TM 1-1510-225-10 3B-94 1.  Course Readout 2.  Range Scale Arc 3.  Distance 4.  Active Flight Plan Leg 5.  Course Bearing/Range Readout 6.  Aircraft Symbol 7.  Waypoint Symbol 8.  Interconnecting Track Lines 9.  Distance Display Figure 3B-57.  EHSI Map Mode Display j.     Alternate Flight Plan Overview.        The alternate flight plan is a complete plan for a mission or a  mission  segment  that  includes  a  route  of  up  to  60 waypoints, with calculations of courses, distance, time, gross weight, and  fuel requirements including reserve allocations.    It  includes  standard  flight  planning  data and provides an electronic hard copy of the flight plan in the FMS-800 that may be modified at any time. Forty alternate flight plans may be stored on the data cartridge  from  either  a  Mission  Planning  Ground Station  (MPGS)  or  laptop  facility,  or  by  manual  entry via the CDU on the aircraft.  One alternate flight plan at  a  time  may  be  selected  and  transferred  into  the CDU  for  viewing  and  the  operations  are  described  in this section.  This alternate flight plan is separate from the active flight plan and does not sequence or change unless  the  crew  modifies  it.    It  can  be  transferred  or added to the active flight plan, Paragraph 3B -19e, and the alternate flight plan will remain intact. The   alternate   flight   plans   stored   on   the   data cartridge    are    not    automatically    updated    with    new waypoint     data     whenever     a     new     primary     ICAO database is loaded onto an FMS data cartridge.  With each ICAO database update, each alternate flight plan should   be   updated   at   a   ground   station   (outdated waypoints  replaced  with  current  ICAO  definition),  and the  on-aircraft  FMS  purged  of  existing  flights  plans.   The updated alternate flight plans can then be used for normal operations. (1)   Alternate    Flight    Plan    Structure.        The alternate    flight    plan    operates    as    a    spreadsheet calculator.      The   crew   inputs   the   flight   plan   routing, wind,    and    aircraft    performance.        The    FMS-800 calculates  the  individual  leg  data  as  well  as  the  flight totals.  Vertical scrolling on the  CDU accesses the legs of the plan (1 through 60).  Complete data for each leg is accessed by lateral scrolling among leg pages with suffixes A, B, and C.  Refer to Figure 3B-58 and Table 3B-42. The     Alternate     Flight     Plan     Waypoints     page presents the alternate  flight  plan  in  a  format  similar  to the    active    flight    plan,    Figure    3B-26.      Modify   the alternate flight plan on this page in the same manner as the active flight plan. (2)   Alternate Flight Plan Access and Transfer.    On  the  Alternate  Flight  Plan  page,  various top-level access and transfer options are offered to the crew.  Refer to Figure 3B-59  and  Table  3B -43.  When an  alternate  flight  plan  is  transferred  or  added  to  the active flight plan, only the sequence of waypoints and the   following   waypoint   attributes   are  transferred:  All others  are  calculated  by  the  FMS-800  using  sensed data    rather    than    the    planned    parameters    of    the alternate flight plan. 1.   Wind for each leg. 2.   Altitude for each waypoint (if assigned). 3.   The    time    associated    with    the    last entered time of arrival. 4.   MFP for each waypoint (if assigned).