Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 3921

e) flight technical error (FTE). 13.2.2 The composite of the above errors with the exclusion of FTE is referred to as total position error. Within 3.7 km (2 NM) of the MLS approach reference datum the permissible total lateral position error for MLS/RNAV equipment at a position 60 m (200 ft) above the MLS datum point on a 3-degree elevation angle and a runway length of 3 000 m (10 000 ft), is 15 m (50 ft) (see the note below). Similarly, the permissible total vertical position error is 3.7 m (12 ft) at the same position. A portion of the total position error budget has been reserved for the MLS/RNAV computer performance (computational error). Within 3.7 km (2 NM) of the MLS approach reference datum, the portion of the error budget reserved for computational error is ±0.6 m (2 ft) both laterally and vertically. The results presented in 13.5 are dependent on meeting this computational accuracy requirement. 23/11/06 ATT G-36 2007/70/II. szám Attac ment G Annex 10 — Aeronautical Communications ATT G-37 23/11/06 13.2.3 Using root sum square methodology the permissible total lateral position error, exclusive of MLS/RNAV computer performance, is slightly less than ±15 m (50 ft). Similarly, the permissible total vertical position error, exclusive of computational error is slightly less than ±3.7 m (12 ft). Hence, the combined error due to ground system performance, airborne sensor performance and ground system geometry effects is not expected to exceed ±15 m (50 ft) laterally and 3.7 m (12 ft) vertically at the described location. Using this information and assumptions about ground and airborne sensor performance, the maximum permissible azimuth and elevation antenna offsets (geometry effects) from the runway centre line can be obtained. 13.2.4 The CMN does not exceed ±7.3 m (24 ft) laterally and ±1.9 m (6.3 ft) vertically, or the linear equivalent of ± 0.1 degree, whichever is less. The linear values are based on nominal antenna sitings (azimuth antenna to threshold distance of 3 300 m (11 000 ft) and datum point to threshold distance of 230 m (760 ft)), with a 3-degree elevation angle. Within 3.7 km (2 NM) of the MLS approach reference datum, the portion of the CMN budget reserved for computational error is 1.1 m (3.5 ft) laterally and 0.6 m (2.0 ft) vertically. Note.— All errors represent 95 percentile errors. 13.3 Siting and accuracy considerations 13.3.1 Theoretical and operational analysis has shown that several factors will impact the amount of azimuth antenna lateral offset that can be permitted and still obtain lateral and vertical position accuracy identified in 13.2. 13.3.2 istance between azimuth and elevation antennas 13.3.2.1 For a given azimuth antenna offset, a short azimuth to elevation distance results in relatively large azimuth angles at positions near the approach reference datum. As a result, the error contribution from the DME is large, and the lateral accuracy may degrade unacceptably. At a runway where a large azimuth antenna offset and a short azimuth to elevation distance exist, use of DME/P rather than DME/N may be required to achieve the required lateral accuracy. 13.3.3 Azimuth accuracy 13.3.3.1 The azimuth antenna offset limits presented in 13.5 are based on the ±6 m (20 ft) azimuth path following error accuracy specification (see Chapter 3, 3.11.4.9.4). The recommended ±4 m (13.5 ft) azimuth accuracy specification would permit larger azimuth antenna offsets and still obtain required computed position accuracy at DH. Azimuth angle accuracy is assumed to degrade in accordance with Chapter 3, 3.11.4.9. 13.3.4 ME accuracy 13.3.4.1 Smaller errors in position determination result when DME/P equipment is used and the final approach segment is contained within 9.3 km (5 NM) of the MLS approach reference datum. There are two DME/P final approach mode accuracy standards in this region. Resulting azimuth antenna offset values when using DME/P as presented in 13.5, are based on final approach mode Standard 1 accuracy. Larger azimuth antenna offset values may be permissible if DME/P equipment meeting final approach mode Standard 2 accuracy is used. DME/P final approach mode Standard 1 ranging accuracy is assumed to degrade in accordance with Chapter 3, 3.5.3.1.3.4 and Table B. DME/N is assumed to degrade in accordance with Chapter 3, 3.5.3.1.3.2. 13.3.5 se of elevation information in the lateral position computation 13.3.5.1 Generally, lateral position computation that excludes elevation information will be sufficient for computed centre line approaches to the primary runway. If elevation information is not used in lateral computation, the lateral error 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I increases. This error increases with azimuth angle, height and decreasing range. Permissible azimuth antenna offsets presented in 13.5 are reduced if elevation information is not used in the lateral computation. Elevation angle accuracy is assumed to degrade in accordance with Chapter 3, 3.11.4.9. 13.4 Equipment considerations 13.4.1 Performance of airborne sensors, MLS ground equipment and MLS/RNAV avionics implementation influence the range of application of computed centre line approaches. Information presented in 13.5 is based on the following equipment considerations. 13.4.2 Airborne sensors 13.4.2.1 It is assumed the receiver will decode all auxiliary data words required for MLS computed centre line approaches unless the information contained in the data words is available from other avionics sources with the same accuracy and integrity as required for auxiliary data. Digital MLS angle data and range data are needed for computing lateral and vertical position. Angle data quantization is 0.01 degrees. Range quantization is 2.0 m (0.001 NM). 13.4.3 RNAV computations 13.4.3.1 No assumption is made about where the RNAV position computations are made. A portion of the computed centre line approach error budget has been reserved for computation error. This permits flexible algorithm implementation. 13.4.4 Permissible azimuth antenna offset calculation techniques 13.4.4.1 RTCA (RTCA/DO-198, Appendix D) has identified several different position determination algorithms. Different algorithms can handle different ground equipment configurations. The algorithm designed to handle any ground equipment geometry is the RTCA case 12 algorithm. Permissible antenna offset values were obtained using Monte Carlo simulation techniques. The results were also obtained using a direct analytical method. The analytical method uses geometric transformations of the maximum MLS angle and range errors to determine system performance. The Monte Carlo technique through the emulation of an MLS/RNAV system is a statistical method used to determine system performance. 13.4.4.2 Possible restriction in position determination. Depending on ground equipment geometry a region of possible multiple solutions to the position determination algorithm may exist. This region of multiple solutions is dependent on the locations of the elevation antenna and DME transponder relative to the runway and computed approach path. The most pronounced effect occurs when the DME transponder lies in the region between the approach path DH point and the elevation antenna. The position ambiguities can be resolved when the DME transponder is located behind the elevation antenna when viewed from the approach direction. When the DME transponder is located in front of the elevation antenna it may not be possible to resolve the position ambiguity. 13.4.5 Ground equipment geometry 13.4.5.1 The nominal ground equipment geometry in terms of the relative position of the ground components is depicted in Figure G-29. The DME/P transponder is assumed to be collocated with the approach azimuth antenna. When DME/P ground equipment is not available, the DME/N transponder is assumed to be located between the MLS approach azimuth and elevation antennas. 13.4.5.2 Because of the relatively large error induced by the DME/N, the location of the DME/N transponder has no significant influence on the calculated permissible azimuth antenna offset. This permits DME/N siting over a large area between the azimuth and elevation antennas. Similarly, the offset of the elevation antenna will have little effect. 23/11/06 ATT G-38 2007/70/II. szám Attac ment G Annex 10 — Aeronautical Communications 13.5 Permissible approach azimuth antenna offset positions for computed centre line approaches to the primary runway 13.5.1 ME results 13.5.1.1 The maximum azimuth offset represents, for a given set of conditions, the largest offset that does not exceed the computed centre line approach error budget identified in 13.2. DME/P results are presented as a function of the azimuth to elevation distance. The permissible azimuth antenna offsets with DME/P are presented in Figure G-30. 13.5.1.2 For a given azimuth to elevation distance, the azimuth antenna can be sited any place in the shaded area and the resulting computed centre line approach meet requirements of 13.2. 13.5.1.3 Results were obtained when DME/N ranging accuracies are used. These results are presented in Figure G-31. 13.6 Low visibility approaches 13.6.1 Possible applications 13.6.1.1 The possibility of low visibility computed centre line applications may be limited to operations on the primary instrument runway because of the geometry considerations involved in achieving adequate accuracy. Primary instrument runway applications where computed centre line capability would be useful are those where the azimuth is offset from the runway centre line due to a severe siting restriction. There may be such azimuth offset applications where low visibility operations would be considered beneficial. 13.6.1.2 The expected airborne implementation for such low visibility computed centre line approaches would use noncomputed elevation guidance (assuming the elevation ground antenna is sited normally) and lateral guidance derived from a combination of azimuth (including MLS siting data contained in the basic and auxiliary data functions) and range from the DME/P transponder. 13.6.2 Airborne system performance 13.6.2.1 Safety-critical software associated with the guidance function for non-computed low visibility approaches mainly involves the MLS receiver. For computed centre line approaches, the DME interrogator and the navigation computations must also be considered. The safety-critical software for these functions will have to be designed, developed, documented and evaluated. 13.6.2.2 The necessary algorithms are relatively simple and do not pose any certification difficulty. However, experience with flight management system (FMS) computers indicates that it would be difficult to certify a safety-critical function implemented within an existing FMS. Current FMS architectures are not partitioned to allow separate certification of different functions to different levels of criticality and the size and complexity of an FMS precludes safety-critical certification of the entire FMS computer. Consequently, alternatives to FMS implementation can be considered for computed centre line capability intended for low visibility applications (e.g. incorporation within the autopilot or within the MLS receiver). These alternatives would provide output guidance with the same output characteristics as a normal straight-in approach. 13.6.3 Ground system performance 13.6.3.1 Based on the implementation assumed in 13.3.5, elevation guidance would be used in exactly the same manner as for basic MLS approaches. Consequently, the elevation ground equipment integrity and continuity of service objectives would remain unchanged from those already given in Table G-15. For lateral guidance, the integrity and continuity ATT G-39 23/11/06 2007/70/II. szám Annex 10 — Aeronautical Communications Volume I of service objectives given in Table G-15 for azimuth would apply to the azimuth and DME combined, resulting in objectives for both that are more stringent than those needed for basic MLS operations. However, a low visibility computed centre line operation to a 30 m (100 ft) DH may be achieved by the use of ground equipment meeting the level 4 objectives contained in Table G-15. 13.6.4 Accuracy 13.6.4.1 MLS/RNAV will support computed paths to Category I decision heights for the primary runway given siting limitations as identified in Figure G-30. In addition, under certain conditions MLS/RNAV may provide sufficient accuracy to support Category II and III approaches. In order to accomplish this, the airborne implementation is as stated in 13.6.1.2. 13.6.4.2 The error budgets for Category II and III procedures are the following. For Category III, the lateral accuracy requirements are the same as the MLS approach azimuth accuracies specified at the approach reference datum. These requirements are ± 6 m (20 ft) for PFE and ± 3.2 m (10.5 ft) for CMN (Chapter 3, 3.11.4.9.4). For Category II the lateral requirements are obtained by splaying the allowed Category III values from the approach reference datum out to the Category II decision height of 30 m (100 ft). The equations used to compute these values (in metres) are: AZ ARD AZ ARD R PFE    u AZ ARD AZ ARD 3.2 R CMN    u CatII CatIII tan R  T Where: AZíARD = distance between approach azimuth antenna and approach reference datum (threshold) R = distance between DHCat II and DHCat III ș = elevation angle As an example, for a 3 000 m runway and a 3-degree elevation with an approach azimuth setback of 300 m, a Category III decision height of 15 m (50 ft) and a Category II decision height of 30 m (100 ft), the following values are obtained: AZ-ARD = 3 300 m R = 286 m PFEDH Cat II = 6.5 m (21.3 ft) CMNDH Cat II = 3.5 m (11.5 ft) 13.6.4.3 The computed centre line capability down to Category II decision height will not necessarily support autoland operations as the guidance may not be provided down to the runway and in the runway region. Also, the more stringent error tolerances for Category II/III will result in more constraints in antenna siting than for Category I. Primarily this will constrain the lateral offset of the approach azimuth from runway centre line. 13.7 Computed centre line approaches to parallel secondary runways 13.7.1 A secondary runway as defined here is a runway that has a different geometric relationship than the one contained in the auxiliary data A words. Computed centre line approaches to a parallel secondary runway are approaches 23/11/06 ATT G-40 2007/70/II. szám Attac ment G Annex 10 — Aeronautical Communications along a computed path on the extended runway centre line which is not aligned with an MLS azimuth radial and/or elevation angle but is parallel to the primary runway centre line. 13.7.2 The material in this section provides guidance on permissible runway geometries for computed centre line approaches to a parallel secondary runway to decision heights of 60 m (200 ft). The material in this section is based on the theoretical application of MLS and DME/P (Standard 1) SARPs. The error budget used is the conservative error budget identified in 13.2, and relaxations of this error budget are described in 13.7.6.1. 13.7.3 Runway geometry considerations 13.7.3.1 Figure G-32 presents the runway and equipment geometry. The secondary runway location is established laterally with the use of runway spacing in metres. Negative values represent secondary runway locations left of the primary runway. The longitudinal position of the secondary runway threshold is referred to as threshold stagger relative to the primary runway. Negative values represent threshold stagger forward of the primary runway threshold. 13.7.4 Large runway spacing considerations 13.7.4.1 Additional considerations are necessary for computed centre line approaches to widely spaced parallel runways. These considerations include:

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