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
What does the autothrust system assume?
That the flight guidance is being followed
What should you do with the flight guidance system is you aren’t going to follow it?
Turn it off. This ensures that the autothrust will default to a variable thrust mode, and airspeed will be maintained with thrust rather than with pitch.
What mode does the autothrust default to if the autopilot and flight directors are both turned off?
Speed mode (or Mach mode, point is it will be a variable mode of thrust where airspeed will be controlled with thrust rather than pitch)
What is the default mode for the autopilot/flight directors if not previously engaged, and then selected on while in flight?
HDG and V/S. On the ground it depends on the flight plan and the settings of the FCU.
What is the difference between managed and selected guidance?
Selected = the pilot directs the speed, lateral, or vertical control
Managed = the FMS provides the guidance commands
A mix of these may be used. You can be in managed speed while manually selecting a heading, etc.
What color are selected vs managed guidance on the PFD?
Selected = blue
Managed = magenta
How does the FMS calculate Vapp?
It takes Vls and adds 1/3 of the headwind component, no less than 5 knots, no more than 15 knots. So for a 21 knot headwind it would add 7 knots to Vls to get Vapp. For a 12 knot headwind, 1/3 of 12 is 4 knots, but 5 is the minimum so it would add 5 knots.
What speeds will the aircraft decelerate to (in managed speed) when an approach is activated in the different flap configurations?
Flaps 0 = green dot
Flaps 1 = S speed (maneuvering speed with the slats extended)
Flaps 2 = F speed (maneuvering speed for both flaps 2 and 3)
Flaps 3 = F speed
Flaps full = Vapp
What does ground speed mini do?
Provides wind shear protection by ensuring a minimum ground speed is flown during an approach. It does this by increasing the indicated airspeed to maintain the ground speed expected on the ground based on the winds reported on the ground.
Ex. If a 20 knots headwind is reported for the runway but on approach the headwind component is 30 knots, it will add 10 knots to your indicated airspeed to keep your ground speed constant.
What can you do to override the effects of ground speed mini?
Pull selected speed
What are all the lateral modes?
Heading
Track
Nav
Localizer
What happens when you pull heading, and then rotate the heading bug to your desired heading? How is that different than selecting a heading and then pulling?
If you pull heading first, and then rotate the knob, the aircraft will turn in the direction the knob was rotated. If you select a heading first and then pull, the aircraft will turn in whichever direction is closer the selected heading. I.e. if you need to turn more than 180 degrees, you should pull heading first, then turn the knob. Otherwise, the aircraft will turn in the wrong direction.
When you pre-select a heading, how long will it be displayed on the FCU window?
Approximately 45 seconds. There are 2 exceptions. Prior to takeoff a heading will remain in the FCU window until heading is pulled. Additionally during certain approach and go-around modes the heading can be preset and it will remain until the heading knob is pulled.
Will open climb or open descent honor an altitude restriction?
No
What controls airspeed in an “open” vertical mode?
Pitch
What thrust setting will the autothrust command during open climb and open descent?
Open climb = THR CLB
Open descent = THR IDLE
What does the EXPED pb on the FCU do?
During climbs pushing the EXPED pb on the FCU will cause “EXP CLB” to be annunciated on the FMA, initiate a climb at green dot speed, and ignore all altitude and speed constraints.
During descents pushing the EXPED pb on the FCU will cause “EXP DES” to be annunciated on the FMA, initiate a descent at 340kias/0.80mach, and ignore all altitude and speed constraints.
How can you get out of EXP DES or EXP CLB before reaching the altitude on the FCU?
Another vertical mode must be selected, e.g., pulling open climb or descent, selecting vertical speed, pushing for 0 vertical speed, etc. pushing the EXPED button again will have no effect.
Why is using vertical speed during climbs or descents potentially problematic if not managed correctly?
During vertical speed climbs and descents, maintaining a commanded speed is not assured. The autothrust system will try to maintain the desired speed by managing thrust but thats not always possible based on the vertical speed selected. Care must be taken and monitored closely.
Can you be in a managed climb or descent during heading mode?
No. You can only be in a managed climb or descent in managed NAV mode
What vertical speed will the aircraft default to if a managed descent is initiated, but the aircraft is already below the computed flight path?
1000fpm
What will happen if you select a managed descent but the aircraft is already above the computed descent path?
The aircraft will accelerate to the top of the managed speed range. If that isn’t sufficient to recapture the path, a “more drag” message will be displayed below the FMA, indicating that at least 1/2 speed brakes are required.
What happens if you change the selected altitude in the FCU during ALT* mode?
The aircraft defaults to vertical speed mode at the aircrafts current vertical speed.
What’s the difference between ALT and ALT CRZ?
ALT CRZ allows the altitude to vary slightly from the selected altitude to minimize thrust variations and improve fuel economy.
What are mode reversions?
They are automatic mode changes that occur unexpectedly. These automatic changes to the engaged mode ensures logical autopilot, flight director, and autothrust operations, in conjunction with flight crew input or when the aircraft reaches a flight plan discontinuity.
What can cause a mode reversion?
-An engaged mode can no longer be managed
-Illogical FCU altitude changes
-Excessively high or low airspeeds
What prompts to the pilots are there when a mode reversion occurs?
A triple click aural alert sounds, and a white box briefly flashes around the vertical mode.
What mode reversion is expected when managed NAV is no longer engaged?
-If the aircraft is in a climb, CLB reverts to OP CLB
-If the aircraft is in a descent, DES reverts to V/S at the aircrafts current rate
What would happen if you’re in a climb and the FCU knob is changed to an altitude below your current altitude?
The vertical mode will revert from CLB or OP CLB to V/S at the aircrafts current vertical rate
What happens to the autothrust and climb mode when the airspeed approaches either Vmax or Vls?
CLB/OP CLB automatically changes to V/S, and the autothrust reverts to speed mode, allowing the aircraft to vary the thrust to adjust the airspeed rather than the pitch.
What happens to the flight directors when the aircraft reaches Vmax+4?
They disengage
What happens if V/S mode is used to climb and an excessive rate of climb is selected?
Airspeed will decrease until reaching VLS. At this point V/S mode is still engaged but the autopilot abandons the vertical speed target and decreases pitch to maintain VLS.
What happens if the aircraft is descending in V/S mode and an excessive vertical speed is selected?
The aircraft will accelerate until reaching VMAX, at which point the autopilot will abandon the vertical speed target and increases pitch to maintain VMAX.
What is SRS mode and what does it do?
SRS stands for speed reference system. It’s a vertical mode that engages during takeoff or a go-around to provide the correct pitch guidance in the event of an engine failure. During takeoff, If both engines are operating, it commands a speed of V2+10. During an engine failure after takeoff it commands V2 or the aircrafts current speed whichever is higher, up to a maximum of V2+15. During a go-around it commands a pitch to maintain the speed that was present when the go-around was initiated or Vapp, whichever is higher. SRS will remain engaged until reaching acceleration altitude, or until any other pitch mode is engaged.
What speed does SRS pitch for during takeoff with both engines running?
V2 + 10
What speed does SRS pitch for during takeoff after an engine failure?
V2 or the aircrafts current speed, whichever is greater, up to V2 + 15
What speed does SRS pitch for during a go-around?
The speed at which the go-around was initiated, or Vapp, whichever is greater.
When will RWY TRK mode become active?
Shortly after takeoff, if a heading was pre-selected before takeoff. It will remain active until another lateral mode is selected.
What does CAT 3 DUAL mean?
It means that both autopilots are engages and the system is “fail operational.” Fail operational means that there is enough redundancy in every monitored system that if something’s fails an autoland is still possible.
What does Cat 3 single mean?
It means “fail passive” which means that if an additional failure occurs and autoland will not be possible. You’ll get Cat 3 single when only one autopilot is engaged or if one or more systems loses redundancy.
What are the wind limitations for an autoland?
For 200, 300, and 700 series aircraft:
-Headwind = 30 knots
-Crosswind = 15 knots
-Tailwind = 10 knots
For 600 series aircraft:
-Headwind = 15 knots
-Crosswind = 10 knots
-Tailwind = 10 knots
*These winds are surface winds reported by ATC. If the winds on ND are in excess of these, the approach may continue. If the tower reports winds in excess of these limits the approach may not continue.
Once “LAND” mode is annunciated on the FMA, how can it be disengaged?
There are only two ways
-TOGA thrust
-Disconnecting both autopilots and flight directors
When will the autoland warning light illuminate?
When the aircraft is below 200 feet, at least one autopilot is engaged in the LAND or FLARE modes, and one of the following occurs:
-LOC deviation exceeds 1/4 dot, or the localizer signal is lost, while above 15’ RA
-G/S deviation exceeds 1 dot, or the G/S signal is lost, while above 100’ RA
-The difference between the 2 RA measurements is greater than 15’
-The last autopilot disengages
-The FMGS detects a long flare
-The FMGS detects an “untimely flare”
-An untimely flare is when one RA is inoperative and the time between LAND mode engagement
and FLARE engagement is less than 2 seconds
What guidance does APP NAV provide?
It provides lateral guidance during a non-precision approach
What guidance does FINAL provide?
It provides vertical guidance during a non-precision approach
When can APP NAV and FINAL modes be armed, and how do you arm them?
They can be armed when a non-precision approach is loaded into the MCDU flight plan. They are armed by pressing the APPR button on the FCU.
What will happen on a non-precision approach if you go 50’ below your minimums with the AP still engaged?
The AP will automatically disconnect, and HDG and V/S will become the active modes
When will the aircraft enter the go-around mode?
When TOGA thrust is applied with the flaps HANDLE at 1 or greater
Will the aircraft honor any altitude constraints in the MCDU during a go-around?
No! That’s why it’s important to check if there are any required levels offs at a low altitude during a go-around/missed approach. If there are any low altitude constraints you’ll need to place them in the FCU panel, and then they’ll be honored.
What pitch mode will the aircraft go into during a go-around? Until when?
Into SRS mode. It will remain in SRS mode until acceleration altitude.
