DOC AIRBUS | AMM A320FCRUISE MODES - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. Engagement Principle
The engagement of the cruise modes on the AP/FD obeys the operational utilization principle of the AFS.
When the pilot wants to manually control a flight parameter, he must select the required value on the FCU then pull the associated selector knob. Then, the AP/FD mode of the manual control of this parameter is engaged.
In order to have a flight parameter controlled by the flight management part of the FMGC, the pilot must push the associated selector knob. The automatic control is then armed or activated.
The engagement of the cruise modes on the AP/FD obeys the operational utilization principle of the AFS.
When the pilot wants to manually control a flight parameter, he must select the required value on the FCU then pull the associated selector knob. Then, the AP/FD mode of the manual control of this parameter is engaged.
In order to have a flight parameter controlled by the flight management part of the FMGC, the pilot must push the associated selector knob. The automatic control is then armed or activated.
B. Engagement on the Ground
In order to facilitate the AFS test, certain cruise modes can be activated on the AP and on the FD, on the ground when the engines are stopped.
All these modes are disengaged at engine start-up on the ground and this causes the return to a configuration in conformity with the takeoff phase.
In order to facilitate the AFS test, certain cruise modes can be activated on the AP and on the FD, on the ground when the engines are stopped.
All these modes are disengaged at engine start-up on the ground and this causes the return to a configuration in conformity with the takeoff phase.
C. Synchronization of Modes Between FMGCs
So as to ensure a consistent operation of the AFS, it is mandatory to have the two FMGCs in operation with the same modes active and armed.
The logic for the selection of the FMGC which has priority takes into account the engagement of the AP, FD and A/THR functions.
This logic is indicated below.
So as to ensure a consistent operation of the AFS, it is mandatory to have the two FMGCs in operation with the same modes active and armed.
The logic for the selection of the FMGC which has priority takes into account the engagement of the AP, FD and A/THR functions.
This logic is indicated below.
| ------------------------------------------------------------------------------- |
| ! AP ENGAGEMENTS ! FD ENGAGEMENTS ! A/THR ENGAGEMENTS ! FMGC HAVING ! |
| !------------------!------------------!-------------------! PRIORITY ! |
| ! 1 ! 2 ! 1 ! 2 ! 1 ! 2 ! ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 1 ! - ! - ! - ! - ! - ! 1 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 1 ! - ! - ! - ! - ! 2 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 0 ! 1 ! - ! - ! - ! 1 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 0 ! 0 ! 1 ! - ! - ! 2 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 0 ! 0 ! 0 ! 1 ! - ! 1 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 0 ! 0 ! 0 ! 0 ! 1 ! 2 ! |
| !--------!---------!---------!--------!---------!---------!-------------------! |
| ! 0 ! 0 ! 0 ! 0 ! 0 ! 0 ! 1 (if FMGC valid) ! |
| ------------------------------------------------------------------------------- |
NOTE: - means : indifferent state
In cruise phase and on condition there is at least one AP/FD engaged, the FMGC which has priority imposes the cruise modes active and armed to the FMGC which has no priority.
In cruise phase and on condition there is at least one AP/FD engaged, the FMGC which has priority imposes the cruise modes active and armed to the FMGC which has no priority.
D. Disengagement Principle
The disengagement of a lateral mode is caused by the engagement of a new lateral mode. The disengagement of a longitudinal mode is caused by the engagement of a new longitudinal mode.
The disengagement of a lateral mode is caused by the engagement of a new lateral mode. The disengagement of a longitudinal mode is caused by the engagement of a new longitudinal mode.
2. System Description
A. Speed Control
In flight, the AFS ensures the permanent control of the SPEED/MACH parameter either through the automatic thrust control or through the AP/FD longitudinal guidance.
The purpose of the control is to acquire and hold a reference speed or Mach or to monitor the evolution of this parameter within an authorized zone, in the case of follow-up of the descent path at reduced thrust.
The speed control is:
In flight, the AFS ensures the permanent control of the SPEED/MACH parameter either through the automatic thrust control or through the AP/FD longitudinal guidance.
The purpose of the control is to acquire and hold a reference speed or Mach or to monitor the evolution of this parameter within an authorized zone, in the case of follow-up of the descent path at reduced thrust.
The speed control is:
- managed when the speed or Mach reference does not come from the FCU. In this case, the speed triangular symbol is magenta on the PFD speed scale.
- selected when this reference is the value displayed in the SPD MACH window of the FCU display. In this case, the speed triangular symbol is cyan on the PFD speed scale.
(1) Selected Speed Control
It is activated:
It is activated:
- upon energization of the FMGC in flight
- five seconds after lift-off, when no FM speed reference is available and the PITCH TAKE OFF, PITCH GO AROUND, GS TRACK and LAND TRACK modes are not engaged
- upon disengagement of two AP/FDs on condition that the aircraft is not in approach phase
- through pull action on the SPEED/MACH selector knob, on the ground with engines stopped or in flight (5 s after lift-off)
(item C) - through FMS request (acceptance of a preset value upon FMS phase change Ref. NOTE 1)
- upon the loss of FM speed reference in flight when the PITCH TAKE OFF, PITCH GO AROUND, GS TRACK and LAND TRACK modes are not engaged.
Speed Control- when the automatic speed control is selected
- upon engine start-up on the ground
- upon engagement of the AP or FD on the ground.
NOTE: The speed is preset on the MCDU.
NOTE: It is not possible to select selected speed control in the configuration : ground (takeoff), engines running, and FD engaged.
NOTE: The request for switching to selected speed will not be accepted if the SRS mode is engaged and the altitude selected on the FCU is lower than the aircraft level.
(2) Managed Speed Control
The speed control can be managed only if a speed reference is available in the FMGC.
The nature of this reference is dependent on the flight phase (V2, V Ref., speed hold reference in climb, descent and cruise).
It is activated:
It is lost when you switch to the selected speed control and on the ground, when the TAKEOFF, GO AROUND AND TRACK modes are not engaged and when the validity of V2 disappears.
The speed control can be managed only if a speed reference is available in the FMGC.
The nature of this reference is dependent on the flight phase (V2, V Ref., speed hold reference in climb, descent and cruise).
It is activated:
- on the ground:
. upon engagement of the AP or FD, with V2 available
. upon engine start-up with FD engaged and V2 available
. upon selection of V2 on the MCDU, with the FD engaged. - on the ground or in flight:
. when the SRS control law is activated due to the TAKE OFF or GO AROUND modes
NOTE: At takeoff, this mode cannot be engaged if V2 is not available.
. when you push the SPD/MACH selector knob and on condition that the reference which corresponds to the flight phase is available in the FMGC
. when the Expedite mode is engaged.
. when you push the SPD/MACH selector knob and on condition that the reference which corresponds to the flight phase is available in the FMGC
. when the Expedite mode is engaged.
It is lost when you switch to the selected speed control and on the ground, when the TAKEOFF, GO AROUND AND TRACK modes are not engaged and when the validity of V2 disappears.
(3) Speed/Mach Switching
(Ref. Para. 2.C.(3)(b))
(Ref. Para. 2.C.(3)(b))
- In automatic speed control, switching is controlled by the FM part.
- In manual speed control, the Speed/Mach switching is automatic and controlled by the FM part according to the switching altitude.
Upon switching, the FCU displays the Mach number (or speed) which corresponds to the speed (or Mach number) selected and to the switching altitude.
This automatic switching can be overriden by the pilot through action on related pushbutton switch (on the FCU) and upon switching, the display is synchronized on the A/C Mach number (or speed).
(4) Target Speed Limitations
The speed control permits to limit the target speed within a margin which guarantees the maneuverability and safety with respect to the stalling speed and maximum speed.
The lower limit is the minimum selectable speed VLS which is 30% higher than the stalling speed.
The upper limit is the maximum operating speed which corresponds to the structural limits or to buffeting.
In managed speed control, when the target speed is determined by the FM part (i.e. outside the takeoff, landing and go around phases), the lower limit is the maneuvering speed (VMAN) 45% higher than the stalling speed.
All these typical speeds are calculated by the FAC. Their definitions and the guarantees they provide are described in 22-60-00 : FAC.
The speed control permits to limit the target speed within a margin which guarantees the maneuverability and safety with respect to the stalling speed and maximum speed.
The lower limit is the minimum selectable speed VLS which is 30% higher than the stalling speed.
The upper limit is the maximum operating speed which corresponds to the structural limits or to buffeting.
In managed speed control, when the target speed is determined by the FM part (i.e. outside the takeoff, landing and go around phases), the lower limit is the maneuvering speed (VMAN) 45% higher than the stalling speed.
All these typical speeds are calculated by the FAC. Their definitions and the guarantees they provide are described in 22-60-00 : FAC.
(5) Synchronization of the SPD MACH Display of the FCU
When the managed speed control is engaged, the SPD MACH window of the FCU displays dashes and the associated automatic control light is on.
(item A)
When in managed speed control, if you turn the SPD MACH selector knob on the FCU, the FMGC causes the synchronization of the FCU SPD MACH window.
(item B)
The value to be synchronized is calculated and transmitted by the FMGC to the FCU.
Then, if the pilot pulls the SPD MACH selector knob, the manual speed control is engaged and the selected speed is taken into account.
(item C)
If the pilot does not pull the SPD MACH selector knob within the 10 s which follow the selection, the dashes are displayed again in the window and the selection is lost.
The different possibilities of synchronization are:
When the managed speed control is engaged, the SPD MACH window of the FCU displays dashes and the associated automatic control light is on.
(item A)
When in managed speed control, if you turn the SPD MACH selector knob on the FCU, the FMGC causes the synchronization of the FCU SPD MACH window.
(item B)
The value to be synchronized is calculated and transmitted by the FMGC to the FCU.
Then, if the pilot pulls the SPD MACH selector knob, the manual speed control is engaged and the selected speed is taken into account.
(item C)
If the pilot does not pull the SPD MACH selector knob within the 10 s which follow the selection, the dashes are displayed again in the window and the selection is lost.
The different possibilities of synchronization are:
(a) Display of a reference in the display window which can be caused:
- by the loss of the two FMGCs ; in this case, the window displays only the speed, and the synchronized value will be the last acquisition of the A/C speed before the loss of the two FMGCs.
- by the engagement of the manual speed control or turn action on the SPD MACH selector knob.
The synchronized value is the aircraft speed or Mach (e.g. energization of AFS or takeoff without V2).
At takeoff or in go around, the synchronized value cannot be lower than "V2 memorized" or "GA speed target".
- by acceptance of a preset value entered on the MCDU.
When the pilot presets a speed or Mach value on the MCDU for the next flight phase when there is an FMS phase change, the manual speed control is selected and this value is displayed on the FCU.
(b) Modification of the speed or Mach reference displayed in the window, caused by the FMGC:
- when the pilot has preset a speed or Mach value on the MCDU for the next flight phase, at the FMS phase change, this value is synchronized
- during climb when the aircraft reaches the SPD-to-MACH switching altitude, the synchronized value is the Mach number calculated by the FMS (Mach number which corresponds to the selected speed and to the switching altitude).
- during descent when the aircraft reaches the MACH-to-SPD switching altitude, the synchronized value is the speed calculated by the FMS.
- when the pilot causes a Speed/Mach switching through action on the related pushbutton switch (on the FCU), the synchronized value is the aircraft speed or Mach number.
NOTE: Display unit limitations:
- between 100 and 399 kts for speed
- between 0.01 and 0.99 for Mach number.
B. Lateral Modes - General
The figure gives:
The figure gives:
- the list of lateral modes active in cruise,
- the control laws and references associated with each mode.
C. Lateral Modes - Heading or Track Hold Modes (HDG/TRK)
(item A)
The choice between heading and track modes is made according to the selection made on the FCU.
After an in-flight energization, the FCU selection is HDG-V/S and the heading hold mode is engaged at the FD.
An action on the FCU related pushbutton switch causes the selection of TRK-FPA, engagement of the TRK mode and the synchronization of the HDG TRK window on the aircraft track.
A second action on the FCU related pushbutton switch causes the selection of HDG-V/S, engagement of the HDG mode and the synchronization of the HDG TRK window on the aircraft heading.
These logic is valid if the aircraft, with HDG or TRK mode active, is not turning (current target < 5 deg).
If not, an action on FCU related pushbutton switch leads to take the previous target for the new one. So the turn is not interrupted.
(item B).
(item A)
The choice between heading and track modes is made according to the selection made on the FCU.
After an in-flight energization, the FCU selection is HDG-V/S and the heading hold mode is engaged at the FD.
An action on the FCU related pushbutton switch causes the selection of TRK-FPA, engagement of the TRK mode and the synchronization of the HDG TRK window on the aircraft track.
A second action on the FCU related pushbutton switch causes the selection of HDG-V/S, engagement of the HDG mode and the synchronization of the HDG TRK window on the aircraft heading.
These logic is valid if the aircraft, with HDG or TRK mode active, is not turning (current target < 5 deg).
If not, an action on FCU related pushbutton switch leads to take the previous target for the new one. So the turn is not interrupted.
(item B).
(1) Operational use
The HDG/TRK mode can be engaged in flight through pull action on the heading/track selector knob of the FCU.
At mode engagement, the HDG TRK window of the FCU is synchronized on the aircraft heading (track).
The HDG/TRK mode enables to acquire and hold the heading (track) displayed on the FCU.
The selection on the FCU can be performed before or after the mode engagement.
In fact, with the mode not engaged, the HDG TRK window displays three dashes and if you turn the heading/track selector knob on the FCU, the window is synchronized on the aircraft heading (track).
The pilot can then select a heading (track) which will be taken into account if he engages the HDG/TRK mode.
If the mode is not engaged within 45 s following the selection, the dashes are displayed again in the window and the selection is lost.
The acquisition of the heading (track) displayed during the initial engagement is made in the shortest way. On the contrary, with the HDG/TRK mode engaged, if a change of selected heading (track) is made on the FCU, the acquisition of the new heading (track) will be made following the direction of rotation of the heading/track selector knob of the FCU for the display.
The HDG/TRK mode can be engaged in flight through pull action on the heading/track selector knob of the FCU.
At mode engagement, the HDG TRK window of the FCU is synchronized on the aircraft heading (track).
The HDG/TRK mode enables to acquire and hold the heading (track) displayed on the FCU.
The selection on the FCU can be performed before or after the mode engagement.
In fact, with the mode not engaged, the HDG TRK window displays three dashes and if you turn the heading/track selector knob on the FCU, the window is synchronized on the aircraft heading (track).
The pilot can then select a heading (track) which will be taken into account if he engages the HDG/TRK mode.
If the mode is not engaged within 45 s following the selection, the dashes are displayed again in the window and the selection is lost.
The acquisition of the heading (track) displayed during the initial engagement is made in the shortest way. On the contrary, with the HDG/TRK mode engaged, if a change of selected heading (track) is made on the FCU, the acquisition of the new heading (track) will be made following the direction of rotation of the heading/track selector knob of the FCU for the display.
(2) Elaboration of orders
This figure gives the principle of elaboration of the AP/FD orders in HDG/TRK mode.
This figure gives the principle of elaboration of the AP/FD orders in HDG/TRK mode.
(3) Operational logic
The HDG/TRACK modes are activated if one of the conditions below is met:
The HDG/TRACK modes are activated if one of the conditions below is met:
- pull action on the HDG TRK selector knob on the ground with engines shut down and in flight 5 s after lift-off
- loss of lateral flight plan, with the NAV mode active and on condition that the FINAL DES mode is not armed or active
- engagement of AP or FD in flight, with no AP/FD engaged
- loss of LOC capture or LOC track due to the loss of the LAND mode, independent of the selection of a lateral mode and of action on the LOC pushbutton switch
- loss of the NAV mode due to the loss of FINAL DES mode active or armed and independent of the selection of a lateral mode (action on the APPR pushbutton switch or selection of the V/S FPA mode)
- loss of the LOC capture or LOC Track mode not in the LAND mode through action on the LOC pushbutton switch
- arming of LOC mode, the NAV mode associated to the FINAL DES mode being active.
D. Lateral Modes - Navigation Mode (NAV)
(1) Characteristics
This mode enables the aircraft to be controlled in the horizontal plane using the commands calculated by the Flight Management (FM) section. The mode includes an arming phase, the support mode can be the HDG/TRK or RUNWAY mode and an active phase.
The NAV mode can only be active or armed if a lateral flight plan, calculated by the FM from data introduced on the MCDU, is available.
The possibilities of navigation in the horizontal plane are described in 22-72-00 Navigation/Lateral Functions.
This mode enables the aircraft to be controlled in the horizontal plane using the commands calculated by the Flight Management (FM) section. The mode includes an arming phase, the support mode can be the HDG/TRK or RUNWAY mode and an active phase.
The NAV mode can only be active or armed if a lateral flight plan, calculated by the FM from data introduced on the MCDU, is available.
The possibilities of navigation in the horizontal plane are described in 22-72-00 Navigation/Lateral Functions.
(2) Operational use
On the ground, the NAV mode is automatically armed as soon as a flight plan is available. At takeoff, the switching to active NAV occurs at 30 ft.
In the same conditions and if the radio altimeters are failed, the NAV mode becomes active 5 s after lift-off.
In flight, the NAV mode is armed through push action on the HDG TRK selector knob except if the LOC mode is active.
The NAV mode becomes active when the capture of the flight plan can be started.
The capture condition is calculated by the FM part.
The NAV mode can become active without passing through the arming phase when the pilot modifies his flight plan through the DIRECT TO procedure on the MCDU.
The arming of the NAV mode is indicated to the pilot through the illumination of the LAT indicator light on the FCU.
When the NAV mode becomes active, the light remains on and dashes are displayed in the HDG TRK window of the FCU display.
On the ground, the NAV mode is automatically armed as soon as a flight plan is available. At takeoff, the switching to active NAV occurs at 30 ft.
In the same conditions and if the radio altimeters are failed, the NAV mode becomes active 5 s after lift-off.
In flight, the NAV mode is armed through push action on the HDG TRK selector knob except if the LOC mode is active.
The NAV mode becomes active when the capture of the flight plan can be started.
The capture condition is calculated by the FM part.
The NAV mode can become active without passing through the arming phase when the pilot modifies his flight plan through the DIRECT TO procedure on the MCDU.
The arming of the NAV mode is indicated to the pilot through the illumination of the LAT indicator light on the FCU.
When the NAV mode becomes active, the light remains on and dashes are displayed in the HDG TRK window of the FCU display.
(3) Guidance
With the NAV mode active, the FM selects the lateral guidance mode and associated target.
The guidance modes available are:
With the NAV mode active, the FM selects the lateral guidance mode and associated target.
The guidance modes available are:
- horizontal path : capture and holding of path that the FM computes
- heading : holding of heading selected by the FM
- track : holding of track selected by the FM
(4) Elaboration of orders
The principle of elaboration of AP/FD orders by the heading or track holding laws has been described in the previous chapter. When the selected guidance consists in holding a horizontal path computed by the FM, the AP/FD orders are elaborated by the horizontal path law.
The principle of elaboration of AP/FD orders by the heading or track holding laws has been described in the previous chapter. When the selected guidance consists in holding a horizontal path computed by the FM, the AP/FD orders are elaborated by the horizontal path law.
NOTE: Phi N is a precommand determined by the FM. XTK and TAE are used to slave the aircraft to this predetermined path.
(5) Operational logic
The logic which enables to arm and activate the NAV mode is as follows :
The logic which enables to arm and activate the NAV mode is as follows :
(a) NAV armed
The NAV is armed if a lateral flight plan is available and if one of the conditions below is present :
The NAV is armed if a lateral flight plan is available and if one of the conditions below is present :
- push action on the heading/track selector knob except if the LOC mode is active
- aircraft on ground on condition that there is no preset heading value or any mode except the Runway mode active
- action on APPR pushbutton switch on the FCU and on condition that a RNAV approach is selected on the MCDU.
- selection of a preset heading value
- pull action on the heading selector knob
- arming of LOC mode (action on the LOC pushbutton switch)
- selection of the GO AROUND mode
- loss of the RNAV approach arming essentially due to action on the APPR pushbutton switch.
(b) NAV active
The NAV mode becomes active in presence of one of the conditions below:
The NAV mode becomes active in presence of one of the conditions below:
- the conditions of capture of the flight plan are met, with the NAV mode armed at takeoff, switching to NAV takes place at 30 ft.
- DIR TO is selected on the MCDU on condition that the LOC mode is not selected below 700 ft.
E. Lateral Modes - LOC Mode Through LOC Pushbutton Switch
(1) Characteristics
This mode enables to capture and track a LOCALIZER beam independently of the GLIDE beam.
This mode is used:
This mode enables to capture and track a LOCALIZER beam independently of the GLIDE beam.
This mode is used:
- on the airfields not provided with glide transmitters
- in the event of very noisy ILS beams (Cat. 1 beams for example).
- an arming phase,
- a capture phase,
- a track phase.
(2) Operational use
After the LOC frequency and the runway heading have been selected on the MCDU or RMP, arming of the LOC mode is controlled through push action on the LOC pushbutton switch on the FCU.
During the arming phase, the support mode must cause the aircraft to follow a path which authorizes capture of the LOC beam.
The conditions for activation of the LOC CPT and LOC TRACK modes and the associated guidance are described in 22-13-00.
Engagement of the LOC mode armed or active is indicated on the FCU through illumination of the 3 green bars on the pushbutton switch and of the LAT indicator light.
After the LOC frequency and the runway heading have been selected on the MCDU or RMP, arming of the LOC mode is controlled through push action on the LOC pushbutton switch on the FCU.
During the arming phase, the support mode must cause the aircraft to follow a path which authorizes capture of the LOC beam.
The conditions for activation of the LOC CPT and LOC TRACK modes and the associated guidance are described in 22-13-00.
Engagement of the LOC mode armed or active is indicated on the FCU through illumination of the 3 green bars on the pushbutton switch and of the LAT indicator light.
(3) Operational logic
(a) LOC mode armed
The LOC mode is armed through action on the LOC pushbutton switch and on condition that:
The LOC mode is armed through action on the LOC pushbutton switch and on condition that:
- one ILS/MMR receiver is available
- radio altitude is higher than 400 ft, (on the ground with engine stopped, this condition is overridden)
- the active modes are not TAKEOFF or GO AROUND.
- a new action on the LOC pushbutton switch (does not arm NAV automatically)
- arming of the NAV mode
- engine starting on the ground
- engagement of the go around mode.
NOTE: The engagement of the NAV mode by DIR TO selection does not disarm the LOC mode.
(b) LOC mode active
This mode becomes active when the capture conditions are met.
This mode is lost upon engagement of another lateral mode, the second action on the LOC pushbutton switch engages the HDG/ TRACK mode.
This mode becomes active when the capture conditions are met.
This mode is lost upon engagement of another lateral mode, the second action on the LOC pushbutton switch engages the HDG/ TRACK mode.
F. Longitudinal Modes - General
To ensure aircraft guidance on the longitudinal axis in AP/FD, the pilot can use:
The level change control is "managed" when the guidance parameters are determined by the FM part.
The list of longitudinal modes and sub-modes active in cruise and the control laws and associated references are given in the figure.
To ensure aircraft guidance on the longitudinal axis in AP/FD, the pilot can use:
- the modes which ensure capture and holding of a level,
- the modes which ensure control of level changes.
The level change control is "managed" when the guidance parameters are determined by the FM part.
The list of longitudinal modes and sub-modes active in cruise and the control laws and associated references are given in the figure.
G. Longitudinal Modes - Altitude Acquisition and Hold Modes
(1) Altitude acquisition mode (ALT ACQ)
(a) Characteristics
This mode permits to acquire the altitude selected in the ALT counter of the FCU or the altitude provided by the FM part when the passage of an altitude constraint in the longitudinal flight plan requires levelling of the aircraft.
The ALT ACQ mode includes an arming phase in which a support mode for level change control ensures convergence toward the desired level.
The ALT ACQ mode becomes active when the capture condition is satisfied i.e. when the aircraft altitude deviation with respect to the target level is lower than a value dependent on the vertical speed.
When the target level is actually reached, the altitude hold mode is automatically engaged and replaces the ALT ACQ mode.
This mode permits to acquire the altitude selected in the ALT counter of the FCU or the altitude provided by the FM part when the passage of an altitude constraint in the longitudinal flight plan requires levelling of the aircraft.
The ALT ACQ mode includes an arming phase in which a support mode for level change control ensures convergence toward the desired level.
The ALT ACQ mode becomes active when the capture condition is satisfied i.e. when the aircraft altitude deviation with respect to the target level is lower than a value dependent on the vertical speed.
When the target level is actually reached, the altitude hold mode is automatically engaged and replaces the ALT ACQ mode.
(b) Operational use
The ALT ACQ mode is always armed except in the cases below:
The ALT ACQ mode is always armed except in the cases below:
- in altitude hold or ALT ACQ mode
- after glide capture
- in V/S-FPA mode when the aircraft deviates from the selected altitude.
1 FCU level acquisition
With the ALT ACQ mode armed, the operating sequence is as follows:
With the ALT ACQ mode armed, the operating sequence is as follows:
- selection of a flight level on the FCU (during selection, the ALT ACQ mode is inhibited)
- engagement of a support mode which permits to reach the selected level (ALT in cyan on the FMA)
- capture of the selected level (ALT * in green on the FMA)
- switching to the altitude hold mode when the altitude deviation becomes lower than 20 ft.
- During the arming phase:
If, when the pilot stops his selection the capture condition is met, the ALT ACQ mode is immediately engaged. - During the capture phase
If, in spite of the reference change the capture condition is still met, the ALT ACQ mode remains active but a performance degradation may occur.
If the capture condition is no longer met, the V/S or FPA mode is engaged with the current aircraft Vz or FPA taken as a target at mode engagement.
2 Acquisition of an altitude constraint
With the ALT ACQ mode armed, the altitude constraint delivered by the FM part will be captured:
The condition for activation of the ALT ACQ mode is the same as for the FCU level capture.
The FMA messages associated to the modes of capture and holding of an altitude constraint are displayed in magenta.
If the conditions required to follow the flight plan disappear (loss of NAV mode or loss of longitudinal flight plan) during the capture, the AP/FD switches to the V/S FPA mode and holds the A/C vertical speed.
The FCU level capture is armed again.
With the ALT ACQ mode armed, the altitude constraint delivered by the FM part will be captured:
- if it is located between the level selected on the FCU and the aircraft level
- and if the support mode is a mode for automatic control of level changes.
The condition for activation of the ALT ACQ mode is the same as for the FCU level capture.
The FMA messages associated to the modes of capture and holding of an altitude constraint are displayed in magenta.
If the conditions required to follow the flight plan disappear (loss of NAV mode or loss of longitudinal flight plan) during the capture, the AP/FD switches to the V/S FPA mode and holds the A/C vertical speed.
The FCU level capture is armed again.
(c) Barometric correction
The captured altitude is dependent on the barometric correction selected on the FCU.
Depending on the standard or BARO selection made on the associated side of the FCU:
The captured altitude is dependent on the barometric correction selected on the FCU.
Depending on the standard or BARO selection made on the associated side of the FCU:
- each FMGC utilizes either the standard altitude or the corrected altitude of the barometric pressure that the ADCs supply.
Thus, in BARO (QNH) selection, the captured altitude corresponds to an altitude with respect to the sea level.
In standard selection, the captured altitude corresponds to a level in the standard atmosphere.
(d) Elaboration of orders
In order to be sure that the level is reached, a fixed value Zo = plus or minus 40 ft brings an adequate correction to the target altitude.
In order to homogenize the duration of capture according to the initial VZBI and to avoid overshoots, the gain FVZ is elaborated with the initial VZ and kept constant during the phase.
In order to be sure that the level is reached, a fixed value Zo = plus or minus 40 ft brings an adequate correction to the target altitude.
In order to homogenize the duration of capture according to the initial VZBI and to avoid overshoots, the gain FVZ is elaborated with the initial VZ and kept constant during the phase.
(e) Operational logic
1 Altitude acquire mode armed.
The ALT ACQ mode can be armed provided that:
The ALT ACQ mode can be armed provided that:
- The modes below are not active:
ALT ACQ
ALT
G/S Capture
G/S Track
Final Des
Land Track
V/S FPA when the selected V/S FPA reference is such that the aircraft deviates from the selected altitude reference.
PITCH TO or PITCH GA when FCU level is lower than aircraft level. - After FCU level capture, a new level is selected or there is a difference greater than 250 ft between the aircraft level and the level selected on the FCU.
2 Altitude acquire mode active
With the ALT ACQ mode armed, the ALT ACQ mode is activated if one of the conditions below is present:
With the ALT ACQ mode armed, the ALT ACQ mode is activated if one of the conditions below is present:
- the capture condition of the FCU level is met.
In this case, the light which indicates the automatic level change on the FCU will go off. - the condition for capture of the altitude constraint provided by the FMS is met.
NOTE: The altitude acquisition mode is inhibited when a level is selected or below 400 ft with the Pitch Takeoff or Pitch Go Around modes active.
(2) Altitude hold mode (ALT HOLD)
(a) Characteristics
This mode permits to hold the altitude selected on the FCU or the altitude constraint delivered by the FM part.
This mode permits to hold the altitude selected on the FCU or the altitude constraint delivered by the FM part.
(b) Operational use
The engagement of the ALT mode is automatic when, with the ALT ACQ mode active, the difference between the aircraft altitude and the target altitude becomes lower than 20 ft.
The level held in ALT mode is the altitude memorized upon engagement of the mode. Then it is not affected by a change of reference in the ALT window of the FCU display or by a change of barometric correction.
With the ALT mode active on the FD, engagement of the AP causes:
- engagement of the ALT ACQ mode and capture of the selected level if the difference between the selected level and the aircraft level is lower than 250 ft.
- if, at AP engagement, the difference between the aircraft level and the selected level is greater than 250 ft., the AP holds the altitude obtained after cancellation of the vertical speed.
The engagement of the ALT mode is automatic when, with the ALT ACQ mode active, the difference between the aircraft altitude and the target altitude becomes lower than 20 ft.
The level held in ALT mode is the altitude memorized upon engagement of the mode. Then it is not affected by a change of reference in the ALT window of the FCU display or by a change of barometric correction.
With the ALT mode active on the FD, engagement of the AP causes:
- engagement of the ALT ACQ mode and capture of the selected level if the difference between the selected level and the aircraft level is lower than 250 ft.
- if, at AP engagement, the difference between the aircraft level and the selected level is greater than 250 ft., the AP holds the altitude obtained after cancellation of the vertical speed.
(c) Elaboration of orders
The Delta Vc curve corresponds to the "ALT Soft" mode.
In the case of flight at high speeds in ALT mode on the AP/FD and Mach hold by the autothrust, it is permitted, if disturbances are present, to have a plus or minus 50 ft altitude variation in order to keep the speed constant and then minimize fuel consumption.
The Delta Vc curve corresponds to the "ALT Soft" mode.
In the case of flight at high speeds in ALT mode on the AP/FD and Mach hold by the autothrust, it is permitted, if disturbances are present, to have a plus or minus 50 ft altitude variation in order to keep the speed constant and then minimize fuel consumption.
(d) Operational logic
The altitude hold mode becomes active if, with the altitude acquire mode engaged, the condition for changing to the altitude mode is met.
When the altitude mode is active, it can engage two different sub-modes:
The altitude hold mode becomes active if, with the altitude acquire mode engaged, the condition for changing to the altitude mode is met.
When the altitude mode is active, it can engage two different sub-modes:
1 Vertical speed: this sub-mode is activated when the AP is engaged, with the altitude mode already active on the flight director.
This control mode cancels the aircraft vertical speed using the vertical speed control law.
This control mode cancels the aircraft vertical speed using the vertical speed control law.
2 Altitude: this sub-mode is engaged:
- when the altitude mode is activated,
- when the vertical speed is cancelled with the vertical speed sub-mode engaged.
- This control mode uses the ALT HOLD control law and its reference is one of the altitudes defined below:
- The reference altitude of the altitude acquire mode when the altitude mode is activated.
- The aircraft altitude when the vertical speed is cancelled as a result of AP engagement with the mode active on the flight director.
NOTE: As the ALT HOLD control law uses the IRS ZBI parameter, the level hold is not disturbed by a barometric pressure change (QNH or QFE) or Baro/standard switching.
H. Longitudinal Modes - Manual Control Modes for Level Changes
The three manual control modes for level changes are:
The three manual control modes for level changes are:
- V/S - FPA
- OPEN CLB, OPEN DES
- EXP CLB, EXP DES.
(1) Vertical speed hold mode or flight path hold mode (V/S or FPA) - General
The choice between the V/S and FPA modes depends on the selection made on the FCU and is described in Para. 2. B. (1).
At each switching, the V/S FPA window of the FCU display is synchronized on the aircraft parameter.
The choice between the V/S and FPA modes depends on the selection made on the FCU and is described in Para. 2. B. (1).
At each switching, the V/S FPA window of the FCU display is synchronized on the aircraft parameter.
(2) Vertical speed hold mode or flight path hold mode (V/S or FPA) - Characteristics
The V/S FPA mode permits to acquire and hold the vertical speed or flight path displayed in the V/S FPA window of the FCU display.
The speed hold must be ensured by the thrust control.
The V/S FPA mode permits to acquire and hold the vertical speed or flight path displayed in the V/S FPA window of the FCU display.
The speed hold must be ensured by the thrust control.
(3) Vertical speed hold mode or flight path hold mode (V/S or FPA) - Operational use
The V/S FPA mode is automatically engaged, upon in-flight energization of the FMGC, through FD engagement.
The V/S FPA mode can be engaged through pull action on the corresponding FCU selector knob.
This action will cause synchronization of the V/S FPA window on the aircraft parameter which will be used as a reference.
A preselection of vertical speed or flight path angle is possible when you turn the related selector knob.
This causes the synchronization of the V/S FPA window on the aircraft parameter.
This value can then be modified.
If the V/S FPA mode is not engaged within the 45 seconds which follow the end of the preselection, the latter is lost.
With the ALT mode active on the AP/FD, the V/S FPA mode can be engaged even if the selected altitude has not been modified.
This means that with this mode it is possible to deviate from the level selected on the FCU (in this case, the ALT ACQ mode is not armed).
If the pilot engages the AP while the V/S FPA mode is engaged on the F/D alone, the FCU window is synchronized on the aircraft parameter.
Then, even if the pilot has not followed the flight director, engagement of the AP does not cause any sharp modification of the aircraft flight path.
The V/S FPA mode is automatically engaged, upon in-flight energization of the FMGC, through FD engagement.
The V/S FPA mode can be engaged through pull action on the corresponding FCU selector knob.
This action will cause synchronization of the V/S FPA window on the aircraft parameter which will be used as a reference.
A preselection of vertical speed or flight path angle is possible when you turn the related selector knob.
This causes the synchronization of the V/S FPA window on the aircraft parameter.
This value can then be modified.
If the V/S FPA mode is not engaged within the 45 seconds which follow the end of the preselection, the latter is lost.
With the ALT mode active on the AP/FD, the V/S FPA mode can be engaged even if the selected altitude has not been modified.
This means that with this mode it is possible to deviate from the level selected on the FCU (in this case, the ALT ACQ mode is not armed).
If the pilot engages the AP while the V/S FPA mode is engaged on the F/D alone, the FCU window is synchronized on the aircraft parameter.
Then, even if the pilot has not followed the flight director, engagement of the AP does not cause any sharp modification of the aircraft flight path.
NOTE: When the aircraft performances no longer permit to ensure speed or Mach hold considering the great V/S or FPA values selected, the OPEN CLB or OPEN DES mode is engaged automatically (Ref. Para. 2.C.(3)(b)).
(4) Vertical speed hold mode or flight path hold mode (V/S or FPA) - Altitude hold in V/S FPA mode
When the pilot selects 00 in the V/S FPA window of the FCU, the AP/FD provides a guidance in V/S FPA mode which permits to hold the altitude obtained after cancellation of the vertical speed.
This type of guidance is cancelled as soon as the selected parameter becomes again different from zero.
When it is active, the ALT indication appears on the FMA.
When it is active, and when the DMC CPIP3 is pin programmed, the VS=0 or FPA=0 indication appears on the FMA.
This feature is achieved via a pushing action on the vertical speed/flight path angle selector knob (PUSH TO LEVEL OFF).
When the pilot selects 00 in the V/S FPA window of the FCU, the AP/FD provides a guidance in V/S FPA mode which permits to hold the altitude obtained after cancellation of the vertical speed.
This type of guidance is cancelled as soon as the selected parameter becomes again different from zero.
When it is active, the ALT indication appears on the FMA.
When it is active, and when the DMC CPIP3 is pin programmed, the VS=0 or FPA=0 indication appears on the FMA.
This feature is achieved via a pushing action on the vertical speed/flight path angle selector knob (PUSH TO LEVEL OFF).
(5) Vertical speed hold mode or flight path hold mode (V/S or FPA) - Elaboration of orders
(6) Vertical speed hold mode or flight path hold mode (V/S or FPA) - Operational logic
The V/S FPA modes are activated if one of the conditions below is met:
The V/S FPA modes are activated if one of the conditions below is met:
- pull action on the V/S FPA selector knob on the ground, with the engine shut down or, in flight 5, seconds after lift-off
- engagement of one AP or FD in flight with no AP/FD previously engaged
- engagement of one AP in flight with no longitudinal mode active
- loss of GS capture or GS track mode due to the loss of LAND mode independent of the selection of a longitudinal mode (Ref. landing mode)
- loss of the FINAL DES mode independent of the selection of a longitudinal mode (action on the APPR pushbutton switch or loss of the active NAV mode) (Ref. R. NAV approach mode)
- loss of the NAV, LOC CPT and LOC TRACK modes or of the longitudinal flight plan in the DES or IM DES modes (Ref. level-change automatic-control modes)
- activation, by the FM part, of a flight phase incompatible with the active mode of the level-change automatic control (activation of the climb, takeoff or go around phase with DES or IM DES mode active).
- with the ALT ACQ mode active :
. loss of FCU level capture conditions after selection of a new FCU target, or
. activation of capture conditions of a lost altitude constraint - with the DES, IM DES, EXP DES or OPEN DES mode active :
the FCU level is set above the aircraft level (the target is the current aircraft vertical speed or flight path angle at the engagement of the V/S FPA mode) - with the CLB, IM CLB, EXP CLB or open CLB mode active :
the FCU level is set below the aircraft level (the target is the current aircraft vertical speed or flight path angle at the engagement of the V/S FPA mode) - in descent modes (DES, IM DES, EXP DES, OPEN DES, F.DES) the aircraft speed becomes lower than VLS-2 kts (or VLS-17 kts if speedbrakes are extended) (speed protections exist with FD only engaged and A/THR active, when FD bars command is not carried out)
- in climb modes (CLB, IM CLB, EXP CLB, OPEN CLB) the aircraft speed becomes higher than VMAX+4 kts (speed protections exist with FD only engaged and A/THR active, when FD bars command is not carried out).
(7) Level change OPEN CLB/OPEN DES mode - General
(8) Level change OPEN CLB/OPEN DES mode - Characteristics
This mode enables to make level changes and minimize pilot actions.
The engagement of this mode activates:
This mode enables to make level changes and minimize pilot actions.
The engagement of this mode activates:
- holding of the speed or target Mach on the AP/FD
- command of a fixed thrust by the A/THR
. either limit thrust in climb
. or reduced thrust in descent.
(9) Level change OPEN CLB/OPEN DES mode - Operational use
The level change mode is engaged through pull action on the altitude selector knob on the FCU whatever the longitudinal mode active, except landing mode.
If the level selected in the ALT window of the FCU is higher than the aircraft level, the OPEN CLB mode is engaged and ensures the climb.
If the selected level is lower than the aircraft level, the OPEN DES mode is engaged and ensures the descent.
The attempt of engagement of the OPEN CLB and OPEN DES modes will not be taken into account if the mode active is ALT HOLD and if the selected altitude has not been modified.
The OPEN CLB (OPEN DES) mode is lost and V/S FPA mode engaged when FCU level is set below (above) aircraft level.
The OPEN CLB or OPEN DES mode is engaged automatically to ensure speed protection of the V/S FPA modes. When the V/S or FPA selected values are such that the aircraft performance no longer permits to maintain speed and if the stipulated minimum or maximum speeds are reached, engagement of OPEN CLB/OPEN DES mode permits to return to speed control on the AP/FD.
For level changes smaller than 1200 ft in OPEN CLB mode with A/THR active, the guidance is provided by the AP/FD in vertical speed mode ( + 1000 ft/mn reference), with the A/THR controlling the speed.
This type of guidance avoids large thrust variations which are obtained through the successive activation of ALT-OPEN-ALT ACQ modes.
The level change mode is engaged through pull action on the altitude selector knob on the FCU whatever the longitudinal mode active, except landing mode.
If the level selected in the ALT window of the FCU is higher than the aircraft level, the OPEN CLB mode is engaged and ensures the climb.
If the selected level is lower than the aircraft level, the OPEN DES mode is engaged and ensures the descent.
The attempt of engagement of the OPEN CLB and OPEN DES modes will not be taken into account if the mode active is ALT HOLD and if the selected altitude has not been modified.
The OPEN CLB (OPEN DES) mode is lost and V/S FPA mode engaged when FCU level is set below (above) aircraft level.
The OPEN CLB or OPEN DES mode is engaged automatically to ensure speed protection of the V/S FPA modes. When the V/S or FPA selected values are such that the aircraft performance no longer permits to maintain speed and if the stipulated minimum or maximum speeds are reached, engagement of OPEN CLB/OPEN DES mode permits to return to speed control on the AP/FD.
For level changes smaller than 1200 ft in OPEN CLB mode with A/THR active, the guidance is provided by the AP/FD in vertical speed mode ( + 1000 ft/mn reference), with the A/THR controlling the speed.
This type of guidance avoids large thrust variations which are obtained through the successive activation of ALT-OPEN-ALT ACQ modes.
(10) Level change OPEN CLB/OPEN DES mode - Speed/Mach switching
In climb mode and manual speed control, the Speed-to-Mach switching is automatic and commanded by the FM part, when the aircraft reaches the switching altitude computed by the FM part, depending on the selected speed.
The corresponding Mach value which corresponds to the switching altitude and displayed on the CLB page of the MCDU is synchronized in the SPD MACH window of the FCU display.
Similarly, in descent mode when the aircraft reaches the switching altitude, the FM part commands the change to speed control, and the speed which corresponds to the Mach number selected and to the switching altitude is synchronized in the FCU window.
This automatic switching can be overridden by the pilot via the related pushbutton switch on the FCU and on switching, the window is synchronized with the aircraft Mach number or speed.
In climb mode and manual speed control, the Speed-to-Mach switching is automatic and commanded by the FM part, when the aircraft reaches the switching altitude computed by the FM part, depending on the selected speed.
The corresponding Mach value which corresponds to the switching altitude and displayed on the CLB page of the MCDU is synchronized in the SPD MACH window of the FCU display.
Similarly, in descent mode when the aircraft reaches the switching altitude, the FM part commands the change to speed control, and the speed which corresponds to the Mach number selected and to the switching altitude is synchronized in the FCU window.
This automatic switching can be overridden by the pilot via the related pushbutton switch on the FCU and on switching, the window is synchronized with the aircraft Mach number or speed.
(11) Level change OPEN CLB/OPEN DES mode - Elaboration of orders
The principle consists in splitting the aircraft total energy into two parts:
The principle consists in splitting the aircraft total energy into two parts:
- 70% for acceleration or deceleration
- 30% for climb or descent.
The total flight path gamma T is the checking parameter.
Upon engagement of the OPEN CLB mode and during establishment of the limit thrust to IDLE, the AP/FD guidance is ensured by the vertical speed law (Reference equal to + 8000 ft/mn).
This type of guidance improves the load factor and speed hold performance during the thrust transient.
In the cases below: - A/THR disengaged or not active,
- deceleration commanded in climb,
(12) Level change OPEN CLB/OPEN DES mode - Operational logic
The OPEN CLB and OPEN DES modes can only be engaged if the conditions below are met:
The OPEN CLB and OPEN DES modes can only be engaged if the conditions below are met:
- the ALT ACQ mode can be armed
- the aircraft is on the ground (engines stopped) or in flight for more than 5 seconds
- the LAND TRACK mode is not active
- the FCU level is above the aircraft level (engagement of OPEN CLB mode) or below the aircraft level (engagement of OPEN DES mode).
- pull action on the altitude selector knob
- with CLB or IM CLB mode active :
. switching to Descent, or
. Approach phase, or
. loss of NAV mode or loss of flight profile validity. - Selection of the manual speed control, when in EXP, takeoff or go around mode (Ref. EXP mode, if fitted)
- the acceleration altitude reached is an armed CLB mode on condition that the NAV mode is not active or the flight profile is not valid (Ref. CLB mode).
- pull action on the altitude selector knob
- selection of manual speed control with the EXP mode engaged (Ref. EXP mode).
- V/S Sel or FPA Sel >0 and speed lower than or equal to VLS + 5kts.
- or V/S Sel or FPA Sel <0 and speed greater than or equal to VMAX - 5kts in clean configuration or VMAX +4kts in flap and slat extended configuration.
NOTE: The speed protection is active 5 seconds after light-off but is inactive if a speed protection from OPEN to V/S FPA mode occurred less than 30 seconds before.
(13) Expedite (EXP) mode - General
(a) Characteristics
The EXP mode permits to perform level changes with the maximum flight path angle in climb as well as in descent.
During climb, the engagement of this mode activates holding of the maneuvering speed on the AP/FD and command of the limit thrust by the A/THR.
During descent, the engagement of the mode activates holding of the maximum operating speed and command of reduced thrust (IDLE) by the A/THR.
The EXP mode permits to perform level changes with the maximum flight path angle in climb as well as in descent.
During climb, the engagement of this mode activates holding of the maneuvering speed on the AP/FD and command of the limit thrust by the A/THR.
During descent, the engagement of the mode activates holding of the maximum operating speed and command of reduced thrust (IDLE) by the A/THR.
(b) Operational use
1 Engagement
The expedite mode can be engaged through action on the EXPED pushbutton switch on the FCU on condition that :
The choice between the EXP CLB or EXP DES mode is based on the aircraft position with respect to the FCU level.
With this mode engaged, the altitude constraints imposed by the FMS are not taken into account and the following appears on the FCU:
The expedite mode can be engaged through action on the EXPED pushbutton switch on the FCU on condition that :
- the level selected on the FCU differs from the aircraft level,
- the target speed delivered by the FM part is available.
- the maneuvering speed in climb,
- the maximum operating speed in descent.
The choice between the EXP CLB or EXP DES mode is based on the aircraft position with respect to the FCU level.
With this mode engaged, the altitude constraints imposed by the FMS are not taken into account and the following appears on the FCU:
- the light for automatic change control is off
- the green bars on the EXPED pushbutton switch are on
- the light for automatic level change control is on.
2 Disengagement
The EXP mode can be disengaged:
When these modes are active, the guidance is essentially dependent on the target speed of the automatic speed control.
The guidance can then no longer be ensured if the manual speed control is selected through engagement of any other longitudinal mode.
The EXP mode can be disengaged:
- through pull action on the speed selector knob which switches the speed control to manual mode and engages the OPEN CLB or OPEN DES mode.
When these modes are active, the guidance is essentially dependent on the target speed of the automatic speed control.
The guidance can then no longer be ensured if the manual speed control is selected through engagement of any other longitudinal mode.
(c) Elaboration of orders
In EXP mode, the AP/FD orders are elaborated by the SPD/Mach law.
The A/THR operates in THRUST mode and commands a fixed thrust.
In EXP mode, the AP/FD orders are elaborated by the SPD/Mach law.
The A/THR operates in THRUST mode and commands a fixed thrust.
(d) Operational logic
The EXP mode is engaged through action on the EXPED pushbutton switch of the FCU and on condition that:
The EXP mode is engaged through action on the EXPED pushbutton switch of the FCU and on condition that:
- the aircraft has been flying for at least 5 seconds or is on the ground with engines shut down,
- the ALT ACQ mode can be armed,
- the LAND TRACK mode is not active.
I. Longitudinal Modes - Level-Change Managed Modes
(1) General
The level-change managed modes ensure guidance by the AP/FD.
This permits to follow the longitudinal flight plan elaborated in the flight management part.
These modes can be armed or active and when active, it is the FM part which selects the type of guidance and the values of target parameters.
The CLB mode can be armed or active during the takeoff, go around, climb and cruise phases on condition that the level selected on the FCU is higher than the aircraft level.
The DES mode can be armed or active during the cruise, descent and approach phases on condition that the level selected on the FCU is lower than the aircraft level.
The level-change managed modes ensure guidance by the AP/FD.
This permits to follow the longitudinal flight plan elaborated in the flight management part.
These modes can be armed or active and when active, it is the FM part which selects the type of guidance and the values of target parameters.
The CLB mode can be armed or active during the takeoff, go around, climb and cruise phases on condition that the level selected on the FCU is higher than the aircraft level.
The DES mode can be armed or active during the cruise, descent and approach phases on condition that the level selected on the FCU is lower than the aircraft level.
(2) Characteristics
With the CLB or DES modes active, the flight management part selects one of the five modes of guidance below:
This last type of guidance can only be activated if the managed speed control is selected.
If this is the case, the FM part performs a "loose" speed hold which consists in checking that this parameter moves within a determined interval.
Whatever the guidance selected, the target parameter values (thrust, flight path angle, vertical speed, longitudinal path, Speed/Mach in automatic speed control) are determined by the FM part.
Only the speed or Mach can be imposed by the pilot if manual speed control is selected.
In automatic speed control, the target speed and Mach are the optimum speed and Mach values computed as according to
The cost index which is the ratio between the time cost and the fuel cost indicates to what extent one of these parameters must be privileged with respect to the other.
The CAS/Mach switching is commanded by the FM part when the aircraft reaches the switching altitude which corresponds to the optimum speed and Mach of the managed speed control.
The elaboration of the longitudinal flight plan and control in the vertical plane are described in 22-73-00 - Performance/Vertical Functions.
With the CLB or DES modes active, the flight management part selects one of the five modes of guidance below:
| - SPEED/THRUST : . target speed or Mach hold by the AP/FD |
| . fixed thrust commanded by the A/THR |
| - V PATH/SPEED : . flight path follow-up, computed |
| by the FM part, by the A/THR |
| - FPA/SPEED : . flight path angle hold by the AP/FD |
| . speed or Mach hold by the A/THR |
| - V.S/SPEED : . vertical speed hold by the AP/FD |
| . speed or Mach hold by the A/THR |
| - V.PATH/THRUST : . flight path follow-up, computed |
| by the FM, by the AP/FD |
| . fixed thrust commanded by the A/THR. |
This last type of guidance can only be activated if the managed speed control is selected.
If this is the case, the FM part performs a "loose" speed hold which consists in checking that this parameter moves within a determined interval.
Whatever the guidance selected, the target parameter values (thrust, flight path angle, vertical speed, longitudinal path, Speed/Mach in automatic speed control) are determined by the FM part.
Only the speed or Mach can be imposed by the pilot if manual speed control is selected.
In automatic speed control, the target speed and Mach are the optimum speed and Mach values computed as according to
- weight,
- weather conditions,
- cost index
The cost index which is the ratio between the time cost and the fuel cost indicates to what extent one of these parameters must be privileged with respect to the other.
The CAS/Mach switching is commanded by the FM part when the aircraft reaches the switching altitude which corresponds to the optimum speed and Mach of the managed speed control.
The elaboration of the longitudinal flight plan and control in the vertical plane are described in 22-73-00 - Performance/Vertical Functions.
(3) Operational use - General
(4) Operational use - Engagement
The engagement of the level-change managed modes is possible only if a longitudinal flight plan is available in the flight management part and if the horizontal NAV mode is active on the AP/FD.
The CLB or DES mode is engaged or armed through push action on the altitude knob on the FCU.
When the CLB and DES modes are active:
The engagement of the level-change managed modes is possible only if a longitudinal flight plan is available in the flight management part and if the horizontal NAV mode is active on the AP/FD.
The CLB or DES mode is engaged or armed through push action on the altitude knob on the FCU.
When the CLB and DES modes are active:
- dashes are displayed in the V/S FPA window of the FCU display,
- the white LVL/CH light comes on on the FCU display.
(5) Operational use - Arming of the CLB and DES modes
The level-change managed modes enable to meet the altitude constraints which may appear in the longitudinal flight plan.
When the capture of an altitude constraint requires leveling off of the aircraft the ALT ACQ mode is activated and the CLB or DES mode is armed.
The altitude constraint is displayed in magenta on the altitude scale of the PFD together with the ALT or ALT * messages armed or active on the FMA.
When the constraint is released, the FM part commands the activation of the CLB or DES mode for continuation of the flight plan.
The level-change managed modes enable to meet the altitude constraints which may appear in the longitudinal flight plan.
When the capture of an altitude constraint requires leveling off of the aircraft the ALT ACQ mode is activated and the CLB or DES mode is armed.
The altitude constraint is displayed in magenta on the altitude scale of the PFD together with the ALT or ALT * messages armed or active on the FMA.
When the constraint is released, the FM part commands the activation of the CLB or DES mode for continuation of the flight plan.
(6) Operational use - Disengagement
The managed level-change control modes are disengaged if there is a discontinuity in the longitudinal flight plan or if the NAV mode is lost.
The same situation is present if the flight phase determined by the FM part becomes incompatible with the CLB or DES mode active.
In these conditions, the reversionary mode engaged at the AP/FD will be V/S-FPA and synchronization of the vertical speed/flight path angle in the FCU display will permit to avoid an abrupt change of flight path, except in CLB where the reversionary mode will be OPEN CLB.
These conditions also cause disarming of the CLB or DES modes when the AP/FD is in altitude hold mode on a constraint.
Finally, the CLB and DES modes active are lost if another longitudinal mode is engaged at the AP/FD or if the pilot selects a level on the FCU lower than the aircraft-in-climb level or higher than the aircraft-in-descent level (Ref. V/S FPA modes).
The managed level-change control modes are disengaged if there is a discontinuity in the longitudinal flight plan or if the NAV mode is lost.
The same situation is present if the flight phase determined by the FM part becomes incompatible with the CLB or DES mode active.
In these conditions, the reversionary mode engaged at the AP/FD will be V/S-FPA and synchronization of the vertical speed/flight path angle in the FCU display will permit to avoid an abrupt change of flight path, except in CLB where the reversionary mode will be OPEN CLB.
These conditions also cause disarming of the CLB or DES modes when the AP/FD is in altitude hold mode on a constraint.
Finally, the CLB and DES modes active are lost if another longitudinal mode is engaged at the AP/FD or if the pilot selects a level on the FCU lower than the aircraft-in-climb level or higher than the aircraft-in-descent level (Ref. V/S FPA modes).
(8) Utilization in takeoff or go around phase - Arming of CLB mode
On the ground, before takeoff, the CLB mode is armed as soon as the pilot selects a flight plan via the MCDU.
During takeoff, the support mode is Pitch Takeoff which ensures guidance at the AP/FD up to the acceleration altitude.
In these conditions, the ALT ACQ mode is also armed but is not displayed on the FMA.
The CLB mode is not armed if an altitude constraint susceptible of being met or the altitude selected on the FCU appears in the flight plan at an altitude lower than the acceleration altitude.
In these conditions, the armed mode displayed on the FMA is ALT ACQ.
In go around phase, arming of the CLB mode obeys the same rules as in the takeoff phase. The only difference is that the CLB mode armed appears only when the Pitch-Go-Around mode is engaged on the AP/FD.
On the ground, before takeoff, the CLB mode is armed as soon as the pilot selects a flight plan via the MCDU.
During takeoff, the support mode is Pitch Takeoff which ensures guidance at the AP/FD up to the acceleration altitude.
In these conditions, the ALT ACQ mode is also armed but is not displayed on the FMA.
The CLB mode is not armed if an altitude constraint susceptible of being met or the altitude selected on the FCU appears in the flight plan at an altitude lower than the acceleration altitude.
In these conditions, the armed mode displayed on the FMA is ALT ACQ.
In go around phase, arming of the CLB mode obeys the same rules as in the takeoff phase. The only difference is that the CLB mode armed appears only when the Pitch-Go-Around mode is engaged on the AP/FD.
(9) Utilization in takeoff or go around phase - Activation
When the aircraft reaches the acceleration altitude with the CLB mode armed, the FM part commands the activation of the climb phase. This results at level of the AP/FD in the activation:
If the FCU level or the first altitude constraint is lower than the acceleration altitude, the acceleration and climb phases are started upon engagement of the ALT ACQ mode and the aircraft accelerates in level flight.
When the aircraft reaches the acceleration altitude with the CLB mode armed, the FM part commands the activation of the climb phase. This results at level of the AP/FD in the activation:
- of the CLB mode if the automatic level-change control can be engaged and particularly if the NAV mode is active on the AP/FD (lateral mode)
- of the OPEN CLB mode in the other cases, particularly if the HDG/TRK mode is active on the AP/FD (lateral mode) or if the heading preset value is selected.
If the FCU level or the first altitude constraint is lower than the acceleration altitude, the acceleration and climb phases are started upon engagement of the ALT ACQ mode and the aircraft accelerates in level flight.
(10) Utilization in takeoff or go around phase - Speed preset for the climb phase
The pilot can preset a speed value for the climb phase when he does not want to use the optimum speed of the automatic speed control.
This preset value is introduced on the CLB page of the MCDU then displayed on this page and on the FMA with the CLB armed message.
When the acceleration altitude is reached, the manual speed control is automatically selected. The preset value is synchronized in the FCU SPD window and then becomes the new target speed for the acceleration and climb phase.
The pilot can preset a speed value for the climb phase when he does not want to use the optimum speed of the automatic speed control.
This preset value is introduced on the CLB page of the MCDU then displayed on this page and on the FMA with the CLB armed message.
When the acceleration altitude is reached, the manual speed control is automatically selected. The preset value is synchronized in the FCU SPD window and then becomes the new target speed for the acceleration and climb phase.
NOTE: The same procedure enables the pilot to preset a Mach value for the cruise phase.
The Mach preset is displayed on the FMA adjacent to the ALT mode armed when the aircraft flies the segment preceding activation of the cruise phase (Ref. 22-70-00 Flight Management System).
The Mach preset is displayed on the FMA adjacent to the ALT mode armed when the aircraft flies the segment preceding activation of the cruise phase (Ref. 22-70-00 Flight Management System).
(11) Elaboration of orders
The control law, flight path, vertical speed and Speed/Mach principles have been described previously.
When the selected guidance is V.PATH/SPEED or V.PATH/THRUST, the AP/FD orders are elaborated by the vertical path follow-up law.
The control law, flight path, vertical speed and Speed/Mach principles have been described previously.
When the selected guidance is V.PATH/SPEED or V.PATH/THRUST, the AP/FD orders are elaborated by the vertical path follow-up law.
(12) Operational logic - General
(13) Operational logic - CLB mode armed
The climb mode is armed:
The climb mode is armed:
- on the ground or when the takeoff and go around modes are engaged, provided that the conditions below are met:
. no mode active except the takeoff or go around mode
. the FCU level or the lowest FMS constraint likely to be respected is above the acceleration level defined (with NAV mode active or armed)
. the acceleration level is valid - in flight, except during the descent and approach phases and on condition that:
. the NAV mode is active
. the FCU level is higher than the aircraft level
. the flight profile is valid and one of the following conditions below is met:
.. capture of an altitude constraint provided by the FMS
.. push action on the altitude selector knob with ALT ACQ mode, ALT mode or ALT submode of the V/S - FPA mode active and provided that the FM permits arming of CLB mode.
NOTE: The climb mode is disarmed by one of the conditions below:
- conditions for arming the climb mode on the ground or in takeoff and go around modes not met
- engagement of the V/S, FPA, EXP (if fitted), CLB, DES, GS CAPTURE, OPEN CLB, OPEN DES, ALT ACQ (FCU level) modes
- FCU level lower than the aircraft level
- FCU level reduced to the FMS constraint with the ALT or ALT ACQ mode active
- loss of NAV mode with ALT or ALT ACQ mode active
- switching to descent or approach phase
- loss of flight profile validity with the ALT or ALT ACQ mode active.
(14) Operational logic - Climb mode active
The conditions required for the climb in automatic level-change control are as follows:
The conditions required for the climb in automatic level-change control are as follows:
- FCU level above the aircraft level
- arming of the ALT ACQ mode possible
- five seconds after lift off
- descent and approach phases not active
- NAV mode active
- flight profile valid
- G/S TRACK, LAND TRACK modes not active.
- acceleration altitude reached with the CLB mode armed
- altitude constraint met with the CLB mode armed
- IM CLB mode is engaged by pushing action on the altitude selector if :
. The ALT ACQ or ALT mode or ALT submode of V/S - FPA mode is not active
. The ALT ACQ or ALT mode or ALT submode of V/S FPA mode is active, the CLB mode is not armed and the FMS does not permit arming of CLB mode.
(15) Operational logic - DES mode armed
The DES mode is armed except in takeoff or go around phases and on condition that :
The DES mode is armed except in takeoff or go around phases and on condition that :
- FCU level lower than the aircraft level
- NAV, LOC CPT, LOC TRACK modes active
- flight profile available
- capture of an altitude constraint provided by the FMS
- push action on the altitude selector knob, with ALT ACQ mode, ALT mode or ALT submode active and provided that FMS enables arming of DES mode.
- engagement of the V/S, FPA, EXP (if fitted), DES, G/S CPT, FINAL DES, GO AROUND, OPEN CLB, OPEN DES modes
- FCU level higher than the aircraft level
- loss of NAV, LOC CPT, LOC TRACK modes
- switching to takeoff, go around or climb phase
- loss of flight profile validity
- FCU level reduced to the FMS constraint with ALT ACQ mode active.
(16) Operational logic - DES mode active
This mode is active on condition that:
IM DES mode is engaged by pushing action on the altitude selector if :
This mode is active on condition that:
- the FCU level is below the aircraft level
- arming of the ALT ACQ mode is possible
- the NAV, LOC CPT or LOC TRACK modes are active
- five s after lift off
- the takeoff, climb, go around phases are not active
- the flight profile is valid
- the active modes are not GS TRACK, LAND TRACK, DESCENT, FINAL DES, TAKEOFF or GO AROUND.
IM DES mode is engaged by pushing action on the altitude selector if :
- The ALT ACQ or ALT mode or ALT submode of V/S FPA mode is not active
- The ALT ACQ or ALT mode or ALT submode of V/S FPA mode is active, the DES mode is not armed and the FMS does not permit arming of DES mode.
(17) AP/FD TCAS mode function
(a) Principle
The principle of AP/FD TCAS Mode function is to couple the Traffic Alert and Collision Avoidance System (TCAS) with the AFS in order to provide with an automatic guidance, or with FD guidance cues. It is based on the vertical speed limit given by the TCAS during a Resolution Advisory.
The engagement of a new AP/FD vertical mode, called "TCAS", operates at any TCAS RA, preventive or corrective.
The principle of AP/FD TCAS Mode function is to couple the Traffic Alert and Collision Avoidance System (TCAS) with the AFS in order to provide with an automatic guidance, or with FD guidance cues. It is based on the vertical speed limit given by the TCAS during a Resolution Advisory.
The engagement of a new AP/FD vertical mode, called "TCAS", operates at any TCAS RA, preventive or corrective.
(b) AP/FD TCAS mode arming
The APFD TCAS mode operates at occurrence of a TCAS Traffic Advisory (TA). Information are shown in cyan in the column of the vertical modes of the FMA.
The arming of the mode disappears when the Traffic Advisory (TA) is cancelled or if it evolves into a Resolution Advisory (RA).
The APFD TCAS mode operates at occurrence of a TCAS Traffic Advisory (TA). Information are shown in cyan in the column of the vertical modes of the FMA.
The arming of the mode disappears when the Traffic Advisory (TA) is cancelled or if it evolves into a Resolution Advisory (RA).
(c) AP/FD TCAS mode engagement
At occurrence of any Resolution Advisory (RA), preventive or corrective:
- If the AP is not engaged, the FD engages, if not already engaged, or remain engaged, in TCAS mode. That gives guidance cues corresponding to the TCAS vertical speed advisory.
- If the AP is engaged, the vertical mode reverts in TCAS mode and provides a vertical guidance based on the TCAS vertical speed advisory.
At occurrence of any Resolution Advisory (RA), preventive or corrective:
- If the AP is not engaged, the FD engages, if not already engaged, or remain engaged, in TCAS mode. That gives guidance cues corresponding to the TCAS vertical speed advisory.
- If the AP is engaged, the vertical mode reverts in TCAS mode and provides a vertical guidance based on the TCAS vertical speed advisory.
(d) AP/FD TCAS mode disengagement
The TCAS mode automatically disengages at the clear of conflict generated by the TCAS.
The TCAS mode automatically disengages at the clear of conflict generated by the TCAS.
(e) Pilot override
At any moment the pilot can override the TCAS mode by selecting any other vertical mode thanks to usual means or manually with the side-stick.
In this case, TCAS can be brought to generate a new alert:
- If the current aircraft vertical speed is outside the red area, the AP/FD TCAS mode will not be re-engaged.
- If the current aircraft vertical speed is within the red zone, AP/FD TCAS mode will engage again, with a target based on the new TCAS order.
At any moment the pilot can override the TCAS mode by selecting any other vertical mode thanks to usual means or manually with the side-stick.
In this case, TCAS can be brought to generate a new alert:
- If the current aircraft vertical speed is outside the red area, the AP/FD TCAS mode will not be re-engaged.
- If the current aircraft vertical speed is within the red zone, AP/FD TCAS mode will engage again, with a target based on the new TCAS order.
J. Displays Associated with the Cruise Modes
(1) FMA
(a) Messages concerning the lateral AP/FD modes
1 General rules
The active mode is always indicated in plain language.
The first line indicates the active mode in green.
The second line indicates the mode armed in cyan.
The active mode is always indicated in plain language.
The first line indicates the active mode in green.
The second line indicates the mode armed in cyan.
a List of messages
1st line
NAV, HDG, TRACK, LOC*, LOC
2nd line
NAV, LOC
1st line
NAV, HDG, TRACK, LOC*, LOC
2nd line
NAV, LOC
(b) Messages concerning the longitudinal AP/FD modes
1 General rules
On the first line, the message is always indicated in plain language except in ALT mode on the cruise flight level with A/THR engaged and NAV mode active where three dashes are displayed.
The first line indicates the active mode in green.
The second line indicates the mode armed in cyan.
The messages which concern an FMS altitude constraint are displayed in magenta.
On the first line, the message is always indicated in plain language except in ALT mode on the cruise flight level with A/THR engaged and NAV mode active where three dashes are displayed.
The first line indicates the active mode in green.
The second line indicates the mode armed in cyan.
The messages which concern an FMS altitude constraint are displayed in magenta.
2 List of messages
1st line
ALT*, ALT, ALT CRZ, ALT CST*, V/S +/- xxxx, FPA +/- x.x deg., EXP CLB, EXP DES, CLB, DES, OP CLB, OP DES
2nd line
ALT, CLB, DES.
3rd line
xxx, .xx
When a preset speed or Mach value has been introduced in the MCDU, the value is displayed with the mode armed when the aircraft is in the flight segment which precedes acceptance of this preset value (SPEED SEL: XXX or MACH SEL: .XX).
1st line
ALT*, ALT, ALT CRZ, ALT CST*, V/S +/- xxxx, FPA +/- x.x deg., EXP CLB, EXP DES, CLB, DES, OP CLB, OP DES
2nd line
ALT, CLB, DES.
3rd line
xxx, .xx
When a preset speed or Mach value has been introduced in the MCDU, the value is displayed with the mode armed when the aircraft is in the flight segment which precedes acceptance of this preset value (SPEED SEL: XXX or MACH SEL: .XX).
(2) FCU "Automatic Control" Lights
The FCU has three lights which come on whenever the automatic control is active or armed.
These lights concern:
The FCU has three lights which come on whenever the automatic control is active or armed.
These lights concern:
- speed control,
- lateral control,
- longitudinal control as far as level changes are concerned.
(a) Speed control
The associated light comes on when the managed speed control is active.
The associated light comes on when the managed speed control is active.
(b) Lateral control
The associated light is on when:
The associated light is on when:
- the lateral guidance is managed, i.e. when the modes below are active:
. NAV
. LOC CPT
. LOC TRACK - the managed lateral guidance is armed, i.e. the modes below are armed:
. NAV
. LOC.
(c) Longitudinal control
The associated light is on when:
The associated light is on when:
- the level change is automatic i.e. when the modes below are active:
. CLB
. DES
. IM CLB
. IM DES - the automatic level change is armed when the modes below are armed:
. CLIMB
. DESCENT.