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OCR for page 39
Airport Toolbox 39 The use of satellite navigation has significantly reduced the financial investment needed to establish or improve an instrument approach. However, aircraft must have approved equipment installed onboard to use the satellite-based approaches, which may require an investment by the aircraft operator. 5.3.1 Required Area Navigation (RNAV) Approaches RNAV refers to a general method of navigation where a pilot can choose any course within a network of navigation beacons, rather than navigating directly between beacons. An extension of RNAV is Required Navigation Performance (RNP); RNP involves a performance specification that an aircraft must meet before the intended flight path can be flown as well as a monitoring and alerting function if the performance specification is not met. Instrument approaches that specifically provide some form of vertical guidance are known as APVs (Approach Procedures with Vertical guidance). With the advent of Wide Area Augmentation Systems (WAAS), the potential for vertically guided approaches to airports without a precision approach has become a reality. WAAS, developed by the FAA, provides improved global position- ing system (GPS) accuracy for all phases of flight. WAAS uses a network of ground-based reference stations that measure changes in GPS satellite signals and transmit the corrections via other satel- lites to WAAS-enabled GPS receivers. RNAV approaches via GPS/WAAS are the primary type of procedure being developed by the FAA. The RNAV satellite-based approaches can include up to three sets of minimums: LPV (Localizer Performance with Vertical guidance)--applicable to aircraft with IFR GPS/ WAAS receivers LNAV/VNAV (Lateral Navigation/Vertical Navigation)--applicable to aircraft with IFR GPS and barometric altimeter input LNAV (non-precision approach, Lateral Navigation only)--applicable to aircraft with at least an IFR GPS receiver The new RNAV approaches via LPV or LNAV/VNAV can provide horizontal and vertical guidance with minimums as low as a 200- to 250-foot ceiling and 1/2-mile visibility, subject to airport facility and terrain/obstacle clearance requirements. Even if an airport cannot support the lowest minimums, RNAV approaches can still provide improved instrument approach capability. Three primary areas are considered by the FAA during the establishment of an instrument approach: Airport design standards Terrain/obstacles on and around the airport, particularly in the approach and missed approach surfaces Airspace, including procedures for surrounding airports Airport Design Standards FAA Order 8260.3B, U.S. Standards for Terminal Instrument Procedures (TERPS), is the pri- mary guidance for establishing instrument approaches. According to TERPS Paragraph 122, "The runway landing surfaces must be adequate to accommodate the aircraft that can be reasonably expected to use the procedure. Appropriate runway markings, hold position markings, and signs required by AC 150/5340-1 shall be in place, and runway design standards in AC 150/5300-13 Appendix 16 must be met." The airport standards for precision instrument approaches, approach procedures with vertical guidance, and non-precision approaches are summarized in Table A16-1 in FAA AC 150/5300-13, Airport Design. APV-RNP approaches provide the greatest opportunity for a GA airport operator to improve the facility's instrument approach procedures. Table 5-5 summarizes key airport design considerations

OCR for page 39
40 Airports and the Newest Generation of General Aviation Aircraft Table 5-5. APV/RNP approach establishment criteria. Visibility Minimum 1 mile mile mile Runway Length 3,200'+ 4,200'+ Clear OFZ (runway length plus 200' each 250' wide 300' wide end) Runway Markings Nonprecision Precision Holding Position Nonprecision Precision Signs and Markings Runway Lighting LIRL/MIRL MIRL/HIRL Parallel Taxiway Recommended Required Approach Lights Recommended Recommended for LPV Clear Threshold Siting Surface1 20:1 (400' x 10,000' 20:1 (800' x 10,000' 34:1 (800' x 10,000' (inner width by x 3,800') x 3,800') x 3,800') length by outer width) Glidepath Qualification Surface - GQS for vertical guidance2 30:1 (runway width+100 feet each side x 10,000' x 1,520') (inner width by length by outer width) 1 Airport design standards, also need to meet overlaying TERPS surfaces 2 If 34:1 surface is clear, 30:1 surface for vertical guidance should be clear Source: FAA AC 150/5300-13, Table A16-1B. that will affect potential APV-RNP minimums for an instrument approach to serve new genera- tion GA aircraft. In general, the lower the minimums, the larger the setback from the runway to buildings and other development. Although approaches that provide lower minimums are gen- erally more precise, they also result in the aircraft descending closer to the airport and the ground before being required to establish visual reference to the airport, thus necessitating larger clear areas or zones. Several steps are needed to establish a new or improved instrument approach procedure, particularly if survey information is not already on file with the FAA: 1. Review existing and future airport plans to determine if airport standards are met. 2. Review weather data (available from the National Climatic Data Center) to identify the need for an instrument approach, if not already identified in airport planning documents. 3. Determine if a vertically guided or non-vertically guided survey is needed. 4. Contract for surveying work per FAA specifications. 5. Complete the survey. 6. Submit the survey for validation. 7. After the survey is validated, formally request a new approach procedure. 8. Monitor the progress of approach procedure development. Airport operators can check on whether or not the FAA is developing a new approach or monitor the status of a known approach procedure being developed at schedule/production. Also, if it has not already occurred during an airport planning process, dur- ing steps 1 and 2 above, it is recommended that the airport operator coordinate with their FAA Airport District Office to ensure the FAA concurs with the type of instrument approach procedure being pursued. This coordination will allow the airport operator to ensure that the extent of the survey effort is appropriate.