Figure 12.

Illustration of the conditions to be met to turn into alignment with a desired path. Depicted are four situations, only one of which (the right) leads to successfully turning the vehicle into alignment with the path. For each situation, the track along which the aircraft traveled to its current position P is drawn. Furthermore, the future track determined by the instantaneous displacement, rate of closure, and change of rate of closure at point P is plotted as a dotted line. Reproduced from Calvert (1955b). The same figure appears in Calvert (1954, 1955a, 1957a).