AUTO FLIGHT - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The auto-flight system is made up of the following sub-systems:

A. Flight Management and Guidance System (FMGS)
The FMGS performs the functions given below :

autopilot (AP)
flight director (FD)
autothrust (A/THR)
flight management which includes navigation, performance and processing of displays.

B. Flight Augmentation (FAC)
The FAC performs the functions given below:

yaw damper
rudder travel limiting
monitoring of the flight envelope and computations of maneuvering speed
yaw autopilot order using power loops of yaw damper and rudder trim
FAC 1: BITE function of the AFS.

** ON A/C NOT FOR ALL

2. Component Location

Layout of the AFS Components

Location of the AFS Computers

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
12CA1	SOLENOID-PITCH & ROLL LOCK, CAPT	193VU	211	22-31-00
12CA2	SOLENOID-PITCH & ROLL LOCK, F/O	182VU	212	22-31-00
** ON A/C ALL
1CA1	FMGC-1	824	127	22-83-34
1CA2	FMGC-2	84VU	128	22-83-34
1CC1	FAC-1	83VU	127	22-66-34
1CC2	FAC-2	84VU	128	22-66-34
2CA	FCU	13VU	210	22-81-12
** ON A/C NOT FOR ALL
3CA3	MCDU-3	101VU	211	22-82-12
** ON A/C ALL
3CA1	MCDU-1	11VU	210	22-82-12
3CA2	MCDU-2	11VU	210	22-82-12
9CC	CTL SW-RUDDER TRIM	110VU	210	22-62-11
8CC	P/BSW-RUD TRIM/RESET	110VU	210	22-62-12
17CC	IND-RUDDER TRIM	110VU	210	22-62-21
2CC	XDCR UNIT-YAW DAMPER POS	325BL	325	27-26-17
3CC1	SERVO ACTR-YAW DAMPER, 1	325BL	325	27-26-51
3CC2	SERVO ACTR-YAW DAMPER, 2	325BR	325	27-26-51
4CC	LIMITATION UNIT-RUDDER TRAVEL	325DL	325	27-23-51
10CC	ACTUATOR-RUDDER TRIM	325AL	325	27-22-51
7CA1	P/BSW-A/THR INST DISC, CAPT	211VU	210	22-31-00
7CA2	P/BSW-A/THR INST DISC, F/O	210VU	210	22-31-00
12CC1	P/BSW-FLT CTL/FAC1	23VU	211	22-62-00
12CC2	P/BSW-FLT CTL/FAC2	24VU	212	22-62-00
** ON A/C NOT FOR ALL
8CE1	P/BSW-TAKEOVER & PRIORITY, CAPT	191VU	211	27-92-41
8CE2	P/BSW-TAKEOVER & PRIORITY, F/O	180VU	212	27-92-41
11RN	SW-RAD PTT, CAPT	191VU	211	23-51-17
12RN	SW-RAD PTT, F/O	180VU	212	23-51-17

** ON A/C NOT FOR ALL

3. System Description

General Architecture of the AFS

AFS - Controls and Indicating

The AFS/FMS includes four computers: two FACs and two FMGCs (8 MCU each) located in the aft electronics rack 80VU.

Location of the AFS Computers

The actuators associated with the FAC are directly connected to the flight controls.
All the controls and displays are in the cockpit:
on the glareshield, overhead panel, maintenance panel and center pedestal.
The system buses which transfer the digital information of the ARINC specification 429 perform:

interconnections between the computers
connections between the computers, control units and sensors.

A. Architecture of AFS
The AFS comprises two sub-systems:

Flight Augmentation Computer system
Flight Management and Guidance Computer system.

These sub-systems include the computers, actuators, control units and associated peripherals.
There are no servo actuators for the autopilot and the autothrust functions.
The system (FMGS) sends the surface deflection commands for the autopilot function to:

ELAC 1 and ELAC 2 for pitch and roll commands
FAC 1 and FAC 2 for yaw commands.

The system (FMGS) sends the thrust command for the autothrust function to:

ECU 1 /EEC 1 (to set the thrust command on the engine 1)
ECU 2 /EEC 2 (to set the thrust command on the engine 2).

The side stick controllers and the throttle control levers do not move when the autopilot and the A/THR are engaged.

B. Controls and Indicating

AFS - Controls and Indicating

(1) Controls

FAC pushbutton switches on FLT CTL panels 23VU and 24VU
Flight Control Unit (FCU) on the glareshield
Multipurpose Control and Display Units (MCDU)
Takeover and priority pushbutton switches
A/THR instinctive disconnect pushbutton switches.

(2) Indicating and Warnings

Primary Flight Display (CAPT and F/O PFDs)
Navigation Display (CAPT and F/O NDs)
upper and lower display units of the ECAM system
rudder trim indicator on the RUD TRIM panel on the center pedestal
MASTER WARN, MASTER CAUT and AUTO LAND lights.

** ON A/C NOT FOR ALL

4. Power Supply

A. 28VDC Supply
The 28VDC power supplies:

FMGC 1 and FAC 1 through 28VDC ESS SHED BUS 801PP
FCU (side 1) through 28VDC ESS BUS 401PP
FMGC 2 , FAC 2, FCU (side 2), Rudder Trim Indicator through 28VDC BUS2 206PP
stick lock and rudder artificial feel relays through 28VDC BAT BUS 301PP.

B. 115VAC Supply
The 115VAC power supplies:

MCDU 1 through 115VAC ESS SHED BUS 801XP-A
MCDU 2 through 115VAC BUS2 202XP-C

C. 26VAC Supply
The 26VAC power supplies:

sensors associated with FAC 1 through 26VAC BUS1 431XP
sensors associated with FAC 2 through 26VAC BUS2 231XP.

D. 5VAC Supply
A 115VAC/5VAC step-down transformer provides power for the integral lighting and lighting of the LCD display.
Potentiometers control the lighting brightness.
The 5VAC power which supplies the pushbutton switches is reduced to 3VAC in DIM conditions.

E. List of the AFS circuit-breakers

-------------------------------------------------------------------------------

PANEL DESIGNATION FIN LOCATION

-------------------------------------------------------------------------------

49VU AUTO FLT/FCU/1 9CA1

121VU AUTO FLT/FCU/2 9CA2

49VU AUTO FLT/FMGC/1 10CA1

121VU AUTO FLT/FMGC/2 10CA2

49VU AUTO FLT/MCDU/1 11CA1

121VU AUTO FLT/MCDU/2 11CA2

121VU AUTO FLT/STICK/LOCK 13CA

121VU AUTO FLT/RUDDER/ARTF/FEEL 14CA

49VU AUTO FLT/FAC1/28VDC 5CC1

121VU AUTO FLT/FAC2/28VDC 5CC2

49VU AUTO FLT/FAC1/26VAC 14CC1

121VU AUTO FLT/FAC2/26VAC 14CC2

** ON A/C NOT FOR ALL

5. Interface

A. Interconnection with Peripherals
The interconnection between the FACs, the FMGCs and the peripherals makes sure that a single failure of a peripheral has no effect on the AFS/FMS functions.

B. Interconnection with Flight Controls

(1) FMGC

(a) Pitch and roll axes
The FMGC 1 and 2 send autopilot orders through output buses to the ELACs.
The ELACs then transmit deflection commands to the surfaces on the pitch and roll axes.
The ELACs use the buses from the FMGC 1 or FMGC 2 according to the autopilot engaged (AP1 has priority when both APs are engaged in ILS approach).

(b) Yaw axis
The FMGC 1 and 2 send autopilot orders to the FACs which control both yaw damper servo actuators (transient commands) and rudder trim actuator (permanent commands).
The FACs use the same priority logic as the ELACs.

(2) FAC
The FACs send yaw damper commands to two hydraulic servo actuators (one per FAC).
They also send commands to four electrical actuators for rudder trim and rudder travel limiting (one per FAC and per function).
All the servomotors operate using the automatic changeover.

C. Interconnection with Engine Controls

Interconnection Between the AFS and the Engines

The FMGCs compute and transmit data to the engines through the FCU, EIU and ECU/EEC using ARINC Specification 429 bus.
To consolidate engine data, the priority FMGC compares the output parameters from the FCU with its own available data by means of associated logic.
Each FMGC receives four ARINC buses for computation : two buses associated with the own side, two others associated with the opposite side.

** ON A/C NOT FOR ALL

6. Component Description
The AFS components (FAC,FCU,MCDU,FMGC) are described in the following topics (ATA REF):
- FAC : 22-66-00
- FCU : 22-81-00
- MCDU: 22-82-00
- FMGC: 22-83-00

** ON A/C NOT FOR ALL

7. Operation

A. Flight Augmentation (FAC)

(1) General

(a) Functions
The FAC performs the functions given below:

yaw damper
rudder trim (manual and automatic)
rudder travel limiting
monitoring of the flight envelope and computations of maneuvering speed
achievement of yaw autopilot order using power loops of yaw damper and rudder trim.

In addition the FAC 1 performs the BITE function of the AFS.

(b) Operating principles
The FAC is a dual-dual type system for yaw damper, rudder trim and rudder travel functions.
FACs 1 and 2 can be engaged at the same time through FAC 1 and FAC 2 pushbutton switches on the overhead panel. Only one system is active at a time : FAC 1 has priority, FAC 2 being in standby and synchronized on FAC 1 orders. An automatic changeover occurs on FAC 2 in case of disengagement or failure of FAC 1.
Partial changeover function per function (yaw damper, rudder trim, RTL) is possible.
When the aircraft electrical network is energized, the functions that follow will operate independently of the FAC pushbutton switches:

monitoring of the flight envelope
computation of maneuvering speed.

The FMGCs and the PFDs receive these information signals as follow:

FMGC 1 and Capt PFD normally use data from FAC 1
FMGC 2 and F/O PFD normally use data from FAC 2

In the event of failure, the FMGCs and the PFDs use the data from the active FAC.

(2) Yaw damper
The yaw damper function provides:

manual yaw stabilization.
The ELACs compute the corresponding data and transmit them to the rudder surface via the servo loop of the yaw damper (FAC).
alternate law for Dutch roll damping when the ELAC no longer computes normal yaw stabilization.
Dutch roll damping (including turn coordination) when the autopilot is engaged in cruise only.
engine failure recovery when the autopilot is engaged (the ELACs provide this function in manual flight).

(3) Rudder trim
The rudder trim function provides:

manual control via a rudder trim control switch located on the center pedestal.
In addition the ELACs compute a command signal for rudder deflection (normal yaw damping law including recovery of engine failure) performed by the trim sub-system in manual flight.
Reset of the rudder trim position is possible using a pushbutton switch located on the center pedestal.
automatic control when the autopilot is engaged which provides the accomplishment of yaw autopilot command and the recovery of engine failure.

(4) Rudder travel limitation
This function provides the limitation of the rudder travel by displacement of a stop as a function of the speed.

(5) Monitoring of flight envelope and computation of maneuvering speed
This function provides the Primary Flight Display (PFD) with the following data displayed on the speed scale:

Display of the FAC Data on the Speed Scale of the PFD

stall warning speed (VSW)
lower selectable speed (VLS)
maximum speed (V MAX)
maximum operational speed (V MAX OP) giving margin against buffeting
airspeed tendency (VC TREND)
maneuvering speed (V MAN) function of the flap and slat positions
minimum flap retraction speed (V3)
minimum slat retraction speed (V4)
predictive VFE at next flap/slat position (V FEN)
In addition :
V MAX and VLS are used in the FMGC for speed limitation of AP/FD and A/THR functions
The FAC computes the conditions of activation of the alpha floor mode of the A/THR functions (angle of attack protection in case of windshear).

(6) Windshear detection (optional)

(7) Low energy detection

(8) BITE function of the system
The FAC 1 performs BITE function of the whole AFS/FMS.
Each computer includes its own BITE function and is linked to the FAC 1.
The MCDU (linked to the CFDIU) displays the content of the maintenance data.

B. Flight Management and Guidance System (FMGS)

(1) General

(a) Functions
The FMGS performs the functions given below:

autopilot (AP)
flight director (FD)
autothrust (A/THR)
flight management which includes navigation, performance and processing of displays.

(b) Operating principles
The FMGS is a dual-dual type system for the autopilot and autothrust functions.
In cruise mode only one autopilot can be engaged.
Both APs can be engaged (through the AP1 and AP2 pushbutton switches located on the FCU) as soon as ILS approach mode is selected.
AP1 has priority, AP2 is in standby (the ELACs and the FACs use the AP1 commands first and switch on the AP2 command in case of AP1 disengagement). A single A/THR pushbutton switch located on the FCU enables engagement of the autothrust function. Both A/THRs are always engaged at the same time but only one (A/THR 1 or A/THR 2) is active depending on AP and FD engagement statuses.

-----------------------------------------------------------

! ENGAGEMENT OF AP ! ENGAGEMENT OF FD ! A/THR ACTIVE !

!---------!---------!---------!---------! !

! 1 ! 2 ! 1 ! 2 ! !

!---------!---------!---------!---------!-----------------!

! ON !ON or OFF!ON or OFF!ON or OFF! A/THR 1 !

!---------!---------!---------!---------!-----------------!

! OFF ! ON !ON or OFF!ON or OFF! A/THR 2 !

!---------!---------!---------!---------!-----------------!

! OFF ! OFF ! ON !ON or OFF! A/THR 1 !

!---------!---------!---------!---------!-----------------!

! OFF ! OFF ! OFF ! ON ! A/THR 2 !

!---------!---------!---------!---------!-----------------!

! OFF ! OFF ! OFF ! OFF ! A/THR 1 !

! ! ! ! ! (OR A/THR 2 IF !

! ! ! ! ! A/THR 1 FAIL) !

-----------------------------------------------------------

The flight director is active when the aircraft electrical network is energized. Then associated FD pushbutton switches on CAPT and F/O EFIS control sections come on. The FMGC 1 normally drives the FD symbols (crossed bars or yaw bar or flight path director symbols) on Capt PFD and the FMGC 2 normally drives the FD symbols on F/O PFD.
In case of the failure of one FMGC, the remaining FMGC drives the FD symbols on both PFDs.

AFS - FD Symbols on the PFD

The flight management system is available when the aircraft electrical network is energized.
The FMGCs work normally in dual mode on the master/slave concept.
Both FMGCs perform the same functions simultaneously and use all crew inputs on MCDU 1 or 2.
The flight management functions are performed by using normally the system input of the associated side (1 or 2).
The slave system synchronizes on the master system for the initialization of flight planning or for the modification and sequencing or for the performance modes or for the guidance modes or for the radio navigation.
The results are compared and, in case of discrepancy, the MCDU displays messages (position, weight, target speeds).
If dual mode cannot be maintained (incompatible data base...), both FMGCs revert to independent mode, i.e. each FMGC controls the MCDU of its own side.
No information is transferred from one FMGC to the other and therefore neither synchronization nor comparison can be performed.
In case of FMGC failure, the opposite FMGC takes control of MCDU 1 and 2 independently and feeds both NDs with the same data. All the functions of the flight management are available through MCDU 1 or 2.

(2) Autopilot (AP)

(a) Autopilot modes
The autopilot performs the modes given below:

cruise modes:

! Vertical Speed (V/S)

! Flight Path Angle (FPA)

! Altitude Hold (ALT)

Longitudinal ! Altitude Acquire (ALT*)

! Open Climb (OP CLB)

! Climb (CLB)

! Open Descent (OP DES)

! Descent (DES)

! Expedite (EXP)

! Heading (HDG)

Lateral ! Track (TRK)

! Lateral Navigation (NAV)

Takeoff/Go Around/Approach modes:

-------------------------------------------------------------------------------

! MODES ! PITCH AXIS ! ROLL AXIS !

!---------------------!----------------------------------!--------------------!

! ! 2 engines ! 1 engine fail ! Runway (RWY) : !

! ! operational ! ! holding of LOC !

! !----------------!-----------------! center line up to !

! TAKEOFF ! Speed Reference! SRS : holding of! 30 ft. and TRACK !

! (TO) ! System (SRS) : ! Va if Va > V2 ! after 30 ft. (not !

! ! holding of ! V2 if Va < V2 ! available on ground!

! ! V2 + 10 kt ! (*) ! for AP) !

!---------------------!----------------------------------!--------------------!

! GO AROUND ! SRS : holding of Va if Va > VAPP ! Track !

! (GA) ! VAPP if Va < VAPP (*) ! !

!---------------------!----------------------------------!--------------------!

! LOCALIZER (LOC) ! ! LOC capture & track!

!---------------------!----------------------------------!--------------------!

! ! ILS ! Glide capture and track (G/S) ! LOC capture & track!

! APPROACH ! approach ! ! Align and roll out !

!(depending!----------!----------------------------------!--------------------!

! on pilot ! non- ! Final descent (FINAL) ! Approach NAV !

!selection)! precision! ! !

! ! approach ! ! !

-------------------------------------------------------------------------------

(*) Va : Aircraft speed when the engine failure occurs

(b) Operational use

1 Engagement of system and selection of modes
The FCU enables the engagement of the AP and the selection of modes through three control panels:

the left and right side panels for the selection of modes on Capt PFD, ND and on F/O PFD, ND respectively
the center panel for the engagement of AP and A/THR and the selection of the AP/FD modes.

The FCU also enables the selection of reference parameters:

heading/track
vertical speed/flight path angle
speed/Mach
altitude.

The operating mode of the AP is in MANUAL CONTROL when the references are selected on the FCU. The AP is in AUTO CONTROL when the flight management system defines these references.
The table below defines the modes which are available in manual and auto controls.

------------------------------------------------

! AUTO CONTROL ! MANUAL CONTROL !

------------------!----------------------!-----------------------!

! ! RWY ! !

! LATERAL ! NAV ! HDG/TRK !

! ! LOC ! !

! ! TRK (GA) ! !

!-----------------!----------------------!-----------------------!

! ! SRS (TO/GA) ! ALT (AUTO ARMED) !

! VERTICAL PATH ! PROFILE ! VS/FPA !

! ! . CLB ! EXP (SPEED AUTO !

! ! . ALT CNST ! CONTROL) !

! ! . DES ! OP CLB !

! ! ! OP DES !

!-----------------!-- -------------------!-----------------------!

! SPEED ! FLT PLN REFERENCE ! FCU REFERENCE !

!-----------------!----------------------!-----------------------!

! APPROACH ! APPR RNAV/ADF/VOR ! !

! ! LAND LOC/GLIDE/FLARE/! !

! ! ALIGN/ROLLOUT/ ! !

! ! RETARD ! !

------------------------------------------------------------------

In auto control:

the corresponding reference is shown by a dashed line on the FCU (for altitude, a value is always shown).
an indicator light comes on near the corresponding reference display on the FCU.

To selection a parameter in manual control mode, you pull and turn the corresponding selector knob on the FCU.
To revert to the auto control mode, you push the corresponding selector knob.

2 Operational rule
The AP/FD or the autothrust system always maintain speed (see para. 7.B (4)).
Modification of altitude requires two actions :

select new altitude
pull the altitude selector knob (for immediate acquisition of value) or push the selector knob (for acquisition according to flight plan).
Pulling a selector knob always leads to an immediate acquisition and hold of the corresponding parameter.

(3) Flight director (FD)
Same as autopilot. In addition the TO mode is available on the ground.

(4) Autothrust (A/THR)
The autothrust function performs these modes:

speed: acquisition and hold (SPD)
Mach: acquisition and hold (MACH)
thrust: acquisition and hold of thrust limit (CLB or MCT or TO/GA)
retard: application of minimum thrust (IDLE) during flare.

(5) Flight mode annunciator (FMA)
The FMA on the upper section of the PFD provides the pilot with status data related to:

engagement of the modes of the A/THR, AP and FD systems
landing capabilities.

This section of the PFD comprises five columns of three lines each which display the various operations of the FMGC.

AFS - Annunciator of the Flight Modes on the PFD

The FMA uses different colors for the display of the annunciations and the messages.
These colors are :

green for active modes
cyan for armed modes
magenta for modes armed or engaged because of a constraint
white for engagement status of AP, FD, A/THR. The display flashes in case of automatic switching of the FMGC

amber for indications which require special attention.
The following tables show the different messages with the associated colors (G for green, C for cyan, M for magenta, R for red, A for amber, W for white).

------------------------------------------------------------------------------

! ZONE A1 ! ZONE B1 ! ZONE C1 ! ZONE D1 ! ZONE E1 !

------------------------------------------------------------------------------

! ! SRS (G) ! HDG(G) ! CAT1 (W)! AP1 (W) !

! ---------- ! ! ! ! !

! !MAN (W) ! ! ! ! ! !

! !TOGA (W)! (W) ! ALT CRZ (G) ! GA TRK(G) ! CAT2 (W)! AP2 (W) !

! ---------- ! ! ! ! !

! ! ALT CST (G) ! LOC (G) ! CAT3 (W)! AP1+2 (W)!

! ---------------- ! ! ! ! !

! !MAN (W) ! ! ! ! ! !

! !FLX (W) XX (C)! (W) ! ! ! ! !

! ---------------- ! ALT CST * (G) ! LOC * (G) ! ! !

! ! ! ! ! !

! ! V/S(G) + or - ! NAV(G) ! ! !

! ! XXXX(C) ! ! ! !

! ---------- ! ! ! ! !

! !MAN (W) ! ! ! ! ! !

! !MCT (W) ! (W) ! FPA(G) + or - ! APP NAV(G) ! ! !

! --------- ! X.X °(C) ! ! ! !

! ! ! ! ! !

! ! EXP CLB (G) ! RWY(G) ! ! !

! ---------- ! ! ! ! !

! !MAN (W) ! ! ! ! ! !

! !THR (W) ! (A) ! EXP DES(G) ! TRACK(G) ! ! !

! ---------- ! ! ! ! !

! ! G/S(G) ! RWY TRK(G) ! ! !

! -------------- ! ! ! ! !

! !A.FLOOR (G) ! (A)* ! ! ! ! !

! !------------- ! ! ! ! !

! ! G/S * (G) ! ! ! !

! ! ! ! ! !

! -------------- ! ! ! ! !

! !TOGA LK (G) ! (A)* ! CLB(G) ! ! ! !

! !------------- ! ! ! ! !

! ! DES(G) ! ! ! !

! SPEED (G) ! ! ! ! !

! ! OP CLB(G) ! ! ! !

! MACH (G) ! ! ! ! !

! ! OP DES(G) ! ! ! !

! ! ! ! ! !

! THR MCT (G) ! ! ! ! !

! ! FINAL(G) ! ! ! !

! THR CLB (G) ! ! ! ! !

! ! ALT(G) ! ! ! !

! THR LVR (G) ! ! ! ! !

! ! ALT* (G) ! ! ! !

! THR IDLE (G) ! ! ! ! !

!----------------------------------------------------------------------------!

(A)* : amber box flashing

------------------------------

! ZONE BC1 !

------------------------------

! FINAL APP(G) !

!----------------------------!

! FLARE(G) !

!----------------------------!

! ROLL OUT(G) !

!----------------------------!

! LAND(G) !

!----------------------------!

------------------------------------------------------------------------------

! ZONE A2 ! ZONE B2 ! ZONE C2 ! ZONE D2 ! ZONE E2 !

------------------------------------------------------------------------------

! ! ALT(M) ! NAV(C) ! SINGLE(W) ! !

! ! ! ! ! !

! ! ALT(C) ! APP NAV(C) ! DUAL(W) ! !

! ! ! ! ! !

! ! CLB(C) ! LOC(C) ! ! 1FD2(W) !

! ! ! ! ! !

! ! DES(C) ! ! ! 1FD1(W) !

! ! ! ! ! !

! ! G/S(C) ! ! ! 2FD2(W) !

! ! ! ! ! !

! ! FINAL(C) ! ! ! 1FD-(W) !

! ! ! ! ! !

! ! ALT(C) G/S(C) ! ! ! 2FD-(W) !

! ! ! ! ! !

! ! ALT(M) G/S(C) ! ! ! -FD1(W) !

! ! ! ! ! !

! ! ALT(C) FINAL(C) ! ! ! -FD2(W) !

! ! ! ! ! !

! ! ALT(M) FINAL(C) ! ! ! !

! ! ! ! ! !

! ! DES(C) G/S(C) ! ! ! !

! ! ! ! ! !

! ! DES(C) FINAL(C) ! ! ! !

! ! ! ! ! !

------------------------------------------------------------------------------

! ZONE A3 ! ZONE B3 ! ZONE C3 ! ZONE D3 ! ZONE E3 !

------------------------------------------------------------------------------

! ! ! ! DH(W)XXX(C) ! A/THR(W) !

! ! ! ! ! !

! LVR ASYM(A) ! ! ! NO DH(H) ! A/THR(C) !

! ! ! ! ! !

! LVR CLB (W)* ! ! ! MDA(W)XXXX(C) ! !

! ! ! ! or ! !

! LVR MCT (W)* ! ! ! MDH(W)XXXX(C) ! !

! ! ! ! ! !

------------------------------------------------------------------------------

(W)* : white wording flashing

---------------------------------

! ZONE AB3 !

---------------------------------

! SPEED SEL : XXX (C) !

! MACH SEL : .XX (C) !

---------------------------------

-----------------------------------

! ZONE BC3 !

-----------------------------------

! SET GREEN DOT SPD(W) !

! !

! DECELERATE(W) !

! !

! MORE DRAG(W) !

! !

! SET MANAGED SPD (W) !

! !

! CHECK APP SEL (W) !

! !

! SET HOLD SPD(W) !

! !

! VERT DISCONT AHEAD(A) !

! !

-----------------------------------

(6) Flight Management System (FMS)

(a) FMS Functions

1 Definition of the flight plan (lateral and vertical)

2 Lateral navigation:

initialization of ADIRS
determination of the aircraft position
follow-up of the flight plan
selection of navaids (manual or automatic).

3 Performance, computation and vertical navigation:

calculation of the optimum speed and of the characteristic speeds
calculation of predictions during the flight plan taking into account the various constraints
follow-up of the vertical flight profile
various supplementary performance calculations.

4 Management of displays:

on the MCDU
on the ND
on the PFD.

(b) Definition of the flight plan
From the navigational data stored in its mass memory, the FMGC permits (via the MCDU 1 or 2) to choose a flight plan :

through the designation of a company route number,
through the designation of the airports of origin and destination.

A company route, as defined in the mass memory may contain, in addition to the origin and destination :

the arrival, route and departure procedures,
the cruise flight level,
a cost index (ratio between the time cost and the fuel cost).

This enables the system to optimize the vertical profile of the flight.
The system then defines a flight plan. The plan is generally associated to an alternate airport.
In the absence of company routes in the memory, the initialization is made:

when the origin/destination couple is called up,
when the crew enters the procedures, cruise level and cost index data.

The MCDU consists of:

a color CRT,
an alphanumeric keyboard with functions keys.

The MCDU 1 or 2 permits, if necessary, to perform the following :

change the cruise altitude and cost index,
modify the arrival or departure procedures (STAR, SID...),
change the lateral flight plan (new route, insertion of holding etc.)
change the vertical flight plan (insertion/deletion of constraints, step climb etc.).

NOTE: The mass memory is updated every 28 days.
On aircraft, external equipment (data loader) is used to update the system.
The system stores permanently in its mass memory the two most recent navigation data updates.
The crew can enter, independently of the mass memory inserted by the load, 20 waypoints, 20 navaids, 10 runways and 3 company routes.
These specific elements are automatically cleared either at the end of each flight or when a new data bank is selected, depending on the airline choice (pin programming).
The definition of the flight plan determines in advance the type of approach to be made at the destination airport (ILS or R.NAV approach).
It is possible to define a second flight plan termed "secondary" which is not active.
This plan has the same characteristics as the active plan and is used to prepare the next flight plan (including fuel), to facilitate training and to evaluate various performance comparisons according to 2 different flight plans.

1 ADIRS initialization on the ground
The coordinates of the airport of origin are supplied to the ADIRS :

if the ADIRS are in align mode,
if an action is made on the MCDU 1 or 2 (ALIGN IRS).

The pilot can modify the coordinates stored in the mass memory.

2 Determination of the aircraft position
The aircraft position is determined from information supplied by the ADIRUs and navaids (DME and VOR).
The calculation can also be made in degraded mode, from inertial data alone.
During approach, the LOC information is used for the lateral re-alignment of the aircraft position.
An information about the accuracy of the position, as calculated by the system, is supplied to the crew.

3 Follow-up of the flight plan
The use of the autopilot or of the flight director and the selection of the lateral autocontrol function (push action on HDG/TRK selector knob on the FCU) make this follow-up possible.
Flight segments can be guided in VOR mode (selection by the crew on the MCDU).

4 Selection of navaids
The FMGC normally ensures the selection of navaids (ADF, ILS) :

automatically as a function of geographical criteria depending on the planned route and on the aircraft position.
manually from the MCDUs.

For information displayed on the ND, the selection of VOR and ILS automatically causes the selection of DME.
The selection of DME frequencies for the calculation of position is fully automatic.
In standby mode, the pilot can take control of the navaid selections side after side, through action on the RMP.

AFS - Selection of Navaids

Consequently, any FMGC selection is overridden and in particular, the management of DME frequencies is cancelled for the calculation of position by the FMGC.

(d) Performance data

1 Calculation of optimum speed
The flight management system enables to minimize the flight cost through the optimization of the speed.
The calculations are dependent on :

the flight plan,
the aircraft weight entered by the crew,
the various models of aircraft and engines stored in the mass memory.

Wind and temperature models are also taken into account for the calculations. The crew can modify these models.

2 Calculation of predictions throughout the flight plan
The vertical profile is sequenced in flight phases :

takeoff
climb
cruise
descent
approach.

The system defines a certain number of pseudo waypoints which are integrated in the flight plan.
These are :

waypoints corresponding to climb, level or descent phase,
waypoints corresponding to change of speed.

The system automatically adapts the aircraft performance :

to time constraints at a waypoint (in the flight plan there can only be one constraint at a waypoint entered by the pilot), or
to speed constraints and/or altitude constraints at various climb or descent waypoints (defined by the flight plan or entered by the pilot).

The system uses the constraints to calculate the speed, altitude, time and fuel when overflying each waypoint. The system also calculates a geographic profile for the climb and approach.

3 Follow-up of vertical profile
The use of the AP or FD enables follow-up of the vertical profile on condition that a vertical speed has not been imposed by the pilot via the FCU.
The follow-up of the optimum speed is made by the AP/FD or by the thrust control system on condition that the pilot has not imposed the speed to be followed.
The follow-up of the vertical profile and of the optimum speed can be simultaneous or independent.
During final approach, if a non-precision approach has been selected, the vertical profile is defined up to the minimum descent altitude (MDA).

4 Supplementary performance calculations
The system makes several performance calculations such as :

calculation of aircraft weight and center of gravity
management of fuel, taking into account reserves, alternate destination and hold, as provided by the fuel policy of each airline
evaluation of cost difference between a flight at constant cruise level and a flight including an intermediate change of cruise level (step-climb or step-descent)
calculation of optimum and maximum flight altitudes
same prediction and management calculations for the fuel on the secondary flight plan
specific calculations in the event of engine failure.

(e) Management of displays

AFS - Display of Flight Management Information

The flight management system displays information required for the definition and follow-up of the flight plan:

on the MCDU 1 and 2
on the NDs
on the PFDs.

1 Displays on the MCDU 1 and 2:

flight plan (waypoints, altitude procedure and estimations, speed, time, wind, fuel)
constraints of the flight plan
condition of the aircraft (absolute or relative position with respect to reference marks, weight, estimated center of gravity)
condition of the system (navigation accuracy, performance mode...)
flight phases and associated performance data
navaids used
all supplementary performance calculations.

2 Displays on the NDs:

aircraft position (identified by a symbol) and deviation with respect to the followed track
flight plans (active or secondary) defined as a function of scale and commands selected on the FCU
pseudo waypoints
various parameters (selected on the FCU by means of CSTR, WPT, VOR.D, NDB and ARPT pushbutton switches):
. constraints of the flight plan, or
. waypoints other than those of the active flight plan, or
. navaids not displayed with the flight plan, or
. NDB beacons, or
. airports other than those of the active flight plan.
VOR and/or NDB beacons selected
flight management information messages.

3 Displays on the PFDs
These messages are given to the crew for the follow-up of the flight plan:

SET VFTO, DECELERATE ...

They indicate the lateral and vertical deviations with respect to the flight plan during an NDB, VOR or RNAV approach (as an alternative to ILS deviations).
The altitude deviation with respect to the descent profile is also displayed during the descent.

[Rev.10 from 2021] 2026.03.31 23:09:48 UTC