TM 55-1510-222-10 alignment.          Movement     during     alignment     requires restarting alignment. (a)   Transient stops. NOTE Action to be taken during a transient stop   depends   upon   time   available and on availability of accurate parking    coordinates    (latitude    and longitude.) 1. Realignment - INS operating. (Recommended    if    sufficient    time    and    accurate parking coordinates are available.) NOTE INS can be downmoded to perform a realignment and azimuth gyro calibration.  Alignment to produce an alignment  state  number  of  5  can  be accomplished    in    approximately    17 minutes.        During    the    17    minute period,   an   automatic   azimuth   gyro recalibration  is  determined  on  basis of difference between inertial present position    before    downmoding    and inserted present position.  To obtain further   refinement   of   azimuth   gyro drift    rate,    calculated    on    basis    of newly  computed  error  data,  INS  can be    left    in    alignment    mode    for    a longer period, allowing the alignment state   number   to   attain   some   value lower than 5. 2. Data selector - STBY, then to ALIGN. 3. Present   position   coordinates   -   Insert, according  to  procedure:    Geographic  Present  Position Insertion or UTM Present Position Insertion. 4. Realignment - INS shutdown. Perform complete alignment procedures. 5. Position update. Recommended if time is not available for realignment. • Perform  position  update  using  parking  coordinates in  accordance  with  procedure:    Insertion  of  Geographic Waypoint  Coordinates.    If  parking  coordinates  are  not available, proceed as follows: • Continue operation in NAV, if INS accuracy appears acceptable. • Perform   position   update   using   best   estimate   of parking coordinates. NOTE INS  can  be  downmoded  to  standby operation which will maintain navigation unit at operating temperature with gyro wheels running.        INS    is    downmoded    to standby as follows: f. Downmoding to standby: Mode selector - STBY. CAUTION Do   not   leave   INS   operating   unless aircraft or ground power and cooling air are available to system. g. Shutdown: Mode selector - OFF. NOTE INS will retain inertial present position  data  computed  at  time  INS is     downmoded.          This     value     is compared with present position inserted     for     next     alignment     and difference     is     used     to     determine azimuth gyro drift rate. e. Abnormal Procedures: (1)   General.        INS    contains    self-testing    features which  provide  one  or  more  warning  indications  when  a failure   occurs.      The   WARN   annunciator   in   the   CDU provides    a    master    warning    for    most    malfunctions occurring  in  the  navigation  unit.    Malfunctions  in  the MSU   or   CDU   will   normally   be   obvious   because   of abnormal  indications  of  displays  and  annunciators.    A battery unit malfunction will shut down INS when battery power is used. (2)   Automatic IN: shutdown. (a)   Overtemperature.      An   overtemperature   in navigation unit will cause INS to shut down (indicated by blank CDU displays) when mode selector is at STBY or ALIGN during ground operation. The WARN annunciator     in     CDU     will     illuminate     and     will     not extinguish  until  mode  selector  is  rotated  to  OFF.    The cooling   system   should   be   checked   and   corrected   if faulty.  If cooling system is satisfactory, navigation unit should be replaced. (b)   Low   battery   charge.      A   low   battery   unit charge   will   cause   INS   to   shut   down   when   INS   is operating     on     battery     unit     power.          Both     WARN annunciator on CDU and BAT annunciator inMSU 3-64