TM 1-1510-225-10 3B-9 (q)  HDG SYNC Button.  The center push button on the data selector is a  HDG SYNC selection.   Pressing the  HDG SYNC button will automatically slew the  selected  heading  bug  to  the  lubber  line.    When FMS 1 is the selected navigation source and the HDG SYNC   button   is   pressed,   the   FMS   heading   bug   is displayed on the MFD and the navigation source label FMS  changes  to  FHDG.   The  FMS  heading  bug  then syncs to the selected heading. (r)   DATA   Selector.        The    data    select knob  is  a  dual  concentric  blind  selector  with  a  center push   button.      The   outer   knob   provides   sequential selection  of  FMS  data  to  include  groundspeed  (GS), True   Airspeed   (TAS),   time   to   go   to   next   waypoint (TTG), Elapsed Time (ET) from WOW, and off-no data displayed. (s)  CURSOR   Reset.    The  cursor  reset (CURSOR  RST) button resets the cursor to the aircraft symbol. 3B-15.  ELECTRONIC ATTITUDE DIRECTOR INDICATOR. a.   Description.  The Electronic Attitude Director Indicator  (EADI),  Figure  3B-4, is an instrument whose primary   function   is   to   display   the   aircraft’s   current attitude. It combines the functions of many electromechanical  indicators  into  a  single  electronic display.    This  display  consists  of  the  Attitude  Display Indicator   (ADI)  display  page  and  the  Primary  Flight Display (PFD).  The default display format on the EADI is the ADI format on powerup. The  ADI  presents  attitude,  comparator  warning annunciations, decision height setting, and rate of turn indicator.    Other  parameters  that  are  displayed  as  a function  of  pilot  selection  are  DH  annunciation,  Radio Altitude,   Rising   Runway,   Vertical   Deviation   (GS   or VNAV),   Speed   Deviation,   Flight   Director   Command Bars   (V   Bars),   Aircraft   Symbol,   Lateral   Deviation, Marker   Beacons,   Flight   Director  Annunciations,  and Course Source (LOC, VOR, or FMS). b.  ADI Display Symbology. (1)   Pitch  and  roll  attitudes  are  indicated  by the    position    of    the    blue    sky    and    brown    ground relationship.    The  aircraft  symbol  is  outlined  in  white with a black interior.  Precise pitch attitude is provided by the position of the pitch scale with reference to the nose  of  the  aircraft  symbol.    Precise  roll  attitude  is provided by the position of the moving roll pointer with reference to the roll scale.  The pitch scale disappears behind the roll pointer and the lateral deviation pointer to prevent interference between the symbols.  Roll is a continuous 360 display and pitch is 90 display. If  an  attitude  sensor  failure  occurs,  an  attitude flag  appears  which  consists  of  a  red  box  with black letters  ATT.    An  attitude  flag  removes  the  pitch  scale, roll scale, roll pointer, sky/ground raster, flight director annunciations and command bars from the display. (2)   The  pitch  scale,  Figure  3B-5, consists of 2.5     increments     between     30     to     40 of pitch.   Approximately  40  of  the  pitch  scale  is  visible  at  any given time. (3)   The   roll   scale   displays   the   current   roll attitude  of  the  aircraft.    It  rotates  about  the  aircraft symbol    such    that    the    aircraft    roll    is    graphically indicated on the bank scale.  The bank scale contains the   10, 20, 30, 45, and 60 increments. The rest of  the  scale  is  white.    If  the  roll  input  is  invalid  or unavailable,  the  bank  scale  and  pointer  are  removed from the screen and the ATT flag appears. (4)   If the pitch attitudes exceed + 30 or - 20 or  if  the  bank  attitude  exceeds     65  all  information except the aircraft symbol, attitude, and attitude sensor annunciation are removed from the ADI, refer to Figure 3B-5.  All ADI information is restored when at + 25 or -15 of pitch or    60  of  roll.    If  the  PFD  is  displayed when    an    extreme    attitude    condition    occurs,    the excessive attitude ADI page automatically is displayed.   Refer to Figure 3B -6.  The PFD is not selectable until the  extreme  attitude  condition  is  removed  and  then  it must be reselected.