TM 1-1510-224-10 the     navigation     source     displayed     in     white     letters. Possible annunciations are  ADF, VOR1, INS, and TCN. (21) Weather   radar   tilt   angle   display.      The weather  radar  tilt  angle  display  (green)  shows  the  angle that   the   weather   radar   antenna   is   tilted   upward   or downward from level in degrees plus or minus. (22) Weather  radar  mode  annunciator.      The weather  radar  mode  annunciator  indicates  the  operating mode of the radar system.  Possible annunciations in the full  compass  format  of  the  EHSI  are   TX  (magenta)  and WX (amber).   TX  indicates  that  the  radar  is  transmitting but not being displayed.   WX  indicates  a  weather  radar system   failure.      Possible   annunciations   in   the   partial compass    format    are    standby    (STBY),    test    (TEST), weather detection (WX), rain echo attenuation compensation technique (RCT), ground mapping (GMAP),     and     fall     (FAIL). All partial compass annunciations are green except FAIL, which is amber. (23) Weather   radar   target   alert   and   variable gain annunciator.  The green  TGT annunciator indicates that  the  target  alert  function  of  the  weather  radar  has been  selected.    The  amber   VAR  annunciator  indicates that variable gain has been selected. (24) Lightning sensor system mode annunciator The   lightning   strike   sensor   system   mode   annunciator indicates   the   operating   mode   of   the   lightning   sensor system.    Possible  annunciations  are    LX,   LX/F,   LX/S, LX/T,    LX/H,    LX/1,    LX/C,    LX/L,    and    LXMN.        All annunciations  are  green  except  LX/F and   LXMN  which are  amber.    These  mode  annunciators  are  described  in the lightning sensor system paragraph in this chapter. (25) Compass system synchronization annunciator.        The    compass    synchronization    system annunciator indicates the state of the compass system in the slaved mode.  The bar represents commands to the compass  gyro  to  slew  to  the  indicated  direction  (+  for increased    heading    and    0    for    decreased    heading). Compass  synchronization  annunciation  will  be  removed during  the  compass  free  gyro  mode.    If  the  cross-side compass display has been selected, the synchronization annunciator will be removed. c. EHSI  Partial  Compass  Format  (fig.    3-15).    The partial  compass  mode  displays  a  90-degree  arc  of  the compass   card.      The   following   additional   features   are available during partial compass operation: (1) Range rings.    Range  rings  are  displayed to aid in the use of radar returns and position of navaids. The outer range ring is the compass card boundary and represents   the   selected   range   on   the   radar.      Range annunciation 1.   Heading Knob 2.   Course Knob A93FE00D0I03  C Figure 3-14.  Flight Director Remote Heading/Course Control Panel " 3-34