TM 1-1510-218-10   3C-53 i.    Disengaging the Autopilot.   The autopilot is normally   disengaged   by   momentarily   pressing   the control  wheel   AP   DISC  switch.    The  autopilot  may, however, be disengaged by any of the following: 1.   Actuation  of  the  control  wheel   AP   DISC button.    Disengagement  is  confirmed  by five flashes of the AP ENG annunciator. 2.   Pressing     the     respective     vertical     gyro FAST ERECT button. 3.   Actuation of respective compass INCREASE / DECREASE switch. 4.   Selection of go-around mode.   Disengagement   is   confirmed   by   the   AP ENG  annunciator  flashing  five  times  and illumination    of    the    GA    and    YD    ENG annunciators. 5.   Pulling   the   autopilot   AP   POWER  circuit breaker. 6.   Pressing the autopilot  AP  ENGAGE push button. 7.   Transferring    between    pilot    and    copilot flight directors. Any of the following malfunctions will cause the autopilot to automatically disengage. 8.   Vertical gyro failure. 9.   Directional gyro failure. 10.    Autopilot power or circuit failure. 11.    Torque limiter failure. Disengaging under any of the last four conditions will   illuminate   the    AP    DISC    annunciator    and    the flashing   MASTER    WARNING   light.      Pressing   the control wheel  AP  DISC  switch  will  extinguish  the   AP  DISC annunciator. j.    Elevator TRIM Annunciators.    The elevator trim annunciator indicates  UP or  DN when a sustained signal   is   being   applied   to   the   elevator   servo.      The annunciator  should  not  be  illuminated  when  engaging the autopilot. NOTE Only  the  TCS  button  on  the  side  that  has the controlling autopilot will permit changing  the  autopilot  without  canceling the other pilot’s GA mode. k.   Touch   Control   Steering   (TCS).     The  TCS  push  button  located  on  the  control  wheel  allows  the pilot   to   manually   change   aircraft   attitude,   altitude, vertical   speed,   and/or   airspeed   without   disengaging the autopilot.  After completing the manual maneuver, the TCS push button is released, and the autopilot will automatically resynchronize to the vertical mode.  For example, with  IAS mode selected, the pilot may press the  TCS  push  button  and  manually change airspeed.   Once   trimmed   at   the   new   airspeed,   the   TCS  push button   is   released   and   the   autopilot   will   hold   this airspeed.  If a large pitch attitude change is made, the pilot  should  trim  the  aircraft  normally  before  releasing the TCS button while in the ALT hold mode. 3C-25.  FLIGHT    MANAGEMENT    SYSTEM    NO.    1 (FMS-800). a.   Description. (1)   System   Overview.      The   FMS-800  flight management    system    provides    global    autonomous guidance  using  GPS  navigation.    This  FMS  guidance may  be  used  to  fly  published  airways,  direct  routing, TACAN   emulation   procedures,   and   published   non- precision or autonomous GPS approaches, as well as various mission patterns. The   FMS-800   permits   pre-flight   loading   of   40 complete mission plans using a data cartridge.  It also permits  the  crew  to  generate  or  modify  mission  plans on    the    aircraft,    using    a    global    International    Civil Aviation  Organization  (ICAO)  data  base  of  waypoints and automatic flight plan calculations. The    FMS-800    also    provides    simplified    crew control of the communication radios. NOTE The C-12  installation  uses  a  single  Control Display   Unit   (CDU).      Any   references   to "designated  pilot"  in  this  manual  refer  to pilot only. (2)   System     Architecture.         Figure     3C-22 shows  a  simplified  diagram  of  the  FMS-800 system.   The CDU provides access to all system functions for a single  crewmember.    It  also  provides  user  interface between the FMS-800  and  MIL-STD -1553B  and  non- 1553B aircraft systems.