no API for FLAASH at this time. However, there is API for using Quac: the http://www.harrisgeospati...cs/enviquactask.html Quac was created by the same developers of FLAASH but uses a different method to calculate surface reflectance. It is easy to use and typically is within +/-15% of the physical model for FLAASH. It is an excellent alternative and I often suggest users try both methods with their data to compare results.