Abstract: When a homing head or seeker is mounted on-board a missile, the inertial reference provided by the seeker may be contaminated to some extent by the motion of the missile body. To alleviate this, seekers are sometimes gimballed and use rate or position gyros or they may be momentum-stabilized--the seeker itself providing the inertial reference. However, gyros are both complex and expensive, and momentum-stabilized seekers tend to have large inertias making it difficult to achieve high scan rates. The guidance system described herein allows the establishment of inertial references via information derived from a seeker which need not be isolated from the missile body, the seeker having a range measuring function which, possibly in combination with one or more accelerometers, is used to control pitch, yaw, roll and stabilization of the missile.