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reported ceiling at the airport of intended landing is at
least 500 feet above the MVA/MIA, and the visibility is
3 SM or more, unless higher minimums are published
for the particular CVFP. When accepting a clearance to
follow a preceding aircraft, pilots are responsible for
maintaining a safe approach interval and wake turbulence separation. Pilots must advise ATC if unable at any
point to continue a charted visual approach or if the pilot
loses sight of the preceding aircraft.
RNAV APPROACHES
Because of the complications with database coding,
naming conventions were changed in January 2001 to
accommodate all approaches using RNAV equipment
into one classification — RNAV. This classification
includes both ground-based and satellite dependent
systems. Eventually all approaches that use some type
of RNAV will reflect RNAV in the approach title. This
changeover is being made to reflect two shifts in
instrument approach technology. The first shift is the
use of the RNP concept outlined in Chapter 2 —
Departure Procedures, in which a single performance
standard concept is being implemented for approach
procedure design. Through the use of RNP, the underlying system of navigation may not be required, provided the aircraft can maintain the appropriate RNP
standard. The second shift is that advanced avionics
systems such as FMSs, used by most airlines, needed a
new navigation standard by which RNAV could be
fully integrated into the instrument approach system.
An FMS uses multi-sensor navigation inputs to produce a composite position. Essentially, the FMS navigation function automatically blends or selects position
5-45
sensors to compute aircraft position. Instrument
approach charts and RNAV databases needed to change
to reflect these issues. A complete discussion of airborne navigation databases is included in Appendix A
— Airborne Navigation Databases.
Due to the multi-faceted nature of RNAV, new
approach criteria have been developed to accommodate the design of RNAV instrument approaches.
This includes criteria for TAAs, RNAV basic
approach criteria, and specific final approach criteria
for different types of RNAV approaches.
TERMINAL ARRIVAL AREAS
TAAs are the method by which aircraft are transitioned
from the RNAV en route structure to the terminal area
with minimal ATC interaction. Terminal arrival areas
are depicted in the planview of the approach chart, and
each waypoint associated with them is also provided
with a unique five character, pronounceable name. The
TAA consists of a designated volume of airspace
designed to allow aircraft to enter a protected area,
offering guaranteed obstacle clearance where the initial
approach course is intercepted based on the location of
the aircraft relative to the airport. Where possible,
TAAs are developed as a basic “T” shape that is divided
into three separate arrival areas around the head of the
“T”: left base, right base, and straight-in. Typically, the
TAA offers an IAF at each of these three arrival areas
that are 3-6 NM from an IF, which often doubles as the
IAF for straight-in approaches, a FAF located approximately 5 NM from the runway threshold, and a MAP.
[Figure 5-33 on page 5-46]
Figure 5-32. Charted Visual Flight Procedures.
5-46
Procedurally, pilots may be cleared to an IAF associated with the TAA. ATC expects the flight to proceed to
the IAF and maintain the altitude depicted for that area
of the TAA, unless cleared otherwise. An obstacle
clearance of at least 1,000 feet is guaranteed within the
boundaries of the TAA.
TAAs are modified or even eliminated if necessary to
meet the requirements of a specific airport and surrounding terrain, or airspace considerations negating
the use of the “T” approach design concept. Alternative
designs are addressed in FAA Order 8260.45A,
Terminal Arrival Area (TAA) Design Criteria.
Variations may eliminate one or both base areas, and/or
limit or modify the angular size of the straight-in area.
When both base areas are eliminated, TAAs are not
depicted in the planview. Normally, a portion of the
TAA underlies an airway. If this is not the case, at least
one feeder route is provided from an airway fix or
NAVAID to the TAA boundary. The feeder route provides a direct course from the en route fix/NAVAID to
the appropriate IF/IAF. Multiple feeder routes may also
be established. In some cases, TAAs may not be
depicted because of airspace congestion or other
operational requirements. [Figure 5-34]
RNAV FINAL APPROACH DESIGN CRITERIA
RNAV encompasses a variety of underlying navigation
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Instrument Procedures Handbook (IPH)仪表程序手册下(129)
