FGCS Lateral Modes
The FGCS pilot selectable lateral navigation modes are:
Roll Hold (ROLL).
Heading Select (HDG).
Lateral Navigation (LNAV).
Localizer (LOC).
Back-course (BC).
Pilot non-selectable mode is:
Track Hold (TRACK).
ROLL HOLD (ROLL)
This is the basic lateral mode and does not provide any airplane guidance.
Depending on the airplane bank angle at the moment of ROLL activation, the autopilot will maintain the following bank angles until another lateral mode is selected:
Bank angle at 6° or below: AP levels the wings.
Bank angle above 6° and below 35°: AP holds present bank angle.
Bank angle at 35° or above: AP maintains bank angle at 35°.
ROLL MODE ACTIVATION
The ROLL Mode is activated under any of the following conditions:
Pressing TOGA button while on the ground and IAS is below 100 kt;
There is no lateral mode active and a vertical mode is selected;
Deselecting an active lateral mode;
COURSE TO INTERCEPT on the FMS is activated.
ROLL MODE DE-ACTIVATION
The ROLL Mode is de-activated when another lateral mode becomes active.
HEADING SELECT (HDG)
This mode provides airplane lateral guidance through the HDG SEL knob.
Pressing the center of the HDG selector knob synchronizes the heading bug to the current heading.
The FD follows the selected heading and respects the direction in which the turn on the HDG SEL knob was commanded, regardless if the turn being commanded is greater than 180°.
HDG MODE ACTIVATION
HDG button is pressed on the Guidance Panel.
HDG MODE DE-ACTIVATION
HDG button is pressed on the Guidance Panel.
When another lateral mode becomes active.
LATERAL NAVIGATION (LNAV)
The LNAV engages when:
LNAV mode is armed, LNAV will automatically engage when passing through 200 ft during a climb.
The airplane is above 200 ft and the NAV button is pressed.
The FMS becomes the source for lateral navigation providing guidance through the Flight Director.
LOCALIZER (LOC)
The LOC mode is selected via the APP button on the GP.
The FD automatically manages the LOC and Back-Course according to Localizer frequency, PFD information and airplane’s position.
The FD is capable of intercepting the LOC when there is no GS signal. Other vertical navigation modes such as FPA or VS can be used for vertical navigation.
The FD opens the bank angle command limit to 35° during Localizer capture.
BACK-COURSE (BC)
The FD will automatically select a BC approach on the PFD.
The FGCS provides commands for capture and tracking of BC localizer indicated on the selected PFD.
TRACK HOLD (TRACK)
The track select mode is used to intercept and maintain an inertial derived airplane track from the IRS. This mode is used for Takeoff and Go-Around.
TAKEOFF
The automatic transition from ROLL to TRACK during takeoff occurs when:
IAS is greater than 100 kt and;
Bank angle is at 3° or below for more than 10 s.
GO AROUND
TRACK ACTIVATION
TOGA button is pressed for go-around.
TRACK DE-ACTIVATION
Another lateral mode is selected.
Canceling the vertical mode of GA does not disengage the TRACK lateral mode.
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