时间：2011-04-18 00:50来源：蓝天飞行翻译 作者：航空 点击：次
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c. Minimum Safe/Sector Altitudes (MSA) are published for emergency use on IAP charts. For conventional navigation systems, the MSA is normally based on the primary omnidirectional facility on which the IAP is predicated. The MSA depiction on the approach chart contains the facility identifier of the NAVAID used to determine the MSA altitudes. For RNAV approaches, the MSA is based on the runway waypoint (RWY WP) for straight.in approaches, or the airport waypoint (APT WP) for circling approaches. For GPS approaches, the MSA center will be the missed approach waypoint (MAWP). MSAs are expressed in feet above mean Arrival Procedures 5.4.6 sea level and normally have a 25 NM radius; however, this radius may be expanded to 30 NM if necessary to encompass the airport landing surfaces. Ideally, a single sector altitude is established and depicted on the plan view of approach charts; however, when necessary to obtain relief from obstructions, the area may be further sectored and as many as four MSAs established. When established, sectors may be no less than 900 in spread. MSAs provide 1,000 feet clearance over all obstructions but do not necessarily assure acceptable navigation signal coverage. d. Terminal Arrival Area (TAA)1.The objective of the TAA is to provide a seamless transition from the en route structure to the terminal environment for arriving aircraft equipped with Flight Management System (FMS) and/or Global Positioning System (GPS) navigational equipment. The underlying instrument approach procedure is an area navigation (RNAV) procedure described in this section. The TAA provides the pilot and air traffic controller with a very efficient method for routing traffic into the terminal environment with little required air traffic control interface, and with minimum altitudes depicted that provide standard obstacle clearance compatible with the instrument procedure associated with it. The TAA will not be found on all RNAV procedures, particularly in areas of heavy concentration of air traffic. When the TAA is published, it replaces the MSA for that approach procedure. See FIG 5.4.9 for a depiction of a RNAV approach chart with a TAA. 2.The RNAV procedure underlying the TAA will be the “T” design (also called the “Basic T”), or a modification of the “T.” The “T” design incorporates from one to three IAFs; an intermediate fix (IF) that serves as a dual purpose IF (IAF); a final approach fix (FAF), and a missed approach point (MAP) usually located at the runway threshold. The three IAFs 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 initial segment is normally from 3.6 NM in length; the intermediate 5.7 NM, and the final segment 5 NM. Specific segment length may be AIM varied to accommodate specific aircraft categories for which the procedure is designed. However, the published segment lengths will reflect the highest category of aircraft normally expected to use the procedure. (a)A standard racetrack holding pattern may be provided at the center IAF, and if present may be necessary for course reversal and for altitude adjustment for entry into the procedure. In the latter case, the pattern provides an extended distance for the descent required by the procedure. Depiction of this pattern in U.S. Government publications will utilize the “hold.in.lieu.of.PT” holding pattern symbol. (b)The published procedure will be anno-tated to indicate when the course reversal is not necessary when flying within a particular TAA area; e.g., “NoPT.” Otherwise, the pilot is expected to execute the course reversal under the provisions of 14 CFR Section 91.175. The pilot may elect to use the course reversal pattern when it is not required by the procedure, but must inform air traffic control and receive clearance to do so. (See FIG 5.4.1, FIG 5.4.2, FIG 5.4.9, and paragraph 5.4.9, Procedure Turn and Hold.in.lieu of Procedure Turn). 3.The “T” design may be modified by the procedure designers where required by terrain or air traffic control considerations. For instance, the “T” design may appear more like a regularly or irregularly shaped “Y”, or may even have one or both outboard IAFs eliminated resulting in an upside down “L” or an “I” configuration. (See FIG 5.4.3 and FIG 5.4.10). Further, the leg lengths associated with the outboard IAFs may differ. (See FIG 5.4.5 and FIG 5.4.6). 4.Another modification of the “T” design may be found at airports with parallel runway configura-tions. Each parallel runway may be served by its own “T” IAF, IF (IAF), and FAF combination, resulting in parallel final approach courses. (See FIG 5.4.4). Common IAFs may serve both runways; however, only the intermediate and final approach segments for the landing runway will be shown on the approach chart. (See FIG 5.4.5 and FIG 5.4.6). Arrival Procedures 5.4.7 FIG 5.4.1 Basic “T” Design FIG 5.4.2 Basic “T” Design Arrival Procedures 5.4.8 FIG 5.4.3 Modified Basic “T” FIG 5.4.4 Modified “T” Approach to Parallel Runways Arrival Procedures 5.4.9 FIG 5.4.5 “T” Approach with Common IAFs to Parallel Runways FIG 5.4.6 “T” Approach with Common IAFs to Parallel Runways Arrival Procedures 5.4.10 FIG 5.4.7 TAA Area 5. 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. (See FIG 5.4.7). 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 stepdown sections defined by arcs based on RNAV distances (DME or ATD) from the IF (IAF). The right/left.base areas can only be subdivided using arcs based on RNAV distances from the IAFs for those areas. Minimum MSL altitudes are charted within each of these defined areas/subdivisions that provide at least 1,000 feet of obstacle clearance, or more as necessary in mountainous areas. |
