May 6, 2007: Although the latest version of the Sidewinder air-to-air missile, the AIM-9X, is superior to older 9M versions, many air forces prefer the older, and cheaper, AIM-9M. The 9Ms only cost about $110,000 each (compared to $180,000 for the 9X), and that makes a big difference for many low budget air forces. The fact is, the Sidewinder was always popular because it delivered lots of bang for the buck. Over half a century later, it still does.

The first Sidewinder (AIM-9B) was 9.28 feet long, weighed 156 pounds and had a max range of five kilometers . The most current one, half a century later (AIM-9X) is 9.5 feet long, weighs 191 pounds and has a max range of over 20 kilometers. The latest version can go after the target from all angles, while the AIM-9B could only be used from directly behind the target. The AIM-9X is about seven times more likely to bring down the target than the AIM-9B.

The 9X entered service in 2000, but the older 9M is nearly as accurate, although more expensive to upgrade. For example, Pakistan recently paid $19,000 each to have 310 AIM-9M Sidewinder air-to-air missiles upgraded to the AIM-9M8/9 standard. The upgrade brought minor improvements in the electronics and maneuverability. The 9X can be reprogrammed for many upgrades, saving lots of upgrade costs.

The Sidewinder is the most successful air-to-air missile ever produced, with nearly 300 kills world-wide to date. But that means for every 380 Sidewinders manufactured, only one brought down an enemy aircraft. Only about one percent of all Sidewinders ever even got used in combat. The vast majority of the 110,000 built, spent their careers being carried by fighters, or stored away, waiting for a war. For that reason, the missile is designed for easy upgrades. Many of those in service have some components that are over twenty years old. The missile itself, is more like an aircraft component, than an expendable weapon.