TM 1-1510-223-10 sources   will   provide   information   to   the   single-needle bearing pointer. (a) TCN.    Single-needle  pointer  receives bearing information from TACAN navigation receiver. (b) INS.    Single-needle  pointer  receives bearing information from the inertial navigation system. (c) ADF.    Single-needle  pointer  receives bearing information from ADF navigation receiver. (d) VOR1. Single-needle pointer receives  bearing  information  from  #  1  VHF  navigation receiver. (e) OFF.  Removes single-needle pointer from the EHSI. 3-20. ELECTRONIC ATTITUDE DIRECTOR INDICATOR (EADI). a. Description.      The   EADI   (fig.   3-9),   combines   a sphere-type   attitude   display   with   lateral   and   vertical computed     steering     signals     to     provide     commands required  to  intercept  and  maintain  a  desired  flightpath The EADI provides the following display information: Attitude display Flight director command cue Flight director mode annunciations Vertical deviation Expanded localizer Radio altitude with rising runway display Decision height setting and annunciations Marker beacon annunciations Air data command Rate of turn Reversionary annunciations Flags Comparison monitors b. EADI Controls, Indicators, and Functions (fig. 3-9). (1) Attitude   source   annunciator.   The   selected attitude source will be displayed on the EADI if it is other than   the   normal   source   for   that   instrument   Possible annunciations are ATT1 (vertical gyro #1), ATI2 (vertical gyro #2), or AT13 (inertial navigation system). As other attitude sources are selected, they will be annunciated in white. When the pilot's and copilot's attitude sources are the same, the annunciation will be amber. (2) Lateral   mode   capture   annunciator.   Flight director  mode  capture  is  annunciated  on  the  EADI  in green.    Possible    annunciations    are    approach    (APR), localizer (LOC), long-range navigation (LNAV), heading (HDG), and navigation (NAV). (3) Attitude sphere.  The  attitude  sphere  moves with respect to the symbolic aircraft reference to display pitch and roll attitude. (4) Roll   attitude   pointer.   Roll   attitude   pointer indicates   aircraft   roll   attitude   with   respect   to   the   roll attitude scale. (5) Roll  attitude  scale.    The  roll  attitude  scale indicates aircraft bank angle in degrees with respect to a moving pointer. (6) Vertical    mode    arm    annunciator.        Flight director   vertical   mode   arming   is   annunciated   on   the EADI in white. Possible annunciations are altitude select (ASEL) and glideslope (GS). (7)     Vertical  mode  capture  annunciator.    Flight director   vertical   mode   capture   is   annunciated   on   the EADI  in  green.  Possible  annunciations  are  glideslope (GS),   vertical   speed   (VS),   indicated   airspeed   (IAS), altitude (ALT), and go-around (GA). (8)     Pitch attitude scale. The pitch attitude scale has white reference marks in 5 degree increments. (9) Horizon  line.  The  horizon  line  is  affixed  to the sphere and remains parallel to the earth's surface. (10)   Glideslope    deviation    pointer,    annunciator, and    scale.    The    glideslope    deviation    pointer    shows aircraft   deviation   from   the   center   of   the   glideslope beam.    The  G  annunciator  on  the  glideslope  deviation pointer indicates that the information being presented is glideslope  deviation.    Deviation  from  the  center  of  the glideslope  beam  is  measured  by  the  glideslope  scale. The distance between two dots is equal to a 0.35 degree deviation.  The glideslope display will not be present on the EADI unless a valid ILS frequency has been tuned. (11) Aircraft symbol. The aircraft symbol serves as  a  stationary  representation  of  the  aircraft.    Aircraft pitch and roll attitudes are displayed by the relationship between 3-25