TM 1-1510-218-10 3C-21 except the aircraft symbol, attitude, and attitude sensor annunciation  are  removed  from  the  ADI.    Refer  to Figure 3C-7.    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  3C-8.    The  PFD  is  not selectable   until    the    extreme   attitude   condition   is removed and then it must be reselected. (5)  Flight   Director   Command   Bar   Display. The command bars are in view when the flight director is being used.  The command bars are removed from view  by  the  flight  director  when  it  is  turned  off,  in standby   mode,   commanded   out   of   view,   and   FD Validity Failed. The     integrated     command     bars     flank     the triangular aircraft symbol  with a  zero command  input. The  command  bars  move  a  maximum  of ± 15 ° pitch and ± 30 ° roll. The   command   bars   are   removed   from    the display  and  the  flight  director  annunciation  appears when the commanded pitch or roll is invalid.  The flight director annunciation consists of the label FD in black on a solid red box. c.   Flight  Director  Annunciations.    The  Flight Director   (FD)   annunciations   are   displayed   in   the Lateral Arm, Lateral Capture, Vertical Capture, Vertical Arm  1,  and  Vertical  Arm  2  annunciator  fields.    The capture    annunciations    are    green    and    the    arm annunciations are white.  To ensure that the flight crew does  not  miss  a  FD  change,   the   FD   annunciation flashes   for   5   seconds   when   a   new   annunciation occurs.    Refer  to  Table  3C-4  for  FD  output  and  their annunciations. The MFD displays red-colored dashes in the FD fields and retains the FD command bars if the FD sets more than one annunciation for that field or if the Data Concentrator Unit fails.  The annunciator fields will be blanked  when  the  command  bars  are  removed  from the  display,   when  the  unit  is   turned   off,   placed   in standby mode, commanded out of view, or FD validity flagged. d.  Vertical  Guidance.    The  FDS-255  supports glideslope and VNAV Guidance.  The glideslope scale and pointer are displayed when the navigation source is  LOC,  the  localizer  is  valid,  and  the  glideslope  is valid.    The  VNAV  scale  and  pointer  will  be  displayed when the navigation course source is FMS, the FMS is valid,  the  VNAV  is  valid,  and  the  VNAV  is  available from the FMS. A  scale  and  pointer  located  on  the  right  side  of the   indicator   displays   deviation   from   the   selected vertical path.  The scale consists of a pair of white dots above  and  below  a  white  center  index.    Maximum travel of the pointer is 2.5 dots. The    glideslope    (GS)    deviation    pointer    is    a magenta  trapezoid  outlined  in  white.    If  a  glideslope failure is detected, the letters GS appear boxed and in red.  The GS  pointer  and scale  will be removed from the  display.    The  GS  pointer  moves  a  maximum  of ± 2.5 dots. The  VNAV  deviation  pointer  is  a  magenta  star outlined in white.  When a VNAV failure is detected the VNAV  annunciation  appears  boxed  and  in  red.    The VNAV pointer and scale will be removed.  The pointer moves a maximum of ± 2.5 dots. e.   Lateral Deviation. The pointer and scale are located on the bottom center of the ADI.  The pointer moves a maximum of ± 2.5 dots.  The scale consists of two white dots on either side of a white center index. The lateral deviation pointer is a white rectangle with two magenta bars for VOR, or non-approach FMS navigation sources.  The  rising  runway  serves  as  the lateral  deviation  pointer  for  LOC,  BC,  and  approach FMS   course   sources.      Back   course   deviation   is reversed on the ADI when the B/C is set via the flight director control panel. If the navigation source is invalid or missing, the course  source  annunciation  is  boxed  in  red  and  the pointer,  rising  runway  (LOC,  BC,  or  FMS  approach), and   lateral   deviation   scale   are   removed   from   the display. The  FMS  Navigation  warning  indicates  that  the information  accuracy  is  in  question  but  usable.    The FMS  navigation  solution  remains  displayed   but   the color changes to amber.