TM 55-1510-219-10 (Example: 87°54.9' West = W 8 7 5 4 9.  Observe that longitude appears in right data display as keys are pressed.) 5.   INSERT/ADVANCE pushbutton- Press. (Observe pushbutton light extinguishes.) (8) To   insert   magnetic   variation.      (Only   if compass is not operational) 1.   Data selector L/L WYPT. 2.   Keys "3" and "9" Press simultaneously. (Observe  that  magnetic  variation,  to  a  tenth  of  an arc-minute, appears in the right data display.) NOTE Magnetic     variation     is     retained from   the   last   NAV   mode   to   be used    for    reasonableness    tests during stored heading alignment. NOTE During NAV mode, magnetic variation is computed when aircraft   roll   is   less   than   9°   and magnetic   heading   input   is   valid (absence of Error Code 17). 3.   If    magnetic    variation        is    to    be loaded, proceed with next two steps. 4.   Magnetic        variation        Load        by pressing keyboard keys in sequence,  starting  with  "E"  or  "W" to indicate east or west. (Example: 14'53.6' East = E 1 4 5 3 6) Observe that INSERT/ADVANCE   pushbutton   light   illuminates   when first  key  is  pressed,  and  magnetic  variation  appears  in right data display). 5.   INSERT/ADVANCE pushbutton Press. (Observe pushbutton light extinguishes.) NOTE If    in    NAV    mode    and    magnetic heading  input  is  valid,  computer will reject loaded value. 6.    To   return   INS   to   normal   display mode, momentarily set data selector  to  any  position  except  L/L WYPT. (9) Data selector DSRTK/STS.  Confirm. 1.   Left  data  display  indicates  desired track angle in computer memory. 2.   Right data display indicates ---84, -- -74,   ---64,   or   ---54,   depending   on which alignment state the computer has reached. (10) To program destinations or TACAN coordinates. NOTE If latitude and longitude coordinates  are  being  used,  skip step I (a) and proceed with step 1 (b).      Enter   all   of   the   data   for   a given destination or TACAN before   starting   to   enter   data   for another. 1.   To  insert waypoint coordinates: (a) Insertion of UTM waypoint coordinates: 1.   Data   selector     UTM WYPT. Data  displays  will  indicate  last  coordinates  inserted into related waypoint. 2.   Thumbwheel            Set      to  waypoint number to be loaded. NOTE UTM  data  may  be  loaded  in  any order and, until final entry, a value may be reloaded. 3.   To   load   zone   and   easting   Press keys in sequence, starting with "E". (Example:   Zone   16,   425   km   East   =   E16   425. Observe  that  zone  and  easting  in  kilometers  appear  in the right data display as keys are pressed.) 4.   INSERT/ADVANCE pushbutton Press. (Observe pushbutton light is illuminated.) 5.   To   load   northing   Press   keys      in sequence,    starting  with  "N"  or  "S" to indicate north or south hemisphere. (Example: 4749 km North = N 4749.  Observe that northing  kilometers  appear  in  the  left  data  display  as keys are pressed.) 3-52