Modeling the Infrared Intensity of a Large Commercial Aircraft

Measuring the infrared signature of large civilian aircraft has become increasingly important due to the proliferation of man-portable air defense systems (MANPADS) and the increasing threat of their use by terrorists. Because of the range of these shoulder-fired weapons, most aircraft flying over 20,000 feet are safe from the threat; however, aircraft taking-off or landing are extremely vulnerable. A radiometric model was developed to simulate a large commercial aircraft's infrared intensity during these two critical phases of flight. The radiometric model was largely based on the dimensions of a Boeing 747-400 aircraft. It is capable of simulating elevation angles between -20 degrees and +20 degrees, as well as 360 degrees in azimuth in its projected area analysis of the faceted model. The model utilizes an obscuration matrix to determine which parts of the aircraft are in view by the observer and thus contribute to the aircraft's intensity. A simple one-bounce reflection matrix was also included to incorporate reflections of hot parts off other body parts as well as earth- and sky-shine contributions to the overall intensity.