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Autopilot System

G500 Systems

This is a work in progress.


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Photo: Magic happens

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How it works . . .

In the G500, the flight director is essentially the higher brain function of the autopilot to do high level things, like takeoff, climb, intercept a course, descend, fly an approach, and land. Most of our interaction with this Flight Director is through the Flight Guidance Panel. The Flight Control Computers provide the inner brain function, the stick and rudder required to do what the higher brain directs. That is the basic autopilot itself.

Most of your interface with the flight director is through the Flight Guidance Panel, though inputs are also made from the Touch Screen Controllers. But for our purposes here, let's get to know the Flight Guidance Panel.

Flight Guidance Panel

The flight director provides guidance for the Flight Control Computers and displays information to the pilots for takeoff, climb, cruise, descent, approach, and landing. It does this by using information from air data sensors, position sensors, the flight management system, and pilot inputs through the touch screen controllers and the flight guidance panel.

As with previous Gulfstreams, after a while most of the Flight Guidance Panel becomes second nature, with the more obscure functions causing confusion now and then. Even with years of experience, you might need a refresher now and then. With that in mind, I'll simply present the uses for each part of the panel from left to right.

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Photo: Flight guidance panel: speed, Symmetry, §2b-21-40, fig. 1

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[Symmetry, §2b-21-40] The guidance panel contains two independent channels. Each channel communicates with one FGC channel. When a FD mode is armed or engaged, the annunciator on the appropriate button on the GP is lit. The annunciation of the mode and the AP engage status is provided on the PFD and SFD.

The guidance panel interfaces using the following switches:

  • TOGA buttons

  • AP DISC/TRIM SYNC

  • A/T engage/disengage buttons.

The guidance panel interfaces with the following systems:

  • Touch screen controllers (TSCs)

  • Throttle quadrant assembly

  • Flight management system (FMS).

Speed Control

  • MAN Button — Pushing the manual speed button activates/deactivates manual speed control. The light above the MAN speed button is lit when manual speed control is active. The light is off when in auto speed mode. Manual mode speed value is manually selected. Auto speed mode value is FMS derived. When manual speeds are selected, the speed target is synchronized to the current speed.

  • Speed Select Knob and CHG Button — The speed select knob is used to manually select the target speed when manual speed mode is active. The selectable range for indicated airspeed (IAS) is 100 to 340 knots, and the range for Mach is 0.40 to 0.93 Mach. Pushing the speed change ( CHG ) button when manual speed mode is active changes the target speed from IAS to Mach, and from Mach to IAS. It also synchronizes to the current speed. For example, if the aircraft is at 250 knots with 280 knots set as the target speed, pushing the CHG button changes the IAS to the equivalent Mach number and sets the current Mach as the new target.

  • Speed Window — On initial power-up, the speed window shows dashes until a valid FMS speed reference is entered, unless manual speed mode is selected. When the speed mode is set to indicated airspeed, then IAS is displayed in the widow next to the target speed. When the speed mode is set to Mach, then M is displayed in the window next to the speed. The speed mode, IAS or Mach, is retained for transitions from FMS auto speed to manual speed. For example, when a Mach FMS target speed is displayed and manual speed mode is selected, the manual target speed will also be displayed as Mach.

  • Speed Constraints

  • Automatic speeds are derived by the FMS as follows:

    • Climb speed is set to minimum with any climb constraints

    • Cruise speed is set to any cruise constraint

    • Descent speed is set to any descent speed.

    If below the speed limit altitude (250 knots/10,000 feet), the climb, cruise, and descent speeds are set to minimum with the speed/altitude limit.

    The automatic speed target is set based on the speed mode.

    • If the speed mode is takeoff, the speed target is V2

    • If the speed mode is departure, the speed target is theminimum of performance initialization departure speed and climb speed

    • If the speed mode is climb, the speed target is climb

    • If the speed mode is cruise, the speed target is cruise

    • If the speed mode is descent, the speed target is descent

    • If the speed mode is approach, the speed target is the minimum of the performance initialization approach speed and descent speed

    • If the speed mode is go-around, the speed target is the minimum of the performance initialization go-around speed and climb speed.

    If in a holding pattern, then the speed is max endurance.

    Limit speeds are applied as follows:

    • High Speed Limiting -- Set the speed target to the minimum of the speed target and VMO.

    • Low Speed Limiting -- Set the Mach speed target to themaximum of the Mach speed target and VREF . If the system is not in the takeoff mode, TSC speed intervention, or FGC manual speed, then set the IAS speed target to the maximum of the CAS speed target and VREF.

    • Placard Speed Limiting -- If flap position is valid, then the speed target is the minimum of speed target and flap/gear placard speed.

Lateral Control

  • HDG/TRK Button — The HDG/TRK button is used to activate/deactivate heading or track mode. The light above the HDG/TRK button lights when heading or track mode is active. The position of the select outer knob determines whether heading or track mode activates when the button is pushed. When the select outer knob is set to HDG and the HDG/TRK button is pushed, the lateral mode becomes heading select. When the select outer knob is set to TRK and the HDG/TRK button is pushed, the lateral mode becomes track select.

  • Select Knob and SYNC Button — The select knob is used to manually select or preselect the heading or track. Rotating the knob clockwise increases the desired heading/track (030_, 031_, 032_, etc.). Rotating the knob counterclockwise decreases the desired heading/track (360_, 359_, 358_, etc.). Pushing SYNC in the center of the select knob synchronizes the heading/track to the current aircraft heading/track.

  • Lateral Window — On initial power-up, the lateral window shows dashes until valid data from the navigation source is entered. When the lateral mode is set to heading, then HDG is displayed in the lateral window. When the lateral mode is set to track, then TRK is displayed in the window. The heading or track value in the window is also displayed as heading or track bugs on the PFD, standby flight display, and on the interactive Map.

  • Lateral Navigation LNAV Button — The lateral navigation button ( LNAV ) is used to activate and deactivate the lateral navigation mode. The lateral navigation mode applies to both long--range (FMS) and short-range (VOR/LOC) navigational sources. When LNAV is armed or active, the light above the button lights and goes out when themode is disarmed or deactivated.

Vertical Control

  • Vertical Navigation (VNAV) Button — The vertical navigation button, ( VNAV ) is used to activate and deactivate the vertical navigation mode. When VNAV is armed or active, the light above the button lights and goes out when the mode is disarmed or deactivated.

  • VS/FPA Button — The button, labeled VS/FPA , is used to engage either vertical speed (VS) or flight path angle (FPA) mode. When either mode is active, the light above the button lights and goes out when the mode is deactivated. When neither VS or FPA mode is active, the flight guidance control system (FGCS) transitions to VSmodewhen the button is pushed.Pushing the VS/FPA button when VS is active, changes the active mode to FPA and synchronizes the target FPA to the current aircraft flight path angle. Pushing the VS/FPA button when FPA is active, keeps the FPA mode active and synchronizes the target FPA to the current aircraft flight path angle.

  • Vertical Select Knob and CHG Button — The vertical select knob is used to change the desired VS or FPA. Rotating the knob clockwise increases the desired vertical speed or flight path angle (0.1° for FPA or 100 feet/minute for VS per detent).Rotating the knob counter clockwise decreases the desired vertical speed or flight path angle. The selectable range for the vertical speed is -8,000 feet/minute to +6,000 feet/minute, and the range for the flight path angle is -9.9° to +19.9°. When VS is the current vertical modeand the CHG button on the vertical select knob is pushed, the target VS changes to the current flight path angle of the aircraft and sets that angle as the new target. When FPA is the current vertical mode and the CHG button on the vertical select knob is pushed, the target FPA changes to the current vertical speed of the aircraft and sets that speed as the new target.

  • Vertical Guidance Window — On initial power-up, the vertical window shows dashes until VS or FPA mode is engaged. When either VS or FPA flight director mode is active, the respective vertical speed or flight path target is displayed in the vertical guidance window. The desired VS, shown as VS in the window, is displayed in feet/minute, and the desired FPA, shown as FPA in the window, is displayed in degrees. Positive values are displayed with a + sign and a - sign for negative values. Transitioning from VS or FPA mode to another vertical mode results in the vertical display to go blank.

  • Flight Level Change (FLCH) Button — The button labeled FLCH , is used to engage the flight level change mode. When the flight level change mode is active, the light above the button lights and goes out when the mode is deactivated.

Altitude Control

  • Altitude HOLD Button — The altitude button, labeled HOLD, is used to activate and deactivate the altitude hold mode. When altitude hold is active, the light above the button lights and goes out when the mode is deactivated. The ALTITUDE window shows the altitude target for guidance via a selected vertical mode. If the HOLD button is selected, with a vertical mode selected, the altitude target becomes the aircraft altitude when HOLD was selected. However, the ALTITUDE window still maintains the previously selected setting until selecting another vertical mode.

  • Altitude Select Knob — The altitude select knob is used to select the desired altitude. Rotating the knob clockwise increases the desired altitude. Rotating the knob counter clockwise decreases the desired altitude. The altitude select knob has two positions: pushed in, or pulled out. When pushed in, rotating the knob increases/decreases the desired altitude in 1,000-foot increments or 100-meter increments. When pulled out, rotating the knob increases/decreases the desired altitude in 100-foot increments or 10-meter increments. When a minimum descent altitude (MDA) has been set on the coupled side TSC, the altitude preselect stops on that altitude. For example, if the current altitude selected is 4000 and the MDA is set to 2200, turning the knob counterclockwise will decrease the altitude in the window until 2200 has been reached and will not set below 2200. In the event that the altitude preselector is already set lower than the MDA entered, turning the knob clockwise or counter clockwise results in the altitude in the window to jump to the MDA value set. From this point, the desired altitude can be set higher than the MDA, but not set back below the MDA.

  • Altitude Window — On initial power-up, the altitude window shows dashes until an altitude has been set with the altitude select knob. When on the ground, first knob movement automatically sets the preselected altitude to the coupled air data system (ADS) barometric altitude plus 1,000 feet. This is designed to reduce the probability of the crew inadvertently setting a preselect altitude below field elevation. However, the altitude can be set to any altitude (above or below field elevation) after the initial movement. When the altitude is displayed in feet, FT is shown next to the altitude and when the altitude is displayed in meters, M is shown next to the altitude. The range of the altitudes available for selection are from -2,000 to 51,000 feet, or -610 to 15,550 meters. Altitudes below the FMS set transition altitude are displayed as XXXXX with no leading zeros (for example 500, 9000, 14500). Altitudes above the FMS set transition altitude are displayed as FLXXX (for example, FL230 or FL090 for two-digit flight levels). If the FMS transition altitude is unavailable, any altitude set at or above 18,000 feet will be displayed as a flight level.

Autoflight Control

  • AUTO Button — The AUTO button is used to engage and disengage the autopilot as well as engage the autothrottle. There are two annunciators associated with the AUTO button, AP and AT. The AP annunciator is located directly above the AUTO button and lights when the autopilot is engaged and goes out when the autopilot is disengaged. The AT annunciator is located next to the SPEED marking on the guidance panel and lights when the autothrottle is engaged and goes out when the autothrottle is disengaged. Pushing the AUTO button with the AT and AP off will attempt to engage both the AP and AT. Pushing the AUTO button with the AP off but AT on will only engage the AP. Pushing the AUTO button with the AP on will disengage the AP but it will not disengage the AT.

  • PFD SRC Button — The PFD SRC button is used to select which PFD the FGCS is coupled to. The arrow to the left of the button lights when coupled to the pilot’s PFD and the arrow to the right of the button lights when coupled to the copilot’s PFD. On initial power-up, the left PFD is automatically selected. Pushing the PFD SRC button toggles between the left and right PFDs. During an ILS dual-coupled approach, both the left and right arrows light up below 1,200 feet (radio altimeter) to indicate the systemis averaging data received from both NAV receivers. If the dual-coupled mode is canceled due to loss of the approach mode, the systemautomatically couples to thePFD thatwas selected prior to initiating the approach.

  • NOTE: Pushing the PFD SRC button when the autopilot is engaged changes the lateral flight director mode to ROL and the vertical mode to FPA , but does not disengage the autopilot.

  • Approach (APR) Button — The APR button is used to arm the NAVAID-based, FMS-based VGP, and LPV approach modes. When an approach is armed or active, the light above the button lights and goes out when the approach is disarmed. Pushing the APR button arms the automatic transition from FMS to NAVAID--based approach mode when the preview mode is active.

References

Gulfstream GVII-G500 Production Aircraft Systems, Revision 1, Oct 1, 2018

Gulfstream Symmetry Flight Deck for the G500 Aircraft Pilot's Guide, April 10/19.

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