View source for Munition:avionic-direct

== Direct ==
Direct fire missiles may be fired at a track or position. When fired with direct guidance, missiles activate their seekers and arm their warheads immediately after launch at the same time as the main engine. It then proceeds in the direction of the target. Direct missiles are not launched at a specific point in space; they only initially given a direction to move in. That means if the missile ends up offset from the launching ship (such as hot launch), the missile may also be offset from the intended target.

When fired on a moving track, direct avionics will try to plot an intercept using the reported position and velocity from the sensor network unless the track is moving toward the shooter (within a 30 deg margin), where they will then default to shooting straight at the target instead.

Direct guidance can set their trajectory to Minimum Angle or Free Approach. The trajectory preference determines how the missile follows its target

    * Minimum Angle prioritizes flying along the imaginary line that connects the launch location with the target. This is most useful for anti-missile missiles as it puts them in a better position to intercept the target. Minimum angle also allows seekers with reduced track information to partially lead targets via a variant of Proportional Navigation. In addition, Missiles on minimum angle will make full use of their maneuverability by using their lateral thrusters for course correction, which maximizes the performance of slower, less maneuverable missiles. However, this can cause instability (eg, missile takes a zig-zag path) on missiles with high speed and low maneuverability, which has pros and cons. It may cause a missile to to a miss against small targets if the missile is closing fast and/or needs to make a sharp turn, but this motion can also dodge point defense fire. Too much deviation from the line will cause the missile to default to free approach.
    * Free Approach makes the missile perform a simple pursuit. This results in a stable path towards the target. Free approach can use seekers with both position and velocity information to lead their targets on an intercept course, but if either position or velocity is missing, it will only perform a direct chase, with no consideration for target movement.