Deploying flare decoys against heat-seeking threats involves various parameters such as flare timing, flare ejection velocity, direction of ejection and the number of flares used. In this study, an attempt has been made to identify the key parameters among these that impact the performance of flares the most. For this, engagement studies involving sixdegrees- of-freedom models for an air-to-air heat-seeking missile and a fighter aircraft were carried out using the CADAC++ simulation environment. The effect of flare parameters was studied using their impact on missile envelopes. Studies show that the effectiveness of the flare decoys is a strong function of the flare timing and the number of flares used. © 2013 The Society for Modeling.