4-4
Approach Procedures
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LNAV/VNAV (Lateral Navigation with Vertical
Navigation)
In this mode, the GPS provides lateral
navigation, providing more accurate guidance than
regular LNAV but easier to follow indications than a
localizer. The vertical navigation is driven by GPS
signals. LNAV/VNAV approaches are operationally
different from LNAV+V in that the glide path is protected
from obstructions but attention still must be applied to
step down fixes. Also, the minimum altitude presented is
a decision altitude/height (DA/DH) – DA being what is on
the altimeter, and DH being the height of the DA above
the touchdown zone elevation. This is not a MDA, thus,
fly it just as though it were an ILS approach: follow the
glide slope all the way to the DA before initiating a
missed approach, if appropriate.
This type of approach is automatically coupled to the
autopilot, meaning that somewhere in the vicinity of the
FAF, with “L/VNAV” annunciated as the HDI source, the
FMS will automatically toggle the autopilot mode to NAV
APPR and GS will either arm or engage depending on
your position relative to the glide path.
LPV (Localizer Precision with Vertical Guidance)
(FMS900w only)
The lateral guidance is significantly
more precise than LNAV, and equivalent to that of a
localizer, except easier to fly. Vertical guidance is
provided to minimums as low as 200’ AGL above the
touchdown zone. Lateral tolerance starts out at 0.3 NM
full-scale (slightly tighter than a localizer at the FAF),
transitioning to 350 feet either side at the runway
threshold (slightly looser than a localizer). The steering
remains linear all the way so you don’t get the difficult to
follow swings of a VHF localizer close to the runway. The
vertical guidance is precise and has a DA/DH (shown as
“DA(H)” on approach charts) rather than a MDA.
This type of approach is also automatically coupled to
your autopilot. In the vicinity of the FAF, with “LPV”
annunciated at the HDI source, the FMS will
