TM 1-1510-225-10 3C-37 (a)  NM  – Displays slant range distance in nautical miles from aircraft to ground station. (b)  KT – Displays groundspeed in knots. (c)  MIN     –    Displays    time    to    TACAN station in minutes. c.     Normal Operating Procedures.  (1)   Equipment Startup. NOTE It  is  assumed  the  Avionics  Master  Power switch    is    on,    and    that    normally    used avionics circuit breakers remain pressed. 1.     TACAN   control   panel   –   Turn   VOL ON / OFF knob  ON. 2.     VOR  ADF  /  TACAN  ADF  Switch  – Select TACAN ADF. 3.     RMI Selector for #1 Needle (yellow) – Select VOR. 4.     HSI Switches – Press TACAN. (2)   Self-test Procedure. 1.     Course   knob   on    HSI   –   Set   180 course. 2.     TACAN   control   panel    –   Hold   test switch engaged while confirming following results: HSI  course  indicator  centers  on  a  180  ±  2 TO indication.      Using   course   knob,   increase   selected course.    Deviation  bar  will  move  to  left.    Decrease selected course: deviation bar will center and move to right  of  center.    Full-scale  deflection  will  be  10 +  1.   In  OSA aircraft, the RMI and HSI bearing pointers will indicate  approximately  a  180  magnetic  bearing.    In aircraft,  only  the  RMI  bearing  pointer  will  indicate  the 180 bearing. (3)   Normal Operation. 1.     VOR  ADF  /  TACAN  ADF Switch   – Select TACAN ADF. 2.     RMI   selector   for   #1   needle   single (yellow) – Select VOR. 3.     HSI switches – Press TACAN. 4.     Mode switch (X / Y) – As required. 5.     TACAN control panel – Select desired channel. 6.     Wait 5 seconds for signal acquisition and lock-on.  If bearing signal lock-on does  not  occur,  the  TACAN  remains in    the    bearing    search    mode.        If bearing     lock-on     is     not     obtained, perform an in-flight self-test to ensure correct     operation     of     the     system.   Anytime the course indicator's flag is in    view,    in    OSA   aircraft,   the    HSI bearing  pointer  will  drive  to  the  park or   3   o'clock   position.      The   course deviation and the TO/FROM information  may  be  inaccurate  and should  be  disregarded.    ANG aircraft are not equipped with an HSI bearing pointer, however, the bearing, course deviation, and TO/FROM information presented   may   also   be   inaccurate and should be disregarded. NOTE On   the   RMI,   there   is   no   warning   flag   to indicate    failure    to    receive    the    station.   Instead,   the   RMI   needle   will   drive   to   the park     or     3     o'clock     position.          Always crosscheck  the  RMI  with  the  HSI  course indicator for a possible warning flag. 7.     Ensure that audio station identification  signal  is  correct  for  the ground station selected. 8.     Course    Knob    (HSI)   –   Set   course desired.    Verify  proper   TO or   FROM pointer  indication.    Intercept  course as  required.    In   OSA  aircraft,  verify intercept heading by reference to the RMI   and   HSI   bearing   pointers.      In ANG aircraft, verify intercept heading by  reference  to  RMI  using  RMI  only procedures. 9.     Course  Deviation  Bar  (HSI)  –  Read deviation from selected course.  The difference between the aircraft's heading and the course pointer, when the  course  deviation  bar  is  centered and     the     aircraft     is     tracking     the selected  course,  will  show  the  wind correction angle.