TM 55-1510-220-10 6. INSERT/ADVANCE pushbutton Press. Observe INSERT/ADVANCE and HOLD pushbutton annunciators remain illuminated.    North  position  error  and east    position    error,    in    tenth    of    a nautical  mile,  will  appear  in  left  and right data displays, respectively. NOTE If    WARN    annunciator    illuminates, proceed  to  step  7;  otherwise  proceed to step 8. 7. Data   selector   DSRTK/STS.      Observe action  code  "02"  and  malfunction  code "49".      This   indicates   that   the   radial error  between  the  loaded  position  and the  INS  position  exceeds  33  nautical miles. Operator must evaluate possibility that either INS is in error or reference point position is incorrect.  It is    possible    to    force    INS    to    accept updated position by setting data selector to L/L POS and proceeding to step 8. 8. If displayed values are within tolerance, press  HOLD  pushbutton  to  return  INS to  normal  operation.    If  one  or  both values  are  out  of  tolerance,  proceed  to step 9. 9. Key    "2"    Press.        Observe    left    data display is "00000 N"; INSERT/ADVANCE and HOLD pushbutton     annunciators     extinguish. Present position appears in data displays.    Present  position  check  and update is complete. 10. INSERT/ADVANCE pushbutton Press.    Observe    INSERT/ADVANCE and    HOLD    pushbutton    annunciators extinguish.  Present position appears in data  displays.    Present  position  check and update is complete. NOTE Within    30    seconds,    computer    will process correction and revised present position  will  appear  in  data  display. If  AI  prior  to  position  update  is  I  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. (b) Extra  precision  geographic  present  position check and update: 1. Data selector DSRTK/STS. 2. Key "2" Press. Observe INSERT/ADVANCE pushbutton annunciator illuminates, "000002" appears in right data display. 3. INSERT/ADVANCE               pushbutton Press.      Observe   right   data   display   is "1...XX2", INSERT/ADVANCE pushbutton annunciator is extinguished, and any TACAN updating is discontinued. 4. Data    selector    ULL    POS.        Observe latitude and longitude of present position  appears  in  left  and  right  data displays, respectively. 5. HOLD  pushbutton Press (when aircraft passes  over  known  position  reference.) Observe HOLD pushbutton annunciator 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  42° 54.0'  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. Change 2       3-67