The Flight Director (FD) functions are engaged automatically as soon as the system is electrically supplied and logic conditions are fulfilled. FD engagement is indicated on the Flight Control Unit (FCU)
by the FD P/BSW green bars and on the top right of each PFD. 1FD2 indication is displayed on each PFD to show that FD1 is engaged on the CAPT side and FD2 is engaged on the F/O side.
NOTE: On ground, as long as no AP/FD mode is active, there are no FD symbols on the PFDs.
PRINCIPLE
The FD displays the Flight Management and Guidance Computer (FMGC) guidance commands on both PFDs. In manual flight, the FD displays guidance orders to help the pilots to apply commands on the controls in order to follow the optimum flight path, which would be ordered by the AP if it was engaged. When the AP is engaged, the FD helps the FMGC demands to be checked.
The FD modes are the same as the AP modes and are selected the same way. The FMGCs calculate AP/FD orders which are transformed into symbols by the Display Management Computers (DMCs). There are two types of symbols: the FD bars, the Flight Path Director (FPD) and Flight Path Vector (FPV) symbols. The central HeaDinG-Vertical Speed (HDG-V/S)/TRacK-Flight Path Angle (TRK-FPA) P/BSW on the FCU makes the pilots switch between these two types of symbols.
FD PUSHBUTTONS
Upon FCU power up, in go around, or when losing the AP during the roll out phase of the landing, the three green bars of the FD P/BSWs come on automatically. A lit FD P/BSW means that the FD symbols can be displayed on the corresponding PFD: PFD 1 for the CAPT FD P/BSW and PFD 2 for the F/O FD P/BSW. If a lit FD P/BSW is pressed, the green bars go off. Pressing the P/BSW again puts the green bars on again. A non lit FD P/BSW means that no FD symbols can be displayed on the corresponding PFD. -FD2 is displayed on each PFD to show that no FD symbols can be displayed on PFD 1 and FD 2 is engaged on the F/O side.
FD BARS
The FD bars can be displayed provided HDG-V/S is selected on the FCU. HDG-V/S is automatically selected at system power up.
NOTE: At certain system configuration changes, the FMGCs send a command to the DMCs to make the FD bars flash for 10 seconds.
AP/FD modes are correctly followed when the FD bars are centered on the fixed aircraft model of the PFDs.
There are three FD bars:
– the pitch bar,
– the roll bar,
– and the yaw bar.
The horizontal pitch bar can be displayed if a vertical mode is active except during the roll out phase of the landing. The vertical roll bar can be displayed if a lateral mode is active. Below 30 feet RA at take-off when a LOCalizer (LOC) signal is available and during landing, the roll bar is replaced by a yaw bar index. This bar is then centered when it is just below the central yellow square.
FPD/FPV SYMBOLS
The FPD and the FPV symbols can be displayed provided TRK-FPA is selected on the FCU.
NOTE: At certain system configuration changes, the FMGCs send a command to the DMCs to make the FPD and FPV symbols flash for 10 seconds.
AP/FD modes are correctly followed when the FPD and FPV symbols are superimposed. The FPD symbol supplies command signals to intercept and fly the lateral and vertical flight path as defined by the FMGCs. The FPD symbol is removed if no guidance mode is provided by the FMGCs. The FPV symbol represents lateral and vertical flight path information in terms of current track and FPA actually being flown. The FPV symbol position is computed by the Air Data Inertial Reference System (ADIRS). NOTE: The yaw bar is identical to the FD bar case and appears with the same conditions.
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