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AUTO FLIGHT
Introduction to the Autoflight System (AFS)
Overview of the AFS on the A320 Family

The Autoflight System (AFS) on the A320 family is designed to assist the pilot in flying the
aircraft within the normal flight envelope, enhancing safety and optimizing performance.
This module serves as an introduction to the AFS.

Basic Conceptual Diagram

The AFS can be represented as four main sections:

1. Computation and Processing Section (The Brain):

o This is the central processing section, which has access to several information
sources.

2. Input Devices:

o The pilots interact with the central processing section via input devices.

3. Output Devices:

o After computation and processing, commands are provided to output devices.

Flight Management Guidance Computers (FMGCs)

In the A320 family, computation and processing are carried out by two Flight Management
Guidance Computers (FMGCs). These two FMGCs are identical and normally work together.
For training purposes, they are grouped as the Flight Management Guidance System (FMGS).

Information Sources for FMGS

The FMGS receives information from the following sources:

 Navigation Information:

o Includes details of airfields, navigation aids, airways, routes, waypoints,

procedures, SIDs, STARs, approaches, missed approaches, etc.

 Aircraft Performance Information

 Air Data and Inertial Reference System (ADIRS):

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o Provides position and dynamic information.

 Global Positioning System (GPS)

 Clock and Radio Navigation Information

Pilot Input to FMGS

The pilots provide inputs to the FMGS using:

 Two Multi-Purpose Control and Display Units (MCDU):

o For long-term interventions.

 Single Flight Control Unit (FCU):

o For short-term interventions.

Outputs from FMGS

The FMGS provides outputs to:

 Flight Directors (FDs) and Autopilots (APs):

o For pitch, roll, and yaw control.

 Autothrust (A/THR):

o For thrust control.

 MCDUs and Electronic Flight Instrument System (EFIS):

o For the display of information.

 Navigation Radios:

o For the automatic tuning of radio aids.

Divisions of FMGS

The FMGS is divided into three main parts:

1. Flight Management:

o Controls navigation, flight planning, performance optimization, predictions,

and display management.

2. Flight Guidance:
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o Provides autopilot commands, autothrust commands, and flight director

commands.

3. Flight Augmentation:

o Provides flight envelope computations, wind shear detection, angle of attack

protection, and yaw functions.

Synchronization and Control Logic

As a general rule, the two FMGCs have access to information provided by on-site sensors,
except for certain parameters or in case of failures. They exchange information for validity
comparison purposes. For example:

 Information from MCDU 1 is received by FMGC 1 and transmitted to FMGC 2. All

FMGCs and MCDUs are then synchronized.

 Inputs from the FCU are fed to both FMGCs, and both FMGCs send their commands
to the FDs, autopilots, and autothrust system.

Master and Operative Channels

According to internal logic, one FMGC is declared master. For example, if Autopilot 1 is on,
FMGC 1 is the master. This determines which autothrust channel is operative.

Controls and Indicators in the Cockpit

 One Flight Control Unit (FCU)

 Two FD Push Buttons: Installed on the flight control system (FCS) control panels
and associated FCS displays.

 Two Multi-Purpose Control and Display Units (MCDU)

 Two Thrust Levers: Mainly interface with autothrust.

Conclusion

You have just reviewed the overall presentation of the Autoflight System (AFS). In the next
modules, each component will be reviewed in more detail.
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FLIGHT CONTROL UNIT

Flight Control Unit (FCU) Overview

The Flight Control Unit (FCU) serves as the interface for short-term actions with the Flight
Management Guidance System (FMGS). It is used to arm or engage guidance modes and to
select their associated targets. Additionally, it allows the pilot to set the autopilot (AP) and
auto thrust (ATHR). The FCU consists of two channels, each capable of driving the entire
FCU.

FCU Components

Center Part of the FCU

The central part of the FCU is critical for selecting targets and arming or engaging related
modes. The pilot uses this area to select targets for speed/Mach, lateral guidance (e.g.,
heading), and vertical guidance (e.g., vertical speed). The pilot also uses it to set the
autopilots and auto thrust to on.

Control Areas and Selector Knobs

The FCU features four selector knobs and associated windows, as well as two mode
engagement push buttons (with an optional third button).

General Rules:

 Turn a Selector Knob: Select a guidance target.

 Pull a Selector Knob: Engage a mode that guides the aircraft to the selected target,
known as a "selected mode." The selected target is displayed on the associated
window and PFD scale using a blue target symbol.

 Push a Selector Knob: Arm or engage a mode that guides the aircraft to a target
managed by the FMGS, known as a "managed mode." In this case, the associated
window (except the altitude one) displays dashes with a white dot.

Speed/Mach Section

The speed/Mach selector knob enables the pilot to select the target speed for the autopilot or
auto thrust. Turning the selector knob allows the pilot to select a speed, which is then
displayed in the window.
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 Pulling the Speed Knob: Engages the selected speed mode for the autopilot and/or
auto thrust, guiding the aircraft to the selected speed target.

 Pushing the Speed Knob: Engages the managed speed mode for the autopilot and/or
auto thrust, guiding the aircraft to the managed speed target profile as computed by
the FMGS. The speed window will then display dashes and an illuminated white
managed speed/Mach dot.

Speed/Mach Selection:

 The selection in the speed window can be either speed or Mach. Normally, the
transition from speed to Mach occurs automatically during the climb at around flight
level 300, and vice versa during descent.

 The pilot can toggle between speed and Mach targets by pushing the speed/Mach
push button on the FCU, with the current selection clearly indicated by a speed or
Mach legend on the display.

Lateral Area

The lateral area of the FCU, like the speed selector, includes the heading/track knob, which
can be turned, pulled, or pushed.

 Turning the Heading/Track Knob: Selects a heading or track target.

 Pulling the Heading/Track Knob: Engages the selected heading or track mode for
the autopilot/flight director.

 Pushing the Heading/Track Knob: Arms or engages the managed navigation mode
for the autopilot/flight director, guiding the aircraft along the active leg of the primary
flight plan. In this mode, the window displays dashes and an illuminated white
managed lateral dot.

Additional Controls:

 Heading/Vertical Speed Track/Flight Path Angle Push Button: Used to toggle the
display of the flight path vector (FPV or "bird") on or off on the PFD. When the
"bird" is on, the flight reference is the aircraft's trajectory. When it is off, the flight
reference is the aircraft's attitude. This toggle changes the basic guidance references
for the autopilot/flight director.
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 Attitude Reference: When the bird is off, the attitude symbol is the flight reference,
and if the flight director is on, crossbars are displayed. This is indicated by
heading/vertical speed legends on the FCU display.

 Flight Path Vector Reference: When the bird is on, the flight path vector symbol
becomes the flight reference, showing the aircraft's current trajectory. If the flight
director is on, the flight path director (FPD) is displayed, and the FCU indicates
track/flight path angle legends.

Vertical Area

The vertical area is divided into two parts: altitude and vertical speed/flight path angle
guidance modes.

Altitude Section

The altitude window always displays the target altitude, which is selected by the crew as the
next applicable clearance altitude. The altitude knob can be pulled or pushed:

 Pulling the Altitude Knob: Engages a selected vertical mode that guides the aircraft
towards the FCU-selected target altitude, disregarding any altitude constraints of the
vertical flight plan.

 Pushing the Altitude Knob: Engages a managed vertical mode, guiding the aircraft
towards the FCU-selected target altitude while matching all altitude constraints of the
vertical flight plan and following the pre-computed descent path. The white level
change light comes on.

Altitude Selector:

 The knob has two parts: an inner selector for setting the altitude target in the window,
and an outer ring for changing the altitude increments (100 feet or 1,000 feet).

Metric Altitude Push Button:

 This button displays the selected altitude in meters on the permanent data display area
at the bottom of the ECAM system display (SD).

Vertical Speed/Flight Path Angle Section

The vertical speed/flight path angle selector knob also has three functions:

 Turning the Selector Knob: Selects a target vertical speed or flight path angle.
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 Pulling the Selector Knob: Engages the selected vertical speed or flight path angle
mode.

 Pushing the Selector Knob: Commands an immediate level of vertical speed or

flight path angle equal to zero, which is then displayed in the window and on the
FMA.

Setting a Value:

 Turning the vertical speed/flight path angle selector knob displays the current flight
path angle or vertical speed in the window. For example, a minus sign indicates a
descent, while a plus sign indicates a climb.

 Pulling the selector knob engages the autopilot/flight director flight path angle
selected mode.

 The pilot can switch between flight path angle and vertical speed references by
changing the basic autopilot/flight director guidance references from flight path angle
to vertical speed.

Displaying Dashes:

 The vertical speed/flight path angle window can display dashes if a vertical managed
mode is engaged. This will be explained in more detail later in the course.

Additional FCU Push Buttons

LOC Push Button

 Arms/engages the LOC mode for localizer-only approaches or intercepting the

localizer. When LOC mode is armed/engaged, the green lights on the push button are
illuminated.

APPR Push Button

 Used to arm/engage the approach modes depending on the selected approach type in
the FMGS flight plan. When engaged, green lights come on the push button.

EXPED Push Button

 Allows the pilot to expedite the climb or descent towards the selected altitude on the
FCU. The target speed is automatically set to the best climb or descent speed to
achieve the goal. When selected, green lights come on the push button.
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Autopilot and Auto Thrust Push Buttons

 AP1/AP2 Push Buttons: Set autopilot 1 and/or autopilot 2 to on.

 Auto Thrust Push Button: Sets auto thrust to on. The push button illuminates green
when auto thrust is on or armed. Note that this button may also be used to set APs
and/or auto thrust to off, but this is not the recommended disconnection procedure in
normal operation.

Conclusion

The FCU is a selector panel with various functions that allow pilots to control the aircraft's
guidance modes. It is crucial to follow the golden rule of always knowing your Flight Mode
Annunciator (FMA) status. Any new selection made on the FCU should be confirmed on the
FMA located on the PFD.
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FLIGHT MODE ANNUNCIATOR

Cross-Checking Long-Term and Short-Term Actions

Long-term actions through the MCDU and short-term actions through the FCU must be
cross-checked on the Flight Mode Annunciator (FMA), located at the top of the PFD, as well
as on the various scales of the PFD. The guidance mode engagement arm status and their
associated guidance targets are provided on the FMA and PFD scales, including speed,
heading, and altitude.

When managed by the FMGS, the targets and modes are displayed on the FMA as the flight
progresses.

Understanding the FMA

The FMA is divided into five columns:

1. Thrust Column: Displays the auto thrust modes.

2. Vertical Modes Column: Displays the vertical modes of the autopilot and flight
directors.

3. Lateral Modes Column: Displays the lateral modes of the autopilot and flight
directors.

4. Approach Capability Column: Displays the approach capability of the autoflight

system and the radio or baro with the related value as entered on the MCDU
performance page.

5. Engagement Status Column: Displays the engagement status of the autopilot, flight
directors, and auto thrust systems.

Combined Columns for Common Modes

In certain cases, the second and third columns are combined to display a single autopilot
flight director mode, which is common laterally and vertically. These modes are common
modes for approach, meaning they are closely linked together.

FMA Line Displays

The FMA can display three lines in each column:

1. First Line: Shows the engaged modes of the flight guidance system.
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o Example: The speed mode is engaged for the auto thrust, meaning the auto
thrust will manage the thrust to track the target speed.

o Vertical Mode: The altitude (ALT) mode is engaged, meaning the autopilot
and flight directors will provide guidance to maintain altitude.

o Lateral Mode: The heading (HDG) mode is engaged, meaning the autopilot
and flight directors will provide guidance to the selected heading.

2. Second Line: Shows armed modes for the flight guidance system.

o Example: GS and LOC in blue indicate that glide slope and localizer capture
modes are armed.

3. Third Line: Shows reminders or messages, which can be spread over one or two
columns.

o Example: Columns 2 and 3 are used for a special message advising to check
the consistency of the selected approach.

Mode Change Notifications

When any mode changes on the FMA, it is boxed for a few seconds to draw the pilot’s
attention to this new status.

 Example: The aircraft is intercepting the localizer. The star after the LOC indication
means the aircraft is in the capture phase. Once established on the localizer, the
indication becomes LOC. The glide slope is still armed.

Learning More About the FMA

You will be learning more and more about the FMA in the following modules as it is
constantly used during all autoflight operations.
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FLIGHT DIRECTOR AUTO PILOT

Engaging the Autopilot

In this module, we will review how to turn the autopilots and all the Flight Directors (FDs)
on.

Autopilot Engagement

As the captain and pilot flying, the autopilot serves as an assistance tool to fly the aircraft.
The autopilot operates within the aircraft's normal flight envelope, allowing the pilot to
engage it whenever the aircraft is within this envelope.

Here, we are just airborne, above 100 feet from the ground. Engage Autopilot 1. The FMA
confirms the engagement of Autopilot 1.

As a general rule:

 When the captain is the pilot flying, Autopilot 1 is used.

 When the first officer is the pilot flying, Autopilot 2 is used.

This ensures that each autopilot is operated alternately. The autopilot can be used just after
liftoff, from around 100 feet until the end of the landing rollout.

In most cases, only one autopilot can be engaged at a time. However, in the case of an ILS
automatic approach, both autopilots may be turned on simultaneously. This ensures the best
level of redundancy required to safely achieve autolands, autorollouts, or low-altitude go-
arounds.

Engaging Both Autopilots

Once cleared for an ILS approach, the pilot presses the approach push button to arm localizer
and glide slope modes. The second autopilot may then be turned on. The AP2 push button has
been pressed to ON. The FMA confirms the engagement status of both autopilots as well as
the resulting level of redundancy achieved ("DUAL"). This will dictate the minimum possible
Decision Height (DH).

Disconnecting the Autopilot

Autopilot Disconnection
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You are now flying an automatic approach. When in sight of the runway, you decide to take
over manually. To turn the autopilot off, press the red autopilot disconnect push button, also
known as the takeover push button, located on either side stick. The weather is fine, and you
are number one for approach. Disconnect the autopilot.

Turning an autopilot off via the takeover push button triggers the following temporary
warnings:

 A cavalry charge or a warning for around one second.

 The master warning flashes for several seconds.

 An "AUTOPILOT OFF" red message appears on the right column of the engine
warning display for several seconds.

By pressing the takeover push button again, you will cancel all these warnings immediately.

Autopilot Status and FMA Indications

Notice that on the FCU, the autopilot's lights are extinguished. On the FMA, "AP1+2" is no
longer displayed. The approach capability is downgraded to CAT1, and on the ECAM
system, all warnings are now off.

The recommended technique to disengage the autopilot is to press the autopilot disconnect
push button on a side stick. They can also be disengaged by:

 Acting on the side stick or rudder pedals with a force beyond a given threshold.

 Pressing an autopilot push button on the FCU when the corresponding autopilot is on.

These last two actions lead to:

 A repetitive cavalry charge.

 A permanent activation of the master warning.

 A permanent red "AUTOPILOT OFF" warning on the left column of the engine
warning display.

This is considered by the flight guidance system as an involuntary autopilot disconnection.

Flight Director (FD) Engagement

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The flight guidance system also drives the Flight Director (FD) symbols displayed on either
PFD. The FD is an assistance tool provided to the pilots to accurately hand-fly the aircraft
along a given segment of a trajectory.

Flight Director Guidance

The FD provides guidance orders to the pilots based on the guidance modes and targets
selected on the FCU. These orders are materialized by specific symbols (e.g., crossbars).

The FD symbols are displayed on either PFD:

 The symbols on PFD1 are driven by FG1.

 The symbols on PFD2 are driven by FG2.

The engagement status of the FD is indicated on the FMA. Here, the FD symbols are called
crossbars and are referenced to the aircraft attitude symbol.

Turning Flight Directors On or Off

To turn the FD on or off, use the FD push button located on either EFIS control panel. When
an FD is on, the green bars of the corresponding push button are illuminated. Here, both FDs
are on. Let’s turn them off.

Each pilot presses their FD push button. The FD bars are removed from the PFD. The FD
engagement status is cleared on the FMA, and the FD push button green lights are
extinguished. Note that we have switched Autopilot 1 off for you.

When both autopilots and FDs are off, note that all mode fields except the one for the auto
thrust (here, MACH) are blank on the FMA.

Auto Thrust Mode Behavior

It is important to notice that if both FDs are set to OFF while autopilots are off, Auto Thrust
(if active) is automatically in speed mode or MACH mode.

Re-engaging the Flight Directors

Let’s now turn the FDs back on. Suppose that the captain presses their FD push button first,
followed by the first officer.

 Flight Director 1 On: The crossbars are displayed on PFD1. The FMA on both PFDs
indicates "1FD1" as FD engagement status, meaning that only FD1 is on.
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 Flight Director 2 On: The FD1-associated modes are shown, and the FD1 push
button illuminates in green on the EFIS control panel.

Let us now turn the first officer's FD back on. When both autopilots and FDs are off, and you
turn one of them back on again, it comes up in basic modes (e.g., Vertical Speed, Heading, or
Flight Path Angle, Track).

Both FDs are now on. The crossbars are displayed on PFD2, and both FMAs indicate "1FD2"
as FD engagement status, meaning that both FDs are on the on-site FD guidance modes. Note
that the FD2 push button illuminates in green on the EFIS control panel.

As a general rule, it is strongly recommended to set both FDs on or off at the same time.

Flight Director Symbols

Crossbars and Attitude Symbol

The FD crossbars are two independent bars referring to the aircraft attitude symbol:

 A horizontal bar indicating the pitch command.

 A vertical bar indicating the roll command.

The roll bar is replaced by a yaw bar index for takeoff and landing rollout functions from an
ILS-equipped runway. The yaw bar helps the pilot to properly track the localizer on the
ground while in low visibility conditions.

The principle of the FD crossbars has been reviewed in the EFIS module.

Flight Path Vector (FPV) and Flight Path Director (FPD)

We have seen the FD crossbar symbology referring to the aircraft attitude symbol. The other
FD symbology refers to the Flight Path Vector (FPV or "bird").

The bird can be displayed on or off from a PFD by pressing the heading/vertical
speed/track/flight path angle push button on the FCU. Click on the heading/vertical
speed/track/flight path angle push button.

Notice that on the PFD, the bird is now displayed. On the FCU, the indications have been
modified to reflect the change to track flight path angle. Let's have a closer look at the PFD.

The FPV is displayed. The crossbars are removed and replaced by the Flight Path Director
(FPD) referenced to the FPV.

Mode Changes on FMA

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In case FD bars are displayed, and the guidance modes are Vertical Speed and/or Heading,
these modes are automatically changed to track flight path angle if you select the bird on.
Have a look while we do this for you.

First, check that the FPV is displayed. You can see that the mode changes are outlined on the
FMA with white boxes. Notice also that the heading target has been changed to a properly
synchronized track target.

Manual Track Change Example

Let’s see an example of a manual track change. We will concentrate on the PFD. When flying
manually, the objective is to center and align the FPV on the FPD.

We will turn onto a track of 140°. The FPD commands a roll to turn onto the selected track.
The aircraft is rolled until the FPV and FPD are aligned. Approaching track 140°, the FPD
demands a roll to level the wings.

FPD Reversion to FD Bars

When in track flight path angle, the FPD reverts to FD bars in case of a go-around. You will
practice the use of the FPV and the FPD in the simulator.
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AUTO THRUST
Automatic Thrust Control Function

We will now look at how the flight guidance system achieves its automatic thrust control
function, known as Auto Thrust.

Auto Thrust Modes

The auto thrust system can work in two different modes:

 Speed Mode: The auto thrust continuously adjusts the thrust to maintain a target
speed or Mach, such as during cruise or approach.

 Thrust Mode: The auto thrust sets a given thrust, such as during climb or idle.

Linking Auto Thrust to Autopilot

The auto thrust modes are automatically linked to autopilot flight director vertical modes:

 Speed Mode: When the autopilot flight director vertical mode controls a trajectory
(e.g., altitude hold, vertical speed, glide slope), the auto thrust is in speed mode.

 Thrust Mode: When the autopilot flight director vertical mode adjusts the aircraft
pitch to keep a target speed or Mach (e.g., climb, descent), the auto thrust is in thrust
mode.

Auto Thrust Controls

The main auto thrust controls available to the pilots are the thrust levers.

On the Airbus fly-by-wire family, the auto thrust does not back-drive the thrust levers while it
adjusts the thrust.

Thrust Lever Quadrant

When the auto thrust is off, the pilot controls the thrust by moving the thrust levers over a
quadrant for forward thrust. This quadrant has four physical detents or stops:

 Idle

 Climb: For max climb thrust

 Flex/MCT: For flex thrust at takeoff or max continuous thrust

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 TOGA: For max takeoff or go-around thrust

Auto Thrust Operation Range

The auto thrust can only work when the thrust levers are set forward of the idle detent and up
to the climb detent (or MCT detent in case of engine failure). If the thrust levers are set in the
reverse position, the auto thrust cannot operate.

Note: The Alpha Floor function is an exception, which will be covered later on.

Thrust Lever Position and Auto Thrust

When the auto thrust is on, the thrust lever position determines the maximum thrust that can
be commanded by the auto thrust. For example, to accelerate in speed mode, the thrust lever
position is indicated by a symbol on the thrust gauge, representing the maximum thrust
available for the auto thrust.

Auto Thrust States

In normal operation, the auto thrust has three states:

1. Disconnected (Off): Auto thrust is off.

2. Armed: Ready to be set to "On" by a specific pilot action on the thrust levers.

3. Active (On): Auto thrust is actively controlling thrust.

Auto Thrust During Taxi

While taxiing to the runway, the auto thrust is necessarily disconnected. This is confirmed by
the absence of any auto thrust-related indications on the Flight Mode Annunciator (FMA) and
the extinguished auto thrust push button on the Flight Control Unit (FCU). Thrust is manually
adjusted by the crew as required to taxi the aircraft.

Auto Thrust During Takeoff

When cleared for takeoff, the pilot flying must manually set the thrust levers to flex or TOGA
to initiate the takeoff roll. As soon as the thrust levers are set in the TOGA position:

 The FMA shows "Auto Thrust Blue," indicating that auto thrust is armed.

 "Manual TOGA White" indicates that the pilot manually controls the thrust via the
thrust levers set in TOGA.

Note: TOGA is the maximum thrust available for takeoff.

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Auto Thrust Arm and Manual Control

At the same time, the auto thrust push button on the FCU illuminates in green. The fact that
the auto thrust is armed means it is ready to be engaged by a pilot action on the thrust levers.
When the auto thrust is armed, the pilot has manual control over the thrust with the thrust
levers.

Thrust Reduction and Climb Detent

Crossing the thrust reduction altitude, the pilot must manually set the thrust levers to the
climb detent. The FMA will flash "Lever Climb" to prompt the pilot to set the thrust levers
back into the climb detent.

Upon setting climb thrust, the FMA will indicate:

 Auto Thrust White: Indicates that auto thrust is on.

 Thrust Climb Green: Indicates that the auto thrust is in thrust mode since the thrust
levers are set to climb, and the autopilot commands a climb mode.

The white boxes around the modes highlight the mode change on the FMA.

Note: The autopilot 1 vertical mode adjusts the pitch to maintain the takeoff scheduled target
speed.

Auto Thrust During Climb

In normal operation, when the auto thrust is on, the levers are left in the climb detent
throughout the flight until the flare. The auto thrust adjusts the thrust as required between idle
and max climb, but the thrust levers, not being back-driven by the auto thrust, remain in the
climb detent as set by the pilots.

Acceleration and Initial Climb Speed

Crossing the acceleration altitude, the FM climb phase is initiated. The auto thrust maintains
climb thrust while the vertical mode climb adjusts the pitch to accelerate the aircraft toward
the new speed target. The initial climb speed here is 250 knots.

Manual Thrust Control

If at any moment the pilot needs additional thrust, they can push the thrust levers forward
from the climb detent and manually control the thrust. In that case:

 Man Thrust: Displayed in white on the FMA.

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 Auto Thrust: Displayed in blue, indicating that the auto thrust is armed.

Whenever the pilot brings the thrust levers back into the climb detent, the auto thrust is
automatically back on in the applicable mode.

Auto Thrust Engagement in Flight

The auto thrust may be on during flight, provided the thrust levers are set above idle to climb
detent (all engines operating) or above idle to MCT (one engine inoperative). Beyond these
detents, the pilot has manual control over the thrust.

Auto Thrust and Altitude Mode

When the aircraft reaches the target altitude, the autopilot flight director switches to altitude
mode. The auto thrust switches to speed/Mach mode as indicated on the FMA. In this mode,
the auto thrust continuously adjusts the thrust to maintain the target speed/Mach.

Auto Thrust in Approach

The auto thrust is also in speed mode when the autopilot flight director vertical modes are:

 Vertical Speed

 Flight Path Angle

 Glide Slope

This generally occurs during the approach phase.

Manual Flare with Auto Thrust

In approach, just before the flare, you fly the aircraft manually with the auto thrust engaged.
Note that the auto thrust is in speed mode.

During a hand-flown flare, the pilot must reduce the thrust for landing by bringing the thrust
levers back to idle at about 20 feet. If the pilot does not do so, the auto thrust will increase
thrust to maintain the speed. An "Auto" callout occurs at about 20 feet as a reminder to the
thrust levers.

Turning Off Auto Thrust

When the thrust levers are set to idle, this turns the auto thrust off. The FMA will no longer
display the white auto thrust indication, and the FMA auto thrust column will be blank.
Additionally, the auto thrust push button on the FCU is now extinguished.
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Auto Thrust Disconnection Procedure

We have just seen how to turn the auto thrust off by setting the thrust levers back to idle for
landing. The recommended procedure to set the auto thrust off in flight (to avoid any thrust
change at auto thrust disconnection) is:

1. Move the thrust levers back so that the thrust lever position symbol roughly matches
the present N1 or EPR.

2. Press the instinctive disconnect push button located on the thrust levers.

Note: Pressing at least one push button for more than 15 seconds will inhibit the auto thrust,
including Alpha Floor protection, for the remainder of the flight.

Turning On Auto Thrust Again

When the auto thrust is off during flight, to turn it on again, press the auto thrust push button
on the FCU with the thrust levers in or below climb detent.

Note: You can disconnect the auto thrust by pressing the auto thrust push button on the FCU.
However, this is not the standard recommended procedure.