Garmin GNS 430AW, Pilot'S Manual & Reference

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2 - NAV PAGES
46
Departure Phase - Defined as when all five of the
following conditions are met:
• It has been determined that the aircraft was previ-
ously “on-ground.”
• The aircraft has a vertical velocity greater than
zero.
• The aircraft has a ground speed greater than 35
knots.
• The aircraft has an altitude greater than 150 feet
AGL and less than 1500 feet AGL.
• The aircraft is within 15 NM of the departure
airport.
NOTE: There are additional factors beyond what
is outlined above that may alter the determined
TERRAIN flight phase.
Nearest Airport Criteria & Terrain Phase of Flight
Changes to the Nearest Airport Criteria Page affect
how the TERRAIN system performs. The nearest air-
port list is used to derive the terrain destination airport
when there is no loaded active flight plan or when
deviating from the active flight plan (whenever the
terrain algorithms go into estimation mode). In turn,
the nearest airport list is used to determine the terrain
phase of flight. The terrain phase of flight dictates
the Required Terrain Clearance (RTC) levels at which
Forward Looking Terrain Avoidance (FLTA) alerting
occurs, as described later in the Forward Looking
Terrain Avoidance section. Premature Descent Alerting
(PDA) is also affected as described later in the PDA
section.
Nearest Airport Criteria Page
As an example, if the pilot configures the unit
to include only airports with runways 5000 feet or
longer, only these are added to the nearest airport list.
The terrain phase of flight is affected in that all airport
runways under 5000 feet are NOT included in terrain
calculations. During a cross-country flight with this
configuration, only airports runways 5000 feet or
greater cause the unit to go into Terminal or Approach
Mode from En Route mode. If the pilot makes an
emergency landing at an airport that did not show up
in the nearest airport list, FLTA alerts would be issued
throughout the descent.
TERRAIN Destination Airport
The TERRAIN destination airport is considered to
be the next airport in the flight plan while adhering
to the flight plan path. If no flight plan is entered, or
if the aircraft is not adhering to the entered flight plan
path, the terrain destination airport is estimated using
the Nearest Airport Criteria as described in the section
above.
Terrain Operation