missile just after launch, before the sustainer motor ignites SAM fired from a M1097
AN/TWQ-1 Avenger Air Defense platform.
Infrared Infrared homing missiles are designed to home-in on a heat source on an aircraft, typically the
engine exhaust plume, and detonate a
warhead near the heat source to destroy or otherwise damage the aircraft. These missiles use
passive guidance, meaning that they do not emit
heat signatures, making them difficult to detect by aircraft employing countermeasure systems.
First generation in use The first missiles deployed in the 1960s were infrared missiles. First generation MANPADS, such as the early prototypes of the American
Redeye, early versions of the Soviet
9K32 Strela-2, and the Chinese
HN-5 (A copy of the Soviet Strela-2), are considered "tail-chase weapons" as their uncooled spin-scan
seekers can only discern the superheated interior of the target's
jet engine from background noise. This means they are only capable of accurately tracking the aircraft from the rear when the engines are fully exposed to the missile's seeker and provide a sufficient thermal signature for engagement. First generation IR missiles are also highly susceptible to interfering thermal signatures from background sources, including the sun, which many experts feel makes them somewhat unreliable, and they are prone to erratic behaviour in the terminal phase of engagement. While less effective than more modern weapons, they remain common in irregular forces as they are not limited by the short shelf-life of gas coolant cartridges used by later systems, requiring only a battery, but the missiles themselves have degraded over the years; For instance, during the
Syrian Civil War, the
Ahfad al-Rasul Brigades captured 50 Strela-2M missiles (decades past their warranty) from a Syrian Army base in late 2012, but none of them worked.
Second generation In 1967, the American FIM-43C Redeye was the first mass-produced design to make use of cooled-detector technology, followed by the Soviet
Strela-3 in 1975. They use gas-cooled seeker heads and a conical scanning technique, which enables the seeker to filter out most interfering background IR sources as well as locking on the cooler portions of the jet exhaust plume and other IR-emitting portions of the aircraft, giving them a limited capability of head-on and side engagements.
Third generation Third generation infrared MANPADS, such as the French
Mistral, the Soviet
9K38 Igla, and the US
FIM-92B, use
rosette scanning detectors to produce a quasi-image of the target. Their seeker compares input from multiple detections bands, either two widely separated IR bands or IR and
UV, giving them much greater ability to discern and reject countermeasures deployed by the target aircraft.
Command line-of-sight Command guidance (CLOS) missiles do not home in on a particular aspect (heat source or radio or radar transmissions) of the targeted aircraft. Instead, the missile operator or gunner visually acquires the target using a magnified optical sight and then uses radio controls to "fly" the missile into the aircraft. One of the benefits of such a missile is that it is virtually immune to flares and other basic countermeasure systems that are designed primarily to defeat IR missiles. The major drawback of CLOS missiles is that they require highly trained and skilled operators. Numerous reports from the
Soviet–Afghan War in the 1980s cite Afghan
mujahedin as being disappointed with the British-supplied
Blowpipe CLOS missile because it was too difficult to learn to use and highly inaccurate, particularly when employed against fast-moving jet aircraft. Given these considerations, many experts believe that CLOS missiles are not as ideally suited for untrained personnel use as IR missiles, which sometimes are referred to as "fire and forget" missiles. Later versions of CLOS missiles, such as the British
Javelin, use a solid-state television camera in lieu of the optical tracker to make the gunner's task easier. The Javelin's manufacturer,
Thales Air Defence, claims that their missile is virtually impervious to countermeasures.
Laser guided Laser guided MANPADS use beam-riding guidance where a sensor in the missile's tail detects the emissions from a laser on the launcher and attempts to steer the missile to fly at the exact middle of the beam, or between two beams. Missiles such as Sweden's
RBS-70 and Britain's
Starstreak can engage aircraft from all angles and only require the operator to continuously track the target using a joystick to keep the laser aim point on the target: the latest version of RBS 70 features a tracking engagement mode where fine aim adjustments of the laser emitter are handled by the launcher itself, with the user only having to make coarse aim corrections. Because there are no radio data links from the ground to the missile, the missile cannot be effectively jammed after it is launched. Even though beam-riding missiles require relatively extensive training and skill to operate, many experts consider these missiles particularly menacing due to the missiles' resistance to most conventional countermeasures in use today. ==Notable uses==