Israel Aircraft Industries (IAI) operates a Jet Thermal Signature and Effects Fac ility (MMSEF). The JETSEF facilitates the simulation of the IR radiation emitted by the exhaust system and gaseous plume of a low-f lying aircraft. The flight is simulated by the effect of an external air stream flowing around the exhaust gas jet. The JETSEF complex includes automatic multichannel radiometric and data reduction systems. Furthermore, the JETSEF has a facility for the creation of an aerosol cloud around the exhaust flow produced by the simulator. The IR radiation, corresponding to an afterburn ing engine setting and flight speed of 0,9 Mach, was measured in the 2 to 3 microns, 3 to 4 microns and 4 to 5 microns wavebands. The angular range covered was fram 00 to 90°, where 0° is defined as the tail-on aspect angle. The data were reduced on-line and the measured radiation was stored on an IHNEAT computer, An aerosol cloud was injected into the air stream surrounding the exhaust jet flow. It was found that the IR radiation emitted by the exhaust system and 'gaseous plume was substantially reduced at all aspect angles. A theoretical model has been developed at IAI which describes the passage of IR radiation through an aerosol cloud. The model takes into consideration the absorption, the multiple scattering and the self-emission of the particles in the aerosol cloud. Using this theoretical model, the attenuation of the IR radiation by the aerosol cloud was estimated. Good agreement between the measured and calculated attenuations was obtained.