Manual command to line of sight

Manual command to line of sight (MCLOS) is a method for guiding guided missiles.

With an MCLOS missile, the operator must track the missile and the target simultaneously and guide the missile to the target. Typically the missile is steered with a joystick, and its path is observed through a periscope-type telescopic sight. The missiles are usually equipped with a magnesium flare in the base that automatically ignites upon launch and allows the gunner to visually track the fast-moving missile in a manner similar in concept to a tracer bullet.

MCLOS requires considerable training and practice to master, since even a minor disruption in the gunner's concentration would likely cause a miss. These guidance systems have marginal accuracy on tank-sized targets, even with perfect line-of-sight by the gunner, due to erratic flight paths requiring timely manual corrections. As demonstrated by the Israeli Army under fire from Soviet-armed Arab states, responding to the distinctive smoke puff of a missile launch with rapid manoeuvres and immediate counter-fire minimizes their accuracy, as very few ATGM gunners maintain their concentration on a fast-moving tank for the entire flight time of the missile while under suppressing fire.