TM 1-1520-218-10 3C-192 x.   Postflight Operations. (1)   Postflight    Operations    Overview.        The FMS-800 postflight operations are as follows. 1.   Saving   and   clearing   GPS   selective availability/anti-spoofing keys 2.   Saving GPS almanac data 3.   Saving system status data 4.   Zeroizing system data 5.   Locking the system (2)   Saving     and     Clearing     GPS     Selective Availability/Anti-Spoofing   (SA/AS)   Keys.      The  GPS SA/AS  functions  are  controlled  on  the  GPS  SA/AS page, which is accessed from the Index 1 page.  The GPS  SA/AS  page  indicates  whether  or  not  the  GPS contains   keys   and   the   current   mission  duration  as reported by the GPS.  To change the mission duration, enter the number of days in the scratchpad and press the  DAYS  line  select  key  on  the  GPS  SA/AS  page.   Entering  a  duration  less  than  the  current  number  of loaded daily keys will zeroize any  keys exceeding the desired mission duration. To     zeroize     the     SA/AS     keys,     access     the Lock/Zeroize page and press the  ZERO ALL or  GPS line  select  key  twice.    If  after  a  zeroize  attempt  the GPS SA/AS keys were not zeroized, for any reason, a NO   KEYS   ZERO   annunciation   appears.      If   it   was zeroized, a SAFE KEYS annunciation will be displayed. (3)   Saving  GPS  Almanac  Data.    Saving  the GPS  almanac  data  to  the  data  cartridge  can  ensure almanac data is available to reduce acquisition time for following   flights.      To   save   the  GPS  almanac  data, access     the     Data     Loader     page     and     press     the ALMANAC SAVE line select key twice. (4)   Saving  System  Status  Data.    The  FMS- 800   maintains   an   in-flight   fail   history   of   all   avionic LRU's including CBIT, IBIT, and bus status failures for later examination by maintenance personnel.  To save this status data to the data cartridge, access the Data Loader  pages  and  press  the   STAT  SAVE  line  select key twice.  The failed history file contains start and end dates of the record.  A new fail history record will begin whenever   the   crew   saves   the   status   data   to   the cartridge. (5)   Zeroizing System Data. The Lock/Zeroize  page  permits  selective  blanking  of  data within  CDU  nonvolatile  memory  and  the  data  loader cartridge.    In  addition  to  selective  blanking,  a  single key commands a master zeroize of all data stored in the system, including V/UHF HAVE QUICK data, and the     GPS     selective     availability/anti-spoofing     keys.   Figure 3C-142 and Table 3C-105 show the Lock/Zeroize   page   and   its   associated   operation   in blanking different portions of system memory. A   ZERO   ALL   command   will   erase   all   system data.    Flight  plan  zeroization  and  erasure  will  delete the  active  waypoint.   Following  flight  plan  zeroization, guidance  will  be  indeterminate  and  revert  to  a  wings- level configuration. (6)   Locking    the    System.        The    FMS-800 provides  a  system  lock  function  to  prevent  improper investigation  or  tampering  of  system  data  while  the aircraft   is   on   the   ground.      The   system   lock,   when activated   with   a   password   entry,   disables   the   CDU function   keys   with  the  exception  of  two  line  select keys.    One  unlocks  the  system  with  the  entry  of  the same password and one that performs a zeroization of system data. To   lock   the   system,   access   the   Lock/Zeroize page,     enter     a     three-character     password     in     the scratchpad, and press the  LOCK line select key.  Both CDU's  will  display  the  lock/zeroize  page  and  display the  LOCKED  annunciation,  indicating  the  system  is locked.    No  function  keys  or  line  select  keys  (other than the LOCK and ZERO ALL) are operational at this point.      Once   the   system   is   locked,   it   can   only   be unlocked and full functionality restored to the CDU's by either re-entering the same password in the scratchpad  of  the  CDU  and  pressing  the   LOCK line select key or pressing the   ZERO ALL line select key twice  on  the  CDU  to  zeroize  system  data.    Refer  to Figure 3C-142 and Table 3C-105.