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An infrared countermeasure (IRCM) is a device designed to protect aircraft from infrared homing ("heat seeking") missiles by confusing the missiles' infrared guidance system so that they miss their target (electronic countermeasure). Heat-seeking missiles were responsible for about 80% of air losses in Operation Desert Storm. The most common method of infrared countermeasure is deploying flares, as the heat produced by the flares creates hundreds of targets for the missile.
Conventional man-portable air defense systems (MANPADS)-launched missiles include an infrared sensor that is sensitive to heat, for example the heat emitted from an aircraft engine. The missile is programmed to home in on the infrared heat signal using a steering system. Using a rotating reticle as a shutter for the sensor, the incoming heat signal is modulated, and, using the modulated signal, an on-board processor performs the calculations necessary to steer the missile to its target. Owing to its portable size, MANPADS missiles have a limited range, and a burn time of a few seconds from launch to extinguishing.
Countermeasure systems are usually integrated into the aircraft, such as in the fuselage, wing, or nose of the aircraft, or fixed to an outer section of the aircraft. Depending on where the systems are mounted, they can increase drag, reducing flight performance and increasing operating cost.
Because they are expensive, such countermeasure systems have been seldom used, primarily on military aircraft. Much time and money is spent on testing, maintaining, servicing, and upgrading systems. These procedures require that the aircraft are grounded for a period of time.