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6/17/21 

AIM 

FIG 5

4

Instrument Approach Procedure Stepdown Fixes 

d.  Terminal Arrival Area (TAA) 

1. 

The TAA provides a transition from the en 

route structure to the terminal environment with little 
required pilot/air traffic control interface for aircraft 
equipped with Area Navigation (RNAV) systems. A 
TAA provides minimum altitudes with standard 
obstacle clearance when operating within the TAA 
boundaries. TAAs are primarily used on RNAV 
approaches but may be used on an ILS approach when 
RNAV is the sole means for navigation to the IF; 
however, they are not normally used in areas of heavy 
concentration of air traffic. 

2. 

The basic design of the RNAV procedure 

underlying the TAA is normally the “T” design (also 
called the “Basic T”). The “T” design incorporates 
two IAFs plus a dual purpose IF/IAF that functions as 
both an intermediate fix and an initial approach fix. 

The T configuration continues from the IF/IAF to the 
final approach fix (FAF) and then to the missed 
approach point (MAP). The two base leg IAFs are 
typically aligned in a straight-line perpendicular to 
the intermediate course connecting at the IF/IAF. A 
Hold-in-Lieu-of Procedure Turn (HILPT) is 
anchored at the IF/IAF and depicted on U.S. 
Government publications using the “hold

in

lieu 

of

PT” holding pattern symbol. When the HILPT is 

necessary for course alignment and/or descent, the 
dual purpose IF/IAF serves as an IAF during the entry 
into the pattern. Following entry into the HILPT 
pattern and when flying a route or sector labeled 
“NoPT,” the dual-purpose fix serves as an IF, marking 
the beginning of the Intermediate Segment. See 
FIG 5

4

2 and FIG 5

4

3 for the Basic “T” TAA 

configuration. 

Arrival Procedures 

5

4