A tracking system in the launcher's optics compared the location of the missile to the line-of-sight and sent it commands over a radio link to guide it.

Further upgrades to the missile added a fully automatic guidance system to produce the Javelin S-15.

[5] Similar in overall appearance to the manual command to line of sight (MCLOS), radio frequency guided Blowpipe, Javelin is slightly smaller, uses semi-automatic command to line of sight (SACLOS) radio frequency guidance and is fitted with an improved warhead.

The operator is equipped with a 6× magnification sight and a long range television (TV) camera to locate targets.

Although the Javelin's accuracy is somewhat susceptible to smoke, fog, or clouds, it cannot be decoyed away from a target with flares because it does not use an infrared or ultraviolet (UV) spectrum seeker.