TM 1-1510-218-10 3-75 waypoint  location  in  terms  of  latitude  and  longitude.   Refer to Figure 3-109. PVW00       NEW FW  –  ABQ   CTR PVW         001°         28.7 NM N     34° 33.21' W    101° 40.01' ENT    CTR+2 Figure 3-109.  CTR 2 Page (2)   Inserting    Center    Waypoints    Into    Flight Plan.     Insert  the  Center  waypoints  into  the  desired flight plan by returning to the CTR 1 page on the right side    and    pressing    the    ENT    button.        The    Center waypoints are inserted into the flight plan in the correct order.  Refer to Figure 3-110. If    inserting    the    waypoints    would    cause    the number   of   waypoints  to  exceed  30,  then  no  Center waypoints   are   displayed   and   the   CTR   1   page   will display, NOT ENOUGH ROOM IN FPL. USE? INVRT?   1:KLBB   2:PVW00   3:BGD00   4:GCK00   5:KMCK FPL 3 CTR 1 E N R   -   L E G CTR WPT INSERTION COMPLETE Figure 3-110.  Insert Center Waypoints After  the  Center  waypoints  have  been  inserted into a flight plan, they may be viewed by returning to the  CTR  2  page.    As  long  as  the  same  flight  plan  is displayed  on  the  left  side  of  the  screen,  the  Center waypoints  may  be  viewed  by  displaying  the  CTR  2 page(s).      The   CTR   1   and   2   pages   return   to   their original  format  any  time  the  specific  flight  plan  is  no longer  displayed  on  the  left  side.    To  view  the  Center waypoints   again,   return   to   the   specific   flight   plan, select the CTR 2 page, and press the  ENT button. Center  waypoints  are  stored  as  part  of  the  250 user-defined waypoints and are considered supplemental  waypoints.    When Center waypoints are viewed  on  the  SUP  page  or  on  the  active  waypoint (ACT)  page,  they  appear  in  the  normal  supplemental waypoint  format.    Center  waypoints  that  are  part  of  a flight   plan   show   up   on   the   OTH   3   page.      Center waypoints that are not part of a flight plan are deleted from  the  list  of  user-defined waypoints when the KLN 90B is turned off. Once  Center  waypoints  have  been  inserted  into a flight plan, they are treated like any other waypoints in  the  flight  plan.    If  a  flight  plan  containing  Center waypoints    is    modified    in    any    way,    new    Center waypoints   may   be   computed.      The   original   Center waypoints   are   now   part   of   the   flight   plan   and   new Center waypoints are computed by treating the original Center waypoints the same as any other waypoints in the flight plan.  If the interior of a flight plan containing Center  waypoints  is  modified,  it  may  be  desirable  to manually  delete  obsolete  Center  waypoints  from  the flight plan before computing new ones. bh.  The   Status   Pages.       There   are   four   status pages.        The   S TA   1   and   STA   2   pages   display information pertaining specifically to the GPS receiver, while     the     STA     3     and     STA     4     pages     display supplementary information pertaining to the KLN 90B. The  STA  1  and  STA  2  pages  may  be  viewed  at any time to determine the status of the GPS receiver and  the  GPS  satellites  being  received.    This  includes which    satellites    are    being    tracked,    the    satellites’ health,    the    signal    to    noise    ratio    for    each    of    the satellites,   the   elevation   of   each   satellite   above   the horizon, and the estimated position error. The GPS receiver in the KLN 90B is capable of using  signals  from  up  to  eight  satellites  to  determine position.  A valid position may be determined using as few  as  four  satellites  alone  or  three  satellites  with  an altitude  input.    However,  four satellites alone or three satellites   with   an   altitude   input   do   not   necessarily ensure  that  navigation  can  take  place.    The  satellites must  be  positioned  relative  to  the  aircraft  such  that sufficient  geometry  exists  to  determine  an  accurate position.        The    satellite    constellation    geometry    is continually   changing   as   each   satellite   rises,   travels across   the   sky,   and   eventually   sets   relative   to   the aircraft's   position.      The   GPS   satellites   are   not   in geosynchronous orbits positioned over the same spot on the  earth  at  all  times.    Rather,  the  GPS  satellites are in orbits that allow them to circle the earth about two times each day. (1)   STA  1  Page.    There  will  be  two  STA  1 pages if more than four satellites are being received.   The GPS state is indicated on line 1.  Refer to Table 3- 17 for GPS status codes and their meanings.