Auto Flight System Flashcards
The automatic flight control system consists of the Autopilot Flight Director System (AFDS) and the autothrottle system.
Each system can be used independently or operated simultaneously to provide maximum automation.
The automatic flight control system consists of the Autopilot Flight Director System (AFDS) and the autothrottle system.
Each system can be used independently or operated simultaneously to provide maximum automation.
The AFDS consists of three Autopilot Flight Director Computers (AFDCs) and the MCP.
The MCP provides control of the Autopilot, Flight Director, Altitude Alert, and Autothrottles.
The MCP is used to arm or engage various lateral and vertical AFDS modes, and establish altitudes, speeds, and climb/descent profiles.
The AFDS consists of three Autopilot Flight Director Computers (AFDCs) and the MCP.
The MCP provides control of the Autopilot, Flight Director, Altitude Alert, and Autothrottles.
The MCP is used to arm or engage various lateral and vertical AFDS modes, and establish altitudes, speeds, and climb/descent profiles.
On the B777, the autopilot does not use servos to move the primary flight control surfaces.
Instead, the autopilot controls the elevators, ailerons, flaperons, and spoilers through Primary Flight Computers (PFCs), Actuator Control Electronics (ACEs), and Power Control Units (PCUs).
When engaged, the autopilot commands are constantly provided for roll and pitch.
Autopilot rudder commands are added only during an autopilot approach and landing.
On the B777, the autopilot does not use servos to move the primary flight control surfaces.
Instead, the autopilot controls the elevators, ailerons, flaperons, and spoilers through Primary Flight Computers (PFCs), Actuator Control Electronics (ACEs), and Power Control Units (PCUs).
When engaged, the autopilot commands are constantly provided for roll and pitch.
Autopilot rudder commands are added only during an autopilot approach and landing.
The AFDS autopilot commands go to the PFCs through the Flight Control ARINC 629 buses.
The PFCs compare signals, select which signal to use, and if an input is not valid, then it is removed from the computation.
This process is called “Mid-Value Selection” and “Voting.”
The AFDS autopilot commands go to the PFCs through the Flight Control ARINC 629 buses.
The PFCs compare signals, select which signal to use, and if an input is not valid, then it is removed from the computation.
This process is called “Mid-Value Selection” and “Voting.”
The PFCs process and change the autopilot commands to flight control commands.
The flight control commands from the PFCs next to the ACEs, and then to the PCUs to move the flight control surfaces.
The PFCs process and change the autopilot commands to flight control commands.
The flight control commands from the PFCs next to the ACEs, and then to the PCUs to move the flight control surfaces.
In a “fly-by-wire” aircraft, there is no natural feedback to the flight controls in the flight deck.
Therefore, a false feel (or backdrive) is generated to give the pilots the expected feedback.
The PFCs send backdrive commands to the AFDCs to operate the backdrive actuators.
The backdrive actuators move the control columns, control wheels and rudder pedals to a position that represents the autopilot command.
In a “fly-by-wire” aircraft, there is no natural feedback to the flight controls in the flight deck.
Therefore, a false feel (or backdrive) is generated to give the pilots the expected feedback.
The PFCs send backdrive commands to the AFDCs to operate the backdrive actuators.
The backdrive actuators move the control columns, control wheels and rudder pedals to a position that represents the autopilot command.
The AFDS does not control the horizontal stabilizer.
Pitch trim control is from the Primary Flight Control System (PFCS).
The AFDS does not control the horizontal stabilizer.
Pitch trim control is from the Primary Flight Control System (PFCS).
The APP mode can be disengaged by selecting another mode until the aircraft is below 1,500’ (RA) with LOC and G/S captured.
The APP mode can be disengaged by selecting another mode until the aircraft is below 1,500’ (RA) with LOC and G/S captured.
The Flight Director steering indications are also displayed as popup guidance when the related flight director switch is OFF and a TO/GA switch is pushed.
This Flight Director popup’s will only occur if airspeed is greater than 80 knots and the leading edge slats are not retracted.
The Flight Director steering indications are also displayed as popup guidance when the related flight director switch is OFF and a TO/GA switch is pushed.
This Flight Director popup’s will only occur if airspeed is greater than 80 knots and the leading edge slats are not retracted.
If a Flight Director popup has occurred, the flight director bars can be removed by cycling the respective flight director switch ON and then OFF.
If a Flight Director popup has occurred, the flight director bars can be removed by cycling the respective flight director switch ON and then OFF.
In addition to mode failures, the operation of the stall and overspeed protection functions will cause the flight director pitch bar to disappear.
In addition to mode failures, the operation of the stall and overspeed protection functions will cause the flight director pitch bar to disappear.
The AFDS Status Annunciator (ASA) is displayed just above the PFD attitude display.
The indications in this area include: FLT DIR (this indicates the flight director is ON and the autopilots are not engaged); A/P (this indicates the autopilots are engaged).
If both the Flight Director and Autopilots are engaged, the annunciation is A/P.
Other indications include LAND 3, LAND 2, and NO AUTOLAND. These will be discussed later in this
The AFDS Status Annunciator (ASA) is displayed just above the PFD attitude display.
The indications in this area include: FLT DIR (this indicates the flight director is ON and the autopilots are not engaged); A/P (this indicates the autopilots are engaged).
If both the Flight Director and Autopilots are engaged, the annunciation is A/P.
Other indications include LAND 3, LAND 2, and NO AUTOLAND. These will be discussed later in this
Roll guidance when the TO/GA mode is engaged provides wings level at lift-off until 5 feet RA. Then, guidance is provided to maintain the existing ground track.
Roll guidance when the TO/GA mode is engaged provides wings level at lift-off until 5 feet RA. Then, guidance is provided to maintain the existing ground track.
In flight, TO/GA is armed when the leading edge slats are extended or at glideslope capture - whichever comes first.
In flight, TO/GA is armed when the leading edge slats are extended or at glideslope capture - whichever comes first.
TO/GA is engaged in flight by pressing a TO/GA switch.
The AFDS maintains the ground track present at mode engagement.
TO/GA is engaged in flight by pressing a TO/GA switch.
The AFDS maintains the ground track present at mode engagement.
Selecting LNAV on the MCP arms the LNAV mode.
This mode can be armed before takeoff and will automatically engage at 50’.
LNAV can also be armed and engaged at any time in flight.
Selecting LNAV on the MCP arms the LNAV mode.
This mode can be armed before takeoff and will automatically engage at 50’.
LNAV can also be armed and engaged at any time in flight.
If not within LNAV capture criteria, LNAV will arm and subsequently engage when the capture parameters are met (aircraft must be above 50’ RA, within 2.5 miles of the active course).
For the LNAV mode to arm, you must have an active route in the FMS.
If not within LNAV capture criteria, LNAV will arm and subsequently engage when the capture parameters are met (aircraft must be above 50’ RA, within 2.5 miles of the active course).
For the LNAV mode to arm, you must have an active route in the FMS.
When ATT is engaged:
· If bank angle is greater than 30 degrees, the AFDS returns to 30 degrees of bank.
· If bank angle is between 30 and 5 degrees, the AFDS holds the bank angle.
· If bank angle is 5 degrees or less, the AFDS commands wings level (and annunciates HDG HLD or TRK HLD, as appropriate).
When ATT is engaged:
· If bank angle is greater than 30 degrees, the AFDS returns to 30 degrees of bank.
· If bank angle is between 30 and 5 degrees, the AFDS holds the bank angle.
· If bank angle is 5 degrees or less, the AFDS commands wings level (and annunciates HDG HLD or TRK HLD, as appropriate).
The Localizer mode engages when the aircraft is in position to capture the localizer beam. Maximum LOC intercept angle is 120 degrees.
The Localizer mode engages when the aircraft is in position to capture the localizer beam. Maximum LOC intercept angle is 120 degrees.
The first mode to discuss is the Takeoff / Go-around mode.
This mode provides pitch and roll guidance for the takeoff and go-around phase of flight.
It is engaged differently depending on whether the aircraft is on the ground or in flight.
The first mode to discuss is the Takeoff / Go-around mode.
This mode provides pitch and roll guidance for the takeoff and go-around phase of flight.
It is engaged differently depending on whether the aircraft is on the ground or in flight.
On the ground, TO/GA is engaged by selecting either flight director switch ON or by pushing either TO/GA switch with airspeed greater than 80 knots.
On the ground, TO/GA is engaged by selecting either flight director switch ON or by pushing either TO/GA switch with airspeed greater than 80 knots.
On the ground, the flight director PFD pitch bar indicates an initial pitch of eight degrees nose up, which is not considered takeoff guidance, but is a normal pre-takeoff indication.
On the ground, the flight director PFD pitch bar indicates an initial pitch of eight degrees nose up, which is not considered takeoff guidance, but is a normal pre-takeoff indication.
For climb rates above 1200 FPM, the AFDS pitch command is a target airspeed of:
· V2 plus 15 knots, or
· If current airspeed remains above the target speed for 5 seconds, the target airspeed is reset to current airspeed, to a maximum of V2 plus 25 knots, or
· The IAS / MACH window speed if the IAS / MACH window speed is changed to a speed greater than the target speed
For climb rates above 1200 FPM, the AFDS pitch command is a target airspeed of:
· V2 plus 15 knots, or
· If current airspeed remains above the target speed for 5 seconds, the target airspeed is reset to current airspeed, to a maximum of V2 plus 25 knots, or
· The IAS / MACH window speed if the IAS / MACH window speed is changed to a speed greater than the target speed
For climb rates between 600 FPM and 1200 FPM, the AFDS pitch command is a mix of airspeed and attitude.
For climb rates between 600 FPM and 1200 FPM, the AFDS pitch command is a mix of airspeed and attitude.
After takeoff, if the climb rate is below 600 FPM, the AFDS pitch command is to hold attitude.
After takeoff, if the climb rate is below 600 FPM, the AFDS pitch command is to hold attitude.
Note: The AFDS uses the speed set in the IAS / MACH window prior to takeoff for V2.
If an engine fails during takeoff, the AFDS pitch command is a mix of airspeed and attitude for climb rates below 1200 FPM.
Note: The AFDS uses the speed set in the IAS / MACH window prior to takeoff for V2.
If an engine fails during takeoff, the AFDS pitch command is a mix of airspeed and attitude for climb rates below 1200 FPM.
For climb rates above 1200 FPM the AFDS pitch command is a target airspeed of:
· V2, if airspeed is below V2, or
· Existing speed, if airspeed is between V2 and V2 + 15.
· If airspeed is above V2 + 15, the AFDS pitch command will be for V2 + 15.
For climb rates above 1200 FPM the AFDS pitch command is a target airspeed of:
· V2, if airspeed is below V2, or
· Existing speed, if airspeed is between V2 and V2 + 15.
· If airspeed is above V2 + 15, the AFDS pitch command will be for V2 + 15.
If a go-around is initiated, the commanded speed is the MCP IAS / MACH window speed or current airspeed, whichever is higher, to a maximum of the IAS / MACH window speed plus 25 knots.
If a go-around is initiated, the commanded speed is the MCP IAS / MACH window speed or current airspeed, whichever is higher, to a maximum of the IAS / MACH window speed plus 25 knots.
f VNAV is armed prior to takeoff, it engages 400’ above runway elevation after takeoff.
VNAV engages in the appropriate VNAV mode as required to maintain the current flight path.
There is a VNAV SPD mode, a VNAV PTH mode, and a VNAV ALT mode.
f VNAV is armed prior to takeoff, it engages 400’ above runway elevation after takeoff.
VNAV engages in the appropriate VNAV mode as required to maintain the current flight path.
There is a VNAV SPD mode, a VNAV PTH mode, and a VNAV ALT mode.
With VNAV engaged, the AFDS maintains the FMC speed displayed on the PFD airspeed tape
With VNAV engaged, the AFDS maintains the FMC speed displayed on the PFD airspeed tape
With VNAV PTH engaged, the AFDS maintains the FMC / CDU altitude or descent path with pitch commands.
With VNAV PTH engaged, the AFDS maintains the FMC / CDU altitude or descent path with pitch commands.
In the example shown here, the MCP altitude is more restrictive so the VNAV ALT mode engaged upon level off.
To continue the descent, change the MCP altitude and push the altitude selector.
The VNAV PTH mode can then engage.
In the example shown here, the MCP altitude is more restrictive so the VNAV ALT mode engaged upon level off.
To continue the descent, change the MCP altitude and push the altitude selector.
The VNAV PTH mode can then engage.
With the first push of either TO/GA switch: The PFDs display roll and pitch guidance to fly the go-around; The autothrottles engage in thrust (THR) mode and provide a 2,000 FPM climb rate; The AFDS maintains the ground track present at mode engagement and increases pitch to hold the selected speed as thrust increases.
If current airspeed remains above the target speed for 5 seconds, the target airspeed is reset to current airspeed, (to a maximum of the IAS / MACH window speed plus 25 knots)
With the first push of either TO/GA switch: The PFDs display roll and pitch guidance to fly the go-around; The autothrottles engage in thrust (THR) mode and provide a 2,000 FPM climb rate; The AFDS maintains the ground track present at mode engagement and increases pitch to hold the selected speed as thrust increases.
If current airspeed remains above the target speed for 5 seconds, the target airspeed is reset to current airspeed, (to a maximum of the IAS / MACH window speed plus 25 knots)
If during the go-around, the TO/GA switches are pressed a second time:
The autothrottles engage in the thrust reference (THR REF) mode for full go-around thrust.
If during the go-around, the TO/GA switches are pressed a second time:
The autothrottles engage in the thrust reference (THR REF) mode for full go-around thrust.
TO/GA level-off:
· At the MCP selected altitude, the AFDS pitch mode changes to altitude hold (ALT)
· If altitude is captured, or if V/S or FPA is engaged, MCP speed is automatically set to:
· The flap placard speed minus 5 knots, · 250 knots if flaps are up, · VREF 30 + 80 knots for engine out, or · A speed value entered into the IAS / MACH window after TO/GA was pushed.
TO/GA level-off:
· At the MCP selected altitude, the AFDS pitch mode changes to altitude hold (ALT)
· If altitude is captured, or if V/S or FPA is engaged, MCP speed is automatically set to:
· The flap placard speed minus 5 knots, · 250 knots if flaps are up, · VREF 30 + 80 knots for engine out, or · A speed value entered into the IAS / MACH window after TO/GA was pushed.
TO/GA mode termination:
· Below 400 feet RA, the AFDS remains in the go-around mode unless the autopilot is disconnected and both flight directors are turned off.
· Above 400 feet RA, select a different MCP pitch or roll mode.
TO/GA mode termination:
· Below 400 feet RA, the AFDS remains in the go-around mode unless the autopilot is disconnected and both flight directors are turned off.
· Above 400 feet RA, select a different MCP pitch or roll mode.
The AFDS provides windshear recovery guidance by means of the normal go-around pitch and roll modes.
Go-around is engaged by pushing a TO/GA switch.
The AFDS commands a pitch-up of 15 degrees or slightly below the pitch limit, whichever is lower.
As rate of climb increases, the AFDS transitions from pitch to airspeed control.
The AFDS provides windshear recovery guidance by means of the normal go-around pitch and roll modes.
Go-around is engaged by pushing a TO/GA switch.
The AFDS commands a pitch-up of 15 degrees or slightly below the pitch limit, whichever is lower.
As rate of climb increases, the AFDS transitions from pitch to airspeed control.
The target airspeed is the IAS / MACH window airspeed or the current airspeed, whichever is greater when TO/GA is engaged.
If current airspeed remains above the selected speed for 5 seconds, the selected airspeed is reset to current airspeed, (to a maximum of the IAS / MACH window plus 25 knots).
The target airspeed is the IAS / MACH window airspeed or the current airspeed, whichever is greater when TO/GA is engaged.
If current airspeed remains above the selected speed for 5 seconds, the selected airspeed is reset to current airspeed, (to a maximum of the IAS / MACH window plus 25 knots).
