TM  55-1510-221-10 FROM-TO   data   display   as keys  are  pressed. NOTE Do   not   press   INSERT/ADVANCE   push- button.  This  would  cause  an  immediate flight  plan  change. 3. Data   selector   -   DIS/TIME. Observe   distance   between desired  waypoints  appears  in left  data  display  to  nearest nautical  mile.  Time  to  travel between  desired  waypoints at   present   ground   speed appears  in  right  data  display to  nearest  tenth  of  a  minute. 4.   CLEAR   pushbutton   -   Press. Observe  INS  returns  to  nor- mal operation. Observe WYPT  CHG  and  INSERT/ ADVANCE  pushbutton  light extinguishes. Waypoints defining   current   navigation leg   appear   in   FROM-TO data   display. (r.) Distance  to  any  TACAN  station: 1. Data   selector   -   DIS/TIME. Observe   distance   to   next waypoint   to   nearest   nautical mile   is   in   left   data   display. Time   to   next   waypoint   to nearest  tenth  of  a  minute  is in  right  data  display. 2.  Keys  “7“  and  “9“  -  Press simultaneously. Observe number   of   TACAN   station being   used   for   navigation flashes on and off in FROM-TO  display.  Distance to  TACAN  station  to  nearest nautical   mile   is   in   left   data display. T i m e   t o next waypoint  is  in  right  data  dis- play. 3.  If  in  aided  TACAN  opera- tion -   Monitor   display. Observe  station  number  is selected  every  30  seconds. 4.     If     not     in     aided     TACAN operation   -   Perform   steps   5 through  7. 5.  WYPT  CHG  pushbutton  - Press. Observe   INSERT/ ADVANCE  and WYPT CHG   pushbutton   lights   illu- minate. Station number flashing   discontinues. 6. Key indicating desired TACAN   station   number   - Press.   Observe   number   will appear   in   left   digit   location of   FROM-TO   data   display. NOTE If   wrong   key   is   pressed,   press   CLEAR; displays  will  revert  to  that  indicated  in step 2. 7.  INSERT/ADVANCE  push- button -  Press.  Observe INSERT/ADVANCE and WYPT   CHG   pushbutton lights  extinguish.  The  loaded digit  will  appear  in  right position  of  FROM-TO  dis- play  and  will  be  flashing  on and  off.  Distance  to  that  sta- tion  to  nearest  nautical  mile appears  in  left  data  display. The  right  display  continues to  display  time  to  next waypoint. 8. Data selector - WIND, momentarily.   Returns   INS to  normal  display  mode. NOTE If  in  aided  TACAN  operation  and  if  the desired  station  is  not  being  selected,  exit aided  operation  per  procedure:  “Switch- ing   From   Aided   to   Unaided   Inertial Operation“,   perform   steps   1   thru   8,   and then  return  to  aided  operation  per  proce- dure:  “Aided  TACAN  Operation“. (s.) Coordinates of any waypoint: 1. Data  selector  -  L/L  WY  PT or  UTM  WY  PT. 2.   Waypoint   thumbwheel   -   Set desired  waypoint.  Observe following: a. L/L  WY  PT:  latitude and l o n g i t u d e   of desired  waypoint,  to  a t e n t h    o f    a    m i n u t e, appear  in  left  and  right 3-64