VSD Climb/Cruise/Descent VNAV
The position of the aircraft symbol on the vertical scale of the VSD is at the bottom for climb-out, in the middle while enroute (cruise) or if the phase is unknown, and close to the top during a descent.
Climb legs beginning from a waypoint ahead of the aircraft or from the aircraft position shall be shown as a horizontal line at the altitude of the next altitude constraint or at the cruise altitude when the aircraft is past the last climb altitude constraint in the flight plan.
The VSD will display the cruise altitude (shown as a horizontal line) as the highest of the departure airport elevation, current altitude, highest planned performance cruise altitude, highest valid constraint in the flight plan, selected altitude, or destination airport elevation. If the aircraft climbs above the planned performance cruise altitude or the selected altitude is set above the entered cruise altitude, the performance cruise altitude and VSD horizontal line will follow the altitude upward.
If the cruise altitude remains unchanged during (or after) an early descent, the PERF algorithm will not predict a climb to return to the programmed cruise altitude unless positive vertical speed greater than 100 FPM is detected and the selected altitude is more than 50 feet above the current altitude.
While enroute and flying to the first descent point, the VSD will display the horizontal line that intercepts the descent at the TOD. Normally, the aircraft will be displayed at the same altitude as the horizontal line and descend at the TOD.
If the aircraft descends before the TOD, the horizontal line may or may not change at that time. If the aircraft is more than 50 NM from the TOD, and the aircraft descends, then the TOD may be removed, and the system will display the horizontal line as the aircraft altitude, highest valid constraint in the flight plan, pilot entered performance cruise altitude (only if the aircraft never reached this cruise altitude), or selected altitude, whichever is highest. If the aircraft is 10 to 50 NMs from the TOD, and the aircraft descends, then the TOD may be removed, and the system will display the horizontal line as the aircraft current altitude, highest valid constraint in the flight plan, or selected altitude, whichever is highest. Updating the cruise altitude and selected altitude to the current or lower expected altitude will likely re-display the TOD. As previously described, the TOD will always appear once 10 NM from the computed descent path. During the descent phase, the flight plan vertical profile shall match VNAV guidance.
The following climb and descent symbols can be displayed on the VSD:
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Climb/Descend Icon |
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If the active leg’s flight plan line is above the highest altitude shown on the VSD, a climb icon will be displayed to the right of the ownship symbol. 1 |
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If the active leg’s flight plan line is below the lowest altitude shown on the VSD, a descend icon will be displayed to the right of the ownship symbol. 1 |
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1This symbol will be displayed in magenta when it is supplying guidance for the active Flight Director (FD) mode, cyan when it will be used for the armed FD mode, green when it is part of the active flight plan leg but not being used for the active FD mode, and white when it is part of the preceding leg or a future leg in the flight plan. |
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