Chapter 3

Automatic Flight

Main Menu

SYSTEM DESCRIPTION

GENERAL

The flight guidance system is controlled by the Flight Guidance Control Panel (FGCP) Flight Mode Annunciators (FMAs) on the instrument panel monitor the armed and active modes of the flight guidance system. The FGCP controls include switches to operate the flight directors, autothrottles and the autopilot. 

Autothrottle Control

The autothrottle portion of the panel has a SPD/MACH knob and readout window, autothrottle switch, and mode select switches. When the desired speed is set in the window, the reference bugs on the airspeed indicator drive to that value. In SPD or MACH mode, the autothrottles adjust to maintain that speed. 

In EPR limit mode, the autothrottle adjust to maintain the EPR limit computed by the TRI/TRP.

Roll Control

The Roll portion of the control panel contains a heading select knob and readout window for controlling basic HDG modes. Mode select switches control navigation roll modes. Setting the heading with the HDG knob drives the heading bug on the ND/HSI to the same value. Left mouse clicking the knob will activate the heading select mode (HDG SEL) and commands a turn to the heading bug. Right mouse clicking the heading knob will activate the heading hold (HDG HLD) mode, in which the system commands a wings level attitude and disregards the heading bug. 

Four navigation modes are available using the roll selector switches.

    NAV - GLASS and COMBO WITH GPS  - Follows the GPS flight plan

    VOR/LOC - Steers to intercept and track either a VOR radial or front course of a localizer, depending on the frequency selected in the NAV1 radio.

    ILS - Intercepts and tracks both the localizer and glide slope.

    AUTOLAND - Performs the ILS approach and then provides automatic runway alignment (ALN), flare (FLAR) and rollout (ROL OUT).

During an ILS or autoland approach, if the flaps are not in landing configuration by 1,500 feet AGL, the ILS or LND armed annunciation flashes. If flaps are not in the landing configuration by 300 feet, the autopilot will disengage.

Pitch Control

The pitch control consists of a pitch control wheel and readout, mode select switches, and a altitude set knob and readout. Three pitch modes are available:

    Altitude Hold (ALT HLD) - Maintains a selected altitude and the pitch window displays V0000.

    Vertiacal Speed (VERT SPD) - maintains the selected vertical rate and the pitch window displays V followed by the vertical rate.

    VNAV - GLASS & COMBO WITH GPS - FMC controls the pitch rate. The pitch window displays V followed by the vertical rate.

Rolling the pitch wheel changes the valve in the pitch window. In Takeoff, go-around, or altitude select modes, initial movement of the pitch wheel also selects vertical speed mode. 

Desired altitude is set in the altitude select window using the altitude set knob. Pulling out (clicking) the knob arms the system to capture the set altitude. This does not initiate a climb or descent, but does enable the system to capture the altitude automatically when the aircraft reaxhes the set altitude. Any change in the altitude set knob will require a click to arm for altitude capture.

FLIGHT MODE ANNUNCIATORS

The FMAs are divided into 4 sections from left to right: AUTOTHROTTLE, ARM, ROLL and PITCH modes.

The following mode annunciators may be displayed:

AUTOTHROTTLE MODE ANNUNCIATORS

 

AUTO

LND       - Autoland preflight ground test is in progress. Appears for approximately 1 minute.

 

CLMP    - Clamp mode. Power is removed from the ATS servo (throttles remain stationary)

 

RETD     - Retard mode. Autothrottles move to idle during the autoland.

 

MACH

764        - Mach select mode. Throttles controlled to maintain .764 Mach as selected in SPD/MACH readout.

 

SPD

250        - Speed select mode. Throttles controlled to maintain 250 knots as selected in SPD/MACH readout.

 

FLAP

LIM       - ATS is active and the reference airspeed in the SPD window exceeds the max flap extended speed.

 

SLAT

LIM      - ATS is active and the reference airspeed in the SPD window exceeds the max slat extended speed.

 

EPR

T/O      - ATS is in EPR LIM mode with T/O thrust selected. Throttles controlled to maintain EPR limit takeoff thrust limit.

 

EPR

50        - ATS in EPR LIM mode for T/O FLX with selected temperature displayed. Throttles controlled to maintain T/O FLX thrust limit.

 

EPR 

G/A     - ATS in go-around mode with G/A thrust selected. Throttles controlled to maintain go-around thrust limit.

 

EPR

MCT   - ATS in EPR LIM mode with MCT thrust selected. Throttles controlled to maintain maximum continuous thrust.

 

EPR

CL      - ATS in EPR LIM mode with CL thrust selected. Throttles controlled to maintain climb thrust.

 

EPR

CR      - ATS in EPR LIM mode with CR thrust selected. Throttles controlled to maintain maximum cruise thrust.

 

ARM MODE ANNUNCIATORS

 

PRE    - Autoland preflight ground test is in progress. Appears for approximately 1 minute.

 

LND   - Automatic landing system is armed for automatic capture of ILS.

 

ILS     - ILS is armed for automatic capture of localizer and glide slope.

 

LOC   - LOC mode armed for automatic capture of localizer course.

 

NAV   - GLASS & COMBO WITH GPS - GPS lateral navigation mode is armed for GPS course tracking.

 

VOR   - VOR mode armed for automatic capture of VOR course.

 

AUT

G/A    - Flight guidance system is armed for a full automatic go-around.

 

FD

G/A    - Flight guidance system is armed for a flight director command of a manual go-around.

 

ROLL MODE ANNUNCIATORS

 

FLT    - Autoland preflight ground test is in progress. Appears for approximately 1 minute.

 

HDG

HLD   - Heading hold engaged and existing magnetic heading is being maintained.

 

HDG

SEL    - Heading select mode engaged NS heading selected in the heading window is being maintained.

 

VOR

TRK   - Airplane is tracking VOR course.

 

LOC

TRK   - Airplane is tracking localizer course.

 

TAK

OFF   - Flight director takeoff mode is engaged. After lift-off the command bar commands wings level to maintain heading.

 

WING

LVL   - Turbulence mode engaged. Command bar commands wings level.

 

GO

RND  - Go-around mode is engaged. Command bars command a wings level attitude to maintain heading.

 

AUT

LND   - Automatic landing mode is engaged.

 

ALN   - Align mode is engaged. airplane is maneuvered to maintain runway alignment.

 

ROL

OUT   - Main gear wheel spinup ha occurred. Autopilot and flight director command to hold runway centerline for roll out.

 

NAV

TRK   - GLASS & COMBO WITH GPS - GPS lateral navigation mode is engaged and tracking the GPS course.

 

PITCH MODE ANNUNCIATIONS

 

TEST  - Autoland preflight ground test is in progress. Appears for approximately 1 minute.

 

VERT

SPD    - Vertical speed engaged. Airplane vertical speed is maintained by rate in the pitch window.

 

ALT

HLD   - Altitude hold mode engaged and altitude maintained by pitch attitude.

 

TURB - Turbulence mode engaged. 

 

TAK

OFF   - Flight director takeoff mode is engaged. After lift-off, command bar on ADI displayes pitch commands for 12 degrees.

 

G/S

TRK   - Airplane is tracking the glide slope.

 

GO

RND  - Go-around mode is engaged. Airplane Pitch is increase to approximately 12 degrees.

 

AUT

LND  - Automatic landing mode is engaged. 

 

FLAR - Automatic landing mode engaged and flare mode initiated.

 

NO

FLR   - ILS mode is engaged and the autopilot remains engaged at a radio altitude of 100 feet. This is a flashing annunciation.

 

ROL

OUT  - Main gear spinup had occurred. Autopilot and flight director command to runway centerline for roll out.

 

VNAV

LVL   - GLASS & COMBO WITH GPS - FMS vertical navigation is engaged and the aircraft is in level flight.

 

VNAV

DES   - GLASS & COMBO WITH GPS - FMS vertical navigation is engaged and tracking its vertical path while descending.

 

ADDITIONAL FMA INDICATOR LIGHTS

 

Red lights on this panel come on for autopilot (AP) or autothrottle (THROTTLE) disengagement. AP-1 or AP-1(not simulated) lights indicate which flight guidance computer is controlling the autopilot. A reset button cancels all lights.

 

ANNUNCIATOR DIGITAL LIGHTS TEST

 

An annunciator and digital lights test switch is located on the overhead panel and tests the digital display lights on the flight guidance control panel, the FMAs, and the VHF NAV control panel. 

 

AUTOTHROTTLE

 

The autothrottle controls the throttles to maintain airspeed (SPD SEL, or MACH SEL) or engine thrust (EPR LIM), according to the selected mode. Autothrottles can be used during all phases of flight. Moving the autothrottle switch on the the FGCP to AUTO THROT engages the autothrottles. To disengage the autothrottles, place the autothrottle switch to the OFF position. When the autothrottles are turned off, the FMA throttle window goes blank and the THROTTLE annunciator illuminates on the FMA. To turn of the warning light, press the reset button or reengage the autothrottles.

 

If the flight guidance system is in the takeoff mode, the autothrottles engage in EPR mode when the EPR LIM buttone is clicked and the autothrottles move the throttles to the takeoff EPR setting indicated on the thrust rating system (TRI/TRP). To enter takeoff mode, Turn the flight director on, select either T.O. or TO FLX on the TRI/TRP and click the GA mode key on the FGCP. The FMAs indicate TAK OFF in both pitch and roll windows. When the autothrottles engage, the throttle window will display EPR T/O if using maximum thrust takeoff or EPR nn (nn = assumed temperature) if using a standard thrust takeoff.

 

In the actual aircraft, the go-around buttons are on the throttle levers. Since this would be hard to simulate in the FS environment and still be able to have a fluid experience, we decided to put a go-around button on the FGCP. When in flight selecting the GA button on the FGCP puts the autothrottles in the go-around mode and EPR/GA appears in the throttle window and GO RND appears in both the roll and pitch windows. The GA switch on the TRI/TRP comes on and the autothrottles drive the throttles to the go-around power setting.

 

On takeoff. when the airspeed reaches 80 knots, the autothrottles will go into clamp (CLMP) mode. In this mode, power is removed and the throttles will remain stationary.

 

Activating any of the three autothrottle modes (EPR, SPD or MACH) will deactivate the other two. You can only have one mode active at a time. Once an autothrottle mode is activated, the autothrottle arm switch must be turned off to completely deactivate the autothrottle system.  

 

NOTE ON AUTOTHROTTLE

 

Flight simulator does not handle EPR values very well. The autothrottle system is custom programmed and the EPR values have been adjusted to compensate for simulator errors. Also since the air file is original and not altered some variation in EPR settings during some phases of flight can be expected. The biggest error occurs at higher altitudes and low speeds. In this situation the EPR setting is lower than it should be. If you fly the aircraft correctly and keep the speed up at altitude (grater than Mach .76 or 300 knots) the EPR settings should be correct. A good technique is to use the EPR LIM for takeoff and initial climb and then transition to Mach or SPD hold as you get into the higher altitudes. You can experiment to find out the right technique for you and if you keep the speed us as described earlier, both methods should work. An error will also occur at lower altitudes and very fast speeds. In these situations, the EPR will be higher than it should be. For example, if you are at 8,000 feet and doing 300 knots, the EPR will be higher than it should be. As in the other example, if you fly the aircraft correctly, the EPR settings should indicated normal.

 

 

 

FLIGHT DIRECTOR

 

The flight director commands are represented on a single V-shaped bar that shows both pitch and roll guidance. Speed commands are annunciated by a slow-fast indicator on the right side of the PFD/ADI. The flight director allows you fly the airplane manually or to monitor the autopilot. A FD/OFF toggle switch on the left side of the FGCP engages or disengages the flight director. When the flight directors are active, they operate in accordance with the current flight guidance system mode.

 

The flight director and slow fast pointers can be referenced to a single DFGC by the FD CMD selector switch on the overhead panel. In NORM, DFGC-1 controls the captain's flight director and slow-fast indicator and DFGC-2 controls the first officer's flight director and slow-fast indicators. In BOTH ON 1 or BOTH ON 2, the selected DFGC controls both pilots' flight directors and slow-fast indicators. When the switch is out of the NORM position, a FD light on the instrument panel comes on.

 

YAW DAMPING

 

Yaw damping provides protection against dutch roll. The yaw damper is controlled by an ON/OFF/OVRD switch on the overhead panel. Yaw damping is provided with the autopilot engaged, whether the switch is ON or OFF. When the autopilot is disengaged, yaw damping is only provided when the switch is ON. To eliminate yaw damping during autopilot and manual operation, place the yaw damper switch to OVRD. With yaw damping inhibited or inoperative, a YAW DAMP OFF annunciator comes on.

 

 

Automatic Flight

 

CONTROLS AND INDICATORS

 

LOCATION: Glare Shield

AUTOTHROTTLE MODES AND CONTROLS

AUTOTHROTTLE SPD/MACH READOUT

Displays the indicated airspeed or Mach selected with the SPD/MACH knob.

 

AUTOTHROTTLE MODE SELECT SWITCHES

 

    GA - Activates the go-around mode. FMA displays GO RND on pitch and roll annunciators. If the autothrottle is engages, the FMA will display

             the mode that is selected in the TRI/TCP in the autothrottle window.

             When on the ground, activates the Take Off mode.

    SPD

    SEL - Autothrottle controls to selected speed. FMA displays SPD and selected numerical value.

 

    MACH

    SEL - Autothrottle controls to selected Mach. FMA displays MACH and selected numerical value.

 

    EPR

    LIM - Autothrottle controls to EPR mode selected on the TRI/TRP. FMA displays EPR plus the selected mode or, in TO FLX, displays EPR

               and assumed temperature.

 

AUTOTHROTTLE SPD/MACH KNOB

 

Sets the Speed or Mach depending on which is the active mode. Also moves the command bug on the airspeed indicator. Clicking the center of the knob changes the display window between speed and Mach. When the autothrottles are in speed or Mach hold. Clicking the center, and changing the other value will not affect autothrottle operation.  

 

AUTOTHROTTLE SWITCH

 

Engages the autothrottle system. If the FMA THROTTLE light is on, placing the switch to AUTO THROT resets the light.

 

 

AIRSPEED COMMAND BUG

 

Set with the autothrottle APD/MACH knob to the value in the SPD/MACH readout.

 

FGCP - ROLL MODES AND PITCH WHEEL

 

 

ROLL MODE SELECT SWITCHES

 

    NAV - GLASS & COMBO WITH GPS - Arms the FGS to capture and track the GPS generated course. FMA displays NAV when armed

                and NAV TRK when tracking.

 

    VOR

    LOC - Arms the FGS to capture and track VOR or LOC course. FMA displays VOR or LOC when armed and VOR TRK or LOC TRK

                when tracking.

 

    ILS - Arms the FGS to capture and track both a localizer course and a glide slope. The FMA displays ILS when armed,  LOC TRK when

              tracking a localizer and GS TRK when tracking the glide slope.

 

    AUTO

    LAND - Arms the FGS to establish AUTO LAND mode after localizer and glide slope capture. When tracking both localizer and glide slope

                   with AUT LND annunciated on the FMA, all other modes are inhibited except go-around.

 

HEADING READOUT

 

Displays the heading selected with the HDG select knob.

 

PITCH READOUT

 

First window indicates the operating mode:

    V = vertical speed

    P = turbulence (pitch attitude)

 

Second window displays pitch reference:

    + = climb

    - = descent

 

Remaining window displays the numerical value.

 

PITCH CONTROL WHEEL

 

    AND - airplane nose down

    ANU - airplane nose up

 

In VERT SPD mode, pitch wheel establishes desired vertical speed which is displayed in the readout. Rotating to less than 100 FPM establishes altitude hold mode. FMA annunciates VERT SPD or ALT HOLD.

 

HDG SELECT KNOB

 

Setting the heading with the HDG knob drives the heading bug on the ND/HSI to the same value. Left mouse clicking the knob will activate the heading select mode (HDG SEL) and commands a turn to the heading bug. Right mouse clicking the heading knob will activate the heading hold (HDG HLD) mode, in which the system commands a wings level attitude and disregards the heading bug. 

 

FGCP - PICH MODES

 

PITCH MODE SELECT SWITCHES

 

    ALT

    HOLD - AP/FD commands to existing altitude. FMA annunciates ALT HLD.

    

    VERT

    SPD - The button is not simulated. The vertical speed mode is attained through the selection of other pitch modes.

 

    TURB - Commands wings level and existing pitch attitude at dampened rate. FMA annunciates WING LVL and TURB. Autothottles disengage

                   and THROTTLE light flashes.

 

    VNAV - GLASS & COMBO WITH GPS - Engages FMS vertical guidance functions. FMA annunciates VNAV LVL or VNAV DES

 

ALTITUDE PRESELECT READOUT

 

Displays altitude selected with ALT knob.

 

ALT SET KNOB

 

Changes the altitude in the altitude readout by 100 foot increments. Left mouse clicking arms capture of preselected altitude. Right mouse clicking cancels the altitude deviation light on the altimeter.

 

AP ON SWITCH

 

Engages autopilot to selected computer.

 

 

FLIGHT DIRECTOR CONTROLS AND INDICATORS

 

 

COMMAND BAR

 

Displays pitch and roll commands from the selected flight guidance computer. Command bars are removed from view if command is invalid or if the guidance information is not valid with the engages computer.

 

AIRPLANE SYMBOL

 

Displays the actual pitch and roll attitude of the aircraft.

 

FAST SLOW POINTER

 

Displays the slow/fast indications referenced to the autothrottle SPD/MACH readout. Full deflection either side of center equals approximately 10 knots.

 

FD SWITCH

    

In NORM, DFGC-1 controls the captain's flight director and slow-fast indicator and DFGC-2 controls the first officer's flight director and slow-fast indicators. In BOTH ON 1 or BOTH ON 2, the selected DFGC controls both pilots' flight directors and slow-fast indicators. 

 

FD LIGHT

 

When the FD CMD switch is out of the NORM position, a FD light on the instrument panel comes on.

 

 

FLIGHT MODE ANNUNCIATOR

 

    

LOCATION: Main Panel

 

THROTTLE WARNING LIGHT

 

Flashes when autothrottles disengage.

 

COMPARATOR LIGHTS

 

Not simulated but work with the light test

 

AUTOFLIGHT MODES

 

Throttle display indicates autothrottle operating mode.

 

Arm display indicates the roll and pitch modes that are armed for operation.

 

Roll display indicates the roll operating mode.

 

Pitch display indicates the pitch operating mode.

 

AP WARNING LIGHT

 

Flashes when autopilot disengages. An aural tone and voice warning accompany the flashing light if the autopilot disengages during an automatic landing..

 

RESET SWITCH

 

Turns off THROTTLE and AP warning lights.

 

AP LIGHTS

 

AP1/AP2 lights indicate which computer is providing input to the autopilot. (AP2 not simulated)

 

 

YAW DAMPER & MACH TRIM

 

 

LOCATION: Overhead

 

YAW DAMP SWITCH

 

    OFF - Yaw damper is disables if autopilot is disengaged. If autopilot is engaged, yaw damper operation is provided.

 

    ON - Yaw damper is provided with autopilot on or off.

 

    OVRD - Inhibits all yaw damper operation.

 

- Indicates yaw damper is off.

 

MACH TRIM COMP SWITCH

 

    NORM - Mach trim compensation operates (not simulated)

 

    OVRD - Mach trim compensation mode is inoperative and trim actuator retracts.

 

- Indicates Mach trim is inoperative.