Predictions

The FMGC computes various predictions for estimated altitudes, speeds and times and updates them continuously during the flight. The predictions are part of the following functions:

Revisions to lateral and vertical flight plans

Current wind and temperatures

Current guidance mode

Symbol	Definition
	Level Symbol, shown at the Top Of Climb (T/C). It shows the position on the flight plan where the aircraft will reach the cruise altitude.
	Top Of Decent. This symbol shows where on the flight plan the aircraft will begin the descent flight phase.
	Start Of Climb, for a step climb.
	Start Of Descent for a step descent
	Intercept of the descent flight path. This will correspond to the vertical deviation shown on the progress page during descent.
	Speed Change symbol. This shows the point where the aircraft will initiate an automatic speed change
	Deceleration point. This is the point where the aircraft will decelerate for the approach phase. It corresponds to the (DECEL) waypoint in t he flight plan.
	Constraint symbol. This circle is placed around any waypoint that has a constraint. It is Magenta if it is deemed to be matched, else it is in amber.
	Energy Circle. This is seen only when NAV mode is not active. It represents the required distance to land, based on the FCU altitude.
	Cross track error. This shows the amount in NM that the aircraft is to the left or the right of the lateral flight path.

Type of Prediction	MCDU Page
Pseudo waypoints : T/C, T/D., SPD LIM . DECEL	Flight Plan Page A and B
Time, Speed and Alt at each waypoint	Flight Plan Page A
EFOB, Distance to destination	Flight Plan Page A and B
ETA, Distance, Waypoint FOB	Flight Plan Page B
Constraints	Flight Plan Page A and B
Altitude Error	Flight Plan Page A
Time & Distance to selected altitude	Performance Climb or Descent
Vertical Deviation	Progress Page
Fuel predictions	Fuel Pred page

These symbols appear on the Nav Display to show the predictions made by the FMGC.