  This paper establishes a more formal definition for an Engagement Zone (EZ)
and derives some basic EZs associated with fundamental engagement models
associated with pursuit-evasion and turret-evasion. The basic EZs presented in
this paper capture the most salient aspects of the Pursuer-Agent and
Turret-Agent engagements: namely the geometry of the aspect angle and the
relative differences in capability (i.e., maximum speeds, range, etc.). One of
the main advantages of utilizing EZs for path planning is that they encode an
overall desire for Agent to go somewhere without requiring an aggressive
maneuver or active evasion should the Pursuer or Turret begin its pursuit. It
is shown that there is some advantage, in terms of time savings, in EZ-based
navigation around a single range-limited Pursuer as compared with
circumnavigating the capturability region.
