TM  55-1510-221-10 7.  ON-OFF  SWITCH.  Activates  or deactivates  system. (2.)  TACAN  distance  indicator. 1. NM INDICATOR. Displays slant range  distance  in  nautical  miles from  aircraft  to  selected  TACAN ground  station. 2.     KT INDICATOR. Displays ground speed in knots. 3.  MIN  INDICATOR.  Displays time  to  TACAN  station  in  min- utes. e. (Non-INS  dedicated)  TACAN  Operation. (I.)   Turn-On   procedure: 1. Power   switch   (TACAN   control panel, fig. 3-20) - ON. 2. Volume control - As required. 3.  Course  indicator  switches  (instru- ment  panel,  fig.  2-29)  -TACAN. 4.  Self-test  procedure:  Course  knob on pilot’s HSI - Set to 180°, press and hold TEST switch. 5. Pilot’s HSI course deviation bar - Centered, with course knob set to 180  ±2  degrees,  and  TO-FROM indicator indicating TO. 6.  RMI  bearing  pointers  (fig.  3-9) and pilot’s HSI bearing pointer - Point to 180 degrees. 7. HSI  course  knob  -  Increase  the selected course. The course devia- tion bar on a 180 ± 2 degrees TO indication and the bearing point- ers  on  each  RMI  indicator  read 180  degrees.  Using  the  course knob,  increase  the  selected  course, the  course  deviation  bar  will move  left.  Decrease  the  selected course, the course bar will center, then move to the right of center. Full  scale  deflection  will  be  10 ± 1°. f.  Normal  Operating  Procedure: 1. RMI  single  needle  switch  (fig.  3-9)  - VOR-TACAN. 2. RMI selector switch (instrument panel, fig.  2-29)  -TACAN. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Course  indicator  selector  switch  (in- strument panel, fig. 2-29) - TACAN. TACAN  X-Y  switch  -  As  required. TACAN  channel  selector  knobs  -  Select desired  channel. Wait  5  seconds  for  signal  acquisition and lock-on. If bearing lock-on is not obtained, per- form an inflight self-test to insure cor- rect operation of the system. Anytime a  course  indicator  NAV  or  VOR  LOC flag  is  in  view,  bearing,  course  devia- tion,  and  TO-FROM  information  may be  inaccurate  and  should  be  disre- garded. Insure  that  audio  station  identification signal is correct for the ground station selected. RMI  single-needle  pointer  and  pilot HSI  bearing  pointer  -Read  bearing  to station. HSI course control knob - Set desired course. HSI course deviation bar - Read devia- tion  from  selected  course.  Course arrow will show wind correction angle when  the  course  deviation  bar  is  cen- tered  and  the  aircraft  is  tracking  the selected  course. TACAN  indicator  and  pilot’s  HSI  - Read distance to station. To  determine  course  TO  or  course FROM a TACAN station, rotate course knob  (pilot’s  HSI)  until  course  devia- tion bar is centered and the TO-FROM pointer reads TO or FROM. To use TACAN during pilot-controlled flight,  control  aircraft  by  manual  con- trols,  responding  to  information  dis- played  on  the  flight  director,  RMI, HSI,  TACAN,  and  other  instruments. To  use  TACAN  with  the  autopilot, engage  autopilot  and  monitor  autopilot performance  on  flight  director,  RMI, HSI  and  TACAN  indicators.  Verify adherence   to   preset   heading   and course,  and  confirm  the  execution  of displayed  steering  commands. 3-37