Abstract: Tracking means for establishing a line-of-sight between a control point to which the second craft is being guided and tracking the line-of-sight to follow the second craft and deriving a signal .sub.a representing the rate of rotation of the line-of-sight about the control point; monitoring means for deriving a signal representing the displacement e of the first craft from the line-of-sight, a signal representing the range R.sub.m between the first craft and the control point, and a signal representing the rate of change R.sub.m of the range R.sub.m, presetting means for providing a signal representing a positive quantity k; and a computer for deriving signals representing .sub.c, .sub.c, and k to satisfy the equation ##EQU1## and minimize the difference -.sub.a, k being initially set equal to k.sub.1 ; control means for deriving from the representations provided by the computer a signal representing f(e)+R.sub.m .sub.c +2R.sub.m .sub.

Abstract: Tracking means for establishing a line-of-sight between a control point towards which the second craft is being guided and tracking the line-of-sight to follow the second craft and deriving a signal .theta..sub.a representing the rate of rotation of the line-of-sight about the control point; monitoring means for deriving a signal e representing the displacement of the first craft from the line-of-sight, a signal representing the range R.sub.m from the control point to the first craft and a signal representing the rate of of change R.sub.m of the range R.sub.m ; ranging means for deriving a signal representing the range R.sub.t from the control point to the second craft and a signal representing the rate of change R.sub.t of the range R.sub.t ; a computer for deriving representations of .theta..sub.c, .theta..sub.c and .theta..sub.c which satisfy the equation.sub.c =-2.theta..sub.c.sup.3 -3.theta..sub.c (R.sub.t /R.sub.t)where the difference .theta..sub.c -.theta..sub.