TM 1-1510-225-10 3A-91 2.   Line select key – Press to position the cursor over the desired waypoint. 3.   VNAV  key   –  Press.    The  VNAV Waypoint  page  appears  with  the cursor over the ALT field. 4.   ALT  – Review or insert new value. NOTE If (AUTO) FPA is displayed, the system has automatically  programmed  a  waypoint  to waypoint FPA for the procedure. 5.   ENTER key  –  Press  until  display returns to Active Flight Plan page. 6.   Repeat    steps    2    through    5    to review or change altitude constraints at remaining waypoints. (b)   Reviewing VNAV Database Waypoints Using VNAV Flight Plan Page. 1.   VNAV key  –  Press  to  display  the VNAV page. 2.   Line select key – Press to position the cursor over the desired waypoint. 3.   ENTER key  –  Press.    The  VNAV Waypoint  page  appears  with  the cursor over the ALT field. 4.   ALT  – Review or insert new value. NOTE If the FPA was retrieved from the database, (DB) will appear in the FPA type field. 5.   ENTER  key   –  Press  to  return  to the VNAV page. 6.   Repeat    steps    2    through    5    to review or change altitude constraints at remaining waypoints. (c)   Reviewing VNAV Database Waypoints Using Direct To Or Navigation Pages. NOTE A  vertical  direct  can  only  be  programmed for a descent. 1.    D   or NAV key – Press to display applicable page. 2.   Line select key – Press to position the cursor over the desired waypoint on the Direct To page or the   TO   waypoint   on   Navigation pages. 3.   VNAV  key   –  Press.    The  VNAV Waypoint page appears with cursor   over   the   FPA   field,   if   an altitude constraint has been programmed and the current barometric   altitude   is   above   the programmed altitude constraint. NOTE When accessing the VNAV Waypoint page from  the  Direct  To  page  or  the  Navigation pages, the FPA pre-fills with (DIR) and the direct FPA value from the aircraft's present position  to  the  VNAV  waypoint,  provided the direct FPA is within the valid range. The VNAV direct waypoint need not be the same as the lateral to waypoint. 4.   ENTER key – Press. The waypoint  will  become  the  current vertical TO waypoint and all constraints   prior   to   the   waypoint will be erased.  The VNAV page 1 will appear displaying vertical deviation. u.  Vertical Navigation – En Route. (1)   Programming  Path  Descents.    The  pilot can use various methods to set a flight path angle that determines the aircraft's path descent. NOTE When the system detects a rapid change of barometric altitude setting or non- continuous data from an air data computer, the vertical deviation output is momentarily interrupted. When vertical deviation returns   to   a   valid   state,   the   appropriate value   of   vertical   deviation   will   again   be displayed. (a)   Programming   Path   Descents   Using Database     FPA.      The database contains FPA associated with waypoints (for example approaches to runway thresholds) that pre-fill when programmed into the   active   flight   plan.      The   FPA   field   on   the   VNAV Waypoint  page  displays  (DB)  and  vertical  deviation  is