TM 55-1510-219-10 NOTE Within  30  seconds,  computer  will process    correction    and    revised present   position   will   appear   in data    display.        If    AI    prior    to position   update   is   1   or   greater, computer    will    accept    over    95 percent   of   correction   shown   in difference   display.      If   AI   is   "0", amount    of    correction    accepted will  be  less  and  is  a  function  of time in NAV mode and number of updates which have been made. (c) Extra  precision  geographic  present position check and update: 1. Data selector DSRTK/STS. 2. Key "2" Press. (Observe INSERT/ADVANCE pushbutton light illuminates, "000002" appears in right data display.) 3. INSERT/ADVANCE pushbutton Press. (Observe right data display is "1...XX2", INSERT/ADVANCE   pushbutton   light   is   extinguished, and any TACAN or data link updating is discontinued.) 4. Data selector L/L POS. (Observe  latitude  and  longitude  of  present  position appear in left and right data displays, respectively.) 5. HOLD pushbutton Press (when    aircraft    passes    over known position reference.) (Observe HOLD pushbutton light illuminates. Latitude and longitude in data displays freeze at values present when HOLD pushbutton was pressed.) 6. Load latitude by pressing keys in  sequence,  starting  with  "N" or   "S"   to   indicate   north   or south. (Example:  4254.0'  North  =  N  4  2  5  4  0.    Observe latitude    appears    in    left    data    display    as    keys    are pressed.) 7. INSERT/ADVANCE pushbutton Press (Observe INSERT/ADVANCE and HOLD pushbuttons remain illuminated.) 8. Load    longitude    by    pressing keys    in    sequence,    starting with    "W"    or    "E"    indicating west or east. (Example: 87°54.9' West = W 8 7 5 4 9.) 9. INSERT/ADVANCE pushbutton Press. (Observe   INSERT/ADVANCE   and   HOLD   pushbutton lights remain illuminated.) 10. INSERT/ADVANCE pushbutton Press. (Observe     arc-seconds     related     to     present     position latitude and longitude, to nearest tenth of a second, appear in left and right data displays, respectively.) 11. Load  related  arc-second  values for  latitude  in  sequence,  starting with "N". (Example: 35.8°  North = N 358.) 12. INSERT/ADVANCE pushbutton Press. (Observe   INSERT/ADVANCE   and   HOLD   pushbuttons remain illuminated.) 13. Load  related  arc-second  values for longitude in sequence, starting with "E". (Example: 20.1 East = E 201.) NOTE Extra  precision  values  are  added  to normal  values  and  normal  displays are not rounded off. NOTE Normal latitude-longitude coordinates  must  always  be  loaded prior to extra precision values. NOTE Directions "N" or "S" and "E" or "W" are established during normal coordinate entry.  Either key may be used   to   initiate   entry   during   extra precision   loads   and   values   will   be added    to    extra    precision    values without affecting direction. NOTE It  is  characteristic  of  the  computer display     routine     to     add     0.2     arc- seconds  to  any  display  of  59.9  arc- seconds.        Value    in    computer    is loaded by operator. 14. Proceed to step (6) in procedure: "Normal Geographic 3-64