A320 Autoflight Flashcards
What does FMGC stand for?
Flight management guidance computer
Which FMGC controls the auto thrust?
Normal, the FMGC that controls the engaged autopilot controls the auto thrust, i.e. FMGC 1 controls the auto thrust when AP1 is selected and FMGC 2 controls the auto thrust when AP 2 is selected. When the autopilot is not selected FMGC 1 controls the auto thrust, but FMGC 2 will take over if FMGC 1 fails. If both FMGC’s fail the auto thrust system will be inoperative.
What happens to the auto thrust when both FMGC’s fail?
Auto thrust becomes inoperative
Under normal circumstances, which FMGC controls the auto thrust when AP2 is selected?
FMGC 2
What color is the “A/THR” indication when the auto thrust is armed? When it’s active? When it’s off?
-When it’s armed A/THR is shown in blue on the top right of the FMA
-When its active A/THR is shown in white on the top right of the FMA
-When it’s off A/THR is NOT shown at all on the top right of the FMA
What does FMA stand for?
Flight mode annunciator
When is autothrust typically armed on the ground?
When the thrust levers are advanced to a takeoff position, either FLEX or TOGA
When is the autothrust automatically armed in flight?
When the thrust levers are advanced to TOGA with the flaps set to 1 or greater
What are the indications that the autothrust is ARMED?
-A/THR is displayed in blue in column 5 of the FMA
-The FCU A/THR pushbutton illuminates
-MAN is displayed in column 1 of the FMA, along with the thrust lever position
What determines the active range of the autothrust?
How many engines are running. If both are running the active range extends from just above IDLE through and including the CL detent. If only one engine is running the active range extends all the way to the MCT detent, but the active range only increases to MCT if the operative engine’s thrust lever is placed in the MCT detent.
What should be used to determine the ACTIVE status of the autothrust?
The A/THR displayed in white on FMA column 5. The A/THR pb illumination should NOT be used to determine active status, as it also illuminates when the autothrust is only ARMED and not ACTIVE.
How many columns are in the FMA?
5
What information is displayed in each of the columns of the FMA?
Column 1 = manual or autothrust settings
Column 2 = vertical navigation modes
Column 3 = lateral navigation modes
Column 4 = Approach category and minimums
Column 5 = AP, FD, and A/THR status
What are the different fixed thrust mode indications?
THR CLB = fixed climb thrust
THR IDLE = fixed idle thrust
THR MCT = fixed maximum continuous thrust
THR LVR = used to indicate that the thrust levers are in a position that limits the autothrust’s authority
What limits the autothrust’s authority?
The autothrust can never command more thrust than the thrust lever position.
What controls the speed of the aircraft in a fixed mode of thrust?
The pitch attitude of the aircraft
What controls the airspeed in a variable mode of thrust?
The thrust of the engines
When is a variable mode of thrust used?
-During climbs and descents when a specific rate is being maintained
-As an altitude is being captured
-During level flight
-When all flight guidance is selected off, but autothrust is still active
What are the variable autothrust modes?
SPEED - thrust varies to maintain IAS
MACH - thrust varies to maintain Mach number
THRUST - autopilot and flight director mode maintains the speed
RETARD - autopilot and flight director engaged in LAND mode during an autoland
How can the autothrust be deactivated?
-Pressing one or both of the “instinctive-disconnect” push buttons located on the thrust levers
-Retarding the thrust levers to idle
What happens when the autothrust is disconnected with either the instinctive disconnect push buttons or retarding the thrust to idle?
-Autothrust disconnects
-A single chime is heard
-The MASTER CAUT lights illuminate temporarily
-An A/THR OFF message is briefly displayed
*When autothrust disconnects the thrust will match the thrust lever position. For this reason the thrust levers should be moved to match the engines output before hitting the instictive disconnect buttons.
What happens to the engines output when the autothrust is disconnected?
The engines output matches the thrust lever position. For this reason be sure to match the engines output with the thrust levers before selecting the autothrust off with the instinctive disconnect buttons.
What indication will be displayed in column 1 of the FMA if the autothrust is active and both thrust levers are moved below the climb detent? What will happen if only one lever is brought below the climb detent?
LVR CLB will flash white when both levers are brought below the CL detent, prompting the pilots to place the levers back in the CL detent. If only one lever is brought below the CL detent then a thrust lever asymmetry ECAM is triggered.
What happens to the autothrust after landing?
It automatically disconnects
What happens if the instinctive disconnect push buttons are pressed and held for more than 15 seconds?
The autothrust is disconnected for the remainder of the flight. All autothrust functions, including alpha floor are lost. They can only be recovered on the ground during the next FMGC power up.
What is THR LK?
It’s a feature designed to alert the crew that the autothrust system has disengaged in an abnormal manner, usually by pressing the A/THR pb while the autothrust is engaged, but also due to a fault. When THR LK is displayed the engine thrust is locked and will not change until either the A/THR pb is pressed and the autothrust re-engaged, or the thrust lever position is moved.
What is alpha floor?
It’s a feature designed to aid the flight crew in recovery from high AOA/low airspeed situations. When activated it increases the thrust to TOGA, regardless of thrust lever position, and A.FLOOR is displayed in green in column 1 of the FMA.
*remember that alpha floor will NOT activate if the autothrust was disconnected permanently by pressing the instinctive disconnect pushbutton for more than 15 seconds.
Can alpha floor be activated in alternate law?
No, only in normal law
During normal operations, when is alpha floor inhibited?
Below 100’ RA during landing
Can alpha max be reached if alpha floor is activated?
Yes. The engines take a considerable amount of time to spool from idle to TOGA. During that time alpha max may still be reached.
What happens to the thrust after alpha floor activates but the conditions for alpha floor no longer exist?
The thrust goes into “TOGA LK” which is similar to THR LK just with the thrust locked at TOGA thrust
How should you recover from alpha floor?
Assuming the aircraft is in a safe state and the aircrafts thrust is in TOGA LK…
1.) Place the thrust levers in the TOGA detent
2.) Press the instinctive disconnect pushbutton
3.) restore the autothrust by placing the thrust levers in the CL detent and then pressing the A/THR pushbutton on the FCU
What sends guidance commands to the 3 autoflight systems?
The FMGC’s