Vertical Navigation - Garmin G1000 Reference Manual

SECTION 1
SYSTEM OVERVIEW
1.5

VERTICAl NAVIGATION

One of two altitude sources is used by the G1000 when
giving vertical navigation guidance. WAAS GPS altitude
is used when giving guidance for a WAAS approach after
the Final Approach Fix. Baro corrected altitude is used
when vertical guidance is given in all other situations and
in non-WAAS systems.
The G1000 system can use altitude constraints
associated with lateral waypoints to give guidance for
vertical navigation. These altitudes are, depending on the
specific instance, entered by the pilot or retrieved from the
published altitudes in the navigation database.
The navigation database only contains altitudes
for procedures that call for "Cross at" altitudes. If the
procedure states "Expect to cross at," then the altitude
is not in the database. In this case the altitude may be
entered manually.
NOTe: All arrival procedure altitudes contained in
the navigation database are for turbojet aircraft only.
Alter or enter altitudes as desired to comply with the
ATC clearance.
When activating or loading an arrival or approach
procedure into an active flight plan, the VNV 'ALT' fields
are populated with any altitudes that can be retrieved
from the navigation database.
Since altitudes loaded with an arrival procedure are
published only for turbojet aircraft, the altitudes are
displayed as white text indicating that the altitudes are
displayed for reference only. An arrival waypoint altitude
may be used (or "designated") as is, or changed to a
different altitude. An altitude is designated by pressing the
FMS Knob and turning the large FMS Knob to place the
cursor on the desired altitude and pressing the ENT Key or
entering a different value and pressing the ENT Key. The
altitude is now displayed as light blue text, indicating that
the altitude is now designated to give vertical speed and
1-10
Garmin G1000 Cockpit Reference Guide for the Cessna Nav III
deviation guidance.
Approach waypoint altitude constraints are automatically
designated when the approach is loaded. These altitudes
are also displayed as light blue text. Waypoint altitude
constraints are designated up to, but not including the FAF.
The FAF is always a "reference only" altitude and cannot be
designated, unless the selected approach does not provide
vertical guidance. In this case, the FAF altitude can be
designated manually.
Altitudes that have been designated for use in vertical
guidance may also be made "non-designated" by placing the
cursor over the desired altitude and pressing the CLR Key.
Other displayed altitudes may change due to re-calculations
or rendered invalid as a result of manually changing an
altitude to a non-designated altitude.
To help interpret the meanings of how the altitudes are
presented, keep the following points in mind:
• When the altitude is displayed in light blue,
the system is using that altitude (designated) to
determine vertical speed and deviation guidance.
• When the altitude is displayed in white, it is not being
used by the system (non-designated) to determine
the vertical speed and deviation guidance.
• An altitude displayed as small text is an altitude that
is published in the navigation database.
• Altitudes displayed as a light blue subdued text
cannot be used in the current vertical navigation
calculations.
Refer to Figure 1-8 and Table 1-1 for more detail
regarding the significance of text size and color.
190-00384-09 Rev. A