Leg Types; Turn Short Path Calculation - Garmin CNX 80 Pilot's Manual

Basic Operation
Flight Planning

LEG TYPES

The GNS 480 is the only panel mount navigator to implement all the available leg types that currently exist in airways, instrument proce-
dures, and approaches. These legs are described in the following diagrams, with associated descriptions of each leg. Because the GNS 480
supports these leg types, it automatically sequences through the majority of the flight plan legs, or allows for a simple one keystroke interface
to sequence when automatic sequencing is not available. This greatly reduces the pilot' s workload during critical phases of flight, such as
departure or approach and landing.
An example of how these leg types are implemented can be found in a simple SID procedure, such as the Farmington Three Departure at
KHIO. If we depart on Runway 30, the text of the departure on the Jeppesen plate is as follows: Turn LEFT to a 120° heading, then intercept
and proceed via UBG R-346 to UBG VOR. Thence via assigned route.
To dissect this example, look on the flight plan page after inserting the departure and see the legs the GNS 480 automatically inserts, the first
being a heading of 305° to an altitude of 604 feet MSL. This is because no turns are allowed below 400 feet AGL for an instrument departure.
Upon reaching the required altitude, the GNS 480 will sequence automatically to a heading to intercept leg of 120° to the 166° course to
UBG. The heading leg of 120° is shown as a Pilot Nav leg and sequencing may be accomplished by pressing the SUSP key once. Once the
flight plan sequences, the guidance to the 166° course will be active on your CDI to complete the intercept. Roll steering is active and you
may engage the NAV mode or roll steering mode as appropriate. After reaching UBG, the system will automatically sequence to the next leg
in your en route flight plan. Roll steering or course guidance is not available on heading legs.
NOTE: If the GNS 480 does not have an altitude input, the system will not sequence automatically on the missed approach. It is advisable to install
the GNS 480 system with an altitude input.

Turn Short Path Calculation

he GNS 480 will automatically calculate a turn short curved path as it sequences between waypoints, when allowed. The size of the
T
turn short curved path radius is calculated based upon aircraft ground speed. This is shown in magenta on the moving map adjacent
to the active waypoint and leading to the course to the next waypoint. The GNS 480 roll steering autopilot commands will follow the
magenta curved path. A turn short is not calculated for course changes in excess of 120°.
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