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Autoflight Flashcards

1
Q

What is the purpose of the FMGCs in relation to the autoflight system?

A

The two Flight Management and Guidance Computers (FMGCs) provide the autoflight system with two functions:
* Flight Management - Used for lateral and vertical navigation, performance optimization, navigation, navigation radio auto tuning, and display management.
* Flight Guidance - Provide commands to the AP, FD, and A/THR

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2
Q

What is the purpose of the FACs in relation to the autoflight system?

A

The two Flight Augmentation Computers (FACs), provide the autoflight system with flight envelope calculations, automatic turn coordination, and yaw damping.

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3
Q

What are the 5 columns of the FMA?

A
  1. A/THR mode
  2. Vertical guidance
  3. Lateral guidance
  4. Approach capability + minimums
  5. AP, FD, and A/THR status
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4
Q

What do the colors represent on the first 3 columns of the FMA?

A

The lines of the first three column follow a general rule:
* Engaged modes of the autoflight system are shown on line 1 in green
* Armed modes are shown on line 2 in blue or magenta

Line 3 is dedicated to presenting FMS and flight control related messages

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5
Q

The information on the FMA will not be displayed unless at least one _____ system is engaged. The FMA white box appears for _____ seconds.

A

Autoflight, 10 seconds

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6
Q

The FMA uses colors to aid in differentiating between each mode:

A
  • Green - Engaged
  • Blue - Armed
  • Magenta - Armed altitude due to a constraint
  • Red - Significant flight control degradation
  • White - Identifies approach capabilities, as well as AP/FD and A/THR status
  • Amber - Identifies A/THR and flight control abnormalities
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7
Q

If the FDs are off and a go-around is performed, they automatically display and FMA indicates _____/_____.

A

SRS, GA TRK

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8
Q

Why is it important to have both FDs on?

A

A/THR commands are based upon flight guidance; flight guidance is active if either FD is on. If the command bars are not followed, large speed deviations may occur, therefore, it is important that pilots fly with both FDs on or both FDs off.

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9
Q

What displays centerline guidance during takeoff?

A

The ground roll command bar indicates the position of the runway centerline by using the localizer to provide the flight crew with runway centerline guidance.

The roll command bar is removed when there is no lateral mode engaged or, when replaced by the ground roll guidance command bar.

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10
Q

The command bars are removed when the aircraft’s bank angle exceeds _____ degrees, or pitch exceeds _____ degrees nose up to _____ degrees nose down. Once the attitude is returned to a normal range, the flight director bars will reappear.

A

45, 25, 13

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11
Q

How would you reset flight guidance?

A

Occasionally, the FMA may display unusual modes, which may happen after an electrical power change, after engine start, or after a rejected takeoff. You may reset the flight guidance modes by resetting the FDs (OFF then ON).

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12
Q

Which FMGC is responsible for providing FMA indications and A/THR commands?

A

The master FMGC is also responsible for providing FMA indications and A/THR commands. If neither AP is engaged, FMGC 1 defaults as the master.

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13
Q

When is it possible to engage more than one AP?

A

Only 1 AP may be engaged unless during an ILS approach, an automatic landing, or during a go-around.

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14
Q

When does the AP disengage?

A

The AP will disengage when:
* When in Normal Law and any of the protections are exceeded.
* When ALPHA PROT is active
* When both thrust levers are set above FLEX/MCT and the aircraft is on the ground (prevents a touch-and-go with AP engaged)

The AP will also disengage when:
* An illuminated AP pb is pressed
* The pitch trim wheels are moved
* Force is applied to either sidestick or rudder pedals

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15
Q

When is A/THR automatically armed?

A
  • On the ground: when the thrust levers are advanced to a takeoff position
  • In-flight: when the thrust levers are advanced to TOGA with the flaps set to one or greater

If the thrust levers are set back to idle during takeoff, A/THR disengages and cannot be rearmed until the aircraft becomes airborne.

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16
Q

Will the A/THR pb illuminate if the A/THR is only armed?

A

The A/THR pb will illuminate even if the A/THR is only armed.

The FMA is the best place to determine if the A/THR is engaged.

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17
Q

Describe the Fixed mode of A/THR.

A

Fixed thrust - Airspeed is controlled with pitch, when a specific rate of climb/descent is not necessary. E.g: THR CLB, THR IDLE, THR MCT, THR LVR
* THR MCT - Used during OEI
* THR LVR - Used to indicate that the thrust levers are in a position that limits A/THR authority

Manually selected modes are only present while the A/THR system is armed. E.g: MAN TOGA, MAN FLX XX

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18
Q

Describe the Variable mode of A/THR.

A

Variable thrust - Indicated with SPEED or MACH
* During climbs and descent when a specific rate is being maintained
* As an altitude is being captured
* During level flight
* When all flight guidance is selected off, but A/THR is still active

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19
Q

What are the indications when A/THR is disconnected?

A
  • A single chime sounds
  • The MASTER CAUT lights illuminate momentarily
  • An A/THR OFF message is displayed
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20
Q

What is Thrust Lock?

A

The Thrust Lock feature alerts the flight crew that the A/THR system has disengaged in a manner that is not normal. THR LK will display on the FMA in amber and engine thrust will not change until a crew member intervenes. To avoid engine surges or changes in airspeed, quickly move the thrust levers to match current thrust output, as thrust lock disengages as soon as the thrust levers are moved.

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21
Q

What is Alpha Floor?

A

Alpha Floor is an A/THR feature designed to aid the flight crew in recovery from high AoA low airspeed situations. This feature is available in all flight phases down to 100’ RA during landing. When Alpha Floor becomes active, the A/THR system automatically increases thrust to TOGA regardless of the thrust lever position or A/THR engagement status. The aircraft must be in Normal Law. Alpha Floor is not depicted on the airspeed tape but typically occurs approximately halfway between alpha prot and alpha max but is inhibited when the TCAS mode is engaged. A. FLOOR displays on the FMA and E/WD. TOGA LK replaces A. FLOOR on the FMA when the conditions for Alpha Floor no longer exist and pilot intervention will be required to disengage TOGA thrust.

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22
Q

How would you manually place A/THR in a variable mode?

A
  • Remove all flight guidance (turn off AP and FDs)
  • Push the V/S to send a level off command to the AP/FD
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23
Q

What do the AP and FDs default to?

A

While airborne, the AP and FDs default to HDG and V/S.

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24
Q

What are the FACs?

A

Two Flight Augmentation Computers (FACs) compute flight envelope and speed function for autoflight use.

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25
Q

What do the FACs provide?

A

The FACs provide:
* Flight envelope computations
* Flight envelope protections
* Low energy warnings
* Windshear detection

The FACs also provide rudder functions to include:
* Automatic turn coordination
* Yaw damping
* Rudder trim
* Rudder limiting

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26
Q

How do the FACs calculate the flight envelope?

A

While airborne, the FACs independently compute the aircraft’s gross weight by using the AoA probes which they then use to calculate the flight envelope for the aircraft. The speeds of the envelope are displayed on the airspeed tape and include:
* VMO/MMO
* Maneuvering speeds (Green dot, S, F)
* VFE
* VLS
* Alpha prot
* Alpha max
* Airspeed trend arrow

Alpha Floor is also calculated by the FACs, but is not depicted on the tape.

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27
Q

What happens if a FAC fails?

A

If either FAC fails during flight, the other FAC automatically takes over and displays information on both PFDs. If both FACs fail, computed speeds are not shown on either PFD, and a red SPD LIM indication is displayed.

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28
Q

When does the aural warning “SPEED SPEED” sound?

A

At low altitudes and when the flaps are in configuration 2 or greater, the FACs monitor airspeed and the flight path angle for low energy conditions. If threshold warnings are reached, an aural warning “SPEED SPEED” sounds to alert the flight crew so that they can preemptively act to avoid triggering Alpha Floor.

This detection is inhibited when:
* TOGA thrust is selected
* The aircraft is below 100’ RA or above 2000’ RA
* A GPWS alert is triggered
* Alpha Floor is engaged
* In Alternate or Direct Law
* If both radio altimeters have failed

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29
Q

Which computers are responsible for detecting windshear?

A

The FACs are also responsible for detecting wind shear during takeoff and landing. The windshear warnings are only available when:
* Flaps 1 or greater is selected
* 3 seconds after liftoff up to 1300’ RA
* From 1300’ RA to 50’ RA during landing

A red WINDSHEAR alert displays on the PFD and an aural alert is heard. The FDs now command the appropriate guidance to recover from the windshear. Windshear detection and warnings are available regardless of FAC pb positioning, as long as the FACs are operational.

30
Q

Which computers provide speed guidance?

A

Speed guidance is provided by the FACs and is displayed on each PFD as a speed target which is then used by the autoflight system. Managed speed is indicated by a magenta speed triangle on the speed tape and dashes on the FCU. Managed speed requires at least one AP or FD to be engaged, except during approach. Managed speed targets consider gross weight, temp., wind, and altitude.

The SPD/MACH pb may be used only in selected speed mode.

31
Q

What is VAPP?

A

VAPP is the reference speed flown when fully configured for landing. It is automatically calculated by adding ⅓ of the headwind component as an additive to VLS, the minimum additive is 5 knots and the maximum is 15 knots.

32
Q

What is GSMINI?

A

GS mini provides windshear protection by ensuring a minimum groundspeed is flown during an approach. GS mini is calculated by subtracting the runway heading from VAPP. GS mini allows for the aircraft to fly at a faster airspeed to compensate for sudden losses of headwind. The managed speed triangle will move on the airspeed tape when GS mini is in effect. Selected speeds will override the effects of GS mini.

33
Q

When setting a heading in the FCU, it will remain in the FCU window for approximately 45 seconds. Two exceptions are:

A
  • Prior to takeoff, a heading can be preset and will remain in the FCU window until the heading knob is pulled
  • During certain approach and go-around modes, the heading can be preset and remain until the heading knob is pulled
34
Q

Can the LOC pb be used for tracking localizer backcourses?

A

The LOC pb is not used for tracking localizer backcourses, only front.

35
Q

What happens when the EXPED pb is pushed?

A

The EXPED pb can be used to increase the rate of climbs and descent. During climbs, the EXPED pb initiates a climb at green dot airspeed and ignores all constraints. During descents, it increases the aircraft’s descent speed to 340/0.80 to increase the descent rate and ignore all constraints, including 250 knots below 10k. To disengage the EXPED mode, another vertical or speed mode must be engaged (pulling for selected, pushing for managed, pulling V/S, pushing V/S).

36
Q

What is ALT CRZ?

A

The FMGS engages the “soft altitude” (SOFT ALT) mode 2 min after the cruise flight level is captured and Mach stabilized. SOFT ALT mode allows the aircraft to deviate ± 50 ft from the target altitude to minimize the thrust variation and reduce the fuel consumption.

(A320; 960-986) In the case of TA, in order to avoid spurious RA, automatically adjusts the V/S to reach the target altitude.

37
Q

When does a mode reversion occur?

A

Mode reversions can occur due to any of the following situations:
* An engaged mode can no longer be managed
* Illogical FCU altitude changes
* Excessively high or low airspeeds

When a mode reversion occurs, a triple click aural alert sounds, and a white box briefly flashes around the vertical mode.

38
Q

When NAV is not engaged, the FMGS assumes that the flight plan is not being followed and as a result when NAV disengages:

A
  • If the aircraft is in a climb, CLB reverts to OP CLB.
  • If the aircraft is in a descent, DES reverse to V/S at the aircraft’s current rate. Anytime the altitude is changed while acquiring an altitude, V/S becomes the active mode.
39
Q

What occurs if the airspeed reaches either VMAX or VLS with AP on?

A

If the airspeed approaches either VMAX or VLS, the engaged Climb mode automatically reverts to V/S. In V/S mode, the A/THR reverts to SPEED mode and reduces the thrust to recover the speed target. The FDs disengage when VMAX+4 is reached (VMAX being VMO, VLE, or VFE).

40
Q

What occurs if climbing in V/S or FPA and the vertical speed is excessive?

A

When climbing with V/S or FPA mode engaged, if the selected vertical speed is excessive, the airspeed begins to decrease. When airspeed reaches VLS, the V/S mode remains engaged; however, the AP abandons the vertical speed target and decreases pitch to maintain airspeed at VLS. The opposite happens with descents in V/S.

41
Q

What are the default modes of the FDs on the ground?

A

The default mode for the FDs on the ground are CLB and NAV. This allows for the FDs to provide correct flight guidance on takeoff and initial climb with little action from the flight crew.

If the clearance altitude hasn’t been entered in the FCU, then the default modes will be ALT and NAV.

42
Q

What is SRS?

A

Speed Reference System (SRS) is designed to provide the correct pitch attitude after liftoff and during go-arounds. V2+10 with two engines. During an engine failure, pitch commands provide a speed of V2 or the aircraft’s current speed, if higher, up to a maximum of V2+15. During go-arounds, it provides pitch guidance to maintain the airspeed that was present when the go-around was initiated, or VAPP, whichever is higher. SRS will remain active until acceleration altitude is reached if another pitch mode is not engaged.

43
Q

What is the RWY FMA?

A

RWY: If the departure runway has an associated localizer, RWY is the active lateral mode and the localizer signal is used to provide lateral guidance during the takeoff roll.
* If a heading was not pre-selected, NAV will become the active lateral mode.
* If a heading was pre-selected prior to takeoff, RWY TRK mode will engage at 30 ft after takeoff. In RWY TRK, the AP and FDs provide roll commands to maintain the current track (but not necissarily the runway centerline), automatically compensating for any wind drift.

44
Q

On the FMA, what does CAT 3 DUAL indicate?

A

CAT 3 DUAL: Indicates both APs are engaged and the system is in a Fail Operational condition. All monitored systems have redundant capabilities and if there is any system failure an autoland is still possible. If the approach capability downgrades for any reason, the Flight Warning Computers provide an aural indication and CAT 3 SINGLE will be displayed.

When CAT 3 operations are unavailable, it will typically be indicated on the STATUS page and CAT 2 will now be displayed on the FMA.

45
Q

On the FMA, what does CAT 3 SINGLE indicate?

A

CAT 3 SINGLE: Indicates that the system is in a Fail Passive condition which may occur if only one AP is engaged or one or more systems loses redundancy. If any system fails while in this condition, a manual landing is required.

When CAT 3 operations are unavailable, it will typically be indicated on the STATUS page and CAT 2 will now be displayed on the FMA.

46
Q

If neither AP is engaged during an ILS approach, what is displayed on the FMA?

A

If neither AP is engaged, CAT 1 is shown on the FMA.

47
Q

When does FINAL mode begin and end?

A

FINAL mode provides vertical guidance and engages at the blue Resume Descent arrow on the ND. The descent continues to 50’ below the minimums for the approach, at which point the AP will automatically disengage and HDG and V/S become the active modes.

48
Q

Describe the Go-Around phase.

A

The aircraft automatically enters the go-around phase when the thrust levers are advanced to TOGA and the FLAPS handle is at 1 or greater.

AP will remain engaged and SRS becomes the active pitch mode and targets the current airspeed or VAPP, whichever is higher. SRS remains active until the go-around acceleration altitude, typically 1500’ AGL. Any altitude constraints are ignored and the FCU altitude must be used to capture an altitude during a go-around.

The active lateral mode is GA TRK. GA TRK commands the existing ground track at the time go-around is engaged.

49
Q

What are the only vertical modes that will honor altitude constraints?

A

CLB and DES

50
Q

The FMGS has three (or four) modes of operation:

A
  • dual mode (the normal mode)
  • independent mode. Each FMGC being controlled by its associated MCDU
  • single mode (using one FMGC only)
  • back-up navigation mode (A319; 535-536, A320, A321)
51
Q

What is Independent Mode?

A

The system automatically selects this degraded mode under specific abnormal conditions (e.g., different database validity on both FMGCs). Both FMGCs work independently and are linked only to peripherals on their own sides of the flight deck (onside peripherals). If this occurs, INDEPENDENT OPERATION appears on both MCDU scratchpads.

52
Q

What is Single Mode?

A

The system automatically selects this degraded mode when one FMGC fails. When this occurs, the failed FMGC displays “OPP FMGC IN PROCESS” in white on the MCDU scratchpad.

SET both NDs on the same range and mode to display the same information from the operative FMGC. When convenient, RESET the failed FMGC. (Refer to COM Supplemental.)

53
Q

What is Back-up Navigation Mode?

A

The Flight Crew selects on the MCDU menu page this degraded mode when both FMGCs fail. The navigation function is recovered through the MCDU and IRS/GPS.

If both FMGCs fail, the back up navigation provides the following functions:
* Flight Planning
* Aircraft position using onside IRS, IRS 3, or GPIRS position
* F-PLN display on ND
* No AP/FD NAV mode
* Limited lateral revision
* F-PLN automatic sequencing

The MCDU continuously memorizes the active flight plan in its memory.

54
Q

What is the MIX IRS position?

A

Each FMGC receives a position from each of the three IRSs, and computes a meanweighted average called the MIX IRS position. If one of the IRSs drifts abnormally, the MIX IRS position uses an algorithm that decreases the influence of the drifting IRS within the MIX IRS position.

If one of the IRSs fails, each FMGC uses only one IRS (onside IRS or IRS3). Each IRS position and inertial speed are continuously tested. If the test fails, the corresponding IRS is rejected.

55
Q

What is the GPIRS position hiearchy?

A

The FMS selection is performed using the following hierarchy:
* Onside GPIRS position
* GPIRS 3
* Opposite GPIRS position

If the GPIRS data does not comply with an integrity criterion that is based on a Horizontal Integrity Limit (HIL) and on the automatic detection of failed satellites, the FMS rejects the GPS mode and uses the radio position update.

56
Q

What is the FM Position?

A

Each FMGC computes its own aircraft position (called the “FM position”) from a MIX IRS position, and a computed radio position or GPS position. The FMGS selects the most accurate position, considering the estimated accuracy and integrity of each positioning equipment.

GPS/INERTIAL is the basic navigation mode, provided GPS data is valid and successfully tested. Otherwise, navaids plus inertial or inertial only are used.

57
Q

The FMGC computes the optimum target speed (ECON SPD/MACH) as a function of:

A
  • gross weight (GW)
  • cost index (CI)
  • cruise flight level (CRZ FL)
  • wind and temperature models
  • performance factor
58
Q

The recommended maximum altitude is the lowest of the maximum altitude that:

A
  • The aircraft can reach with a 0.3 g buffet margin
  • The aircraft can fly in level flight at MAX CRZ rating
  • The aircraft can maintain a V/S of 300 feet/minute at MAX CLB thrust
  • The aircraft can fly, at a speed higher than Green Dot, and lower than VMO/MMO
  • The aircraft is certified at

Anti-ice is not taken into account for this computation. Refer to the QRM charts if icing conditions are expected.

59
Q

What are the PERF and IDLE factors?

A

The FMGS contains a performance database to compute the predictions and the performance data. This performance database has a model of several aircraft configurations (aircraft type/engine model) to tune the performance and the FMGS predictions. For some aircraft configurations, the model can differ from the real aircraft performance. In these cases, the FMGS has to correct the computation of the performance and the predictions. This is the aim of PERF and IDLE factors.

60
Q

What is IDLE Factor?

A

The FMGS uses the IDLE factor to adjust the computation of the vertical profile during the descent phase (IDLE segment).

The IDLE Factor adjusts the value of the given thrust by an addition of a delta (DELTA) thrust to IDLE thrust. With this additional thrust, the IDLE Factor gives flexibility to maintain the aircraft on the computed vertical profile in case of external perturbations such as windy conditions (previously entered by the Flight Crew in WIND pages).

61
Q

What is PERF Factor?

A

The FMGS uses the PERF factor to correct the predicted fuel flow that is used for the computation of the fuel predictions.

This correction is applied throughout the entire flight, and modifies the performance predictions and the ECON speed or Mach.

62
Q

What is the crossover altitude?

A

The crossover altitude is the altitude where a specific Indicated Airspeed (IAS) becomes a specific Mach number (M).

In managed speed, at the crossover altitude, the FMGC automatically changes the managed speed target to the corresponding MACH target.

63
Q

What is VLS?

A

VLS is the lowest airspeed that the autoflight system will allow the aircraft to fly in Normal Law.

64
Q

How can the flight crew exit Alpha Floor?

A

By reducing the AoA.

65
Q

What would appear on the FMA after exiting Alpha Floor?

A

TOGA LK

66
Q

How would the flight crew cancel TOGA LK?

A

Disconnect the A/THR

67
Q

What would happen if the thrust levers are not in the climb detent and the A/THR pb is selected?

A

A/THR Disconnect

Thrust Lock only occcurs when the thrust levers are in the climb detent.

68
Q

What can the flight crew do if the A/THR will not engage?

A

Change the master FMGC

69
Q

Which Laws are Alpha Floor available in?

A

Normal Law

70
Q

Is there any way in flight to disable Alpha Floor?

A

Disable A/THR by puhsing the indistinctive pbs for more than 15 seconds.

71
Q
A
72
Q
A

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