TM 1-1510-225-10 3A-92 provided  at  the  programmed  angle  when  the  waypoint becomes the vertical TO waypoint. (b)   Programming   Path   Descents   Using Default FPA.   The pilot can select the default FPA, set on  the  VNAV  Data  page,  by   pressing the   BACK key when   the   cursor   is   on   the   FPA   field   of   the   VNAV Waypoint  page.    The  FPA  field  displays  (DEF)  and vertical deviation is provided at the programmed angle when the waypoint becomes the vertical TO waypoint. (c)   Programming   Path   Descents   Using Manual FPA.   The pilot can enter a desired flight path angle  on  the  VNAV  Waypoint  page.    The  FPA  field displays (DEF) and vertical deviation is provided at the programmed  angle  when  the  waypoint  becomes  the vertical TO waypoint. (d)   Programming   Path   Descents  Using Automatic FPA.   The (AUTO) mode is provided to link together  descent  waypoints  that  have  cross  at  type constraints  and  provide  a  computed  flight  path  angle between them. The  (AUTO)  mode  may  be  selected  only  if  the chosen    waypoint    has    a    cross    at    type    constraint programmed.  All cross at waypoints that are a part of a STAR or approach are automatically put into (AUTO) mode    when    the    procedure    is    retrieved    from    the database and loaded onto the active flight plan. If the waypoint prior to the selected (AUTO) FPA waypoint has a cross at or above, cross at or below, or cross  between  constraint  programmed,  an  automatic angle of the programmed default angle on VNAV Data page is assigned.  Vertical deviation is provided at the programmed  angle  when  the  waypoint  becomes  the descent reference waypoint. NOTE If    no    ALT    constraints    are    programmed before  the  selected  AUTO  FPA  waypoint, the AUTO FPA is the same as the DEF FPA. Unless     an     FPA     is     programmed     at     a waypoint, the system uses the DEF FPA to the first waypoint on the flight plan with an altitude  constraint  to  establish  #TOD.    To help     establish     #TOD,     the     system     will automatically   load   the   destination   airport elevation  on  the  flight  plan,  provided  the flight plan was not obtained from AFIS.  An altitude     constraint     and     FPA     must     be programmed  to  establish  a  path  descent and activate vertical deviation. (2)   Editing   Altitude   Constraints.      The   pilot can edit altitude constraints for waypoints on subsequent  VNAV  pages,  referred  to  as  VNAV  Flight Plan  pages,  by  using  the  VNAV  page  or  the  VNAV Waypoint page. (a)   Editing    Altitude    Constraints    Using VNAV Page. 1.   VNAV    key    –    Press    to    display VNAV    1/2    page.        The    altitude constraint may be changed on this page  if  the  current  TO  waypoint has     a     constraint     programmed.   Type   the   altitude   in   the  altitude field.    All  parameters  associated with   the   previous   constraint   will remain  unchanged  (that  is,  FPA, A, B, G, or OFFSET). 2.   VNAV key  – Press to position the cursor  over  the  desired  waypoint altitude. 3.   Line select key – Press to position the cursor over the desired waypoint altitude. 4.   Altitude   constraint   –   Insert   new altitude   constraint   followed   by   A (at or above) or B (at or below), if applicable.    Any  altitude  entered greater than the transition level is converted    and    displayed    as    FL (flight    level,    rounded    off    to    the nearest hundred feet).  An altitude less     than     1000     feet     must     be entered with a preceding zero. 5.   ENTER key – Press. (b)   Editing    Altitude    Constraints    Using VNAV Waypoint Page. 1.   NAV,  FPL,  or   D  key  – Press to display applicable page. 2.   Line select key – Press to position cursor over desired waypoint. NOTE On Navigation pages, only the TO waypoint can be selected. 3.   VNAV    key    –    Press    to    display VNAV Waypoint page for selected waypoint. 4.   ALT    –    Insert    altitude    constraint followed  by  A  (at  or  above)  or  B