Flight Training Instruction - Cnatra - U.S. Navy

1000. INTRODUCTION
CHAPTER TEN
GPS APPROACH PROCEDURES
Prior to conducting any Global Positioning System (GPS) approach training, it is essential that
the student read the T-6B NATOPS Flight Manual GPS section and be thoroughly familiar with
the components and operation of the FMS and GPS. Some basic concepts follow.
Two major types of GPS approaches exist, GPS stand-alone, and GPS overlay approaches. The
skills and knowledge required to fly these approaches are basically the same, however, some
small procedural changes exist between these GPS approaches.
1001. GPS STAND-ALONE APPROACHES
The GPS stand-alone approach is commonly known as the terminal arrival area (TAA) or “Basic
T” approach (Figure 10-1). The objective of the TAA is to provide a seamless transition from
the enroute structure to the terminal environment for arriving aircraft equipped with GPS. GPS
TAA approaches make use of both Fly-Over and Fly-By waypoints. Fly-By waypoints are used
when an aircraft should begin a turn to the next course prior to reaching the waypoint separating
the two route segments. This is known as turn anticipation and is compensated for in the
airspace and terrain clearance. Approach waypoints, except for the Missed Approach waypoint
(MAWP) are normally Fly-By waypoints. Fly-Over waypoints are used when the aircraft must
fly over the waypoint prior to executing a turn. Approach charts depict Fly-Over waypoints with
a circle around the waypoint.
The “T” design will normally have from one to three IAF's; an intermediate fix (IF) that serves
as a dual purpose IF/IAF; a FAF, and a MAP, usually located at the runway threshold. The three
IAF's are normally aligned in a straight line perpendicular to the intermediate course, which is an
extension of the final course leading to the runway, forming a “T.” The standard TAA consists
of three areas defined by the extension of the IAF legs and the intermediate segment course.
These areas are called the straight-in, left-base, and right-base areas. TAA lateral boundaries are
identified by magnetic courses TO the IF/IAF.
The TAA procedure is a portion of the new and rapidly evolving GPS arrival procedure program.
For the most current and in-depth information on the TAA approach, consult the AIM.
1002. GPS OVERLAY APPROACHES
Overlay approaches consist of GPS waypoints overlayed on conventional (VOR, VOR/DME,
etc.) non-precision approaches (Figure 10-2). Though overlays have the same minimums as the
underlying approach, they offer the opportunity to fly an instrument approach procedure using
GPS. Because GPS approaches are designed as a TO-TO system (meaning you navigate to one
fix, cross it, and proceed to the next fix), overlays are not a perfect fit with the underlying
procedure. Some conventional approaches, for example, have no FAF. Without a FAF, the GPS
would not be able to navigate to the fix, nor would it know when to switch the CDI sensitivity.
GPS APPROACH PROCEDURES 10-1