Basics

For the complete documentation index, see llms.txt. Markdown versions of documentation pages are available by appending .md to page URLs; this page is available as Markdown.

Basics

The custom FMS is operated from the two MCDUs on the pedestal. Captain and First Officer units are independent displays and scratchpads, but they share one flight plan.

On power-up the MCDU shows RADIO. Before RTE, FPL, PERF, PROG, or NAV can be used, NAV IDENT must be displayed once (confirm date, UTC, and the active navigation database).

Function keys

Key	Page
RADIO	Radio 1 (COM / NAV / XPDR)
RTE	ACT RTE
FPL	ACTIVE FLT PLAN
PERF	PERF INDEX 1/2
PROG	PROGRESS 1/3
NAV	NAV INDEX 1/2
DLK	Datalink MAIN MENU
TRS	THRUST RATING SELECT
MENU	MENU
CB	Circuit breaker pages
PREV / NEXT	Previous / next page of the current function

See RTE, F-PLN, PERF, PROG, NAV, DATALINK, RADIO, MENU, and TRS.

Scratchpad and line-select keys

Type into the scratchpad, then press a line-select key (LSK) to insert the value.

• CLR — clears an alert, then the scratchpad, one character at a time.

• DEL — puts *DELETE* in the scratchpad. Press an LSK to delete that field.

• Alphanumeric keys, ., /, and +/- enter data.

ACT and MOD

Edits to the route or flight plan create a MOD (temporary) plan. The title shows MOD.

• ACTIVATE (typically LSK 6R) copies the modification into the active plan.

• CANCEL discards the modification and returns to the active plan.

Captain and First Officer can independently view ACT or MOD while sharing the same FMS data.

Dual MCDU

• Left and right MCDUs have separate brightness, scratchpads, and onside sensors (GPS / IRS / ADS).

• The primary MCDU follows the autopilot source (SRC on the glareshield).

• There is no dedicated DIR key. Direct-to is done from the flight-plan page (left LSK).

Keyboard entry

Click the MCDU to capture the keyboard. Tab releases it.

Keyboard	MCDU
Letters, numbers	Scratchpad
Backspace	CLR
Delete	DEL
. / + -	Dot, slash, sign
F1–F6	LSK 1L–6L
Shift+F1–F6	LSK 1R–6R
Left / Right	PREV / NEXT
Up / Down	BRT / DIM
[	PERF
]	MENU
End	NAV
\	DLK
Insert	FPL
Home	PROG
Page Up	RTE
Page Down	RADIO