Airbus A320 FLIGHT CONTROL UNIT (FCU)
The FCU (Flight Control Unit) which is installed in the center of glare-shield is used for the automatic flight controls. The FCU has
two channels (for safety reason) each of which can independently command the
central panel. If one channel fails, the
other channel can control all the required functions.
FCU Philosophy in Auto flight
When aircraft fly in auto flight mode, there are two types of guidance systems that control the aircraft. The Flight Management Guidance System (FMGS) control the auto flight in one System. The other system relies & follows the target quantity manually entered by Pilots. The FCU windows display dashes and the white dots next to those windows light up when the aircraft uses target quantities from the FMGS. The windows display the selected numbers and the white dots do not light up when the aircraft employs target quantities entered by the pilot.
Selector Knobs
The Flight Control Unit (FCU) has four selector knobs for
the Input/Change the target quantities.
- SPD-MACH
- HDG - TRK
- ALT
- V / S - FPA
FCU's selector knobs can be turned, pushed in, and pulled
out. To arm or engage managed guidance for a specific mode, users simply turn
the selector knob associated with that mode.
Turn the selection knob to set the desired value, then pull
the knob out to activate the selected guidance mode with a target value equal
to the intended value.
The value displayed when a selector knob is spun without
being pulled is the sum of the current target and the turn action value.
SPD/MACH Knob
Selector knob for SPD/MACH: The speed ranges from 100 to 399 knots, while the Mach number ranges
from 0.10 to 0.99. A single spin of the knob equals approximately 32 knots or
0.32 Mach.
SPD/MACH Pushbutton
By pressing the SPD/MACH button, the SPD target is switched
to the equivalent MACH target, and vice versa.
HDG/TRK Knob
Selector knob for HDG/TRK The display range is 0° to 359°.
One turn of the knob equals 32 degrees (1 degree per click).
LOC pushbutton
The LOC (Localizer) mode is armed, engaged, or disengaged by
pressing the LOC pushbutton.
HDG V/S- TRK FPA pushbutton
This pushbutton is used by the pilot to choose between HDG
and TRK (associated with FPA).
Pushing it will do the following functions:
- Displays the FPV (Flight Path Vector) on the PFD (Primary Flight Display) or deletes it.
- This button changes the FD crossbar display to the aircraft Flight Path Director and vice versa on the PFD.
- Also Changes heading reference into track reference in the HDG/TRK window and vice versa.
- Also Changes vertical speed reference target into flight path angle reference target in the V/S-FPA window and vice versa.
ALT Knob
The pilot's target value is always displayed in the FCU
Altitude window. The ALT window never displayed dashes.
Inner and outer altitude selector knobs have the display
range from 100 to 49000 feet.
There are two positions on the outer ALT knob of are 100 and
1000.
Depending on the position of the outer knob, the inner ALT
knob adjusts the altitude in the FCU windows in increments of 100 or 1000 feet.
Metric ALT Pushbutton
Metric ALT Pushbutton converts the altitude in meter from
feet or vice versa. Pressing the pushbutton
will display the current altitude FCU/FM altitude targets in meters on the (PFD)Primary Flight Display. or FCU altitude in meters on ECAM page.
AP1 AP2 pushbuttons
AP1 AP2 pushbuttons are used to engage or disengage the
autopilots.
When the autopilot is turned on, the buttons turn green.
A/THR Pushbutton
This pushbutton is used to arm, activate, and disconnect the
auto thrust (A/THR).
If the A/THR is armed or operating, this button glows green.
EXPED pushbutton:
The expedite mode is activated by pressing EXPED Pushbutton.
LOC Pushbutton
The LOC (Localizer) mode can be armed, engaged, or
disengaged by pressing the LOC pushbutton
APPR Pushbutton
If an ILS approach is selected in the active F-PLN, APPR
pushbutton arms, disarms, engages, or disengages the approach modes: LOC and
G/S modes. If a non-precision approach is selected in the active F-PLN, APP
NAV-FINAL modes are used.
 Functions Explained){kind=link}
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