TM 55-1510-220-10 NOTE UL    WY    PT:    A    coordinate    is    the addition  of  values  for  degrees,  whole minutes, and seconds. Example:   W   87°   54'   58.6"   will   be displayed as "87°54.9W" and 58.6°. UTM  WY  PT:  A  coordinate  is  the addition of values for kilometers and meters. Example:   S   2,   474,706   m   will   be displayed as "2474 S" and "706". 5. INSERT/ADVANCE pushbutton Press. Observe TACAN station altitude,  in  feet,  will  appear  in  right data display; degree symbol and decimal  points  should  be  disregarded. Left data display is blank. 6. INSERT/ADVANCE pushbutton Press. Observe TACAN station channel   number,   in   whole   numbers, will  appear  in  left  data  display;  data symbol   and   decimal   point   should   be disregarded.      Right   data   display   is blank. NOTE If  INSERT/ADVANCE  pushbutton  is pressed, the normal coordinates indicated in step 3 will be displayed. NOTE Waypoint thumbwheel may be moved at  any  time  and  normal  coordinates for     new     TACAN     station     will     be displayed. 7. Data     selector     Momentarily     to     any position other than LUL WY PT, UTM WY PT or DIS/TIME.  (Returns INS to normal operation). (u) True heading. 1. Data  selector HDG/DA.  Observe true heading to nearest tenth degree appears in left data display. 2. Keys  "3"  and  "9"  Press  simultaneously and  hold.    Observe  magnetic  variation to nearest tenth of a degree appears in left data  display.    Drift  angle  continues  to be displayed in right data display. 3. Keys "3" and "9" Release.  Observe left data display reverts to true heading. (13) INS updating: (a) Normal   geographic   present   position   check and update: 1. Data    selector    UL    POS.        Observe latitude and longitude of present position  appear  in  left  and  right  data displays, respectively. 2. HOLD    pushbutton    Press.        Observe latitude  and  longitude  in  data  displays freeze  at  values  present  when  HOLD pushbutton is pressed. HOLD pushbutton illuminates. NOTE While HOLD pushbutton annunciator is illuminated, TACAN is inhibited. 3. Keys Press in sequence to load latitude of position reference, starting with "N" or    "S"    to    indicate    north    or    south. Example:   42   north   =   N   4   2   5   4   0. Observe INSERT/ADVANCE pushbutton annunciator illuminates when  first  key  is  pressed,  and  latitude appears in left data display as keys are pressed. 4. INSERT/ADVANCE pushbutton Press.      Observe   INSERT/ADVANCE pushbutton annunciator remains illuminated,    and    previous    value    of latitude reappears. 5: Keys Press in sequence to load longitude of position reference, starting with  "W"  or  "E"  to  indicate  west  or east.  Example: 87'54.9' = W 8 7 5 4 9. Observe longitude appears in right data display as keys are pressed. Change 2  3-66