TM 1-1510-218-10 3B-57 3B-28.  WEATHER RADAR (KWX-58) SYSTEM. a.     Description.      The   KWX-58   color   weather radar   not   only   displays   in-flight   weather,   but   also permits  incorporation  of  the  KGR-358  radar  graphics unit.      The   color   weather   radar   is   used   to   detect significant   enroute   weather   formations   to   preclude undesirable    penetration    of    heavy    weather    and    its usually   associated   turbulence.      The   weather   radar system  provides  a  320  nm  display,  with  a  250  nm weather   avoidance   range   plus   weather   penetration advantages.  With the radar graphics unit in the NAV mode,   navigation   information   is   integrated   with   the weather   display.      The   phased   array   antenna   (flat plate),   located   in   the   nose   of   the   aircraft,   is   fully stabilized to compensate for aircraft pitch and roll.  The antenna provides a full 90° scan angle, + 12° tilt, and a 3.75  microsecond  pulse  width  in  both  weather  and ground mapping modes. Extended Sensitivity Time Control (STC) increases the displayed intensity of storms outside the normal  STC  range.    Extended  STC  relates  the  storm intensity  to  its  distance  and  assigns  a  corresponding color.      As   a   result,   the   display   presents   a   more accurate picture of storm intensity. Weather  systems  are  displayed  as  four  colors, depicting  rainfall  intensity  overlaid  with  range  rings.   Bearing  marks  at  dead  ahead  and  20°  on  either  side aid   the   pilot   in   judging   the   bearing   of   storms   and necessary heading changes. With  radar  graphics  interfaced,  activate  a  circle mode by pressing the page button located on the radar graphics  control  panel.    Functional  operation  in  this mode is the same as in the standard display mode and is  available  in  both  weather  and  SBY  modes.    The range information is displayed in the upper right corner and    represents    the    outer    ring.        The    inside    ring represents half the displayed distance.  The off screen pointer is replaced by an RMI BUG placed on the outer ring  in  the  direction  of  the  active  waypoint  and  color coded   to   each   navigation   system.    Position  of  the aircraft is indicated by the green airplane symbol in the center of the screen. Indicator brightness is adjustable to accommodate  varying  ambient  light  conditions  while automatically  maintaining  equal  brightness  between the   four   display   colors.      The   system   is   protected through a 5-ampere circuit breaker, placarded RADAR,    located    on    the    overhead    circuit    breaker panel, Figure 2-16, Sheet 3. b.    Controls  and  Functions.    Refer  to  Figure 3B-20. 1.  Mode Selector Control Knob 2.  RANGE Selector Control Knob 3.  TILT Control Knob 4.  BRIGHT/GAIN/MAX Control Knob 5.  STBY OFF/ON Switch Figure 3B-20.  Weather Radar Control Indicator (1)   Mode Selector Control Knob.  The mode selector knob turns the system on and off and selects SBY, TEST, WX, WXT, and MAP positions. (a)   OFF.  Turns the system off. (b)   SBY.    In  SBY  mode  the  display  is blanked  and  transmitter  circuits  are  disabled  with  the magnetron heater remaining on. (c)   TEST.  When placed in the test mode all  circuitry  is  activated,  except  the  transmitter.    All weather  colors  will  display  for   verification  in  the  test mode as well as the WX, WXT, and MAP modes. (d)   WX.    The  WX  mode  is  the  normal weather     mode     with     green     for     light,     yellow     for moderate,  red  for  heavy,  and  magenta  for  extremely heavy precipitation. (e)   WXT.      The   WXT   mode   is   used   to alert the pilot of weather that is beyond the displayed range.  Only returns of significant intensity between 83 and  320  nm  are  displayed  with  a  white  arc  at  the approximate azimuth of the storm.  A yellow T on a red background  will  appear  in  the  upper  left  corner of the display,    indicating    that    a    storm    target    has    been located. (f)    MAP.    The  MAP  mode  is  used  for terrain  mapping.    Prominent  ground  features  such  as lakes,   bays,   rivers,   cities,   coastlines,   and   offshore drilling  rigs  can  be  clearly  discerned  and  used  as  a