FMGC Description #
FMGC in airbus stands for Flight Management and Guidance Computer.
The Flight Management Guidance Computer (FMGC) contains a navigation database which provides navaid auto-tuning, position computation, navigational accuracy checks, and flight planning through the Multifunction Control Display Unit (MCDU). The MCDU contains a performance database that provides predictions of fuel, time, distance, speed, and altitude.
Each FMGC is linked to its own onside MCDU, RMP, and EFIS control panel. After entry of the flight plan and other required performance data into the MCDU, the FMGS generates the climb and descent profiles for departure and arrival, provides automatic airplane guidance, and computes current and predicted progress along the flight plan.
MCDU Page Title #
The Page Title identifies the page in view.
MCDU Line Select Keys #
The Line Select Keys identified as 1L – 6L and 1R – 6R and provide access to data in the left and right data fields respectively.
Keys enable data entered into the scratchpad to be line-selected (moved) to the appropriate data entry field.
If a caret (< or >) appears next to the key, selecting the key accesses another MCDU page.
If an asterisk (*) appears next to the key, selecting the key activates a specific function
MCDU Scratch Pads #
MCDU Scratch Pad displays typed alphanumeric characters and FMGC-generated messages (up to 22 characters).
The two MCDU scratch pads operate independently for data entry.
MCDU Slew Keys #
MCDU vertical slew keys can be used to slew a page up and down if a page contains more data than fits on the screen as indicated by arrow(s) in the lower right hand corner of the screen.
The vertical slew keys can also be used to change latitude and longitude as indicated by the vertical arrows next to the associated data field.
MCDU Fail Annunciator #
MCDU FAIL Annunciator illuminates when the MCDU has failed.
MCDU FM Annunciator #
MCDU FM Annunciator illuminates when the FMGC is not the active system and it has been sent a message.
Use the MCDU MENU key to return to the FMGC page.
MCDU Alphanumeric Keys
The Alphanumeric Keys enable entry of letters and numbers into the scratchpad. The +/- key alternates between a + and – for positive and negative figures. The slash key (/) is used to separate pairs of entries in the same data field (e.g., wind direction/speed: 270/110).
The trailing entry of a pair must be preceded by a slash if it is entered alone, except for frequencies and identifiers entered on the RADIO NAV page.
MCDU Top Annunciator Keys #
FM1 or FM2 indicate a failure of that FMGC.
IND indicates the FMGCs are operating in the independent mode.
RDY light indicates that the FMGC has passed its power-on test.
MCDU Additional Page Arrow #
MCDU Additional page arrow indicates additional pages are available.
Additional pages may be viewed by pressing the horizontal slew keys.
MCDU Page Keys #
To view a description of the various MCDU pages click on the appropriate key :
DIR, PROG, PERF, INIT, DATA, F-PLN, RAD NAV, et cetra
MCDU BRT and DIM Selector #
The BRT/DIM Selector controls intensity of MCDU display pages.
MCDU MENU Annunciator #
MCDU MENU Annunciator illuminates when a system linked to the MCDU requests the display.
The system can be changed using the MCDU MENU key.
MCDU SP Key #
The SP Key inserts a space in an alphanumeric sequence.
A short press on the BRT key performs a power-up of the MCDU.
A long press of the DIM key starts the MCDU power-off.
MCDU OVFY Δ Key #
When pushed, Δ appears in the scratchpad. Line selecting the waypoint to be overflown causes the Δ to appear next to that waypoint designator in the flight plan, and the lateral flight plan is modified so that the airplane directly overflies the waypoint.
The overfly function provides for flight directly over a waypoint while maintaining NAV.
Once a waypoint has been commanded to be overflown, OVFY Δ can only be removed by reentering the waypoint name.
MCDU Clear Key #
Clears messages and data from the scratchpad or an individual data field.
If alphanumeric characters have been entered into the scratchpad, a single, short press of the key erases the last character entered. A longer press of the key erases the entire scratchpad entry.
When the key is pushed and the scratchpad is empty, CLR appears in the scratchpad. If a line select key is then pressed, the adjacent data field is cleared, or will change to a defaulted or FMGC-calculated value.
If the data field to be cleared is a leg in the flight plan, the leg is deleted from the flight plan, and a discontinuity created (in most cases). CLR can be removed from the scratchpad by pushing the key a second time or by entering an alphanumeric character.
