The Stinger (formerly the REDEYE II) is (as has been noted by Jurph
) a U.S. made MANPADS
system, designed to be operated by a dismounted soldier. The complete system consists of the launcher/gripstock, the missile (packaged 'all-up'), and an IFF tranceiver
, typically worn on the belt. The missile round is attached to the gripstock preparatory to firing. At this point, batteries and stored coolant
in the missile loading tube are used to run the electronics of the launcher and missile seeker (the coolant is required to operate the IR seeker on the missile). When the missile detects a target within range (defined as approx. 2 miles horizontal, and up to 4800ft altitude) the IFF transceiver (if available) will interrogate the target. If the response does not match, the launcher will sound a quiet buzzing to indicate to the operator that the missile has acquired the target.
At launch, a launching charge pushes the missile out of the tube (breaking the tube seals) and several feet away from the launcher, at which point the booster motor fires. The Stinger round will reach velocities in excess of 1200mph at its maximum range. The missile guides itself during flight in a variety of ways, depending on the missile variant. All models have an impact ('hit-to-kill') fuzing system, as well as an end-of-run self-destruct.
The Basic Stinger (FIM-92A) is effective out to approximately 4,000-4,500 meters. It uses a basic passive infrared seeker with a linear reticle scan pattern, with analog single-component signal processing to discriminate between an aircraft signature and background clutter. The Stinger-POST (FIM-92B) adds an ultraviolet sensor, for a two-signal lock; in addition, its seeker scans in a 'rosette' pattern for better coverage of the field of view and better performance against maneuvering targets. Finally, the POST model incorporates digital signal processing (DSP) into the missile for better discrimination against countermeasures and environmental noise. The third model, known as the Stinger-RMP (FIM-92C) contains reprogrammable microprocessor systems (cool TLA, huh?) which allow it to be updated in order to handle newer threat signatures or countermeasures over time.
The Stinger is also used in a 'mounted' form. The U.S. Army built an air-defense vehicle called Avenger which consisted of a .50-caliber machine gun mounted on a turret between two vehicular missile launchers. Each launcher holds four packaged Stinger rounds. The assembly is mounted on a HMMWV chassis, and is used against helicopter threats and/or low-flying fixed-wing aircraft. There is a variant certified for use on helicopters called Air-to-Air Stinger; there are also installations aboard naval vessels. The missile has been both sold abroad (FMS) as well as entered licensed production (by Switzerland, for example). In 1985, the number of Stingers produced passed the 10,000 mark.
During the Soviet invasion of Afghanistan, the CIA distributed approximately 1,000 Stingers of various types to the Afghani mujahedin for use in their fight against the Red Army. The resistance fighters managed to score around a 60% hit rate against Soviet helicopters. However, only half, or perhaps less, of these weapons were actually expended during the conflict. The U.S. (the CIA and the military) offered a 'buy-back' program after the conflict, indicating that they would pay up to $35,000 per missile for all those returned to the U.S. However, by that point the price of these proven weapons on the black market was much, much higher, and few were recovered.
There are conflicting stories about how many remain on the world arms market, as well as how hard the U.S. agencies involved really tried to retrieve them after the Soviets withdrew. Some have claimed that there is a tremendous danger to U.S. and other nations' commercial aviation from these remaining missiles; they point to instances in which Soviet versions (the SAM-7, notably) have been used to down passenger aircraft. A shoot-down of a Boeing 737 in the Congo is perhaps the most widely-cited example. The danger arises from the fact that the Stinger is a completely self-contained weapon, designed to be used with minimal training, with a long shelf life. It is small enough to place in the trunk of a large car in assembled form, or disassembled can be packed into suitcase-sized containers. Terrorists might conceivably smuggle a Stinger or three into the U.S. to use on American passenger airliners, or even Air Force One if they could get close enough. The government of Colombia received warnings in the 1980s that local guerrillas planned to assassinate the president of that country by using SAM-7 rockets against his plane. They put protection in place (guarding approaches, decoy aircraft, etc.) and nothing happened. However, some months later, several SAM-7s were found in a captured rebel stronghold, indicating that the threat was at least plausible.
There are a few things to keep in mind when applying this to the current situation. First of all, just because they're small doesn't mean that the Stinger components are easy to smuggle. You'd probably have to drive them in from Canada or Mexico, or bring them aboard a ship. This latter is most likely, since a ship or boat could also be used to launch the missile against coastal city air traffic. However, they are designed to attack close-in low-flying targets. Therefore, in order to hit a civilian airliner, the launcher would (realistically) need to be within two miles of the aircraft's liftoff point; once the target has lifted above 5,000 feet, it is fairly safe from shoulder-fired weapons.
More importantly, the consumables in the Stinger system degrade over time. Those given to the mujahedin were transferred in 1981, making them twenty years old. Batteries for electronics and liquified gases for coolant both will escape or run flat. While batteries might be easily replaced, the act of doing so will involve 'unsealing' a missile round, modifying it, and repackaging it. While this is not impossible, it is not easily accomplished either; at least, not in such a way that the user can be relatively sure the missile will function. IR seekers are extremely sensitive to damage, contaminants, and other environmental hazards.
So, is there a threat? Sure. Is that threat unique to stingers? Nope. The SAM-7 and other Eastern Bloc MANPADS systems work too, and they're out there in greater numbers. While some have been used, we have not yet seen their use by terrorists in an essentially non-combat zone.
Some stats, to finish up: