The problem is addressed for cases in which standard linearization techniques cannot be performed to simplify the equations of motion due to a large deviation from the nominal collision course geometry. Many classical planar guidance strategies, such as proportional navigation (PN) and its variants, implement parallel navigation because it is economic in its usage of energy. PN variants, such as pure PN and true PN, consist of amplifying the relative line of sight (LOS) angular velocity. The equivalent linear system of the first approach involves a pseudocontroller that influences the interception range. In the second approach, the pseudocontroller influences the LOS angle. The planar nonlinear (NL) problem of an ideal aerial interceptor pursuing an evasive target is studied. New closed-loop analytical optimal-feedback linearization-based guidance laws (OFL-GLs) are proposed using feedback linearization (FL) and OC theory, with zero-effort time-to-go estimation.