AFF stands for Automated Flight Following System, which is used in aerial fire fighting to insure that the fire retardant is dropped in the drop zone even though with the smoke the visibility is very low making it difficult to see. As one aircraft goes in another follows in behind it. This off the shelf technology has been used for over a decade now and with the advances of GPS accuracy and GIS modeling of surface terrain by satellite its uses should be incorporated into the laying of smart dust.