CFR § 91.175. The pilot may elect to use the course reversal  pattern when it is not required by the procedure, but must  receive clearance from air traffic control before beginning  the procedure.  ATC should not clear an aircraft to the left base leg or right  base leg IAF within a TAA at an intercept angle exceeding 90  degrees. Pilots must not execute the HILO course reversal  when the sector or procedure segment is labeled “NoPT.”  ATC may clear aircraft direct to the fix labeled IF/IAF if  the course to the IF/IAF is within the straight-in sector  labeled “NoPT” and the intercept angle does not exceed  90 degrees. Pilots are expected to proceed direct to the IF/  IAF and accomplish a straight-in approach. Do not execute  HILO course reversal. Pilots are also expected to fly the  straight−in approach when ATC provides radar vectors and  monitoring to the IF/IAF and issues a“straight-in” approach  clearance; otherwise, the pilot is expected to execute the  HILO course reversal. (See AIM Paragraph 5−4−6, Approach  Clearance)  On rare occasions, ATC may clear the aircraft for an  approach at the airport without specifying the approach  procedure by name or by a specific approach (e.g., “cleared  RNAV Runway 34 approach”) without specifying a particular  IAF. In either case, the pilot should proceed direct to the IAF  or to the IF/IAF associated with the sector that the aircraft  will enter the TAA and join the approach course from that  point and if required by that sector (i.e., sector is not labeled  “NoPT), complete the HILO course reversal.  Note: If approaching with a TO bearing that is on a sector  boundary, the pilot is expected to proceed in accordance  with a “NoPT” routing unless otherwise instructed by ATC.  Altitudes published within the TAA replace the MSA alti­ tude. However, unlike MSA altitudes the TAA altitudes are  operationally usable altitudes. These altitudes provide at  least 1,000 feet of obstacle clearance, and more in moun­ tainous areas. It is important that the pilot knows which  area of the TAA that the aircraft will enter in order to com­ ply with the minimum altitude requirements. The pilot  can determine which area of the TAA the aircraft will enter  by determining the magnetic bearing of the aircraft TO  the fix labeled IF/IAF. The bearing should then be com­ pared to the published lateral boundary bearings that  define the TAA areas. Do not use magnetic bearing to the  right-base or left-base IAFs to determine position.  An ATC clearance direct to an IAF or to the IF/IAF with­ out an approach clearance does not authorize a pilot to  descend to a lower TAA altitude. If a pilot desires a low­ of RNAV instrument approaches. This includes criteria for  terminal arrival areas (TAAs), RNAV basic approach criteria,  and specific final approach criteria for different types of  RNAV approaches.  The Terminal Arrival Area (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.  TAAs provide 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 . [Figure 4-36]  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 FAF and then to the 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 (HILO) 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  HILO 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 HILO 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.  The standard TAA based on the “T” design consists of  three areas defined by the IAF legs and the intermediate  segment course beginning at the IF/IAF. These areas are  called the straight−in, left−base, and right−base areas.  [Figure 4-36] TAA area lateral boundaries are identified  by magnetic courses TO the IF/IAF. The straight−in area  can be further divided into pie−shaped sectors with the  boundaries identified by magnetic courses TO the IF/ IAF,  and may contain step-down sections defined by arcs based  on RNAV distances from the IF/IAF.  Entry from the terminal area onto the procedure is normally  accomplished via a no procedure turn (NoPT) routing or via  a course reversal maneuver. The published procedure will  be annotated “NoPT” to indicate when the course reversal  is not authorized when flying within a particular TAA sector  [Figures 4-36 and 4-37]. Otherwise, the pilot is expected  to execute the course reversal under the provisions of 14  4-58  Terminal Arrival Areas 