Copyright D.P. Browne 2011

 

 

 

 

Home.Cockpit.Aircraft Systems.Worked Example.Program Controls.Before Flight.

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.