TM 1-1510-218-10 3C-28 (5)   Glideslope Deviation. Glideslope deviation   is   sent   to   the   flight   director   when   it   is available. (6)   Roll  Steering.    The  bottom  MFD  outputs roll steering to the flight director when the flight director is valid and the course source is FMS. e.   HSI Graphic Format.   The following graphics are used on the EHSI during the HSI Mode.  Refer to Figure 3C-10. (1)   Course   Readout/Label.      When   a   valid source  is  tuned,  the  course  selected  is  displayed  in white.  Next to the course readout is the label  CRS or DTK in white letters.  The digital  CRS  or  DTK readout is always associated with the course source. (a)   Radial  Source  (VOR).     The course label    is    CRS    and    the    digital    course    readout    is independently controlled by each MFD control panel. (b)   FMS -800   Operation.      The   label   is CRS   when   the   primary   source   is   not   FMS.      If   the primary   source   is   tuned   to   FMS,   the   CRS   will   be replaced  with  Desired  Track  (DTK) for all FMS modes except TO / FROM mode (TACAN Emulation).  When FMS is the course source, the course is automatically set by FMS. (c)   KLN 90B Operation.  Refer to OBS / LEG switch in Paragraph 3-7.al for a description of the course readout. (2)   FMS    Message    Alert.        The    message (MSG) alert appears whenever the FMS sends an alert to  the  MFD.    The  amber  MSG  alert  indicates  to  the crew that they should look at FMS on the selected side of the cockpit [on-side/x (cross) side]. (3)   FMS  Heading  Bug.    The  FMS  heading bug  is  only  available  for  display  when  the  FMS-800 is the NAV source and the FMS is commanding the bug to  be  displayed.    The  FMS  heading  bug is white and travels about the aircraft symbol around the outer edge of the compass.  The center of the FMS heading bug indicates    the    selected    heading    in   1     increments.   When the FMS selected heading is set, the FMS  NAV  source label is replaced with  FHDG  1 in white letters.   If the FMS selected heading is invalid, unavailable, or the primary course source is not FMS 1, the heading bug  will  not  be  displayed.    The  FMS-selected heading bug is displayed in amber when a cross-side source is selected. (4)   Course    Deviation    Scale.        Four    white lateral   deviation   scale   dots   indicate   deviation   from course.  The course deviation scale rotates about the aircraft     symbol     such     that     the     scale     is     always perpendicular  to  the  selected  primary  course.    The maximum deviation is    2.5 dots.  When the selected course or source is invalid, the course deviation scale is removed from the display. The  EHSI  outputs  lateral  deviation  and  lateral deviation  validity  to  the  flight  director  and/or autopilot.   The  lateral  deviation  validity  signal  corresponds  with the  selected  course  source’s  lateral  deviation.    The lateral   deviation   output   flag   is   displayed   when   the lateral   deviation   for   the   selected   primary   navigation source  is  invalid  or  an  MFD  failure  results  in  bad  or failed lateral deviation output. (5)   Vertical   Deviation   Scale.      The   vertical deviation  scale,  four  small  circles  located  on  the  right side of the MFD, indicate the vertical deviation of the aircraft. (6)   Vertical  Deviation  Pointer.    The  vertical deviation pointer, represented by a white star, displays the deviation with respect to the selected source. (7)   Lateral  Deviation  Bar.    The  center  of  the course   pointer   moves   laterally   with   respect   to   the aircraft symbol and the four white deviation scale dots to   indicate   lateral   deviation.      The   course  deviation scale   rotates   about   the   aircraft   symbol   so   that   the scale is always perpendicular to the selected primary course. (8)   Course     Source     Annunciations.          The navigation  sensor  is  annunciated  in  white  at  the  right center   of   the   display.      The   possible   course  source annunciations are as follows. 1.   FMS 1 or FHDG 1 2.   FMS 2 3.   VOR 1, TCN 1, LOC 1, or BC 1 4.   VOR 2, LOC 2, or BC 2 The   NAV   source   label   is   displayed   in   amber when a cross-side source is selected.  When both the on-side  and  cross-side  displays  have  the  same  NAV source   selected,   the   NAV   source   label   is   boxed   in amber. If a NAV sensor failure is detected while selected as     the     course     source,     the     sensor     annunciator becomes red and boxed. If   FMS   1   is   selected   and   a   FMS   NAV   Warn occurs,  the  FMS  1  course  source  annunciator  turns amber.