PART 1 - DESCRIPTIVE
     

     48.  Radar ranging (A.R.I. 5820)
     
          NOTE.-The aircraft should not be landed with the
                system switched NO.
     
     (a)  The radar ranging ON/OFF switch (35) on the port shelf
          controls the system; an adjacent magnetic indicator shows
          white with the system in use and black when its use is
          discontinued.
          
     (b)  Radar ranging automatically provides the GGS with
          target range information within the limits of 200-800
          yards.  The radar searches from maximum range down
          to minimum range until a target is found.  If no target
          is found within the search area the search is automatically
          repeated  When a target is found the radar locks on to it,
          and a blue light (54) on the right of the GGS lights up
          to indicate this.
          
     (c)  A spring-loaded TARGET REJECT IN-OUT switch
          (18) is on the port wall.  Its function is to unlock the
          radar from an unwanted target or to check that it is
          locked on to the correct target.  When IN is selected, the
          radar unlocks from the target and searches inward to
          minimum range.  If no fresh target is found the normal
          search cycle commences whether the switch is retained
          at IN or not.  When OUT is selected the radar unlocks
          from the target and searches outwards to maximum
          range.  It will remain at maximum range if the switch is
          retained at OUT but when released, the normal search
          cycle is commenced.
          
     (d)  To check that the radar is locked on the correct target
          set the span knob of the GGS that of the target type.
          If the correct target is being ranged the GGS graticule
          should just encompass the target span.  If the target span
          extends beyond the graticule (over ranging) or does not
          extend to the graticule (under ranging), the wrong target
          is being ranged and REJECT IN or REJECT OUT
          respectively should be selected.
          
          NOTE.-(1) When the manual twist-grip is set to a
                   shorter range than that of the target the
                   radar cannot control the graticule until the
                   target comes within the range set by the twist-
                   grip, when the radar takes over the ranging.
 
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