TM 1-1510-218-10 3B-16 (8)   Compass    Synchronization    Annunciator.   The compass synchronization annunciator consists of a 1 and X symbol display.  When the compass system is    in    the    slaved    mode,    the    display    will    oscillate between the  1  and  X  symbol,  indicating  the  heading dial  is  synchronized  with  a  gyro-stabilized  magnetic heading. (9)   Course    Knob.        Positions    the    course indicator. (10)   Course Deviation Dots. In VOR operation,  each  dot  represents  5°  deviation  from the centerline    (+    10°).        In    ILS    operation,    each    dot represents 1° deviation from the centerline. (11)   Aircraft   Symbol.        The    fixed    miniature aircraft symbol corresponds to the longitudinal axis of the   aircraft   and   lubber   line   markings.      The   symbol shows  aircraft position and heading with respect to a radio course and the rotating heading dial. (12)   Heading   Knob.      Positions   the   heading bug to a preselected compass heading. (13)   Glideslope    Pointer/Scale.        The    glide- slope    pointer    displays    glideslope    deviation.        The pointer   is   in   view   only   when   tuned   to   a   localizer frequency.  If the aircraft is below glideslope path, the pointer is displayed upward on the scale.  Each dot on the scale represents approximately 0.4° displacement. (14)   Course    Deviation    Bar.        The    course deviation bar represents the centerline of the selected VOR or localizer course.  The miniature aircraft symbol pictorially  shows  actual  aircraft  position  in  relation  to this selected course. (15)   Heading    Bug.        The    notched    orange heading  bug  is  positioned  on  the  rotating  heading dial by    the    heading    knob,    and    displays    preselected compass  heading.    The  bug  rotates  with  the  heading dial.    The  difference  between  the  bug  and  the  fore (upper)   lubber   line   index   is   the   amount   of   heading error  applied  to  the  flight  director  computer.    In  the heading  mode,  the  ADI  will  display  the  proper  bank commands   to   turn   to   and   maintain   this   selected heading. The  copilot’s  HSI  also  has  an  HDG  flag  which indicates  loss  of  heading  information,  a  VERT  flag which covers the glideslope pointer when not receiving glideslope information, and a NAV flag which indicates a loss of NAV 2. 3B-15.  PILOT'S ATTITUDE DIRECTOR INDICATOR. a.     Description.      The   pilot's   Attitude   Director Indicator  (ADI)  combines  the  attitude  sphere  display with   computed   steering   information   to   provide   the commands    required    to    intercept    and    maintain    a desired  flight  path.    It  also  contains  an  eyelid  display, expanded  localizer,  glideslope,  radio  altitude  display, rate-of-turn  indicator,  mode  annunciators,  go-around and   decision   height   annunciators,  and  inclinometer.   Any   warning   flag   in   view   indicates   that   portion   of information is unreliable. b.    Controls/Indicators and Functions.   Refer to Figure 3B-8. (1)   Attitude Sphere.     Moves  with  respect  to the  symbolic  aircraft  reference  to  display  actual  pitch and   roll   attitude.      Pitch   attitude   marks   are   in   5° increments on a blue and brown sphere. (2)   Roll  Attitude  Index.    Displays  actual  roll attitude   through   a   movable   index   and   fixed   scale reference marks at 0, 10, 20, 30, 45, 60 and 90°. (3)   Go Around (GA) Annunciator.  Illuminates when go-around mode has been selected. (4)   SPD    Annunciator.        Illuminates    when airspeed  is  being  held  by  the  flight  director  in  the  IAS mode. (5)   ALT     Annunciator.          Illuminates     when altitude is being held by the flight director. (6)   HDG    Annunciator.        Illuminates    when heading is being held by the flight director in the NAV ARM or BC ARM mode. (7)   NAV    Annunciator.        Illuminates    when navigation  is  being  controlled  by  the  flight  director,  in the NAV CAP, VOR APR mode. (8)   LOC  Annunciator.    Illuminates  whenever the flight director is controlling a localizer approach, in the NAV CAP mode. (9)   APR  Annunciator.    Illuminates  whenever the  flight  director  is  controlling  an  approach,  in  the NAV CAP, VOR APR mode. (10)   GS   Annunciator.      Illuminates   whenever the  flight  director  is  in  GS  CAP mode, and glideslope has been captured. (11)   BC   Annunciator.      Illuminates   whenever the   flight   director   is   in   BC   CAP   mode,   and   has captured the back course approach heading.