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Section 6
Approaches, SIDs and STARs
The GNC 300’s approach navigation mode allows you to fly non-precision
approaches to airports with GPS and overlay procedures using information contained
on your Jeppesen NavData
®
card. GPS approaches are similar to existing IFR
approach procedures, but provide additional course and distance information for a
higher level of accuracy, efficiency and safety. The non-precision approaches available
in the GNC 300 are executed using the GPS route features covered in Section 5, so
it’s important to understand routes before attempting approach navigation. A GPS
approach is a sequence of waypoints linked together as a subroute which replaces
your destination airport waypoint when selected. It may be based on an existing
RNAV, VOR or NDB approach procedure, or be an entirely new approach created
specifically for GPS. Regardless of the type of approach on which a GPS procedure is
based, the procedure is flown as a sequence of route legs in the active route.
The GNC 300’s auto-arming feature provides automatic control of the two phas-
es of approach operations: arm approach and active approach. The arm approach
phase consists of selecting an approach from the database and ensuring that the
receiver is ready to begin the tighter integrity monitoring and CDI adjustment
required for approach navigation. The active approach phase tightens the accuracy
requirements and sensitivity one step further to meet TSO standards for the non-pre-
cision approach. Auto-arming of the approach will occur once you are within 30 nm
of the destination airport, and will be indicated by an ‘ARM’ message on the external
GPS APPR switch. The approach will then transition to the active phase when the air-
craft is within 2 nm of the FAF along the inbound course to the final approach fix.
72
APPROACH NAVI-
GATION
Overview
Once an approach is selected, the GNC 300 will
replace the destination airport with the appropri-
ate approach waypoints. The initial approach fix,
final approach fix and missed approach point
waypoints are indicated by ‘if’, ‘ff’ and ‘mp’ desig-
nators to the immediate left of the waypoints.
In many instances, there may be approach way-
points in the GPS approach that are not shown on
the approach plate. These waypoints are usually
intermediate fixes designed to help the GPS pro-
vide smooth navigation along the approach path.
SECTION
6
APPROACH NAV
Overview
300 7/14/98 8:50 AM Page 72