TM 1-1510-218-10 3C-25 green.  If the radio altimeter system fails, the decision height readout is removed. When  the  radio  altitude  is  at  or  below  the  DH setting, the yellow letters DH appear in the right center portion    of    the    ADI    or    PFD    display.        The    DH annunciation  flashes  for  10  seconds  after  it  appears. Once the DH annunciation appears, it will be removed when  the  radio  altitude  climbs  at  least  25 feet  above the decision height setting or if the radio altitude is less than  10  feet.    If  the  radio  altimeter  system  fails,  the decision height annunciator is removed and the  radio altitude flag appears. j.    Fast/Slow  Deviation  and  Pointer.    Speed deviation indicates whether the aircraft is fast or slow relative   to   an   established   reference.      The   speed deviation  scale  consists  of  four  white  dots  with  the letters F and S to the left of the top and bottom dots. The scale is located on the left side of the ADI.  The speed deviation pointer is a magenta diamond outlined in white.  The scale is relative to FMS speed (FSPD) associated  with  FMS  1.    Whenever  FMS  speed  is available,  the  letters  FSPD  in   white  are  positioned below  the  scale.    When  selected,  fast/slow  input  is invalid and the source is drawn in black on a solid red box.      The   speed   deviation   pointer   is   displayed   in amber   when   the   cross-side   FMS   is   the   selected navigational  source.    The  pointer  and  scale  will  be removed from the display. k.  Inclinometer Indicator.   The  inclinometer  is a separate element mounted under each display.  The inclinometer is a weighted ball in a liquid-filled curved glass tube to provide assistance in making coordinated maneuvers.    Aircraft  slip/skid  movement  is  shown  by the movement of the ball. l.    Marker Beacons.  The inner, middle, or outer marker beacon annunciation is displayed on the center left  of  the  display  when  set  by  the  marker  beacon receiver.      The   marker   beacon   annunciator   will   be removed  from  the  display  when  the  marker  beacon signal  is  no  longer  available  from  the  marker  beacon receiver. The marker beacon annunciator consists  of  an  O  in  amber  for  the  outer  marker,  M in cyan for the middle marker, and I in white for the inner marker. m.   Free  Format  Line.    The  free  format  line  is used to display system faults only. n.  Comparator  Warning  Annunciation.    Each display  compares  pitch  attitude,  heading,  glideslope deviation, localizer deviation, and radio  altitude to the cross-side (X-side) display.  If the comparison exceeds a  threshold,  the  appropriate  annunciation  appears  at the top of the EADI. o.  Primary    Flight    Display    Format.        For reversionary  purposes.    The  Primary  Flight  Display mode consists of an ADI positioned on  top  of an HSI with a 360 compass rose.  Refer to Figure 3C-9.  The differences  in  the  display  are  listed  in  the  following paragraphs. (1)  The  rising  runway  and  lateral  deviation pointer is removed from the ADI. (2)  Approximately  30 of  the  pitch  scale  is visible. (3)  The  lubber  line  is  a  solid  white  triangle pointer and heading is not digitally displayed. (4)  Approximately 200 of the compass rose is displayed.  The bottom half of the compass rose is clipped from view. (5)  No wind text label. (6)  No   off   the   display   heading   readout   or pointer for the heading bug. In    extreme    pitch    attitudes,    the    presentation reverts to the normal excessive attitude display that is a modified full ADI display.