TM 55-1510-219-10 (20) 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.) (a) 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". 1. Data   selector   STBY,   then   to ALIGN. 2. Present     position     coordinates Insert,  according  to  procedure: "Geographic   Present   Position Insertion"        or  "UTM  Present Position Insertion." (b)    Realignment INS shutdown.  Perform complete alignment procedures. (c)    Position     update     (recommended     if time is not available for realignment.) NOTE 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. (d)    Downmoding to standby: 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: 1. Mode selector STBY. Caution Do not leave INS operating unless aircraft    or    ground    power    and cooling air are available to system. (e)    Shutdown: 1. 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. d. Abnormal Procedures. (1)    General. INS contains self-testing features which provide one or more warning indications when  a  failure  occurs.    The  WARN  lamp  on  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  lamps.    A  battery unit malfunction will shut down INS when battery power is used. (2) Automatic INS shutdown. (a) Overtemperature.  An overtemp- erature  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    lamp    on    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. 3-67