Top Of Descent (T/D)
The point where the cruise phase changes to the descent phase is the top of
descent. The T/D point is shown on the map as a green open circle with the
label T/D. T/D is calculated from an end of descent (E/D) point.
Intermediate T/D points show on the map as green open circles with the label
T/D–XXXXX (altitude). Intermediate T/D points exist when path segments
between altitude restricted waypoints produce a level path segment. The
intermediate T/D point shows where the descent will resume.
FLT MGT NAV
Sec. 6.11 Page 20 737
Rev. 11/15/02 #41 Continental Flight Manual End of Descent (E/D)
The FMC calculates a descent path based on airspeed restrictions, altitude
restrictions and the end of descent (E/D) point. The E/D point is shown on the
map as a green open circle with the label E/D. The E/D is the last of the
following, which is not preceded by a lateral discontinuity:
· The runway threshold for approaches with a runway waypoint on the RTE
LEGS page, or
· The missed approach point for approaches not showing a runway waypoint
on the RTE LEGS page, or
· The lowest “at” altitude restriction if no arrival procedure is entered.
Entering an instrument arrival procedure provides an E/D point.
If there is no E/D point, FMC predictions assume a computed profile to 1000
feet above the destination field elevation at a position, which varies according to
selection of arrival procedures. The FMC provides a slowdown profile for
approach. VNAV path descent is not available if there is no E/D point.