DOC AIRBUS | AMM A320FMULTIPURPOSE CONTROL AND DISPLAY UNIT (MCDU) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Multipurpose Control and Display Units (MCDU) provide access to the following:
** ON A/C NOT FOR ALL The Multipurpose Control and Display Units (MCDU) provide access to the following:
MCDU Interface- FMGC (Flight Management function)
- DATA LINK (ACARS)-optional
- CFDS (Centralized Fault and Display System)
- AIDS-optional
- SAT (SATCOM)-optional
- ATSU-optional.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 3CA3 | MCDU-3 | 101VU | 211 | 22-82-12 | |
| ** ON A/C ALL | |||||
| 3CA1 | MCDU-1 | 11VU | 210 | 22-82-12 | |
| 3CA2 | MCDU-2 | 11VU | 210 | 22-82-12 | |
3. Component Description
(1) The screen
The MCDU display contains 14 lines, each having 24 characters. Of these 14 lines, the top line (line 1) is normally used as a title line or to display data to which the pilot does not have access. The bottom line (line 14) is the scratchpad line and is used by the pilot to alter the data in the data fields.
Lines 2 through 13 are data lines arranged into six pairs (lines 2-3, 4 -5, 6-7, 8-9, 10-11, 12-13). Each pair of lines has a label line (the top of the two lines) and a data line. The data lines are adjacent to the line select keys, and the label line is just above the data line.
The line pairs are referenced by line select keys as follows:
The line select keys allow entry of data into a field and access to a data or a function identified by that field.
The MCDU display contains 14 lines, each having 24 characters. Of these 14 lines, the top line (line 1) is normally used as a title line or to display data to which the pilot does not have access. The bottom line (line 14) is the scratchpad line and is used by the pilot to alter the data in the data fields.
Lines 2 through 13 are data lines arranged into six pairs (lines 2-3, 4 -5, 6-7, 8-9, 10-11, 12-13). Each pair of lines has a label line (the top of the two lines) and a data line. The data lines are adjacent to the line select keys, and the label line is just above the data line.
The line pairs are referenced by line select keys as follows:
| Reference Screen lines |
| 1L - 1R 2 - 3 |
| 2L - 2R 4 - 5 |
| 3L - 3R 6 - 7 |
| 4L - 4R 8 - 9 |
| 5L - 5R 10 - 11 |
| 6L - 6R 12 - 13 |
The line select keys allow entry of data into a field and access to a data or a function identified by that field.
(2) The keyboard
(a) Alphanumeric keys
Pressing an alphanumeric key (O through 9, A through Z, . (full point), + (plus), - (minus) and / (slash)) enters that character into the scratchpad of the MCDU.
Pressing an alphanumeric key (O through 9, A through Z, . (full point), + (plus), - (minus) and / (slash)) enters that character into the scratchpad of the MCDU.
(b) Mode keys
Pressing a mode key causes a new MCDU page to be displayed and allows access to certain functions.
The available mode keys are:
Pressing a mode key causes a new MCDU page to be displayed and allows access to certain functions.
The available mode keys are:
- AIRPORT
- F-PLN
- DIR
- PROG
- PERF
- INIT
- DATA
- RAD NAV (Radio Navigation)
- FUEL PRED (Fuel Prediction)
- SEC F-PLN (Secondary flight plan)
(FMGS mode keys) - MCDU MENU
(multi-purpose key) - ATC COMM
(optional Air Traffic Control mode key for datalink communication). - Spare key
(c) Function keys
The function keys are described below:
The function keys are described below:
- (Right arrow)= causes horizontal forward page slewing to occur when allowed (also called "Next Page").
- (Left arrow)= causes horizontal backward page slewing to occur when allowed (also called "Previous Page").
- (Slew up) = causes upward vertical slewing to occur.
- (Slew down) = causes downward vertical slewing to occur.
- CLR = allows clearing of scratchpad and data fields.
- Delta (OVFY) = enters a Delta into the scratchpad.
- one spare key.
(3) Front panel annunciators
There are three illuminable annunciators on the MCDU front panel:
There are three illuminable annunciators on the MCDU front panel:
- FAIL: This annunciator comes on (amber) when the MCDU has failed.
- MCDU MENU: This annunciator comes on (white) when a system linked to the MCDU requests the display
- FM: This annunciator comes on when an FM page is not displayed.
(4) BRT/DIM keys
The BRT/DIM keys allows brightness adjustment of the screen.
The fully decreasing of the brightness switches off the MCDU.
The BRT/DIM keys allows brightness adjustment of the screen.
The fully decreasing of the brightness switches off the MCDU.
(5) Top panel annunciators
There are five illuminable annunciators across the top of the MCDU front panel of which one is spare and not utilized. The spare annunciator is unlabeled but it contains an amber light.
There are five illuminable annunciators across the top of the MCDU front panel of which one is spare and not utilized. The spare annunciator is unlabeled but it contains an amber light.
(a) FM1 and FM2
The FM failure annunciators at the top of the MCDU indicate when a FM failure occurs.
The FM1 failure light on MCDU1 and/or MCDU2 comes on (amber) if FM1 is the selected FM, the MCDU BRT knob is at ON and the FM1 subsystem identifier word (label 172) is not received for three seconds by the MCDU.
Likewise, the FM2 failure light on MCDU1 and /or MCDU2 comes on (amber) if FM2 is the selected FM, the MCDU BRT knob is at ON and the FM2 subsystem identifier word is not received for three seconds by the MCDU.
The corresponding FM failure annunciator on MCDU3 comes on only if MCDU3 operates as a backup to MCDU1 or MCDU2. It comes on only in the context of the failed MCDU selected FM.
Additionally, a MCDU never has both its FM failure annunciators on. The FM failure annunciators are off when an identifier word is received from the appropriate FM.
The FM failure annunciators at the top of the MCDU indicate when a FM failure occurs.
The FM1 failure light on MCDU1 and/or MCDU2 comes on (amber) if FM1 is the selected FM, the MCDU BRT knob is at ON and the FM1 subsystem identifier word (label 172) is not received for three seconds by the MCDU.
Likewise, the FM2 failure light on MCDU1 and /or MCDU2 comes on (amber) if FM2 is the selected FM, the MCDU BRT knob is at ON and the FM2 subsystem identifier word is not received for three seconds by the MCDU.
The corresponding FM failure annunciator on MCDU3 comes on only if MCDU3 operates as a backup to MCDU1 or MCDU2. It comes on only in the context of the failed MCDU selected FM.
Additionally, a MCDU never has both its FM failure annunciators on. The FM failure annunciators are off when an identifier word is received from the appropriate FM.
(b) RDY
This annunciator comes on (green) when the MCDU passes its long-term power up or power off reset test after its BRT knob is turned to OFF.
This annunciator comes on (green) when the MCDU passes its long-term power up or power off reset test after its BRT knob is turned to OFF.
(c) IND
This annunciator comes on (amber) when the selected FM detects an independent operation (loss of dual mode) while both FMs are healthy. If either FM is failed, the annunciator is not on, regardless of the state of the intersystem bus.
This annunciator comes on (amber) when the selected FM detects an independent operation (loss of dual mode) while both FMs are healthy. If either FM is failed, the annunciator is not on, regardless of the state of the intersystem bus.
(6) The screen
The MCDU display contains 14 lines, each having 24 characters. Of these 14 lines, the top line (line 1) is normally used as a title line or to display data to which the pilot does not have access. The bottom line (line 14) is the scratchpad line and is used by the pilot to alter the data in the data fields.
Lines 2 through 13 are data lines arranged into six pairs (lines 2-3, 4 -5, 6-7, 8-9, 10-11, 12-13). Each pair of lines has a label line (the top of the two lines) and a data line. The data lines are adjacent to the line select keys, and the label line is just above the data line.
The line pairs are referenced by line select keys as follows:
The line select keys allow entry of data into a field and access to a data or a function identified by that field.
The MCDU display contains 14 lines, each having 24 characters. Of these 14 lines, the top line (line 1) is normally used as a title line or to display data to which the pilot does not have access. The bottom line (line 14) is the scratchpad line and is used by the pilot to alter the data in the data fields.
Lines 2 through 13 are data lines arranged into six pairs (lines 2-3, 4 -5, 6-7, 8-9, 10-11, 12-13). Each pair of lines has a label line (the top of the two lines) and a data line. The data lines are adjacent to the line select keys, and the label line is just above the data line.
The line pairs are referenced by line select keys as follows:
| Reference Screen lines |
| 1L - 1R 2 - 3 |
| 2L - 2R 4 - 5 |
| 3L - 3R 6 - 7 |
| 4L - 4R 8 - 9 |
| 5L - 5R 10 - 11 |
| 6L - 6R 12 - 13 |
The line select keys allow entry of data into a field and access to a data or a function identified by that field.
(7) The keyboard
(a) Alphanumeric keys
Pressing an alphanumeric key (O through 9, A through Z, . (full point), + (plus), - (minus) and / (slash)) enters that character into the scratchpad of the MCDU.
Pressing an alphanumeric key (O through 9, A through Z, . (full point), + (plus), - (minus) and / (slash)) enters that character into the scratchpad of the MCDU.
(b) Mode keys
Pressing a mode key causes a new MCDU page to be displayed and allows access to certain functions.
The available mode keys are:
Pressing a mode key causes a new MCDU page to be displayed and allows access to certain functions.
The available mode keys are:
- AIRPORT
- F-PLN
- DIR
- PROG
- PERF
- INIT
- DATA
- RAD NAV (Radio Navigation)
- FUEL PRED (Fuel Prediction)
- SEC F-PLN (Secondary flight plan)
(FMGS mode keys) - MCDU MENU
(multi-purpose key) - ATC COMM
(optional Air Traffic Control mode key for datalink communication). - Spare key
(c) Function keys
The function keys are described below:
The function keys are described below:
- (Right arrow)= causes horizontal forward page slewing to occur when allowed (also called "Next Page").
- (Left arrow)= causes horizontal backward page slewing to occur when allowed (also called "Previous Page").
- (Slew up) = causes upward vertical slewing to occur.
- (Slew down) = causes downward vertical slewing to occur.
- CLR = allows clearing of scratchpad and data fields.
- Delta (OVFY) = enters a Delta into the scratchpad.
- one spare key.
(8) Front panel annunciators
There are three illuminable annunciators on the MCDU front panel:
There are three illuminable annunciators on the MCDU front panel:
- FAIL: This annunciator comes on (amber) when the MCDU has failed.
- MCDU MENU: This annunciator comes on (white) when a system linked to the MCDU (other than the FM) requests the display
- FM: This annunciator comes on (white) when FM is not the active system and has sent an important message.
(9) BRT/DIM keys
The BRT/DIM keys allows brightness adjustment of the screen.
The fully decreasing of the brightness switches off the MCDU.
The BRT/DIM keys allows brightness adjustment of the screen.
The fully decreasing of the brightness switches off the MCDU.
(10) Top panel annunciators
There are five illuminable annunciators across the top of the MCDU front panel of which one is spare and not utilized. The spare annunciator is unlabeled but it contains an amber light.
There are five illuminable annunciators across the top of the MCDU front panel of which one is spare and not utilized. The spare annunciator is unlabeled but it contains an amber light.
(a) FM1 and FM2
The FM failure annunciators at the top of the MCDU indicate when a FM failure occurs.
The FM1 failure light on MCDU1 and/or MCDU2 comes on (amber) if FM1 is the selected FM, the MCDU BRT knob is at ON and the FM1 subsystem identifier word (label 172) is not received for three seconds by the MCDU.
Likewise, the FM2 failure light on MCDU1 and /or MCDU2 comes on (amber) if FM2 is the selected FM, the MCDU BRT knob is at ON and the FM2 subsystem identifier word is not received for three seconds by the MCDU.
The corresponding FM failure annunciator on MCDU3 comes on only if MCDU3 operates as a backup to MCDU1 or MCDU2. It comes on only in the context of the failed MCDU selected FM.
Additionally, a MCDU never has both its FM failure annunciators on. The FM failure annunciators are off when an identifier word is received from the appropriate FM.
The FM failure annunciators at the top of the MCDU indicate when a FM failure occurs.
The FM1 failure light on MCDU1 and/or MCDU2 comes on (amber) if FM1 is the selected FM, the MCDU BRT knob is at ON and the FM1 subsystem identifier word (label 172) is not received for three seconds by the MCDU.
Likewise, the FM2 failure light on MCDU1 and /or MCDU2 comes on (amber) if FM2 is the selected FM, the MCDU BRT knob is at ON and the FM2 subsystem identifier word is not received for three seconds by the MCDU.
The corresponding FM failure annunciator on MCDU3 comes on only if MCDU3 operates as a backup to MCDU1 or MCDU2. It comes on only in the context of the failed MCDU selected FM.
Additionally, a MCDU never has both its FM failure annunciators on. The FM failure annunciators are off when an identifier word is received from the appropriate FM.
(b) RDY
This annunciator comes on (green) when the MCDU passes its long-term power up or power off reset test after its BRT knob is turned to OFF.
This annunciator comes on (green) when the MCDU passes its long-term power up or power off reset test after its BRT knob is turned to OFF.
(c) IND
This annunciator comes on (amber) when the selected FM detects an independent operation (loss of dual mode) while both FMs are healthy. If either FM is failed, the annunciator is not on, regardless of the state of the intersystem bus.
This annunciator comes on (amber) when the selected FM detects an independent operation (loss of dual mode) while both FMs are healthy. If either FM is failed, the annunciator is not on, regardless of the state of the intersystem bus.
B. Internal Description
The MCDU includes:
The MCDU includes:
- the interconnection function (A1)
- the power supply function (A2)
- the graphic processing function (A3)
- the back lighting function (A4)
- the LCD (Liquid Crystal Display) matrix and drivers function (A5)
- the keyboard and annunciators function (A6).
- the interconnection function (A1)
- the power supply function (A2)
- the graphic processing function (A3)
- the back lighting function (A4)
- the LCD (Liquid Crystal Display) matrix and drivers function (A5)
- the keyboard and annunciators function (A6).
4. Operation
A. Multifunction Usage
(1) Functioning
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
- if an active system exists, the MCDU allows the active system to control the display,
- if no active system exists, the MCDU will continue to display the MCDU MENU page.
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
- When a system other than the FMGC is the active one, pressing any FMGC mode key activates the FMGC.
- At the same time both MCDUs may communicate each with a different system.
(MCDU 1 - DATA LINK)
(MCDU 2 - FMGC) - When the FMGC is not the active system, if it has to send an important message, it illuminates the FMGC annunciator.
(2) Data fields
(a) 1L - FMGC : allows to activate communication with the FMGCs (A/C status page displayed).
(b) 2L - DATA LINK : allows to activate communication with the DATA LINK.
(c) 3L - AIDS : allows to activate communication with the AIDS.
(d) 4L - CFDS : allows to activate communication with the CFDS.
(e) 5L - ATSU : allows to activate communication with the ATSU.
(f) 6R - RETURN : allows to return to the currently active system.
(g) "(REQ)" may be displayed on any line (1L - 5L) with a space immediately after the requesting system ident to indicate that the system is requesting the MCDU.
"(TIME OUT)" may be displayed if the communication is not established with the system.
"(TIME OUT)" may be displayed if the communication is not established with the system.
(h) Messages are displayed in the scratchpad to guide the pilot.
- When MCDU MENU mode key has been pressed, SELECT DESIRED SYSTEM is displayed.
- When a system has been called, WAIT FOR SYSTEM RESPONSE is displayed.
- If the called system does not answer, PRESS MCDU MENU KEY is displayed.
(i) The currently active system is displayed in green, remaining systems are displayed in white.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
(3) Functioning
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
- if an active system exists, the MCDU allows the active system to control the display,
- if no active system exists, the MCDU will continue to display the MCDU MENU page.
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
- When a system other than the FMGC is the active one, pressing any FMGC mode key activates the FMGC.
- At the same time both MCDUs may communicate each with a different system.
(MCDU 1 - DATA LINK)
(MCDU 2 - FMGC) - When the FMGC is not the active system, if it has to send an important message, it illuminates the FMGC annunciator.
(4) Data fields
(a) 1L - FMGC : allows to activate communication with the FMGCs (A/C status page displayed).
(b) 2L - DATA LINK : allows to activate communication with the DATA LINK.
(c) 3L - AIDS : allows to activate communication with the AIDS.
(d) 4L - CFDS : allows to activate communication with the CFDS.
(e) 5L - ATSU : allows to activate communication with the ATSU.
(f) 1R - SELECT NAV B/UP : allows to indicates Standby Nav availability. The availability is determined by the MCDU and indicated in the label and prompt lines adjacent to 1R. Standby Navigation is available on MCDU1 and MCDU2 only if the SWITCHING/FM selector switch is at NORM. It is unavailable at all other times.
Standby Nav is never available on MCDU3 at any time, even when it operates as a backup to MCDU1 or MCDU2.
If Standby Nav is available, NAV B/UP> is displayed in large font right justified to column 24 of the data line and the label line contains its active/inactive status. When Standby Navigation is inactive, SELECT is displayed in small white font beginning in column 18 of the label line and NAV B/UP is displayed in large white font. When Standby Navigation is active, DESELECT is displayed in small white font beginning in column 16 of the label line and NAV B/UP is displayed in large green font. If Standby Nav is unavailable, both of these fields shall be "blank".
The Standby Nav prompt operates as an ON/OFF switch for activation and deactivation of the Standby Nav function. Selection of 1R when SELECT is displayed results in the activation of Standby Navigation function and display of the Standby Nav page. Selection of 1R when DESELECT is displayed results in the deactivation of the Standby Navigation function; the MCDU MENU page remains displayed in this case. Selection of 1R when the field is blank has no operational effect.
Standby Nav is never available on MCDU3 at any time, even when it operates as a backup to MCDU1 or MCDU2.
If Standby Nav is available, NAV B/UP> is displayed in large font right justified to column 24 of the data line and the label line contains its active/inactive status. When Standby Navigation is inactive, SELECT is displayed in small white font beginning in column 18 of the label line and NAV B/UP is displayed in large white font. When Standby Navigation is active, DESELECT is displayed in small white font beginning in column 16 of the label line and NAV B/UP is displayed in large green font. If Standby Nav is unavailable, both of these fields shall be "blank".
The Standby Nav prompt operates as an ON/OFF switch for activation and deactivation of the Standby Nav function. Selection of 1R when SELECT is displayed results in the activation of Standby Navigation function and display of the Standby Nav page. Selection of 1R when DESELECT is displayed results in the deactivation of the Standby Navigation function; the MCDU MENU page remains displayed in this case. Selection of 1R when the field is blank has no operational effect.
(g) 4R : no prompt displayed if no subsystem connected. In this case, it allows the insertion of "MCDUMAINT" password which command the access to MCDU internal memory. This password is not displayed on scratchpad.
(h) 6R - RETURN : allows to return to the currently active system.
(i) "(REQ)" may be displayed on any line (1L - 5L) with a space immediately after the requesting system ident to indicate that the system is requesting the MCDU.
"(TIME OUT)" may be displayed if the communication is not established with the system.
"(TIME OUT)" may be displayed if the communication is not established with the system.
(j) Messages are displayed in the scratchpad to guide the pilot.
- When MCDU MENU mode key has been pressed, SELECT DESIRED SYSTEM is displayed.
- When a system has been called, WAIT FOR SYSTEM RESPONSE is displayed.
- If the called system does not answer, PRESS MCDU MENU KEY is displayed.
(k) The currently active system is displayed in green, remaining systems are displayed in white.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
(5) Functioning
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
- if an active system exists, the MCDU allows the active system to control the display,
- if no active system exists, the MCDU will continue to display the MCDU MENU page.
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
- When a system other than the FMGC is the active one, pressing any FMGC mode key activates the FMGC.
- At the same time both MCDUs may communicate each with a different system.
(MCDU 1 - DATA LINK)
(MCDU 2 - FMGC) - When the FMGC is not the active system, if it has to send an important message, it illuminates the FMGC annunciator.
(6) Data fields
(a) 1L - FMGC : allows to activate communication with the FMGCs (A/C status page displayed).
(b) 2L - DATA LINK : allows to activate communication with the DATA LINK.
(c) 3L - AIDS : allows to activate communication with the AIDS.
(d) 4L - CFDS : allows to activate communication with the CFDS.
(e) 5L - ATSU : allows to activate communication with the ATSU.
(f) 1R - SELECT NAV B/UP : allows to indicate Standby Nav availability. The availability is determined by the MCDU and indicated in the label and prompt lines adjacent to 1R. When MCDU is mounted on A320 with its J1 and J2 connectors wired, the standby navigation is available, provided that the pin 30 (NAV BKUP OPT) on J2 is appropriately connected.
When available, the Standby Nav shall always be selectable, except in the following case : onside FM healthy and offside FM failed. In this case, any attempt of Standby Nav selection shall result in the display of the "NOT ALLOWED" scratchpad message.
Standby Nav is never available on MCDU3 at any time, even when it operates as a backup to MCDU1 or MCDU2.
If Standby Nav is available, NAV B/UP> is displayed in large font right justified to column 24 of the data line and the label line contains its active/inactive status. When Standby Navigation is inactive, SELECT is displayed in small white font beginning in column 18 of the label line and NAV B/UP is displayed in large white font. When Standby Navigation is active, DESELECT is displayed in small white font beginning in column 16 of the label line and NAV B/UP is displayed in large green font. If Standby Nav is unavailable, both of these fields shall be "blank".
The Standby Nav prompt operates as an ON/OFF switch for activation and deactivation of the Standby Nav function. Selection of 1R when SELECT is displayed results in the activation of Standby Navigation function and display of the Standby Nav page. Selection of 1R when DESELECT is displayed results in the deactivation of the Standby Navigation function; the MCDU MENU page remains displayed in this case. Selection of 1R when the field is blank has no operational effect.
When available, the Standby Nav shall always be selectable, except in the following case : onside FM healthy and offside FM failed. In this case, any attempt of Standby Nav selection shall result in the display of the "NOT ALLOWED" scratchpad message.
Standby Nav is never available on MCDU3 at any time, even when it operates as a backup to MCDU1 or MCDU2.
If Standby Nav is available, NAV B/UP> is displayed in large font right justified to column 24 of the data line and the label line contains its active/inactive status. When Standby Navigation is inactive, SELECT is displayed in small white font beginning in column 18 of the label line and NAV B/UP is displayed in large white font. When Standby Navigation is active, DESELECT is displayed in small white font beginning in column 16 of the label line and NAV B/UP is displayed in large green font. If Standby Nav is unavailable, both of these fields shall be "blank".
The Standby Nav prompt operates as an ON/OFF switch for activation and deactivation of the Standby Nav function. Selection of 1R when SELECT is displayed results in the activation of Standby Navigation function and display of the Standby Nav page. Selection of 1R when DESELECT is displayed results in the deactivation of the Standby Navigation function; the MCDU MENU page remains displayed in this case. Selection of 1R when the field is blank has no operational effect.
(g) 4R : no prompt displayed if no subsystem connected. In this case, it allows the insertion of "MCDUMAINT" password which commands the access to MCDU maintenance pages. This password is not displayed on scratchpad.
(h) 6R - RETURN : allows to return to the currently active system.
(i) "(REQ)" may be displayed on any line (1L - 5L) with a space immediately after the requesting system ident to indicate that the system is requesting the MCDU.
"(TIME OUT)" may be displayed if the communication is not established with the system.
"(TIME OUT)" may be displayed if the communication is not established with the system.
(j) Messages are displayed in the scratchpad to guide the pilot.
- When MCDU MENU mode key has been pressed, SELECT DESIRED SYSTEM is displayed.
- When a system has been called, WAIT FOR SYSTEM RESPONSE is displayed.
- If the called system does not answer, PRESS MCDU MENU KEY is displayed.
(k) The currently active system is displayed in green, remaining systems are displayed in white.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
(7) Functioning
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
The MCDU is linked to both FMGCs, CFDS, and optional systems.
At power-up or after a long term power interrupt, the MCDU communicates with the FMGC and the A/C STATUS page is displayed.
To initiate communications with another system other than the FMGC, the pilot presses the MCDU MENU mode key. Then a menu page is displayed (item a) indicating which system is currently active (green) and any system requesting service (white with (REQ) displayed with a space immediately after each menu system identifier).
If the operator does not press any line key after 60 seconds, the MCDU does one of the following actions:
- if an active system exists, the MCDU allows the active system to control the display,
- if no active system exists, the MCDU will continue to display the MCDU MENU page.
If the line select key corresponds to the currently active system, the communication continues with the system. During the time between selecting the system and receipt of the first text from the selected system, the display as shown in figure (item b) appears.
If communication with the selected system is not established, the MCDU displays the data as shown in figure (item c).
When a system other than the currently active desires to communicate with the MCDU, it illuminates the MCDU MENU annunciator on both MCDUs to warn the operator.
The operator has to press the MCDU MENU mode key to have the MCDU MENU page to know what system is requesting the MCDU.
- When a system other than the FMGC is the active one, pressing any FMGC mode key activates the FMGC.
- At the same time both MCDUs may communicate each with a different system.
(MCDU 1 - DATA LINK)
(MCDU 2 - FMGC) - When the FMGC is not the active system, if it has to send an important message, it illuminates the FMGC annunciator.
(8) Data fields
(a) 1L - FMGC : allows to activate communication with the FMGCs (A/C status page displayed).
(b) 2L - DATA LINK : allows to activate communication with the DATA LINK.
(c) 3L - AIDS : allows to activate communication with the AIDS.
(d) 4L - CFDS : allows to activate communication with the CFDS.
(e) 5L - ATSU : allows to activate communication with the ATSU.
(f) 4R - MCDU MAINT : allows the access to MCDU maintenance pages.
(g) 6R - RETURN : allows to return to the currently active system.
(h) "(REQ)" may be displayed on any line (1L - 5L) with a space immediately after the requesting system ident to indicate that the system is requesting the MCDU.
"(TIME OUT)" may be displayed if the communication is not established with the system.
"(TIME OUT)" may be displayed if the communication is not established with the system.
(i) Messages are displayed in the scratchpad to guide the pilot.
- When MCDU MENU mode key has been pressed, SELECT DESIRED SYSTEM is displayed.
- When a system has been called, WAIT FOR SYSTEM RESPONSE is displayed.
- If the called system does not answer, PRESS MCDU MENU KEY is displayed.
(j) The currently active system is displayed in green, remaining systems are displayed in white.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
When one system is selected (line select key has been pressed) only this line is displayed in cyan with WAIT FOR SYSTEM RESPONSE in the scratchpad.
B. Switching Logic (FM only)
Each MCDU receives the state of its own FMGC on the discrete FMGC healthy.
When there is no failure (discrete in ground state), each MCDU talks to its own FMGC both ways.
When one FMGC is failed discrete open, both MCDUs talk with the remaining FMGC and the OPP FMGC IN PROCESS indication is displayed in the scratchpad (on the MCDU which switched).
The functioning of both MCDUs remains totally independent as if both FMGCs were valid. In particular each MCDU can talk with any system the operator has selected on the MCDU MENU page.
As soon as the failed FMGC is no more failed, the MCDU reverts to talk with it.
Each MCDU receives the state of its own FMGC on the discrete FMGC healthy.
When there is no failure (discrete in ground state), each MCDU talks to its own FMGC both ways.
When one FMGC is failed discrete open, both MCDUs talk with the remaining FMGC and the OPP FMGC IN PROCESS indication is displayed in the scratchpad (on the MCDU which switched).
The functioning of both MCDUs remains totally independent as if both FMGCs were valid. In particular each MCDU can talk with any system the operator has selected on the MCDU MENU page.
As soon as the failed FMGC is no more failed, the MCDU reverts to talk with it.