VIA/GO TO
 Figure 038

 (10)
 Alternates (Ref. Fig. 039)

 (a)
 List of alternates This revision allows to change the alternate destination. This is performed through a special page (via LAT REV at destination) on which the prestored alternate destinations are displayed with the option NO ALTN; moreover the pilot can select an alternate other than the one stored with the primary destination (Ref. DATA BASE chapter). For each alternate, the following items are displayed:

 -Airway distance (from primary destination to Alternate destination).
 -track (great circle).

 -Extra at alternate destination.
 For NO ALTN the extra is also computed and displayed.
 To select another alternate the pilot has to enter an identifier
 on the MCDU in the OTHER ALTN field. If he wants computations for
 that alternate, he has to enter a distance as well (airway
 distance is assumed).
 Selecting one of the alternates creates a temporary flight plan.
 The other alternate may be selected in temporary even if a
 distance is not entered on the MCDU. In this case the FMGC
 computes predictions for this alternate (distance, track, extra).

 (b)
 Enable alternate It is used to activate the alternate portion of the F-PLN. The alternate F-PLN is inserted in the primary F-PLN. This revision creates a temporary flight plan. The revise waypoint may be any waypoint (except the FROM) of the active Primary F-PLN (including destination and missed approach) and there must be an alternate destination. All waypoints in the active primary portion of the F-PLN beyond the revise point are deleted (This includes the Primary destination and missed approach). The revise point is strung to the Alternate origin waypoint (the first one after the ex-Primary destination), with a discontinuity.

 (11)
 Direct Modifications through F-PLN Page Two lateral revisions may be performed on the F-PLN page A or B without creating a temporary flight plan:

 -insertion of a new waypoint
 -clearing a waypoint or discontinuity.

 Alternates
 Figure 039

 (a)
 Insert a new waypoint This function results from the direct entry of a new waypoint into the flight plan via the F-PLN page. This function is essentially identical to the next waypoint function in LAT REV (Ref. para. C. (5). The new waypoint is inserted at the position selected by the pilot (all markers are included). However it cannot be inserted directly following FM, or VM legs or at the FROM waypoint.

 (b)
 Clear waypoint or discontinuity This function is invoked by first pressing the CLR key with the F-PLN page displayed and the scratchpad empty. Then, the left line-select key, next to the selected waypoint, is pressed. The function performed depends on whether the waypoint is a downpath waypoint, a TO waypoint or a FROM waypoint.

 -
Clearing a downpath lateral waypoint or discontinuity deletes the selected leg from the flight plan.

 -
Clearing the TO waypoint is not allowed when NAV is engaged. A message NOT ALLOWED IN NAV will be displayed on the MCDU.

 -
Clearing the FROM waypoint is not allowed when NAV is engaged.

 -
Clearing a discontinuity is allowed except just after PPOS.

 ORIGINAL F-PLN  F-PLN AFTER XYZ ENTRY
 FROM  FROM
 ABC  ABC
 BCD  BCD
 --F-PLN DISCONTINUITY-- --F-PLN DISCONTINUITY--
Waypoint XYZ  XYZ
 entered here --->  CDE
 DEF  --F-PLN DISCONTINUITY--
CDE
 DEF

 (12) DIR (Direct) TO (Ref. Fig. 040) This function allows the pilot to insert a direct path from the aircraft present position to a selected fixed waypoint. It is invoked by using the DIR TO page. There is no temporary situation for this revision. The rules for the DIRECT TO functions are as follows:
 -If the DIRECT TO waypoint is identical to any fixed waypoint in the flight plan (including the FROM waypoint), then a DF leg is strung to that waypoint. All original legs up to that waypoint are deleted and T-P becomes the FROM waypoint followed by the DF leg.

 DIR TO
 Figure 040

 -If the DIRECT TO waypoint is not identical to any waypoint in the flight plan, a DF leg is strung to that waypoint followed by a discontinuity. The discontinuity stringing rule applies to the flight plan from the TO waypoint on. T-P becomes the FROM waypoint.
 -DIRECT TO is activated when the DF leg is strung by the above rules.

 D. Vertical Revisions

 (1)
 General The vertical revise function allows the flight crew to define or modify the following vertical flight plan elements:
　
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