Autoflight Flashcards
The three MCDUs and two channels for FCU provide a means for input to the
FMGS.
Each FMGS is described in four parts:
Flight Management FM, Flight Guidance FG, Flight Envelope FE and Fault isolation and detection system FIDS
The Thrust Levers are the main interface between
FMGC, Full Authority Digital Engine Control FADEC, and the Pilot
The Flight Management Guidance and Envelope System (FMGES) contains the following units:
‐ Two Flight Management Guidance and Envelope Computers (FMGEC) ‐ Three Multipurpose Control and Display Units (MCDU) ‐ One Flight Control Unit (FCU) ‐ One Flight Management source selection device.
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The FMGES has four modes of operation:
‐ Dual mode (the normal mode) ‐ Independent mode. Each FMGEC being controlled by its associated MCDU ‐ Single mode (using one FMGEC only) ‐ Back-up navigation mode.
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If each FMGEC is loaded with a different database
DO NOT SWITCH the navigation databases. MAKE the same entries on both MCDUs to have both AP/FD similar orders. Both FGs being valid, 2 APs may be engaged for CAT II or CAT III operations.
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MCDU 3 is not able to operate as back up navigation even when it replaces MCDU 1 or 2. The back up navigation mode is only accessible
on the MCDU MENU page if the FM source selector is set to NORM position.
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If the flight crew turns and does not pull a knob, it displays a value that is
the sum of the current target and the turn action value. The value remains displayed 45 s before the dashes reappear.
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The flight crew uses this pushbutton to select HDG (associated with V/S) or TRK (associated with FPA). Pushing it:
‐ Displays the Flight Path Vector (FPV) on the Primary Flight Display (PFD) or deletes it. ‐ On the PFD, changes the FD crossbar display (with the aircraft attitude as its reference) to the aircraft Flight Path Director (with the flight path vector as its reference) and vice versa. ‐ Changes heading reference into track reference in the HDG/TRK window and vice versa. ‐ Changes vertical speed reference target into flight path angle reference target in the V/S-FPA window and vice versa.
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ALT pb The flight crew uses this pushbutton to
command an immediate level-off
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Computations made by FE and FMGC are based on the gross weight information transmitted by the
FCMC (Fuel Control and Monitoring Computer).
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The FLS beam is defined by:
‐ An anchor point ‐ A course ‐ A slope.
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CI is the ratio of flight time cost (CT)
to fuel cost (CF)
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The Flight Guidance (FG) part of the FMGES controls:
‐ The Flight Director (FD) ‐ The Autopilot (AP) ‐ The Autothrust (A/THR).
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At takeoff, the managed modes engage automatically when the flight crew sets
the thrust levers at the TO or FLX detent.
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The AP/FD pitch modes can control a target SPD/MACH or a vertical trajectory, and the A/THR mode can control
a fixed thrust or a target SPD/MACH. AP/FD and A/THR cannot simultaneously control a target SPD/MACH.
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If an AP/FD pitch mode controls a vertical trajectory,
the A/THR mode controls the target SPD/MACH.
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If an AP/FD pitch mode controls a target SPD/MACH,
the A/THR mode controls the thrust.
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If no AP/FD pitch mode is engaged,
the A/THR mode reverts to controlling the SPD/MACH mode.
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AP/FD pitch modes: V/S - FPA DES (geometric path) ALT, ALT, ALT CST, ALT CST G/S*, G/S FINAL TCAS, and AP/FD OFF =
A/THR modes: SPD/MACH MOD
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AP/FD pitch modes: OP CLB/OP DES CLB/DES (idle path) SRS = A/THR modes:
THR (CLB, IDLE) MODE
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AP/FD pitch modes: FLARE = A/THR modes:
RETARD (IDLE)
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If one AP was engaged when FDs are switched OFF, this AP remains engaged in the active modes but
the FDs are no longer displayed.
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to engage the OPEN CLB/DES mode
Pull out the ALT knob
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Select a target vertical speed (V/S) and pull out
the V/S or FPA knob to engage V/S mode.
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Mode reversions are automatic mode changes that unexpectedly occur, but are designed to ensure coherent
AP, FD, and A/THR operations, in conjunction with flight crew input (or when entering a F-PLN discontinuity).
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DES mode, when engaged, reverts to V/S (FPA) mode on current value This reversion to V/S (FPA) mode on the current V/S target does not
modify the pitch behavior of the aircraft. It is the flight crew’s responsibility to adapt pitch, if necessary.
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When OPEN CLB or V/S engages following the NAV mode disengagement,
the lateral mode is boxed white for 10 s. The vertical mode is boxed white.
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If disengagement of the NAV mode is not confirmed by one of the following actions within 5 s:
‐ New FCU altitude target ‐ Level-off ‐ V/S selection then, the triple click aural warning sounds. The white box flashes around the vertical mode for additional 10 s.
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With ALT* engaged, if the target altitude is changed by any value greater than
250 ft, V/S (or FPA) engages on currents V/S (or FPA)
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If within 5 s after the reversion to V/S (or FPA) the flight crew does not confirm the altitude target change by:
‐ Pulling the ALT knob, or ‐ Setting a new V/S (or FPA) target, or ‐ Pushing the ALT pb on the FCU, then, a triple click aural warning sounds, and the V/S (or FPA) is boxed white for additional 10 s.
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FDs are engaged in an OPEN mode in climb with AP not engaged. If FDs are engaged in CLIMB, or OPEN CLIMB mode and the flight crew does not follow the FD bars to maintain the commanded climb (pitch too low and autothrust in maximum climb thrust),
the aircraft accelerates. Both FDs disengage when VMAX+4 is reached (VMAX being VMO, VLE or VFE). If the A/THR is active, it reverts to SPEED mode and reduces the thrust to recover the speed target. A triple click aural warning sounds.
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If the selected V/S value is excessive (with regards to thrust and speed), the FMGES maintains the V/S target, but the airspeed decreases. When reaching VLS (or VLS-5, if the speed target is VLS),
the AP temporarily abandons the V/S target, and automatically decreases the vertical speed to maintain VLS. The same applies, if FPA mode is used with an excessive FPA target.
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SRS mode controls pitch to steer the aircraft along
a path in the vertical plan at a speed defined by the SRS guidance law.
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The SRS mode disengages: ‐ Automatically, at the acceleration altitude (ACC ALT), or if ALT* or ALT CST* mode engages (above 400 ft RA) ‐ If the flight crew engages another vertical mode, and…
‐ If the flight crew selects a speed while in SRS mode: SRS reverts to OP CLB mode, and a triple-click aural warning is heard. Note: In Engine Out conditions, the SRS mode does not automatically disengage at EO ACC ALT.
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The SRS mode automatically engages when the thrust levers are set to the TOGA or FLX/MCT detent, or a derated level, providing:
‐ V2 has been inserted in the MCDU PERF TAKEOFF page. If V2 has not been inserted, V/S mode engages 5 s after lift-off on the current V/S value ‐ The slats are extended ‐ The aircraft has been on ground for at least 30 s.
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The SRS mode disengages:
‐ Automatically, at the acceleration altitude (ACC ALT), or if ALT* or ALT CST* mode engages (above 400 ft RA) ‐ If the flight crew engages another vertical mode ‐ If the flight crew selects a speed while in SRS mode: SRS reverts to OP CLB mode, and a triple-click aural warning is heard. Note: In Engine Out conditions, the SRS mode does not automatically disengage at EO ACC ALT.
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The SRS guidance law also includes:
‐ Attitude protection to reduce aircraft nose-up effect during takeoff (17.5 ° or 22.5 ° maximum in case of windshear) ‐ Flight path angle protection that ensures a minimum climb slope of 0.5 ° ‐ A speed protection limiting the target speed to V2+15 kt.
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The Final Descent Point (FDP) is the waypoint from which starts
the FMS segment with coded FPA. For RNAV(RNP) approaches, this point may be indicated on the chart as FDP or “VIP” Vertical Intersection Point.
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There are a considerable number of A/THR arming conditions. The following is a list of the most important ones:
‐ One FMGEC operative ‐ Two ADIRS operative ‐ Two FADECs operative ‐ One operative FCU channel ‐ All the engines are running in the same rating mode EPR or N1. - Not more than one engine in N1 degraded mode. ‐ A/THR is not manually disabled (instinctive disconnect pb has not been pressed for more than 15 s).
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ALPHA FLOOR protection is triggered when the FMGECs receive a signal elaborated by the PRIMs. This signal is sent when
the aircraft’s angle of attack is above a pre-determined threshold function of the aircraft’s configuration. A/THR is automatically activated and commands TOGA thrust, regardless of the thrust levers positions. This protection is available from liftoff to 100 ft RA in approach.
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Auto Flight System is composed by:
2 FMGC (Flight Management Guidance and Envelope Computers), 3 MCDU Multi Control and Display Units, 1 FCU Flight Control Unit, 1 Flight Management Source Selection Device
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Each PFD displays
Status Automatic modes selected , and target guidance parameters
Selected had priority over
Managed
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Long term- managed- FMS four thrust, pitch, lateral guidance - MCDU inputs
Short term:
Selected- speed, lateral, vertical inputs- not thrust, lateral, vertical of Flight plan
FM Source selector- if FMGS fails, Source selector switches
data offside MCDU + EFIS display
FMGS signals to operate Auto Pilot auto thrust:
Guidance, Flight directors + displays EFIS
FM has the following functions:
Position determination, navigation lateral Flight plan + Management navigation radios; performance optimization; predictions; display management
FMGS is described as:
Flight Management, Flight Guidance, Flight Envelope, and Fault Isolation and Detection System (FIDS)
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Flight Guidance comprises:
Auto Pilot, Auto Thrust, Flight Director
Flight Envelope has the functions:
Compute speeds VLS minimum selected speed, max VMO, VFE; monitoring flight director and Flight envelope; computation of GW and CG
The functions of FIDS are:
Maintenance data aquisition and concentration; and interface of Central Maintenance Computer (CMC)
Glareshield, next to FCU- Rose selected inputs are:
ARC,ROSE NAV, ROSE VOR, ROSE ILS, PLSN and ENG. Output displays on ND.
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Thrust levers are never
Automatically positioned.
Thrust lever positions are
Go around, Max TO, Max Cont(MCT), Flex TO (FLX), Max Climb. TO GA (go around , Max TO) / Flex MCT (flex TO(FLX) / CL (Max Climb (CL)
FM source selector enables crew to
transfer FMGEC data to the offside MCDU and EFIS in case of FM failure
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Trust levers are the auto thrust at takeoff when crew selects
FLX or TOGA
The crew can access the INIT A page for Flight Plan initialization only in the preflight phase. In flight, only
Alternate Flight Plan can be modified.
The INIT B page is not accessible after engine start.
