# AC 90-45A CHG 2: Approval of Area Navigation Systems for Use in the U.S. National Airspace System

- Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it)
- Status: Historical
- Approved: February 21, 1975
- Family: AC 90-45
- Pages: 76
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/633CD6CD012D5336862569E7006DAA1A.0001
- Page: https://openairdocs.org/ac/90-45

## Versions

- AC 90-45A CHG 2 (Historical), approved Feb 21, 1975

## Text

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AC NO: 90-45A DATE: 2121175

**ADVISORY**

CIRCULAR APPROVAL OF AREA NAVIGATION SYSTEMS FOR USE IN THE Uo So

**NATIONAL AIRSPACE SYSTEM**

**DEPARTMENT OF TRANSPORTATION**

FEDERAL AVIATION ADMINISTRATION fnitiated by: AFS-260

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AC NO: 90-45A DATE: 2/21/75

**ADVISORY**

**CIRCULAR**

**DEPARTMENT OF TRANSPORTATION**

FEDERAL AVIATION ADMINISTRATION APPROVAL OF AREA NAVIGATION SYSTEMS FOR USE IN THESUBJECT: U.S. NATIONAL AIRSPACE SYSTEM

1. PURPOSE. This Advisory Circular provides guidelines for implementation of two-dimensional area navigation (2D RNAV) within the U.S. National Airspace System (NAS). It provides for both VOR/DME dependent systems and self-contained systems such as Inertial Navigation Systems (INS)~ etc. The airborne requirements for three-dimensional area navigation (3D RNAV) are specified. Implementation instructions for 3D RNAV are P.Ot included herein. They vdll be contained in appropriate agency orders. Until such orders are issued, use of airborne 3D-fu~AV systems on 2D-RNAV procedures to stabilize flight paths, etc. is permitted provided the minimum/maxinum altitudes specified in procedures are observed.

Additiondl changes may be expected which reflect elements of the Ir.dustry /FAA Task Force Report as they become verified.

2. CANCELLATION. Advisory Circular 90-45, Approval of Area Navigation Systems for Use in the U.S. National Airspace Sytitem, dated August 18, 1969, and Change 1 dated October 20, 1970, are canceled.

3. REFERENCES. "U.S. Standard for Terminal Instrument Procedures (TERPs)";

AC 90-28, "Course Changes While Operating under IFR below 18000' MSL";

AC 90-63, "ATC Procedures for Random Area t<avigation Routes"; AC 95-1, "A.invay and Route Obstruction Clearances"; FAR Parts 21, 23, 25, 27, 29, 43, 71, 75, 91, 95, 97, 121, and 135 as applicable.

**4. HOW TO OBTAIN THIS PUBLICATION.**

a. Copies of this circular may be obtained free of charge from:

Department of Transportation Publications Section TAD-443.1 Washington D. C. 20590 Initiated by: AFS-260

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b. Identify the publication in your order as:

FAA Advisory Circular 90-45A Approval of Area Navigation Systems for Use in the U. S. National Airspace System -· Dated February 1975 CK,JR.

Acting Director, Fli ht Standards Se

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**AC 90-45A CHG 2**

TABLE OF CONTENTS Page No.

1. Background and Definitions 1

2. Where to Apply for Approval 5

3. Area Navigation Equipment 5

4. Procedures 6

5. Turn Anticipation 6

6. Ground Facilities 6 APPENDIX A. AIRBORNE AREA NAVIGATION SYSTEMS: ACCEPTABLE MEANS OF COMPLIANCE WITH AIRWORTHINESS REGULATIONS (15 Pages)

1. Introductory Remarks 1

2. Acceptable Means of Compliance (IFR Use) 2

3. Testing Procedure (IFR Use) 10

4. Acceptable Means of Compliance (VFR Use) 13

5. Military Means of Compliance 14 APPENDIX B. PROCEDURE FOR OBTAINING FAA DATA APPROVAL BY SUPPLE­

MENTAL TYPE CERTIFICATE (STC) OR MAJOR REPAIR AND ALTERATION (FAA FORM .337) (FOR EQUIPMENT PROVIDED FOR USE UNDER INSTRUMENT FLIGHT RULES) (2 Pages)

1. Approval of Technical Data by STC 1

2. Approval of Technical Data by FAA Fonn 337 2 APPENDIX C. SOURCES OF NAVIGATION SYSTEM ERROR (5 Pages)

1. General 1

2. Current Relationship Between Navigation Accuracy and Route Width 1

3. Current Relationship Between Vertical Navigation Accuracy and Separation Standards 1

4. Sources of Error 1

5. Combining the Error Elements 4

6. Error Budgeting 4 APPENOIX D. INSTRUMENT FLIGHT PROCEDURES (23 Pages)

1. General 1 Section I

2. Enroute Criteria 4

3. Terminal Criteria 5

4. Instrument Approach Procedure Criteria 9 Section II

5. Background 19

6. Concept of Vertical Obstacle Clearance 22

7. Obstacle Clearance Requirements 23 Page i

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APPENDIX E. MAINTENANCE (1 Page)

1. Maintenance

2. Inspection and Test Procedures APPENDIX F. AIR CARRIERS/AIR TAXI AND COMMERCIAL OPERATORS OF LARGE AIRCRAFT/TRAVEL CLUBS (3 Pages)

1. Training Program

2. Operations Manual

3. Minimum Equipment List (MEL)

4. Authorization

5. Approach Minimums APPENDIX G. GENERAL AVIATION (1 Page)

1. Training Program

2. Approach Minimums APPENDIX H. AIR TAXI (1 Page)

1. Air Taxis Using Small Aircraft

2. Approach Minimums APPENDIX I. COMPUTATION OF CROSS-TRACK AND ALONG-TRACK ERROR COMPONENTS (5 Pages)

1. Track Error

2. Cross-Track

3. Along-Track *APPENDIX J. COMPUTATION OF GEODESIC INFORMATION (6 Pages)

1. Method

2. Computation of a Geodesic Line Given Two Geodetic Points

3. Computation of the Geodetic Description of a True Bearing and Distance from a Given Geodetic Point Page No.

1 1 1 1 1 1 2 1 1 1 1 1 1 3 1 1 4 * Page ii

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2/~1/75 AC 90-45A

**1. BACKGROUND AND DEFINITIONS.**

a. Present navigational methods, based on the use of VOR/DME/TACAN ground facilities, result in routes or airways which lead either directly toward or away from the station. This results in limitations on the configuration and the number of r outes available between two points.

b. These limitations take on even more importance considering that arrival and departure procedures are based, in large measure, on the same ground station s which serve the enroute structure.

This means the funneling effect is compounded by altitude changes for traffic transitioning to or from the enroute structure.

c. The employment of airborne area navigation systems (RNAV) permits flight over predetermined tracks within prescribed accuracy tolerances without the need to overfly ground-based VOR/DME (VORTAC) navigation faci lities. Area nav i ga tion has three prin­ cipal applications : between any given departure and arrival points along a route structure so organized as to permit reduc­ tion in flight distan ces or reduction in traff i c congestion; in terminal areas to permit aircraft to be flown on preorganized arrival and departure flight paths to assist in expediting traffic flow and reduc e pilot and controller workload; and to permit instrument approaches within certain limit at i ons.

d. Area navigation allows the use of routes not solely limited by air navigation facility location. These additional routes pro ­ vide operational advantages for pilots and controllers by in­ creasing route capability and flexibility.

e. Definitions of particular significance .

(1) Along-Track Distance (ATD) Fix - The ATD fix is an alo ng­ track position defined with referenc e to a waypoint and with geographical coo rdin ates.

(2) Along-Track Error - A fix error along the flight track resultin g from the total error contributions of the airborne and gr-ound equipment only.

(3) Area Navig a tion (RNAV) - A method of navigation that permits aircraft operations on any des ired cou rse within the coverage of station referen ced navigation signals or within the limits of self-contained system capability. In addition, RNAV utili zing capabilities in the horizontal plane only is 2-D while RNAV which also incorporates vertical guidance is 3-D.

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(4) Area Navigation (RNAV) Equipment - Airborne equipment that provides for area navigation.

(5) Changeover Point - The point at which navigation reference is shifted from one r eference facility to the next reference facility.

(6) Circular Position Error (CPE) - The probable navigation error expressed in terms of the radius of a circle centered on the desired geo graphic point.

(7) Cross-Track Error - A fix error to the left or right from the desired track to the present position, measured perpen­ dicular to the desired track. This error includes airborne equipment; ground equipment, and FTE.

(8) Designated RNAV Route - An area navigation route, based on the current high altitude or low altitude VOR/DME coverage, as designated by the Administrator and published in FARs 71 and 75.

(9) Established RNAV Route - A predefined enroute segment, arrival, or departure route (inc luding RNAV SIDs and STARs) . It also includes enroute segments established with gaps in VOR/DME coverage for use of aircraft equipped with RNAV systems capable of automatic dead reckoning.

(10) Flight Path Angle - A vertical angle defining an ascending or descending path TO a specified altitude (MSL) a t a specified waypoint. *

(11) Flight Technical Error (FTE) - Flight Technical Error refers to the accurac y with which the pilot controls the a ircraft as measured by his success in causing the indicat ed aircraft position to mat ch the i ndicated command or desir ed p os itio n.

It does not include procedural blunders.

(12) Instrument Approach Waypoints - Fixes used in definin g RNAV instrument approach procedures,including the INITIAL APPROACH WAYPOINT (IAWP), INTERMEDIATE WAYPOINT (INWP), the FINAL APPROACH WAYPOINT (FAWP), the MISSED APPROACH WAYPOINT (MAWP), and the RUNWAY WAYPOINT (RWY WP). *

(13) Parallel Of fset Route - A desired parallel track t o the left or right of the "parent" or designated route specified in whole nautical miles.

(14) Referen ce Facility - The ground VOR/DME facility used for the identification and establishment of an area navi ga tion route, waypoint, or flight pro cedure.

(15) RNAV Instrument Approach Procedures - Instrument approa ch procedures based on RNAV and identified by the prefix RNAV followed by the pro cedure number; i.e. , RNAV Rwy 21 or RNAV-A.

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**7/22)76 AC 90-45A CHG 2**

(16) RNAV Transition Routes for Initial Approach - Transition routes, based on RNAV, from the enroute environment to the initial approach waypoint of an instrument approach procedure.

RNAV transition routes may be included in conven .tional approach procedures such as ILS, as well as in complete RNAV approach procedures.

(17) Route Segment - Two subsequently related waypoints (or ATD fixes) define a route segment.

(18) Slant Range - The actual distance between aircraft in flight and certain air navigational aids (radar, DME). This distance is greater than the geographical range because of the altitude of the aircraft.

(19) Slant Range Error - Slant range error is the difference between the distance of an aircraft to a point on the surface and the distance from that point along the surface to a point directly beneath the aircraft.

(20) Tangent Point - The point from which a line perpendicular to the RNAV route centerline passes through a specified VORTAC.

(21) Tangent Point Distance (TPD) - Distance from VORTAC to tangent point.

(22) Track Angle - Settings used in station oriented RNAV systems to identify prescribed routes and tracks over the ground from point to point.

(23) Turn Points - A waypoint which identifies a change from one Great Circle track to another along a given route.

(24) Vertical Navigation (VNAV) - That function of RNAV equipment which provides guidance in the vertical plane.

(25) Vertical Path Angle- (See Flight Path Angle).* *

(26) Waypoint - A predetermined geographical position used for route definition and/or progress reporting purposes that is defined relative to a VORTAC reference facility.

(27) Waypoint Displacement Area - The rectangular area formed around the plotted position of the waypoint. The rectangle is oriented along the desired track with the waypoint at its center. Its dimensions are two times (plus-and-minus) the appropriate along-track and cross-track fix displacement error values.

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•Application of area navigation equipment and procedures in the National Airspace System requires that they be compatible with the VOR/DNE system on which route structure and air traffic control are based. Implementation, therefore, requires that area navigation devices employed assure proper positioning with respect to the VOR/DME route structure by reference to the geographic locations of VOR/DME ground facilities. Such systems must further permit navi­ gation along, and within the protected airspace of, conventional VOR routes, airways, and terminal procedures.

2-D Systems - To assure compatibility with existing ATC routes and procedures, z~o area navigation systems typically compute distances, bearings, and/or command guidance signals relative to "waypoints 11 that are used to define RNAV route segments in relation to VOR/DME station locations. A succession of these waypoints defines the centerline of the route to be flown.

3-D area navigation systems include the functions of 2-D systems with vertical guidance added. Vertical guidance includes computed deviation from desired ascending or descending path to a specified altitude at the waypoint, which is included in the route definition.

The advantages of area navigation are applicable to VFR as well as IFR operations. For VFR operations, straight line point-to-point navigation, bypassing of congested and restricted area, and elimination of air navigational facility overhead requirements are the principal advantages gained, and each contributes to the reduction of pilot workload and to flight safety. Installation requirements for VFR use only are shown in Appendix A, Page 13, Paragraph 4.

For IFR operations, area navigation offers similar benefits, but must be conducted in accordance with standards and procedures designed to ensure the safe, expeditious, and orderly movement and control of air traffic within prescribed airspace dimensions.

Introduction of an area navigation capability into the National Airspace System provides a means for overcoming many of the dis­ advantages of the VOR structure. By eliminating the requirement to fly along radials that lead directly to or from the ground station, it is possible to design routes and procedures that better facilitate the movement of traffic. Typical of the benefits that result are:

(1) Congested area bypass routes.

(2) Multiple routes to allow segregation of traffic according to speed or other operating characteristics.

(3) Pilot navigation of commonly flown radar vector paths.

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(4) Improved alignment of routes.

(5) Dual routes for one-way traffic.

(6) Increased instrument approach capability.

(7) Optimum location of holding patterns.

(8) Procedures designed for STOL and helicopter operations.

1. FAA encourages the installation of area navigation equipment and has established routes and terminal procedures that are specifically designed for, and are beneficial to, properly equipped users.

m. Previous action was directed to the development of transcontinental and major hub connecting routes along with terminal procedures to serve these routes. Development of other routes and terminal pro­ cedures will be consistent with user needs whenever possible.

**2. WHERE TO APPLY FOR APPROVAL.**

a. Application for approval of an area navigation equipment installa­ tion other than those relating to an application for a Supplemental Type Certificate (STC) may be made to any FAA Air Carrier, General Aviation District Office, or Flight Standards District Office.

b. Application for a Supplemental Type Certificate covering an area navigation equipment installation may be made to any FAA Regional Engineering and Manufacturing Office.

c. Application for approval of new area navigation routes and instrument approach procedures should be made to the appropriate FAA regional office. Air carrier/air taxi requests should be forwarded to the appropriate Flight Standards District Office.

d. Air carriers should advise the certificate-holding office of any application made to other offices.

3. AREA NAVIGATION EQUIPMENT. Equipment that meets the performance spec­ ifications outlined in Appendix A is suitable for use within the NAS.

A single system will be considered suitable to meet these requirements.

Equipment may include doppler radar, inertial, pictorial display/course line computers, or any other technique/device that will ensure com­ patibility with the operational procedures, route widths, vertical separation, and obstacle clearance requirements prescribed. Pictorial displays or course line computers provide one of the typical methods of operating on an area basis. This method is predicated on utilizing the signals from VOR/DME ground stations, or other facilities offering equivalent accuracy. The airborne equipment standard is the minimum for IFR. However, the NAS will recognize various levels of equipment sophistication. The more sophisticated equipment will include track Par 1 Page 5

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smoothing, turn anticipation, parallel offset capability, and at least a 6 waypoint storage for 2-D and at least a 10 waypoint storage capability for 3-D. They will normally use ARINC quality components which are more accurate than the minimum standards require and often utilize more than DME/VOR inputs. They typically use heading and air data or even inertial and ILS information to improve on the basic accuracy. The minimum equip­ ment will use the published reference facility. It normally does not employ track smoothing and rarely utilizes more than two waypoints. It is the minimum for IFR approval. This level of equipment is expected to be limited ultimately in the NAS, particularly in the terminal area where the cockpit workload is such that 6 to 10 waypoint storage, para1lel off­ set and turn anticipation features will be very desirable.

RNAV will be used in all phases of the NAS. Although current use is pri­ marily enroute, it is expected to become increasingly important in termi­ nal airspace. Sophisticated RNAV systems -- especially when supplemented with airborne 3-D capability -- are expected to provide the user with significantly improved instrument approach ca9ability when compared with the non-precision approaches currently used. The minimum RNAV systems on the other hand will be of limited usefulness in the terminal area. The minimum system cannot supplant VOR/DME and localizer for use as an ap­ proach aid except under special conditions where certain geometries can show an advantage for this level of RNAV. RNAV approach procedures which cater to the minimum equipment levels will normally not be developed in high density terminal areas except where a definite operational advantage can be the result as at an airport located over 10 miles from the refer­ ence facility or where circling minimums only apply, or where a localizer back course is unflyable; etc., or to sati~fy a specific user need.

4. PROCEDURES. In order to prolong the usefulness of the minimum equipment systems, procedures will be developed, where possible, with only two required waypoints. It must be noted, however, that procedures in com­ plex terminals may require.the use of up to 6 waypointsin rapid succes­ sion for 2-D and up to 10 for 3-D. The minimum equipment systems, although sufficiently accu+ate to meet present RNAV requirements, will find these complex procedures unflyable because of the extremely high cockpit workload.

5. TURN ANTICIPATION. Pilots flying the system are expected to initiate a turn prior to reaching the turning point in order to intercept the next segment without overshoot. Pilots flying systems which do not automati­ cally anticipate the turn should use a method which involves "leading" the turn by approximately one mile for each 100 knots true airspeed. Au­ tomatic coupled systems must have the capability of similar methodology.

6. GROUND FACILITIES. Throughout the text of this Advisory Circular, ground * facility references are to VOR/DME. Where TACAN service is provided in the NAS, any TACAN user whose equipment meets the minimum system perfor­ mance characteristics of the U.S. National Aviation Standard for VORTAC (AC 00-31) may apply TACAN to all VOR/DME ref~rences herein. * Page 6 Par 3

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Appendix A APPENDIX A. AIRBORNE AREA NAVIGATION SYST

COMPLIANCE WITH AIRWORTHINESS EMS: ACCEPTABLE MEANS

**REGULATIONS OF**

**1. INTRODUCTORY REMARKS.**

a. Area navigation systems based on VORTAC stations have fo ur sou rces of error: (1) ground VOR/DME radiated signal; (2) airborne VOR/DME equipment; (3) flight technical (pilotage);and (4) the air nav i­ gation equipment itself. It is assumed further that these are independent errors having such distribution that they may be com­ bined root-sum-square (RSS) fashion. See Appendix C.

b. The means of compliance presented herein apply to systems that use VOR/DME sensor signals either for direct aircraft position deter ­ mination or for updating aircraft position derived from other sources such as air data computers and magnet ic compasses, inertial navigation systems, and doppler radar navigation systems . However, RNAV systems may employ sensor inputs other than VOR/ DME without VOR/DME updating if equivalent accuracies can be demonstrated by means suitable to such systems.

c . The problem of slant range error takes on particular significance under the area navi ga tion concept because of a direct effect upon the intended rout e of flight. Airborne systems that are dependent upon ground s t atio n signals for course guid an ce are subject to this error, while self-contained systems are not. Of the former, some systems are designed to compensate for slant range error and others are not. The problem is even more s igni f icant above FL 180 , where airspace buffers are not planned.

2-D airborne sys t ems affected by slan t range error are accommodated through proc edur al compensation by the airspace plannin g and air traffic control system s outside the terminal area below FL 180 . Route design compensations will take the form of limitation s of the proxim ity of route centerlines to the reference facility, in creased lateral dimensions for routes that must pass in proximity to referen ce facilities and increased lateral spacing of dual or parallel routes .

Air traffic contr ol compensation is in the form of longitudi nal and lateral separation criteria that encompasses th e extremes of slant ran ge erro r possibilities.

3-D Systems are expected to incorporate slant range correction because the input data for the correction is nor mally available, therefore, 3-D r oute planning and traffic control will NOT allow for slant range error.

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AC 90-45A 2/21/75Appendix A ~limination of slant range error and its attendant compensating procedures is prerequisite to the development of optimum routes and separation criteria. FAA plans to initiate rulemaking action in the near future requiring slant range correction in terminal hubs and at FL 180 and above. This level may be lowered as operational experience is gained.

2. ACCETPABLE MEANS OF COHPLIANCE (FOR USE UNDER INSTRUMENT FLIGHT RULES) An acceptable means of compliance with Section -.1301. -.1309. -.1431.

and -.1581, of Part 23, 25, 27 or 29 (as applicable), with respect to area navigation systems. provided for use under IFR conditions, is to satisfy the criteria set. forth in this paragraph.

a. Accuracy.

(l) 2-D RNAV System using Reference Facility for continuous navigation information. The total of the error contributions of the airborne equipment (receivers plus area navigation - including desired track setting as well as waypoint setting errors) when combined RSS with the following specific error contributions should not exceed the error values shown in Table 1, Appendix A VOR ground station + 1.9° DME ground station ,:!:0.1 NM

(2) 2-D RNAV systems whicn use VOR/DME information from other than the Reference Facilities must show that the algorithm used will always select a station that will provide cross track/along track errors equal to or les s than the greater of the RNAV system errors of the reference facility for any RNAV track (Table 1) or the errors shown in paragraph 2.a.(3).

(3) 2-D ~~AV System not using VOR/DME for continuous navigation information. The total of the error contributions of the airborne equipment (including update, aircraft position and computational error s ), when combined with appropriate flight technical errors listed in 2.a.(4) below, should not exceed the following with 95 % confidence (Z-sigma) over a period of time equal to the update cycle:

Cross Track Along Track Enroute 2.5 NM 1. 5 h"M Terminal 1.5 NM 1.1 NM Approach 0.6 NM 0.3 NM

(4) 2-D Flight Technical Errors (FTE) when combined RSS with the errors discus s ed in (1) and/or (a) above det e rmine the Total Page 2 Par 1

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Appendix A System error. The Total System error is used by airspace planners and includes the following specific FTE values for determining cross-track position accuracies. Values larger than these must be offset by corresponding reduction in other system errors. (See Appendix C~ No FTE is used in determining the along-track accuracy.

Enroute + 2.0 NM Terminal + 1.0 NM Approach + 0. 5 NM

(5) 3-D RNAV Systems. The total of the error contributions of the airborne equipment, including sensors and area navigation:

(a) Should not contribute any new horizontal error, and

(b) When combined RSS with tbe specific vertical error contributions for "Flight Technicalu listed in Table B of this Appendix, should not exceed the total RSS accuracy requirements of Table B, Appendix A.

(c) Vertical Navigation Equipment (VNAV) Total vertical navigation system accuracy criteria are based largely on the satisfactory expcrienc~ of many years with the present separation standard of 1000 feet, while also anticipating the probable needs of the air traffic system in the future.

The total 3-D system accuracy requirements for level flight are stated in Table A. The requirements are based on final approach, terminal area, and enroute operations in level flight. The specific requirements are based on the obstacle clearance standards for final approach and on airspace protection standards up to FL 290. The require­ ments for operations above FL 290, where separation standards chanr,e, are based on performance levels typical of altimetry systems meeting accuracy requirements for final approach and en route operations up to FL 290.

The 3-D system accuracy for other than level flight varies with the ascent/descent angle. This variance is due to the flight technical error which has been shown to vary with the angle of ascent or descent. These variations are shown in Table B.

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2/21/75AC 90-45A Appendix A

**MINIMUM ACCURACY REQUIREMENTS FOR VERTICAL GUIDANCE EQUIPMENT**

EMPLOYED IN AIRBORNE VERTICAL NAVIGATION SYSTEMS Level Flight Flight Segment Altitude Re~don Total Vertical Error in Feet _(3g)_ ~99.7% confidence) Remarks Final Approach At or below 5000' MSL 200 Meets the obstacle clearance requirements of 250'.

Terminal Area At or below 10000' MSL 350 Meets the 1000' level flight vertical separation require­ ment.

Enroute All altitudes 350 Meets the 1000' level flight vertical separation require­ ment.

TABLE A Table B illustrates typical error budgets where errors are assumed to be independent and are combined by the root-sum­ square (RSS)method. These accuracy requirements provide an adequate buffer zone to accommodate all normally encountered atmospheric anomalies and reference discrepancies without jeopardizing the validity of the 1000 foot vertical separation standard in level flight.

The table lists vertical position error budgets without regard for horizontal position uncertainty. In a dynamic situation, additional vertical errors must be considered during ascending and descending flight because the aircraft may be either ahead of or behind its assumed position along track. For systems meeting minimum horizontal position accuracy requirements, this additional error is generally larger than the non position-dependent vertical position errors shown. The airborne computer calculates the descent angle and commands an altitude for the assumed position.

If the aircraft is behind the assumed position. the air­ craft is below the intended track by an amount proportional to the along-track error. This error must be added (RSS) to the basic vertical position errors shown when calculating airspace protection and obstacle clearance during descent.

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Appendix A SU~~RY OR REPRESENTATIVE

ERROR BUDGET IN FEET *Final Approach Error 5000 feet HSL Source and below Level Ascent or Flight Descent VERTICAL GUID&~CE

99.7% (3C1) *Terminal 10,000 feet MSL and below Level Ascent !Enroute (1) All altitudes or . Level Ascent or Flight Descent Flight Descent iA.ltimetry (3) 90 140 200 265 250 350 jvNAV Equipment (4) 100 100 150 150 0 (2) 220 Flight Technical (5) 150 200 250 300 250 300 TOTAL RSS (36) 200 265 350 430 l 350 510 I

TABLE B NOTE 1. }fuximum operating altitudes to be predicated on compliance with total accuracy tolerance.

*When final approach and terminal area procedures are developed above altitudes shown, error is increased proportionately in the altimetry and RNAV parameters to provide airspace and obstacle clearance protection.

NOTE 2. In the event that VNAV guidance is used in level flight enroute the incremental error component contributed by the VNAV equipment must be offset by a corresponding reduction in other error components, such as flight technical error, to ensure that the total error budget is not exceeded.

NOTE 3. Altimetry Error. Refers to the electrical output and includes all errors attributable to the aircraft altimetry installation including position effects resulting from normal aircraft flight attitudes. In high performance aircraft, it is exp~cted that altimetry correction will be necessary to meet these require­ ments. Such correction should be done automatically. In lower performance aircraft, upgrading of the altimetry system may be necessary. The larger errors shown for ascent/descent are typical of automatically corrected altimeter systems which meet the level flight error budget.

NOTE 4. VNAV Equipment Error. Includes all errors resulting from the vertical guidance equipment installation. Does not include Par 2 Page 5

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Appendix A errors of altimeter system but does include any additional errors resulting from the addition of the VNAV equipment.

This error component may be disregarded in level enroute flights if the operation is limited to guidance by means of the altimeter only. It should not be disregarded in the terminal and approach operations. where the pilot is expected to follow the VNAV indications.

NOTE 5. Flight Technical Error. Includes errors in pilot interpretation of vertical guidance instrumentation, pilot activation of aircraft vertical controls, and deviations caused by aircraft response characteristics. Consideration is given to the relatively high pilot proficiency and good aircraft characteristics expected to be found in most operations at the higher altitudes . These values represent consensus estimates based upon experience and some limited testing; and for cases in which there is no relevant experience, they are conservative estimates. It is recognized that there are several design and operational parameters that could affect those values including display configuration, autopilot coupling versus manual control, pilot workload, and variation of aircraft response with increasing gross weight and altitude.

As operational experience and experimental data are accumulated and analyzed, the values will be suitably adjusted.

(6) All RNAV equipment approved for use under Instrument Flight Rules (IFR) must meet the appropriate accuracy criteria.

Should it not meet these criteria, a placard must be installed in the aircraft which reads "IFR Operation Not Authorized."

(7) equipment presented will be approved by issuance of an STC or, upon prior approval from the appropriate regional office, may be approved by a properly processed Form 337 in the field.

b. Area Navigation System Design.

(1) General. The systems will normally use VOR/DME input sensor signals (or use combinations of VOR and DME for updating purposes) and indicate aircraft positions relative to the llliAV route and selected waypoint. Systems may be designed to utilize other Page 6 Par 2

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Appendix A sensor inputs if equivalent accuracy can be demonstrated.

Installations intended for final approach should use position information that is essentailly continuous with interruptions no longer than would result from switching from one preprogramed waypoint to another. The system should give no operationally significant misleading information.

(2) Vertisal Guidance Input Controls.

In the absence of pre-stored or automatically inserted flight profile parameters, pilot controls shall provide for at least the following inputs:

(a) Station Elevation. For systems employing slant range error correction, elevation of the VOR/DME ground station in increments not greater than 100 feet if used during final approach, and for other phases in increments not greater than 1000 feet.

(b) Waypoint. Waypoint altitude in increments not greater than 10 feet if used during final approach, and for other phases in increments not greater than 100 feet. Waypoint horizontal position shall be entered in increments not greater than 0.1 nautical mile or 0.2 degree bearing from the station or the equivalent.

(c) Flight Path Angle. Vertical gradient from a zero degree origin in increments not greater than 0.1 degree or the equivalent.

(3) Checking of Input. Provisions should be made to enable the pilot to check the correctness of the inputs.

(4) Altimeter Setting. The system shall be so designed that there is no requirement to insert separate barometric correction inputs into the vertical guidance computer. Adjusting one of the barometric pressure altimeters in the cockpit should automatically provide the corrected input to the vertical computer. In order to avoid the abrupt irregularity in the computer vertical flight path at the transitional level, the pilot will make altimeter setting changes between local and standard 29.92" Hg. above the transitional level. Airspace will be buffered above this level to account for the discontinuities in the vertical flight path and the pilot will be expected to make the change gradually so as not to introduce unacceptably abrupt flight path requirements.

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AC 90-45A Appendix A 2/21/75

(5) Vertical Guidance Display. The equipment shall provide a vertical guidance presentation compatible with the aircraft's flight instrumentation such that the pilot is continuously furnished vertical deviation of the aircraft with respect to a pre­ programed ascent/descent or level flight profile· ~

(6) Failure Warning. Provision should be made to alert the crew upon occurrence of any probable failure of major system functions or loss of inputs, including those that would affect aircraft position, heading, command course, command heading, altitude, or vertical guidance indications.

(7) Performance Check. Provision should be made for checking the system's performance on the ground and in flight. This may be a built-in check, an auxiliary test system or a procedural check.

(8) Response Time. The navigation display should indicate air­ craft position, to the accuracy specified in Paragraph 2.a., assuming that navigation sensor outputs are available:

(a) During flight in any direction at the maximum ground speed declared by the equipment manufacturer, and

(b) During ascent or descent at the maximum rates declared by the equipment manufacturer, and

(c) Within five seconds after any normal maneuver, assuming sensor inputs are not lost during the maneuver.

(d) The time lag between time of data input and guidance derived from the display of the data should not be operationally significant.

NOTE: Terminal area speed limitations are taken into account in connection with this provision. Moving elements of the navigation display may be damped.

(9) Coordination of Displays. In installations incorporating both horizontal and vertical guidance, there should be no operationally significant difference between the various displays used by the flight crew. For example, if a descent is programmed to end at a waypoint, the command to level off should be operationally coincidental with the waypoint indication. This is not intended to preclude maneuver anticipation.

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Appendix A

(10) Environmental Conditions. The area navigation equipment should be capable of satisfying the criteria set forth in Paragraph

2.a. and 2.b. above over the environmental ranges expected to be encountered in actual aeronautical operations. In demon­ strating compliance, the environmental conditions outlined in Radio Technical Commission for Aeronautics Document D0-138 titled "Environmental Conditions and Test Procedures for Air­ borne Electronic/Electrical Equipment and Instruments" dated June 27, 1968, or other appropriate environmental standards may be used.

(11) Auto Tune Systems. Systems which automatically tune/select VOR/DME facilitie s for navigation or update should be limited to a search range of 130 NM for high altitude facilities and 40 NM at 18,000 feet and below for low altitude facilities in keeping with the NAS frequency protection criteria unless through computer logic or a 'reasonableness test' fault y infor­ mation is rejected.

(12) Turn Anticipation and Parallel Offset.

(a) RNAV systems which provide for parallel offset tracks must also limit the turning maneuver. Turn s shall be anticipated and flown in such a way as to cause the aircraft to remain within + 2.5 NM of the desired track centerline enroute and + 1.5 NM of the cen terline in the t erminal area. Pilots flying syst ems which do not automatically anticipate the turn are expected to lead a turn by 1 NM pe r 100 knots true airsp eed .

(b) 3-D systems shall not require additional con trols to assure t hat the offset route is in the same horizonta l plane as the pare nt route at the waypoint. The plane is measured on the bis ecto r angle between cen t er lines of the adjacent r oute segme nt s .

c . Area Navigation Equipment Installation.

(1) Location of the RNAV display. Each display element to be used as a primar y flight instrun,ent in the g uid ance and control of the aircraft should be located where i t is clearly visible to the pilot with the least practicable deviation from his normal position and from his line of vision when he is looking forward along the flight path .

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Appendix A

(2) Failure protection. Any probable failure of the airborne area navigation equipment should not derogate the normal operation of required equipment connected to it, nor cause a flight hazard.

(3) Radio frequency interference. The area navigat.ion equipment should not be the source of objectionable radio frequency interference,nor be adversely affected by radio frequency emissions from other equipment in the aircraft.

(4) Manufacturer's instructions. The area navigation equipment should be installed in accordance with instructions and limita­ tions provided by the manufacturer.

d. Aircraft Flight Manual. If an aircraft flight manual is provided by the aircraft manufacturer, its FAA approved portion may contain the following information on the area navigation equipment:

(1) Normal procedure for operating the equipment;

(2) Equipment operating limitations; and,

(3) Emergency operating procedures (if applicable).

If not contained in the aircraft flight manual, information on equipment operating limitations should be provided to the pilot by means of placards. The aircraft flight manual or placard should state "RNAV Instrument Approaches Not Authorized" if the instrumentation is such that FTE cannot be resolved to meet ap­ propriate criteria. Revisions or supplements to the flight manual must be approved by the Regional Chief of the Engineering and Manufacturing Branch.

**3. TESTING PROCEDURE (FOR EQUIPMENT PROVIDED FOR USE UNDER INSTRUMENT**

**FLIGHT RULES)**

a. Generalo An applicant for approval of an area navigation system installation in an aircraft may show that he has satisfied the criteria in Paragraph 2 by a combination of bench tests of the individual components (in~luding VOR and DME) and ground/flight tests of the entire installed area navigation system. The bench tests may have already been performed by the individual component manufacturer (during design and construction) or by the installer (on behalf of a previous customer). Such bench test data, if certified by the manufacturer or installer are acceptable. In addition, the applicant may refer to applicable TSO standards, if the manufacturer of the equipment certifies that his equipment meets those standards.

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Appendix A

b. Bench Tests. The following tests may be performed on the bench or with the navigation system insta lled in the a ircraf t:

(1) Test equipment. Bench test equipment shou l d be capable of simulating the input signals from VOR/DME and/or_ .. the altimeter or other sensors and of var ying those signals ove r t he ran ges for which the equipment i s designed.

(2) Accuracy testing.

(a) Variables to be considere d . Each variable that has a significant effect on pos ition err or should be inv es ti­ gated over its entire ran ge, and the error analysi s should show the effects of reasonab ly probable var iation s of these variables on total syste m accura cy . The stat i stica l technique described in RTCA Document No. D0-153 entitled "Minimum Performance Standards -- Airborne VOR Receiving Equi pment Operating Within the Radio Fr equency Range of 108-118 Megahertz" dat ed August 18 , 1972, may be used as a euide.

(b) Static test. Horizqntal and/or vertical pos 1t1on accuracy should be measured statically as the e rror iu displayed position relative to .the theoretical position obtained from perfect signal inputs (range and bearing from a known station location and/or altitude). Simulated ran ge and bearing and/or altitude signals are introduced into t he ., area navigation equipment. Combinations of ran ge s from zero up to the maximum distance for which t he equipment is designed, bearings from zero to 360 degrees, ID1d alti­ tudes up to the naximum certificated altitude fo r the aircraft should be inserted as input signals. For each set of input signals, the corresponding display output should be compared to the theoretical pos ition and recor ded as an &~AV system error. The errors for each t es t po int are then combined statistically to determine t he 2o (YS%) probable error. ID1en this value exceeds the RNAV system error element shown on Table 1, the total horizontal systen error must be computed by adding t he RNAV system error RSS to the other system errors. See Appendix C.

They should be within the values shown in '!able 1 if the syst em is to be used in IF R fli ght. !~ote that only one error table is provided. This r ep resents the requir ed accurac y for IFR of VOR/DHE equipment us ing the reference facility. The only variable betwe en euroute, terminal, and approach is FTE (shown in 2.a.(4) above). Separate tables are redundant.

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Appendix A The vertical system error is computed by adding RSS the values for FTE (Table B) and altimetry appropriate to the installation.

The values shown in Table 1 and the RSS totals in Table B should not be exceeded.

(c) pynamic test. In addition to the static test, a dynamic accuracy test should be performed utilizing simulated VOR/DME and/or altimeter inputs varied in range, bearing and/or altitude in order to assess the ability of the system to smooth variable input signals without incurring excessive lag. These tests should be performed with representative simulated airspeeds throughout the range for which the equipment is designed. During these tests the measured RNAV equipment error should be consistent with the total system accuracies specified in Paragraph 2.

Alternatively, an in-flight demonstration of satisfactory dynamic characteristics may be accepted.

(d) Systems having map type displays. If the system uses a map type pictorial display of aircraft position as a primary means of steering guidance, the accuracy deter­ mination should take into account any error contribution by the cartography.

(e) Altimetry tests. The accuracy of the installed altimetry system should be determined by tests, evaluation of previously approved data, or both, to assure that the altimetry error budget of Table B is not exceeded. Static system error determined during aircraft certification or determined by currently recognized means may be combined RSS with scale error data for the altimeter.

c. Ground/flight tests.

(1) Ground tests. After the area navigation system has been installed, but before the aircraft is flown, an operational/ functional check should be performed to ensure that the system has been installed in accordance with the installation criteria in Paragraph 2.c. (and with all applicable airworthiness regu­ lations) and that it functions properly and safely.

(2) Determination of when flight tests are necessary. At least one flight test for accuracy in the approach case is necessary. Additional flight tests for accuracy are necessary if the system accuracy is not adequately deter­ mined by signal simulation as described in 3.b. above, or if it appears that the resolution of the pilot display is such Page 12 Par 3

### Page 24

Appendix A That the assumed FTt: of 2.0 NH (enroute), 1.0 NN (terminal) or 0.5 ~11 (approach), will be exceeded.

NOTE: The "Approach" mode is defined as the flight operation between the final approach waypoint and the airport. The "Terminal" mode is defined as the ingress/egress flight operation between Enroute and Approach, normally below FL 180 within SO miles of the airport. The "Enroute" mode is defined as the cruisin g fli ght operation between Terminal areas.

(3) Accuracy tests in flight. When the bench check data required by paragraph 3.b. above are not available, flight tests are necessary. Therefore, in addition to ground tests, to demonstrate satisfactory performance of the area navigation equipment, the airplane should be flown solely by reference to the RNAV display and other standard flight instruments, at a relatively low altitude under VFR conditions, with a safety pilot, and if practicable under ground radar surveil­ lance as follO\\IS:

(a) Along the length of an FAA approved Rl-iAV route segment.

(b) In accordance with an FAA approved RNAV terminal area procedure; and

(c) In accordance with an FAA approved RNAV approach procedure.

(d) During ascent and descent flight in terminal and/or final approach operation with theodolite observation or equiva­ lent to check vertical angle performance of 3-D RNAV.

Final approach performance may be compared against ILS signals.

In each case, the area navigation system is satisfactory if the equipment meets the accuracy requirements of Paragraph 2.a.

as determined by direct vis ual reference or other s uitable methods to identifiable ground check points and a lar ge scale map of the area on which are shown route segment centerlines and boundary widths applicable to the distance from the reference facility.

(4) Functional test in flight. The area navigation system should be checked out in flight to determine whether the design and installation criteria in Paragraph 2.b. and 2.c. are satisfied.

4. ACCt:PTABLE I-lEANS OF COMPLIANCE (FOR J::QUIP:HliliT PROVIDlllJ FOR USE UNDER

**VISUAL FLIGHT RULES ONLY)**

a. An acceptable means of compliance with Sections -.1301, -.1309, -.1431 and -.1581, of Part 23, 25, 27, or 29 (as applicable), with Par 3 Page 13

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AC 90-45A 2/21/7 5 Appendix A respect to area navigation systems provided for use under VFR conditions only, is to satisfy the criteria in Paragraphs 2.c.

and 3.c.(l) above, and to placrad the aircraft to limit the use of the area navigation system to VFR only.

b. Airborne area navigation equipment installed under Paragraph 4.a.

may be approved by means of a Form 337 or Supplemental Type Certificate.

5. MILITARY MEANS OF COMPLIANCE. Militar y RNAV equipment approval pro­ cedures, the means for designating equipment for use under VFR flight conditions only, and methods by which pilots are to be informed of equipment limitations will be accomplished by the individual military services. Military use of TACAN azimuth and distance information is assumed where VOR/DME is required.

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Appendix A VORIDMEfTACAN STATION REFERENCED AREA NAVIGATION ERROR TABLE (95% PROBABI LITY)

DISTANCE ALONG TRACK FROM TANGENT POINT 0 10 15 20 2 5 ) 0 35 40 50 60 70 80 90 100 110 1 20 130 !50 20 0 0 (x tr lc.) • 6 . 8 1 . 1 1.3 1.t 1 .9 2.2 2.5 3 .1 3 .7 4. 4 5 . 0 5 . b 6 . 2 6.8 7.4 8 .1 9 . 3 1< . 4 (a1g trl<) .7 .7 . 7 .d .9 :. .o l.2 l.J 1.6 1.9 2. 2 2 .5 2.3 3.0 3.3 >-• ) .9 4 .) 6 . 0 s (x << <) .7 .7 . s 1 .1 1.4 1.6 1 , 9 2 .2 2.5 3. 2 3 . 8 4.4 ;.o s. o o . 2 o. 5 7 .5 8 .1 9.3 12.4 ( a l g en.) . o .7 . d .8 .9 1. 0 1. 1 1.2 1.4 1. 6 1. 9 2 . 2 2.5 2.a ) .1 3. 4 3.7 4 .v 4.6 0.1 lO( x tr k) .7 .8 . ~ 1 .1 1 . 4 1 .7 2 . 0 2 .3 2 . 6 3 . 2 3.8 4. 4 5.0 5.6 6 . 2 o . 9 7. ) 6 . 1 9 . 3 12.4 ( a lg t r k) .a . s . 9 .9 1. 0 1 . 1 1 .2 1 .4 1 .5 1.7 z.o 2. 3 2.6 2.9 3.1 3 . 4 3 . 7 4.0 4 . 6 6. 1 1 5( x trk ) . 7 , 8 . 9 1 .2 1. 4 1 . 7 2.0 2. 3 2 . 6 3 . 2 3.8 4 . 4 5 . 0 ;.o o . 3 6.9 7.3 8.1 9 . 3 12.4 (a 1 g trl<. ) 1. 1 1.1 1.1 1 . 2 1.2 1.3 1 . 4 1.5 1. 6 1 .9 2 .1 2. 4 2.7 3.J 3. 2 3 .5 3.8 4 .1 4,7 ~.2 20(x tr k ) . ~ .9 1.0 1. 2 1.5 1. 8 2. 1 2.3 2.6 3.2 3 .~ 4,4 5.1 5. 7 b . 3 6.9 7. 5 8 .1 9.4 1 2.> (a1g trk) 1 .3 1.4 1.4 1 . 4 1.5 1.6 1.7 1.8 1.9 2. 1 2 .3 2.6 2. ~ 3.1 3.4 3. 6 3. 9 4.2 4. 8 6 . z 2 5 ( x trl<) . 9 1.0 1. 1 1. 3 1 .6 1. 8 2.1 2 .4 2.7 3.3 3. 9 4. 5 5. 1 5. 7 6.3 6. 9 7. 5 8 .1 9. 4 1 2.> ( a 1 ~ t r k) 1. 6 1.6 1 .7 1 . 7 1.6 1. 8 1 . 9 2 . 0 2 . 1 2.3 2 . 5 2, 7 ) . 0 3.2 3 . 5 3 . d 4 , 0 4 .3 4 .9 6.3 30(x t rk) 1. 0 l.l 1.2 1. 4 1. 7 1.9 2.2 2.5 2 . 7 f"'l.3l ) .9 4 . 5 S.1 ) . 7 6 .3 6 . ~ 7.6 d.2 9 . 4 12.5 { ~ l p; trk. ) 1. 9 1.9 2 . 0 2.0 2.1 2.1 2.2 2. 3 2 . 3 ~ 2.7 2 . 9 3.2 3.4 ).7 3 .9 4.2 4 . 5 5.0 6 ·" l 5 (x trk ) 1.2 1. 2 1. 4 1.5 1. 8 2. 0 2. 3 2. 5 2.8 3.4 •.o 4 . 6 5 . 2 5 . a 6 . 4 1 . 0 1 . o 8 .2 '1. 4 12 . 5 ( a1~ tr l<. ) 2 .2 2.2 2.3 2 . 3 2 .3 2.4 2 . 5 2 .5 2.6 2 .8 3. 0 3. 2 ) .4 ). 6 3. 9 4,1 4. 4 4 . o 5.2 6.5 40(x trk) 1.3 1.4 1.5 1.6 1.9 2.1 2.3 2.6 2.9 ) , 4 4.0 4.6 5 . 2 5.d 6.4 7 . 0 7.6 8 .2 9.5 12. 5 (a1g t< k) 2.5 2.5 2. 6 2.6 2.6 2.7 2. 7 2 . 8 2.9 ) . 0 3 .2 3. 4 ).6 3 .8 4. 0 4 . 3 4,5 4. 8 5.3 6 .7 50( x t rk) 1. 6 1 .6 1 .7 1.9 2 .1 2.3 2 . 5 2. 8 ).0 3. 6 4 .1 4.7 5.3 5. 9 6.5 7 .1 7. 7 8.3 9 . 5 12.6 (a l g trk) ) . 1 3 . 2 3. 2 3.2 3.2 ]. ) 3.3 3. 4 3.4 3.6 3. 7 3. 9 4.1 4.3 4 . 5 4.7 4 . 9 5. 2 5. 7 7.0 60( x tr k) 1 . 9 1.9 2 . 0 2. 1 2 . 3 2.5 2 . 7 3 .0 3.2 3 . 7 4.) 4 . 8 5 . 4 6 . 0 6.6 7 . 2 7 . ~ ~- · 9 . 6 1l.6 (a 1g trk ) 3 . 7 3. 8 3. 8 ) . 8 3.8 ]. 9 3.9 4 .0 4. 0 4.1 4 .3 4.4 4.6 4. 8 5 .0 5.2 5.4 5. 6 6 .o 7. J ~ 70(x tck ) 2.2 2.2 2. 3 2.4 2.6 2. 7 2. 9 ].2 3.4 3 .9 4,4 5. 0 5 . 5 6 . 1 6. 7 7.3 7 . 9 8 . 5 9 . 7 12.7 ~ (alg trk) 4,4 4.4 4,4 4.4 4,4 4,5 4 .5 4.6 4, 6 4.7 4.8 5. 0 5 . 1 5.3 5. 5 5.6 ).8 6 . 0 6 . 5 7.7 es 80(x tr<) 2.5 2.5 2. 6 2 . 7 2.8 3.0 3.2 ).4 3.6 4 .1 4,6 5.1 5.7 6 . 2 6.8 7. 4 8 . 0 8. 6 9.8 1 2 . 8

c.. (alg trk ) s.o 5 .o s. o 5 . 0 5.1 5.1 5 .1 5.2 5.2 5.3 5 .4 5 .5 5. 7 5. 8 o.o 6 . l 6 .3 6 .5 6.9 a.o 90( x tr k) 2.8 2 , 8 2 . 9 J,O 3.1 ) . 2 ) , 4 3 .6 3. 8 4 . 3 4.8 5 . 3 5.8 6.4 6 .9 7 ,5 8.1 8 .7 9 . 9 12.9 ( a lg trk) 5.6 5 . 6 5 . 6 5.6 5 .7 5.7 5.7 5.6 5 .8 5 . 9 6.0 6. 1 6.2 6.4 6 .5 6.7 6.8 7 . 0 1. • a.5 100( x t rk ) 3. 0 3 .1 3.1 3.2 3.4 3.5 3. 7 3. 9 4 . 0 4 . 5 s.o 5 . 5 6.0 6 . 5 7 . 1 7 . 6 8.2 8 . ~ 10 . 0 12.9 ( a1g trk) 6 . 2 6 .2 6. 2 6 ,3 o .3 o.J 6 .3 6 .4 6.4 6.5 6. 6 6,7 6 .~ 6 . 9 7 . 1 7 .2 7 . 4 7 .5 7.9 8.9 llO(x trio.) 3.3 3.4 ),4 3.5 3.6 3.3 3.9 4.1 4.3 4, 7 5 ,2 5 . 6 6 .2 6 . 7 7 . 2 7 . 8 8. 3 8 . 9 10 . 1 13. 0 (•1s trk) 6 . 8 6,8 6. 9 6 .9 6.9 6.9 6 .9 7.0 7.0 7 . 1 7.2 7.3 7. 4 7. 5 7. 6 7 . ~ 7 .9 8 . 1 8. 4 9 .4 120(x trk ) 3.6 ).7 ).7 3. 8 3.9 4.0 4 ,2 4.4 4,5 4, 9 5. 4 5.8 6. ) 6 . 8 7.4 7 . 9 8 .5 9 .0 10 . 2 1 3. 1 (a 1g tr k) 7. 4 7 ,; 7. 5 7.5 7 .5 7.5 7. 6 7 ,6 7. 6 7.7 7 ,8 7. 9 8.0 8 . 1 8 . 2 8. 3 8. 5 8 .6 9.0 9.9 130( x tr k) 3 .9 4 . 0 4 , 0 4.1 4 .2 4, 3 4.5 4.6 4, 8 5.2 5.6 6. 0 6.5 7.0 7 .5 8 . 1 8 . 6 9 .2 10.3 1 3.2 (a1g t r k) 8.1 8. 1 8 . 1 8 .1 ~ .1 8 . 1 8.2 8.2 8 . 2 8. 3 8.4 8 . 5 8. 6 8 . 7 8 . 8 8. 9 9.0 9 . 2 9 . 5 10 . 4 140(x trk ) 4 ,2 4 . 3 4. 3 4.4 4 .5 4.6 4. 7 4 .9 S. O 5.4 5 . 8 6. 3 6 . 7 7. 2 7 . 7 8 . 2 8 . 8 9 .3 10.5 1 3. 3 (al~ trk) 8. 7 8.7 8.7 8.7 8. 7 8. 8 8 . 8 8.8 8, 8 8.9 9 . 0 9.1 9 .2 9 .3 9. 4 9 . 5 9,6 9 . 7 10 . 0 10 . 9 l50(x trk) 4.5 4,6 4. 6 4 . 7 4.8 4.9 5. 0 5,2 5.3 5, 7 6.0 6. 5 6 . 9 7 .4 7.9 8 . 4 9.0 9 .5 10 . 6 13. 5 (alg trk ) 9 .3 9.3 9.3 9 . 3 9.4 9.4 9 .4 9.4 9.5 9.5 9 .6 9 , 7 9.8 9. 9 10.0 10.1 10 .2 10 .3 10 . 6 11,4 TO Fl ND THE CROSS-TRACK AND ALONG-TRACK ELECTRONIC ERROR ELEMENTS ~Q SYSTEM ERROR QESS PILOTAGE) AT A POINT, ENTER TABLE GROUND Vl WITH PERPENDICULAR DISTANCE AND Dl STANCE ALONG VOR I. c1J 0 TRACK FROM TANGENT POl NT, i.e . • when the Perp Dist is c.. DME 0.1 NM 0! 30 and the along-track dist is 50, the cross-track error ...... AIRBORN£ c.. VOR is +3. 3 NM and the along-track error is 2. 5 NM. 3.00

- if OM£ 3% or 0.5 NM RNAV SYSTEM 0.5 NM Tangent PI ALONG TRACK D I ST PILOT ZERO TABLE 1 Page 15

### Page 27

Appendix B APPENDIX B. PROCEDURE FOR OBTAINING FAA DATA APPROVAL BY SUPPLEMENTAL

TYPE CERTIFICATE (STC) OR MAJOR REPAIR AND ALTERATION (FORM 337) (FOR EQUIPMENT PROVIDED FOR USE UNDER INSTRUMENT

**FLIGHT RULES)**

**1. APPROVAL OF TECHNICAL DATA BY SUPPLEMENTAL TYPE CERTIFICATE (STC).**

a. What the STC applicant does:

(1) Makes an application for STC at the FAA Regional Engineering and Manufacturing office. Early contact is wise, since sched­ uling may be critical. FAA evaluates the data submitted by the applicant (see Paragraph l.b.), issues a Type Inspection Authorization (TIA), and participates in ground/flight tests outlined in Appendix A, Paragraph 3.c. An STC is issued when all airworthiness requirments are met. If the submitted data is adequate, the STC authorizes similar installations in the same aircraft type.

(2) Designs and constructs his area navigation system installation to the criteria set forth in Appendix A, Paragraph 2.

(3) Obtains, from the equipment manufacturer or the installer, the bench test data described in Appendix A, Paragraph 3.b., or an appropriate certification of accuracv per Paragraph 3.a., or conducts these bench tests himself.

(4) Makes available an aircraft (with the area navigation system installed) for ground inspection and flight test. The appli­ cant is responsible for furnishing a qualified flight crew for conducting the required flight tests.

b. Data submitted by the STC applicant. The following kinds of data be submitted for FAA airworthiness evaluation:

(1) Equipment data, such as:

(a) Equipment schematics.

(b) Equipment manufacturer's operating instructions and instal­ lation instructions.

(c) Equipment manufacturer's quality control procedures.

NOTE: Equipment data is submitted for original installation only .

(2) Fault analysis covering installation.

(3) Installation information and/or photographs.

Par 1 Page 1

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2/21/75AC 90-45A Appendix n

(4) Any needed structural substantiation.

(5) Electrical schematics.

(6) Any needed flight manual revision or supplement, or placard dr a~vinp,s.

(7) Evidence of previously approved data.

c. What the Equipment Hanufacturer Can Do.

(1) Assist the STC applicant by supplyin e the data specified in Paragraphs l.a.(3) and l.b.(l).

(2) Perform the bench tests described in Appendix A, Paragraph 3.b.

and certify (to the applicant and FAA) that the accuracy criteria in Appendix A, Paragraph 2.a., are satisfie d.

2. APPROVAL OF TECHNICAL DATA BY FORH 337, Najor Repair and Alteration (Airframe, powerplant, propeller or appliance) Otffi 04-R060.1 (FOR USE UNDER INSTRUl'lliNT FLIGHT RULES).

a. Data Submitted by the Applicant. The following alteration data for the equipment installation will be submitted with a properly executed Form 337.

(1) Data to confirm that the requirements of Appendix A, Paragraph 2, have been met.

(2) Data to confirm that the requirer :ents of Appendix A, Paragraphs

3.h. and 3.c. have been met.

b. Additional Data Hhich Nay he Required. If required for FM Air­ t-rorthiness evaluation by the FAA District Office approvin~ the technical data, the applicant may also be required to furnish a copy of the equipment schematics, manufacturer's operatin g and installation instructions, fault analysis for installation, instal­ lation details and/or photographs, substantiation of structural changes, electrical schematics, and any appropriate proposed flight manual revision and/or placards.

c. Inspection of Aircraft. Hake the aircraft available for data conformity inspection.

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Appendix C APPENDIX C. SOURCES OF NAVIGATION SYSTEM ERROR

1. GENERAL. The establishment of relationships between navi~ation system accuracy and IFR aircraft separation criteria or route widths is a complex process. The first problem is t~ determine a reasonably achievable level of navigation systef'l accurac;r. '!'his Must be based not only on analysis of the measurable systeM error ele~ents for state-of­ the-art equipment but also on a series of intangibles iudped primarily on the basis of experience.

Current separation criteria~ based on such analysis an<"l experience, provide aircraft under IFR control a hirh degree of nrotectjon aRainst collision with other aircraft or obstructions. These criteria take into account the measured accuracies of the VOR/m'E p.round facilities and airborne equipment and iudgrnents as to hmv pilots actually fly their airplanes. Accumulatinr, evidence shoHS that VOP/DHF information, when used with area navi~ation computinp and display devices and presented properly to the pilot, offers the potential for an even ~ore efficient utilization of the airspace while Tflaintainin~ current standards of in­ flight safety.

2. CURRENT REtATIONSHIP BFT..JEFN NAVIGATJf)N ACCURACY AND ROUTF. 'f.!IDTP.. The system of airways and routes used in the Pnited States has 'lddths of route protection used on a VOR svstem use accuracy of± 4.5 degrees on a 95 percent probability basis. The± 4.5 degrees for VOR justifies the application of + 4 nautica1 mi.le route l-Tidth out to a distance of 51 NM from the facility and a l..ridening of route protection on the + 4. 5 degree basis beyond 51 miles.

3. CURRENT RELATIONSHIP BET't-.Tf,EN VERTICAL NAVIGATION ACCURACY Ai\lfl SEPARATI"N STk~DARDS. The system of ai~Jays used in the United States allow for altimetry systems errors and atmospheric errors of vari .ous amounts dependent on mode of flight and alti.tude of the flight operations.

Altimeter standards for accuracy (TSO C lOh) requires certain demonstra­ tions of accuracy over a wide ranp.e of conditions includinr. temperature.

vibration -and pressure. These accuracies combined with the expected chanp,es in atmospheric pressure over the distances used and pilotage factors do not exceed a value which would interfere with other IFR aircraft operatinr with 1000' vertical separation beloH FL 290 and with 2000' vertical separation above FL 290. These are the vertical separation standards currently used.

Efforts have been made to improve altimeter performance above FL 290 in order to permit application of 1000' vertical separation ahove, as well as below, this flight level. The accuracy requirements of the cu~rent altimeter standards are not stringent enough to meet this goal but the minimum accuracy requirements of Appendix A, Tables A and B are intended to support 1000 1 vertical separation at all flihht levels.

**4. SOURCES OF ERROR.**

a. Horizontal Errors. The basic assumption is that four sources of Page 1Par 1

### Page 30

Appendix C error - ground VOR and DME radiated stgnal, airborne VO'R receiver equipment, area navigation equipmen~ and pilotage - contribute independent errors of such distribution that they may be combined in RSS fashion. This i.s the normal assumption used traditionally by the FAA and is requjred hy the method recommended by ICAO Annex 10 for the determination of VOR system use accuracy (ICA0 Annex 10, Second F.dition, April 1968, Attachment C to Part I, Para~raph 3.6, VOR System Accuracy). All errors are hased on a 95 percent probability basis.

Errors from the four major sources listed above are actually com­ posite values includin g error contributions from various factors.

For example, "Errors in radiated signals" include propagation errors as well as errors in the transmitted signals arisin g from geographi­ cal siting and magnetic alignment of the ground station.

(1) "Airborne VOR equipment errors," in accordance with common practice include not only errors in the receiver outputs, but also errors contributed by the converter and the conventional course selector and deviation indicator. In those cases in which an area navigation system accepts inputs directly from the receiver, the error components normally included for the converter and indicator are not incurred and, therefore, the appropriate value for "ai.rborne VOR equipment error" can be correspondingly reduced. (NOTE: This factor is considered sub seque ntly as one type of error compensation that may be afforded by area navigation equipment.) The errors for DME rec eiver s to be used in conjunction with area navigation equipment, although small compared to the total system use error, are taken into account in Tables 1, 2, and 3, Appendix A.

(2) r:Area navigation equipment error" includes error components contributed by any input, output, or signal conversion equip­ ment used, by any computing element employed, by the display as it presents either aircraft po sit ion or guidan ce commands

(e.g., course deviation or command headin g) , and by any course definition entry devices employed. For sys tems in which charts are incorporated as integral parts of the display, the "area navi gation equipment error" necessaril y includes charting errors to the exte nt that they actually result in errors in controlling the position of the aircraft r e l ative to a desired path over the ground . To be consistent, in d1e case of symbolic displa ys not employing integral charts, any errors in waypoint definition directly attributabl e to errors in refer­ ence charts used in determining tvaypoint positions shou ld be included as a component of "area navig a tion equipment erro r."

This t ype of error is vir tua lly i mposs ible to handle and in general practice highly accu rate published waypoint locations are used to the greatest extent possible in settin g up such systems to avoid such errors (and to r educ e workload) .

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Appendix C

(3) The 'flight technical error' refers to the accuracy with which the pilot controls the aircraft as measured by his success in causing the indicated aircraft position to match the indicated command or desired position on the display. ~~ual insertion errors are due to the human interface with the control ana display units that affect the performance of an RNAV operation. The resulting error causes a deviation from the defined RNAV flight plan. These errors are usually recognized and corrected before developing in magnitude to a point where they may be considered blunders. However, "manual" errors also include undetected errors such as inaccuracies ~n track setting and in setting waypoint bearing information in some types of systems.

Blunder errors are gross errors in human judgment or attentive­ ness that cause the pilot to stray significantly from his area navigation flight plan, and are not included in the area navigation system error budget. Blunder tendency is, however, an important system design consideration.

Pilotage error will vary widely, depending on such factors as pilot experience, pilot workload, fatigue, and motivation.

Equipment design and ambient environment variables also affect pilotage directly and measurably, such as:

Processing of the basic display inputs (i.e., smoothing and quickening), whether or not heading is presented integrally with position and/or command guidance indications, display scale factors, numerous display configuration variables, aircraft control dynamics, air turbulence, and many more.

Strictly speaking, with autopilot coupling, "flight technical errorn becomes "autopilot error." These factors must be taken into account in arriving at empirical values for pilotage contribution to system use accuracy.

Evaluation of area navigation equipment to the present time indicates that the flight technical error, using such equipment, is linear in nature. A value of ±. 2.0 NM is typical for the enroute case and + 0.5 is typical for final approach operations.

ul'lanualu errors, however, are not linear in nature. Track setting error, for example, is angular, and its effect on cross-track error is a function of distance from the waypoi~t.

The term "pilotage error" in the RNAV equipment error bud2:et Appendix A includes ONLY the FLIGHT TECHNICAL ERROR element described above, and "manual"~ errors must be considered in the AIRBORNE EQUIPMENT ERROR BUDGET.

b. Vertical Errors. The sources of vertical error are listed in Appendix A, paragraph 2a(5)(c) Table B, of this advisory circular.

Par 4 Page 3

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Appendix C

5. COIUHi~l~G THE !!:RROR ELEHENTS. r.ased on the assumptions that the variable errors from the various sources are normally distributed and independent, they may be combined in RSS (root-sun-square:>) fashion. Thus, the standard deviations obtained from the various coutributing _sources may be combined geometrically rather than arithmetically by taking the square root of the sum of their squares:

d total = ~ d 12 + 0 2 2 ••• + 6 n2

b. ERROR BUL>GETING.

a. In optimizing a navigation system design, it is generally desirable to avoid having the error from one source much larger th~l those from the other sources since, by the RSS method of combination, it contributes disproportionately to the total error. However, it may be technically easier, cheaper, or operationally more desirable to reduce the error from one source rather than another in order to meet a total system use accuracy requirement.

b. In establishing an error budget, a system designer may trade off reduction in the errors from one or more sources against increases in the errors from others. Thus, in adding an area navigation computing ~d display capability to the basic VOR/L>HE system, it is necessary and possible to compensate for the errors introduced by the new equipment by means of reductions in errors from other sources. Any of the airborne error elements, including Fligltt Technical Error. may be traded provided th~ total system accuracy reflected in Appendix o. Tables 2, 3 and 4 are met.

(1) Assume that a comp~y sells an airborne VOR system designed to fly within a + 4 NH route width to a distance of 51 NH from a ground facility on the basis of the following error budget:

(2) Ground VOR Station 1rror +1.9°@ 51 NH = 1.7 NH cross-track error Airborne VOR Equipment hrror +3.0° (.'!51 NH = 2.7 NH cross-track error Ground mlli Error +D.l WI on radial = 0.0 Ntl cross-track error Pilotage Error +2 • 5° ~ 51 i'\1'1 = 2 • 2 NH cross-track error

(3) The error elements combine to make:

Total Error = + 1. 72 + 2.72 + 2.22v = + 3.8S Page 4 Par 5

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Appendix C

(4) In designing a new system containing area navigation devices contributing an error element of ±2 NM (equivalent to ±2.3° at 51 NMO, the system engineer finds that the total error of the new system would not satisfy the requirement of a ±4 NM route width at 51 NM range if the other error elements remained the same. However, he also finds that he can compensate for the added error component in two ways:

(a) By picking off signals directly from the VOR receiver and using a digital course selector in the RNAV equip­ ment the usual converter and indicator errors are not incurred so that the airborne VOR equipment error is reduced from 3° to 2° thus the cross-track error becomes ±1.8 NM.

(b) By employing a linear RNAV display which permits an assumed pilotage error of ±2.0 NM which is consistent with values shown in Appendix A, Paragraph 2.a. (4).

(5) The system engineer now recomputes the total system error on the basis of the following error budget:

Total Error = ± ~1.72 + 1.82 + 2.02 + 2.02 ± 3,76 NM at 51 NM from the facility (95% probability) The new system meets the design accuracy requirement with an increased margin of safety. In this example, the DME errors did not contribute to cross-track error. With track orienta­ tion other than along a radial, an increase in DME contribution will be offset by a decrease in VOR effect.

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Appendix D APPENDIX D. I NSTRUMENT FLIGHT PROCEDURES

1. GENERAL. This appendix contains obstacle clearance req uirements fo r RNAV instrument flight procedures. Section I provi des guidelines which are applicable to all RNAV proced ures. Sec tion II discusses the con­ cept of 3-D RNAV only. Obstacle clearance requirements will be incl uded in the U. S. Standard for Terminal Instrument Proce dur es (TERPs) .

a. Approval of RNAV procedures will be based on FAA capability to provide serv ice , anticipated volume of traff ic , and compatibility of the procedure with exi s ting airwa ys, routes, traffic and procedures.

b. All approved area navigation routings and procedures will be assured adequate signal coverage and frequenc y protection. Those approved for public use will be published in t he United States governmen t flight i nformation publication enroute and terminal cha rts, YAR's and/or Airman's Informati on Manual (AIM).

c. Pil ots should refer to AC 90-63, "Air Traffi c Control Procedures for Random Area Navigat ion Routes" t o insur e correct use of off­ airways route s.

d. RNAV routes whi ch require VOR/DME inputs will be provi~ed uninter­ rupted VOR/DME sign al r ecep tion as opposed to Victor a i n~ay s whi ch may incorporate signal gap areas.

e. RNAV waypoints will be identified by lat/long (nearest 1/10 min.)

and a radial and distance from the ground facility on which they are based. Additionally, geographical names (5 letter pronounce­ able words) will be assigned to waypoints if required for flight planning or ATC purposes . Along-Track Distance (ATD) fixes are normally used in lieu of a final approach waypoint when no lat e ral course change is required at that point. It is us~d to simplify pilot workload. MI. ATll fix may be used in lieu of a missed appr oach waypoint when the runway waypoint is NOT the NAP. Changeover points on RJ.~AV routes will be defined using distance from an established waypoint.

f. Terminal area routes are normally flown 'to' the waypoint, -and are compatible with 3-D concepts. However, simplified procedures designed for the minim um equipment 2-D system may be flown 'to' or 'from' the waypoints. Changeover points will not be used unless more than one facility is required to support the procedure.

g. RNAV route segments are numbered in a manner similar to VOR airways and jet routes. The suffix 'R' identifie s the route as an RNAV route. For example~ J 830 R indicates a hi gh a ltitude RNAV route while V 762 R indicates a low altitude RNAV route. RNAV standard Par 1 Page 1

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Appendix D Instrument Departures (SID) and Standard Terminal Arrival Routes (STAR) will be identified by the term RNAV immediately preceding the words "departure" and "arrival." For example: Brooks One RNAV Departure, Richards Three RNAV Arrival.

h. Terminal RNAV instrument procedures will be developed as requested by the users and required by the NAS. They may be of two types as follows:

(1) Simplified procedures will be developed at small airports, typically with less than 4000' runways, or in areas where air traffic problems are minimal. They will use at the most two waypoints and will be supplemented with ATD fixes. The runway threshold will be one of the waypoints. The other will provide transitions to the Final Approach course. They will be flyable with minimum equipment systems.

(2) Standard procedures will be developed in large terminals based upon air traffic requirements, and to the extent possible, the desires of the users. These procedures will use up to six or even ten waypoints in rapid succession. They will be flyable in aircraft with sufficient waypoint storage, but are expected to generate a high cockpit workload to the extent that they will be unflyable with minimum equipment.

i. RNAV instrument approach procedures will be identified as follows:

(1) Straight-in Approach. Procedures which meet criteria for authorization of straight-in landing minimums will be identified by the word RNAV and the runway to which the straight-in approach is made; for example, RNAV Rwy 21.

(2) Circling Approach. When a procedure does not meet criteria for straight-in landing minimums authorization, it will be identified alphabetically in sequence; for example: RNAV A, RNAV B, etc.

j. Units of Measurement. Units of measurement in RNAV procedures shall be expressed as follows:

(1) Radials and bearings in degrees magnetic.

(2) Altitudes in feet.

(3) Distances in nautical miles except visibility \vhich shall be expressed in statute miles and RVR which shall be expressed in feet.

Page 2 Par 1

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Appendix D

(4) Aircraft speeds in knots.

(5) Track angles shall be expressed in degrees.

Par 1 Page 3

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AC 90-4SA 2/21/75Appendix D

**SECTION I 2D RNAV CONSIDERATIONS**

2. ENROUTE CRITERIA. Enroute procedures shall be evaluated using existing flight inspection facility performance data, or by flight · inspection of the procedure when facility data is lacking.

a. RNAV Routes Protected Areas. The area to be protected is shown in Figure 1, the Area Navigation Route Width Summary, and is described as follows:

(1) Four miles each side of routes in ~.,hich the tangent point distance of the route cent~rline is within 102 miles of the ground station.

The route boundaries splay at 3.25° beginning at the point where the route centerline exits the eight-mile zone.

(2) When the tangent point distance is beyond the 102 mile limit, the minimum width of the protected area each side of the route at the tangent point distance is increased at the rate of 0.25 miles for each 10 miles increase in distance from the ground station.

The route boundaries splay 3.25° from this reinimum width at the tangent point distance.

(3) Parallel offset route s are not charted in flight information publications. When a pilot is cleared to fly a parallel off­ set route, he i s expec ted to fly it in precisely the same fashion as the parent route. Parallel offsets wi ll be used to separate overtakin g traffic and other simil a r appli cations.

Enroute, it will not always be possible to'develop a parallel offset route on both s ides of the parent route due to s ignal loss on the s ide of the parent route farthe s t from the reference station. When develop ing parallel offset routes consideration must be given to MOCA and MRA on both sides of the par ent route.

In the event that the MEA is higher than the par ent route, offset parallel operations will normally not be authorized on the side to which the higher MEA appli es .

(4) Enroute ver tical sepa ration will be provid ed as prescribed in Air Traf f ic Control procertures handbooks ~.,here c limb or descent is made us ing 3-D RNAV airborne equipment.

(5) When using re fere nce facilities not on the route the track angle must be computed relative to the r eferen ce facility being used. These tra ck angles may change when us ing different refe rence facilities due to meridian divergen ce /con ve rgence.

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AC 90-45A2/21/75 Appendix D

b. Obstacle Clearance Requirements. Obstacle clearance will be pro­ vided as described in Advisory Circular 95-1, paragraphs 4, 5, and 7, except that the primary obstacle clearance areas will be as specified in paragraphs 2.a.(l) and 2.a.(2) above.

(1) Secondary obstacle clearance areas extend laterally 2 miles on each side of the primary area and splay at 4.9° where the primary area splays at 3.25° .

(2) Obstacle clearance areas are expanded as specified in para­ graph 3.c of AC 95-1 and as illustrated in Figure 3 to accommodate turns of more than 15 degrees .

c. Enroute Waypoint Displacement Area . The enroute waypoint displace­ ment area is a rectangular or square area formed around the plotted position of the waypoint. The dimensions of this area are derived from the appropriate along-track and cross-track error values. See Table 2, Appendix D. The enroute waypoint displacement area shall be considered for each waypoint when developing RNAV enroute procedures.

3• TERMINAL CRITERIA. Terminal routes provide access to the enroute structure for aircraft departing an airport and routing to enter an instrument approach procedure for arriving aircraft. Parallel offset terminal routes will be used where practical for spacing and to separate overtaking aircraft. Terminal routes shall be evaluated by flight inspection concurrently with associated instrument approach and departure procedures.

Terminal arrival routes will be designed for efficient traffic flow to the final approach aid - normally ILS. To the extent possible the altitudes specified on the arrival routes will provide for a 300' per mile rate of descent from the enroute environment to the runway or the point where the final approach aid is intercepted. To facilitate the transition and to standardize the terminal route structure, the last waypoint on the arrival route will be established approximately 8 miles from the runway at the intermediate fix. The altitude at the eight mile waypoint should agree with the glide slope or provide an approximate 300'/mile gradient to the runway as appropriate to the type of final approach utilized.

Terminal departure routes will be designed from the departure end of the runway to the enroute structure. The first waypoint will be shown at the departure end of the runway. Immediate turns at the end of the runway are discouraged. Insofar as possible from the standpoint of airspace management the second waypoint will be established on the runway centerline extended.

Par 2 Page 5

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r* x

### Page 40

Appendix D 'o, ',' ~__...,=-o~iiiiil-o- ;

, ," ;

;

' ' o' ' I ' I I I I '1­ I I I I FIGURE 2. TYPICAL RNAV ARRIVAL AND DEPARTURE ROUTE CONFIGURATION ... ... ....

' ' ' ... ... ....

' ...

'I ~ I '0·------ ---<l ' I I I 7 I 0·-.------- 0 " ' Par 3 Page 7

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AC 90-45A CHG 2 Appendix D 7/22/76 * FIX AREAS DETERMINED BY CROSS-TRACK AND ALONG-TRACK ERRORS AREA EXPANDED lAW AC 95-1 ABOVE 10,000 \ \ ··-­ /

- ,--­,, I ( ,'~--~====~~---------------------------------- / / {\' / ,,,,,, ,,, , ,,,, \ - 70 NM I ~ @Expansion for 11 Corner cutter" begins at a distance prior to the earliest point the waypoint can be received:

3 NM below 8000' - 7 NM 8000-18000' - 12 NM above FL 180.

@ Angle of splay for expanding area is 1/2 the amount of the course change.

FIX AREAS DETERMINED BY CROSS-TRACK AND ALONG-TRACK ERRORS FIGURE 3. TYPICAL TURNING AREAS ..---20NM ~ 20 NM I A

TERMINAL TURNING * AREA\ • ..

Page 8 Par 3.

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Appendix D

a. RNAV Routes Protected Areas. The area to be protected is as in Figure 1 and is described as follows:

shown

(1) Primary obstacle clearance areas extend laterally two miles each side of routes in which the tangent point distance of the route centerline is within 53 miles of the ground station. The 0route boundaries splay 3.25 beginning at the point where the route centerline exits the four-mile zone. *

(2) Secondary obstacle clearance areas extend laterally 1 mile each 0 side of the primary area and splay 4.9 where the primary area splays at 3.25°. *

(3) Obstacle clearance areas are expanded as specified in paragraph

3.e in AC 95-1 and as illustrated in Figure 3 to accommodate turns of more than 15 degrees.

(4) Paragraphs 2.a(3) and 2.b(2) above which concern parallel off­ sets and turning areas also apply.

b. Obstacle Clearance Requirements. Obstacle clearance will be pr o­ vided as described in FAA Handbook 8260.3A (TERPS), paragraph 232.c.

c. Terminal Waypoint Displacement Area. The terminal waypoint displace­ ment area is a rectangular or square area formed around the plot t ed position of the waypoint. The dimensions of this area are derived from the appropriate along-track and cross-track error values. See Table 3, Appendix D. The terminal waypoint displacement err or sha l l be considered for each waypoint when used in RNAV departures and arrivals, including initial and intermediate approach waypoints.

d. Holding Pattern Area Determination. The holding pattern is a race­ track pattern flown at a waypoint or an ATD fix and at an lAS appropriate to the aircraft and altitude. The holding lAS for heli­ copters is 90 knots. The RNAV holding area will have the outbound leg length specified in nautical miles. Minimum leg length for helicopters is 2 NM. Determination of required area is made using Table 2 or Table 3, Appendix D, appropriate lAS, an omnidirectiona l wind of 50 knots increasing 3 knots per 2000' above 4000 AGL, pattern entry direction, ICAO standard atmosphere plus 15°C and fix passage tolerance of 5 seconds . Turning radii are based on a standard rate 0turn or a 25 angle of bank whichever is less . The following example is for helicopters holding at a sea level terminal area, but the method applies to all aircraft by using the appropriate lAS, alti­ tude, and table for the mode of flight; i . e., enroute (Tabl e 2) or terminal (Table 3) . * Par 3 Page 8-1

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Appendix D * Example: lAS = 90 KTS ATD = 30 NM Alt = 6000' MSL &AGL TPD =30 NM OAT = 3° + 15° = l8°C xwind = 50 + 3 = 53 KTS From Table 3, Appendix D; cross-track error {x trk) = 2.4 NM, along­ track error (alg trk) = 2.2 NM.

(1) The cross-track area is determined as follows.

(a) Holding side. The area on the holding side is determined by the cross-track navigation system errors, the effect of wind and the area required for a standard rate turn (max 25°) from entries along-track or the reciprocal and including all directions from the nonholding side.

The contribution due to winds will be ,88 NM during the 180° turn outbound (assume crosswind for worst case).

The cross-track error value and the wind contribution are root-sum-squared, yielding :

RSS =V2.42 + .ss2 =2.55 NM The angle of bank at 90 KTS {95 KTS, TAS) for a standard rate turn is determined by the following:

tan~~ .00275V, V = KTS, TAS .00275(95) = .26125 then ~ = 14.64° = 15° The turning radius (r) at TAS = 95 KTS and bank angle (~) of 15° is determined by the following:

5 21.4589 x 10- v h r = tan 0 , w ere V KTS, TAS

1.4589 X 10-5 (95) 2 r = .2679 r = .49 NM The cross-track contribution due to the turn is:

2r = .98 NM.

Hence, the total cross-track displacement on the HOLDING side is:

cross-track RSS + 2r: 2.55 + .98 =3.53 NM. * Page 8 .. 2 Par 3

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AC 90-45A CHG 27/22/76 Appendix D * (b) Nonholding side. The cross-track displacement on the NONHOLDING side is either one-half of the route width at the ATD fix, as discussed below, or the area required to make an entry from the holding side , whicheve~ is greater.

One-half of the route width in the termin~ area (50 NM or less) is 2:0 NM. In the enroute area (more than 50 NM but less than 102 ~ one-half of the route width is 4 NM. At distances greater than 102 NM, one-half of the route is 4 NM plus a 3.25° splay. (See Figure 1). For parallel entry at the 70° sector line (worst case), cross-track dis­ placement is determined as follows (see Figure 3-l):

r· I I I I I I I I D - L F c D E M

PRIMARY AREA -­ -­I I EXPAN DED PRIMAR Y AREA.__ -­ - -- ­ - -­ FIGURE 3-l. HOLDING AREA DETERMI NA T1 ON A - DME leg distance H - Fix passage tolerance (sin Q) B - Turn radius I - Nonholding side entry RSS c - Fix passage tolerance J - Turn radiu s (1 + cos Q) D - Direct entry RSS K - Fix passage tolerance (cos Q) E - 2(Turn radius) L - Holding side entry RSS F - Cross-track RSS M - 1/2 Route width G - Turn radiu s (l + sin Q) * Par 3 Page 8-3

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Appendix D * The wind contribution during the 110° turn to parallel the outbound is .54 NM.

When RSS'd with the cross-track error:

2RSS = "(2.4) 2 + (.54) = 2.46 NM The turn contribution is r(l +sin Q): {here Q = 20°) .49(1.3420) = .66 NM The fix passage tolerance is:

(5 sees @ 95 KTAS)sin 20° ~ .05 NM The cross-track displacement on the NONHOLDING side is then:

parallel ent~ RSS + r(l + sin Q) + fix passage tolerance {sin Q):

2.46 + .66 + .05 = 3.17 NM Since this exceeds 2.0 NM half route width, it is the width to be protected.

{2) The along-track area for a direct (or reciprocal) entry or an ent9' from the nonholdina side is determined as follows.

The contribution due to winds during the 180° turn outbound is .44 NM (assume direct entry and tailwind for worst case).

When RSS'd with the along-track error;

RSS = 4/(2.2) 2 + (.44) 2 = 2.24 NM fix passage tolerance (5 sees) @ 95 KTAS = .13 NM.

The total along-track displacement is:

2 (nonholding side entry RSS) + 2(r) + 2 fix passage tolerance + DME leg 2(2.24) + 2(.49) + 2(.13) + 2 = 7.72 NM * Page 8-4 Par 3

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{3) The along-track error for an entry from the holding side (70°* sector line for worst case) will elongate the entry end and is determined as follows.

The wind contribution during the 160° turn to fly the pattern is . 79 NM.

When RSS'd with the along-track error:

2RSS = 1/{2.2) 2 + {.79) = 2.33 NM The turn contribution is r(l +cos 9): (here 9 = 20°) .49{1 . 9397) = .95 NM The fix passage tolerance ~s :

(5 sees@ 95 KTAS)cos 20° = . 12 NM The total along-track displacement is the sum of the entry , leg distance and inbound turn displacements:

holding side entry RSS + r{l + cos Q) + fix passage tolerance {cos 9) + DME leg+ direct entry RSS + r + fix passage tolerance:

2.33 + . 95 + .12 + 2.0 + 2.24 + .49 + .13 = 8.26 NM A secondary area of one-half of the cross-track error or 2 NM, whichever is greate r , is added to the perimeter of the pattern for obstacle clearance . *

4. INSTRUMENT APPROACH PROCEDURE CRITERIA. FAA Handbook 8260 . 3A, The United States Standard for Terminal Instrument Procedures (TERPS), prescribes criteria for the design of instrument approach procedur es.

Although it does not at the present time contain speci a l criteria for the design of RNAV procedures , most of the TERPS criteria are applicable to RNAV procedures with minor modifications. This appendix will therefore provide only the criteria necessary to modify TERPS for RNAV procedure application . In applying TERPS to RNAV procedures , the term "fix" is equivalent to "waypoint," thus, "Final Approach Fix (FAF)" becomes "Final Approach Waypoint (FAWP)."

a. Procedures Construction . An RNAV instrument approach procedure may have four separate segments. They are the initial, the inter­ mediate, the final and the missed approach segments . In addition , an area for circling the airport under visual cond i tions shall be considered. The approach segments begin and end at waypoi nts or Par 3 Page 9

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Appendix D along-track distance (ATD) fixes which are identified to coincide with the associated segment. For example, the intermediate segment begins at the intermediate waypoint (INWP) and ends at the Final Approach Waypoint (FAWP) or ATD fix.

(1) Descent Gradients. TERPS descent gradients will apply to all RNAV procedures except where an uninterrupted descent gradient of 300 feet per mile (+20', -50') can be established from the initial approach through the final approach. It shall be done to provide stabilized descent throughout the arrival procedures.

(2) Runway Waypoint and Flight Path Angle. Both standard and* simplified procedures should incorporate a waypoint at the runway threshold. This waypoint will be used as the point from which the Flight Path Angle is computed. On ILS runways, the Flight Path Angle shall be computed using the runway waypoint elevation equal to the ILS threshold crossing height . Where no ILS glide path is present, the Flight Path Angle shall be com­ puted from the runway waypoint elevation 50 feet higher than the runway threshold elevation for runways 4,000 feet and longer.

It may be established as low as 37 feet for runways less than 4,000 feet in length. The procedure shall specify the runway waypoint elevation under additional flight data. Example: Rwy W/P elevation 1827'. *

b. Transition Routes. When transition routes are required from the en route structure to the initial approach waypoint, they should be designed to coincide with the local air traffic flow. En route RNAV obstacle clearance criteria (paragraph Z.b. above) shall apply to transition routes in which the tangent point distance (TPD) of the route centerline is more than 53 miles from the ground station. When the TPD is within 53 miles of the ground station, RNAV terminal route obstacle clearance criteria (paragraph 3.b. above) shall apply.

c. Initial Approach Segment. The RNAV instrument approach procedure commences at the Initial Approach Waypoint (IAWP). In the initial approach, the aircraft has departed the en route phase of flight and is maneuvering to enter the intermediate segment. Standard RNAV procedures -- as opposed to simplified procedures -- may utilize several initial approach segments to accommodate the traffic flow requirements. En route RNAV obstacle clearance criteria (paragraph

2.b. above) shall apply to initial approaches in which the TPD of the initial approach course is more than 53 miles from the ground sta­ tion. When the TPD is within 53 miles of the ground station, RNAV terminal route obstacle clearance criteria (paragraph 3.b. above) shall apply.

(1) Initial approach segments based on a procedure turn shall not be established. Where course reversal is required, a holding pattern shall be established in lieu of a procedure turn.

Standard holding pattern obstacle clearance shall apply.

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Appendix D

d. Intermediate Approach Segment. The purpose of the intermediate segment is to blend the initial approach into the final approach and provide an area in which aircraft configuration, speed and positioning adjustments are made for entry into the f~nal approach segment. The intermediate segment begins at the Intermediate Waypoint (INWP) and ends at the FAWP or ATD fix.

(1) Alignment. The course to be flown in the intermediate segment should be the same as the final approach course whenever possible. When it is not practical for the courses to be identical, the intermediate course may not differ from the final approach course by more'than 60 degrees.

(2) Distance from runway. For Standard procedures the intermediate waypcint shall be established approximately 8 miles from the runway. For the Simplified procedure the intermediate fix will be established as necessary to accommodate a procedure which utilizes only two waypoints. See paragraph l.h.

(3) Length. The minimum length is 3 miles with standard procedures.

e. Final Approach Segment. This is the segment in which alignment and final descent for landing are accomplished. The final approach segment begins at the final approach waypoint or Along-Track Distance (ATD) fix and ends at the missed approach point, normally the runway threshold waypoint. When it is not at the runway threshold, it is an ATD fix based on a distance to the runway waypoint. Final approach may be made to a runway for straight-in landing, or to an airport for a circling approach. Only one final approach shall be specified for a procedure.

(1) Alignment. ~Tienever possible, the final approach course shall be aligned with the straight-in landing runway. When the alignment exceeds 15°, straight-in minimums are not authorized.

(2) Final Approach Area. The area considered for obstacle clearance starts at the earliest point the Final Approach Waypoint (FAWP) or ATD fix can be received and ends at the latest point the Missed Approach Waypoint (MAWP) can be received or at the runway threshold whi.chever occurs last. See Table 4, Appendix D, for fix errors. When the final approach course is a continuation of the intermediate course, an ATD fix shall be used instead of a FAWP. Additional ATD fixes may be established as step-down fixes.

(a) Length. The OPTIMUM length of the final approach segment is 5 miles. The MAXIMUM length is 10 miles. The MINIMUM length of the final approach segment shall provide adequate distance for an aircraft to make the required descent, and Par 4 Page 11

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AC 90-45A CHG Appendix D 2 7/22/76 td regain course alignment when a turn is required over the final approach waypoint. Table 1, Appendix D, shall be used to determine the minimum length needed to regain the course.

! MINIMUM LENGTH OF THE FINAL APPROACH SEGMENT (MILES) APPROACH Magnitude of turn over the Final Approach Waypoint (FAWP)CATEGORY 10° 20° 30u 40u sou 60u A 1.0 1.5 2.0 3.0 4.0 5.0 B 1.5 2.0 2.5 3.5 4.5 5.5 c 2.0 2.5 3.0 4.0 5 . 0 6.0 ! D 2.5 3.0 3.5 4.5 5.5 6.5 Table 1

(b) Width. The final approach primary area is centered longi­ tudinally on the final approach course. The primary area is t 2 miles wide either side of the final approach course at the final approach fix. It narrows to the width of the fix displacement area at the runway threshold. See Table 4, Appendix D. A secondary area one mile in width is established on each side of the primary area . Figure 4 illustrates a typical final approach area.

* FIX DISPlACEMENT AREAS * Page 12 Par 4 SECONDAoy -­ -" AREA I ±2 Ml PRIMARY AREA AT FAF FIGURE 4. TYPICAL INTERMEDIATE/FINAL AREAS

### Page 50

**TERMINAL OR**

ENROUTE AREA 15• SPlAY 7/22/76 AC 90-45A CHG 2 Appendix D

(c) Obstacle Clearance. The minimum obstacle clearance in the primary area is 250 feet. In the secondary area the full obstacle clearance of the adjacent primary area is provided at the inner edge, tapering uniformly to zero at the outer edge of the secondary area.

f. Missed Approach Segment. A missed approach procedure shall be establisHed for each instrument approach procedure. The missed approach shall be initiated no later than the runway threshold waypoint. The missed approach should be simple and shall specify an altitude and a clearance limit. The missed approach altitude specified in the procedure shall be sufficient to permit holding or enroute flight.

(1) Straight Missed Approach Area. The straight missed approach area may be used when the missed approach track does not differ more than 15 degrees from the final approach track.

The area starts at the plotted position of the missed approach waypoint and has the same width as the final approach primary and secondary areas at the MAWP. The primary missed approach area splays at 15 degrees each side of the missed approach track until it reaches the width of the appropriate terminal or* enroute obstacle clearance area. The secondary areas expand uniformly from one mile to the width of the appropriate enroute secondary areas. See Figure .5.

Fl NAL APPROACH AREA

MISSED APPROACH POINT FIGURE 5. STRAIGHT MISSED APPROACH AREA * Par 4 Page 13

### Page 51

AC 90-45A CHG 2 7/22/76Appendix D

(2) Straight Missed Approach Obstacle Clearance. Within the primary missed approach area no obstacle may penetrate the 40:1 missed approach surface. This surface begins at the plotted position of the MAWP when the along-track _error at the MAWP is one mile or less. When the along-track error (Table 4, Appendi x D) at the MAWP exceeds one mile, the surface begins at a distance past the plotted position of the MAWP equal to the amount of along-track error in excess of one mile. The missed approach surface beginning height is determined by subtracting the required final approach obstacle clearance from the minimum descent altitude. In the secondary area, no obstacle may penetrate a 12:1 slope which extends upward and outward from the 40:1 surface at the inner boundaries of the secondary area. See Figure 5.

* NOTE: Helicopter procedures use a 20:1 missed approach surface with 4:1 slopes in the secondary areas.

(Ref. TERPS 1119 & 1120)

(3) Turning Missed Approach. The turning missed approach will be as prescribed in FAA Handbook 8260.3A (TERPS) except that * the starting point for the 40:1 obstacle clearance surface will be prescribed in the preceding paragraph (4.£.(2)).

g. Approach Minimums. Published civil RNAV approach minimums shall meet the criteria for nonprecision approach systems as specified in FAA Handbook 8260.3A (TERrS) . Table 6 criteria which relates* * minimum visibility t o distance from station shall be applied as a variation of cross-track displacement area (Table 4, Appendix D) as follows :

Cross-track area 0.6 - 0.8 NM use Column 0-10 II II II II II

0.9 - 1.0 NM 10-15 II II II It It

1.1 - 1.2 NM 15-20 II II II ItII. 1.3 - 1.6 NM 20-25 II II II II II Over 1.6 NM Over 25

h. Approach Waypoint Displacement Area. The approach waypoint displacement area is a rectangular or square area formed around the plotted position of the waypoint. The dimensions of the area are derived from the appropriate along-track and cross-track error values. See Table 4, Appendix D. The approach waypoint * displacement area shall be considered for each waypoint used in developing RNAV final approach procedures including the FAWP, MAWP, and any stepdOWn WP or ATD fixes used on final. * Page 14 Par 4

### Page 52

ENROUTE AREA FIX DISPLACEMENT ERROR (95% Probability)

DISTANCE ALONG TRACK FROM TANGENT POINT 0 10 20 30 40 so 60 70 80 90 100 110 120 130 140 uo 20 0 O(x trlr.)

(a1g trlr.)

2.~

l.)

2. 5

1.)

2.5 I':>

2.8

1...1

3.2 1 • ) ).7

1.6

4. 2

1.9

4. 8 2 . 2

5.4

2.)

5 . 9

2.8

6. 5 3 .0 7 . 1 j,)

7. 7

3.6

8.)

3.9

8.9 4,2 9 . 5

4.5 12 . 6 6, 0 lO(x trk) (alii trk)

2.~

l. J

2. 5

1. 5

2. 5

l.J

2.8 1 • "

3. 3

l.S

3.7

1.7

4.)

2.0

4.8

2. 3

s. 4 2 . 6 &.0

2.9

6.6

3. 1

7.1

3.4

7. 7

3.7

8.3

4.0 8 .9 4 .3

9.~

4.6

12.6

6.1 20(x t"rk) (alg trk) JO(x trk) (alg trk)

2.5

l.j

2. 5

1.9

z. .5

1. )

2.5

2.0

2. 5

1.5

2.6

2.1

2.9

1.7 ).0

2. 2

3. 3

1.9

3.4

2. 3 ).6

2.1

3.9

2. 5

4.)

2. 3

14.41 ~

4.9

2. 6

4. 9

2.9

5.4

2. 8

5.5

3.2

6.0

3. 1 6 , 1

3.4

6.6

3.4

6.6

3. 7

7. 2

3. 6

7.2

3.9

7.8 ).9

7.8

4. 2

8.4 4,2 8,4

4. 5

9.0

4. 5

9.0

4.7 9 . 6

4.8

9.6 s.o

12.6 6,2

12.6

6.4 ~ "" 0 > 0 I­ I- z 0

0..

..... z...

0 z :!.

~ 0 """­ LU v z :!.

Vl · a 40(x trk) (alg trk) ~O(x trk) (alg trk.)

60(x trk.)

(al& trk.)

70(x trk.)

(alg trk) 80(x trk) (alg tr lr.)

90(• trlr.)

(ah trk.)

100(" trk) (alii trk) llO(x trk) (alg trk) 120(x trk) (alg trk) lJO(x trk) (all! trk)

2. 5

2.5

2.6

3.1

2. 1 3 . 7

2.9 4 .4 3 . 2 5 . 0

3.4

5.6

3.6

6.2

3.11

6.8

4.2

7. 4 4,4

8. 1

2.5

2.6

2.6

3.2 2 , ·8 3 . 8

3.0

4.4 ).)

5.0 3 .5 ~.6

3.7

6.2

4.0

6.9

4. 2

7.5

4.5

8. 1

2. 7

2. 6

2.9 3,2

3.1

3.8

3.2

4.4 3 .5

5.1 3 . 1 5 . 7

3.9

6.3 4 . 2 {>.9

4.4

7.5 4 . 7 8 .1

3. 1

2. 7

3. 2 3 ,)

3.4

3.9 3 . 6 4 .5

3.8

5. 1

4.0

5.7

4.2 6 . ) 4 . 4

6. 9

4. 6

7.6

4.9 8,2

3. 5 2,9

3.6

3.4

3.8 4,0

3.9

4. 6

4. 1

5.2 4 , 3

5.8 4,!)

6.4

4. 7

7. 0

5.0

7. 6

5. 2

8. 2

4.0 3,0 4 .1

3.6

4.2

4. 1 4,4

4.7

4. 5 ~-3

4. 1

5.9

4. 9 6,)

5. 1

7. 1

s. 3 7 • 7

5. 5

8. 3

4. 5

3. 2

4.6

3.7

4. 7

4. 3

4.8

4.8

5. 0 5 .4 5 .2 6,0

5.)

6.6

5. 5

7. 2

s. 7

7. 8

5.9

8.4

5.0

3.4

5.1

3.9

5. 2

4.4

5.4 5 .0

5. 5 5 .5

5.6 6 .l

5.8

6. 7

6.0

7. 3

6. 2

7. 9

6.4

8. s 5 .6

3. 6 ~. 7

4.1

5.8 4 . 6 5 . 9

5. 1

6.0

s. 1

6. 2

6. 2

6. 3

6.8

6. s 7 . 4

6. 6 8 .0

6. 8

8. 6 6 . 1

3.8

6.2

4. 3 6 .l

4.8

6.4

5. 3 6,5

5.8

6. 1

6.4

6.8

6.9

7. 0

7. 5

7. l

8. 1

7. 3

8. 7

6.7

4. 0

6.8

4. 5

6.9 5 . 0

7.0

5. 5 1 • 1

6.0

7.2

6. 5

7.4

7.1 7 . 5

7. 6

7.6

8. 2

7. 8

8.6

7.3

4.3

7.4

4.7

7.4 ~.2

1.5

5.6 7 .7

6.2

7.8

6. 7

7.9

1.2

8.0

7.8

8. 2

8. 3

8. 3

8.9

7. 9

4.~

7.9

4.9

8.0 ~-4

8.1 5 . 8

8. 2 6 . )

8.)

6.8

8.4

7.4 8,6

7.9

8. 7

8.5 8,9 9,0 8,5

4.8

8.~

5.2 8 . 6

5.6

8. 7

6.0

8.8

6.~

8.9

7. 0

9.0

7. 5

9. 1 8.1

9.3

8.6

9.4

9.2

9.1

5.0

9. 1

5.4

9.2

5.8

9.3

6.3 9 .4

6. 7 9 .5

7.2 9,6

7. 7

9. 7

8.2 9,8

8.8

10.0

9.3

9. 7

5.3

9. 7

5. 1

9.8

6.0

9.9 6 . 5 10 .0

6.9 10 . 1

7.4 10 . 2

7. 9

10.3 8 .4 10 . 4

9.0 10 . 5

9.~

12. 7

6. 7

12. 7

7.0 12 .8

7. 3

12.9 1 . 7

12.9 8 , 0 ll.O

8.5

13.1 8 . 9

13.2 9.4

13.3

9. 9

13.4

10./j 140(x trk.)

(alg trk)

4. 7

8. 1

4.8

8.7

4. 9

8. 1 5 . 1

8.8

5.4

8.8

5.8

8.9

6. l

9.0

6.6

9. 1 7 . 0

9. 2 7 .5

9. )

8.0

9.4

8.5

9.5

9.0

9.6

9.5

9.7

10.1

9.9

10.6 10 . 0 1 3.5

10.9 UO(x trk) (alg trk) 5,0

9.3 5 ,0

9. 3 5 . 2

9.4 5 . 4

9.4

5. 7

9. s

6.0

9. 5

6.4

9.6

6.8

9. 7 7 • 2

9.8

7. 7 9 . 9 8,2 10 .0

8.7 10,1

9.2

10.2

9.7

10.3

10.2 10 .5

10.8 10 .6 13 .6 11 .4 ER ROR £LEMENTS ..... z w 0 z TO FIND THE CROSS TRACK AND ALONG TRAC K .

**ERROR AT THIS POIN T 1 ENTER TABLE WITH TANGENT**

DISTANCE AND DISTANCE ALONG TRACK FROM TANGEN T POINT, i.e ., when the distance to TP ~ 30 and the along track distance ~ 60, the X track error isl4 .4 NM and th e along track error ist2 .7 NM.

GROUND VOR Dh\~ AI R!\0~: 1( VOR OME

RNAV SYSITM PI LOr I. <fl

0.1 NM

3.rf 3:.or 0.5 r-;M

0. S NM ~ CROSS·TRA CK 2. 0 DISTANCE ALONG TRACK TABLE 2 ALONG· TRA CK ZERO

### Page 53

Appendix D TERMINAL AREA FIX DIS PLACEMENT ERROR (95% PROBAB I lilY) *

DISTANCE ALONG TRACK FROM TANGENT POINT 0 10 20 30 40 50 60 70 80 90 100 O(x trk) 1.5 1.5 1.7 2.2 2.7 3.3 3.9 4.5 5.1 5.7 6.3 (alg trk) 1.1 1.1 1.1 1.1 1.3 1.6 1.9 2.2 2 5 2.8 3.0 ~ 10 (~ trk) 1.:. l.!J 1.7 2.2 2.8 3.3 3.9 4.5 5.1 5.7 6.3 t- 1.1 1.1 0: (a1g tri.) 1.1 1.2 1.5 1,7 2.0 2.3 2.6 2.9 3,1 0 > 20(x trk.) 1,) 1.5 1.8 2.3 2.8 3.4 4.0 4.6 5.2 5.8 6.4 (alg trk) 1.3 1.4 1.5 1.7 1.9 2.1 2.3 2. 6. 2.8 3.1 3.4 0 t­ 30 (x trk) l.i 1.6 1.9 2.4 2.9 3.5 4.6 5.2 5.8 6,4tz (alg trk) 1.9 2.0 2.1 2,2 2.3 2.5 []7 2.9 3.2 3.4 3.7 5 0.. 40(x trk) 1.6 1.8 2.1 2.5 3.0 3.6 4.1 4.7 5.3 5,9 6.5 (alg trk) 2.5 2.6 2.6 2.7 2.9 3.0 3.2 3.4 3.6 3.8 4,0tz LU 50 (x trk) 1.9 2.0 2.3 2. 7 3.2 3.7 4.2 4,8 5.4 6.0 6.6 (alg trk) 3.1 3.2 3,2 3,3 3.4 3.6 3.7 3.9 4.1 4.3 4.5 <-'z ~ ~ 0 ..:: u..

LU u z ~ "" Q TO FIND THE CROSS TRACK AND ALONG TRACK ERROR ElEMENTS

ERROR AT THIS POINT, ENTER TABLE WITH TANGENT GROUND VOR 1.9'1DISTANCE AND DISTANCE ALONG TRACK FROM DME 0.1 NM TANGENT POINT, i.e., when the distance to TP = AIR80RNE VOR 3.rfJ30 and the along track distance = 60, the X track DME ~arO.~NM .... error ist4.0 NM and the along track error ist2.7 NM • RNAV SYSlEM 0.~ NMz PILOT CROSS·TRACK 1.0 LU AlONC·TRAC~ ZERO ~~=========================~==~======

DISTANCE ALONG TRACK TABLE 3 Terminal waypoint displacement errors apply to waypoints used in arrival and departure procedures i ncl udi ng Initial and Intermediate approach waypoints.

(para 3c) * Page 16 Par 4

### Page 54

Appendix D * FINAL AREA FIX 0 ISPLACEMENT ERROR (95% PROBABILITY)

DISTANCE ALONG TRACK FROM TANGENT POINT 0 5 10 15 20 25 30..... z O(x trk) • 8 .9 1.2 1.4 1.7 2.00 (alg trk) • 7 • 7 • 7 • 8 .9 1.0a.

1- 5(x t rk) . • 9 .9 1.2 1.4 1.7 2.0z w (alg trk) .6 • 7 8 .s • 9 1.0 1.1 C) t] z lO(x trk) .9 .9 1.0 1.2 1.5 1.7 (alg t rk) • 8 • 8 .9 • 9 1.0 1.1 ~ ~ 0:: lS(x trk) • 9 • 9 1.1 1.3 1.5 1.80~ (a1g trk) 1.1 1.1 1.1 1.2 1.2 1.3 0:: > u.

0 20 (x trk) • 9 1.0 1.1 1.3 1.6 w 1- (a1g trk) 1.3 1.4 1.4 1.4 1.5 u z 25(x trk) 1.0 1.1 1.2 1.4~ V) (alg trk) 1.6 1.6 1.7 1.7 0 30(x trk) 1.2 1.2 (a1g trk.) 1.9 1.9 TO FIND THE CROSS TRACK AND ALONG TRACK ERROR ELEA'tNTS

ERROR AT THIS POINT, ENTER TABLE WITH TANGENT GROUNO DISTANCE AND DISTANCE ALONG TRACK FROM VOR t.tfJ OM£ 0.1 NM TANGENT POINT, i.e., when the distance to TP = AIRBORN£ VOR 3.rf5 and the along trac;.k distance = 10, the X track DME ):f. or 0.5 NM error is'fl. 0 NM and the along track error is!.8 NM . RNAV SYSlrM 0. 5 NM..... z PILOT w CROSS-TRACK 0.5

ALONG-TRACK ZERO ~ ===========================~==:3~=

DISTANCE ALONG TRACK TABLE 4 Final waypoint displacement errors apply to the waypoints used in the Final approach segment. (para 4h) * Par 4 Page 17 (and 18)

### Page 55

Appendix D

**SECTION II 3D RNAV CONSIDF.FATIONS**

5. BACKGROUND. Adding a third dimension of vertical guidance to the two dimensional RNAV system can achieve significant operational advantages.

Briefly, a 3D RNAV capability permits altitude ch<mge bv fo1lot,7ing vertical routes (tubes) of known dimensions thus vertical ~uidance is available for stabilized descent in instrument app~oach procedures using computed glide path information. In soMe cases, the computed glide path can make it possible to safely eliminate ohstacles from consideration. This section discusses the operational prohlems and capabilities of 3D RNAV and provides criteria for vertical instrument flight procedures.

a. Level Flight RNAV Longitudinal and Vertical Errors.

(1) In level flight, the . plus or mfnus vertical position .error is due to altimetry and flight technical errors. Current standards for aircraft separation and obstacle clearance allow for these errors, and in addition, provide an allowance for atmospheric anomalies.

D

BASIC CONCEPT FIGURE 6. LEVEL FLIGHT VERTICAL ERROR Par 5 Page 19

### Page 56

2/21/75AC 90-45A Appendix D

(2) Also, in level flight the combination of ground station, airborne equipment, and computer errors produce a plus-or-minus longitudinal position error called along-track error. No flight technical error is involved.

HORIZONTAl PROBABiliTY FIGURE 7 . ALONG-TRACK ERROR

(3) Thus, providing airsp a ce for aircraft in level flight using RNAV is simply a matter of containing the plus-or-minus vertical and longitudinal position errors as the air craft progresses along the intended flight path.

VERTICAL·HORIZONTAL PROBABiliTY ----- ----- ------- --- - - - ~-- - - --------- ------ - -

• =- ~......~ !3 ---------------- - -- -- -- ~--------- - ----------- - FIGURE 8 . AIRSPACE IN LEVEL FLIGHT Page 20 Par 5

### Page 57

---- Appendix D

b. Vertical Flight RNAV Errors. To provide vertical guidance during ascent or descent, the 3D RNAV equipment compares the indicated altitude with the desired altitude and presents th~ computer correction instrumentally; typically in the form offly up/fly down cross pointer information. The computation and comparison process produces vertical position errors which are additional to those affecting the aircraft in level flight.

ADDITIONAL VERTICAL CONTRIBUTION USING VNAV FIGURE 9. ADDITIONAL ERROR ALLOWANCE FOR ASCENDING/DESCENDING FLIGHT.

(1) The along-track error also has significance in vertically guided flight. When an aircraft is ahead or behind its assumed position, it will be either above or below its intended path.

**FIGURE 10. EFFECTS OF ALONG-TRACK ERROR.**

Par 5 Page 21

### Page 58

-- Appendix D

(2) The angle at which climb or descent is made al~o affects the required obstacle clearanc·e because as the vertical angle increases, there is a corresponding increase in the effect of the along~track error on the thickness of the tube.

VARIATIONS OF VERTICAL CLEARANCE -~~~-----~-----,9--- -- ~g:.:··- -­ ---~-----~------~---LEVEL FLIGKT

. … _

-~~ ---~-- -- -~ ~ ----------- ~ -­

- ....._ ....._ ....._ .:HALLOW ANGLE ----------­ FIGURE 11. VARIATIO~S OF TUBE SIZE T0 CONTAIN POSITION ERRORS AS VERTICAL ANGLE INCREASES.

6. CONCEPT OF VERTICAL OBSTACLE CLEARANCE. In prescribinp, obstacle clearance for 3D RNAV, it is useful to think of the vertical route as being the center of a tube of airspace. The lateral dimension of the tube is the width of the RNAV route as described in Section I of this appendix. The vertical dimension of the tube is sufficient to contain the combined 3D RNAV vertical errors. The longitudinal dimension of the tube is limited only by its operational use; for example: The distance requi.red to climb 10,000 feet at a climb angle of 2°, or the descent from the final approach waypoint to the missed approach waypoint at a descent angle of 3°. For obstacle clearance, it is necessary to consider only that portion of the tube which is at and below the designed vertical flight path. An aircraft is protected from obstacles when no obstacles penetrate the tube from below.

Page 22 Par 5

### Page 59

AC 90-~5A2/21/75 Appendix D

7. OBSTACLE CLEARANCE REQUIREMENTS. 3D obstacle clearance requirements will be included in FAA Handbook 8260.3A, "u.s. Standard for Terminal Instrument Procedures (TERPs).

NOTE: Use of 3D ru~AV on 2D RNAV procedures is not prohibited. 2D RNAV procedures are annotated with Flight Path Angles measured from the TCH at the runway threshold waypoint to the altitude at the Final Approach ATD. These FPA may be flown as may any other FPA generated by the airborne equipment PROVIDED that the minimum and maximum altitudes specified in the flight procedures or in Air Traffic Control clearances are not violated.

Par 7 Page 23 (and 2~

### Page 60

Appendix E APPENDIX E. MAINTENANCE

1. MAINTENANCE. All maintenance will be performed in acccrrdance with FAR 43 and the manufacturer's instructions, or in accordance with a manual under an approved maintenance procedure. Records of mainte­ nance should be entered in the airplane maintenance records required by FAR 43.9, or in the records required by the operator's approved maintenance procedures. Following repair or alteratio n, the system should be checked before predicating any operation on its use.

Compatibility of the airborne area navigation system replacement components should be assured unless the replacement is of the same make and model as those upon which original approval was based.

2. INSPECTION AND TEST PROCEDURES . Operators using aircraft under IFR with an airborne area navigation system and not under an approved maintenance procedure should establish procedures which will be used to inspect and test the equipment periodically to determine that it is operating in accordance with at least the accuracy specified in Appendix A for minimum equipment. Such procedures should include a method for analyzing malfunctions and defects to determine that the established inspections and tests give reasonable assurance that the equipment is maintaining its accuracy. Test and inspection pro­ cedures and intervals should be adjusted in accordance with the results of the analysis.

Par 1 Page 1

### Page 61

Appendix F APP~~IX F. AIR CARRIERS/AIR TAXI AND COMMERCIAL OPERATORS OF LARGE AIRCRAFT/TRAVEL CLUBS* 1 . TRAINING PROGRAM. This type of operator should outline the training program he plans to set up to comply with the referenced FAR 121 parts.

Under these rules, the training program is acceptable if:

a. It encompasses all phases of the operation and fully covers all responsibilities of flight crewmembers, dispatchers and maintenance personnel.

b. Its technical content fo~ pilots covers:

(1) Theory and procedures, limitatLons, detection of malfunctions, preflight and inflight testing, cross-checking methods, etc., relating to the operations; and,

(2) An operational explanation of all systems, together with a review of navigation and flight planning.

c. Its recurrent training program includes area navigation training.

d. Each pilot assigned as an operating crewmember completes as many trips over a route or area (either in actual operation or, in part in an approved simulator or approved procedural trainer or training device) under the supervision of an appropriate instructor or a check airman, as may be necessary to:

(1) Ensure his qualification in the system; and,

(2) Enable cectification of his proficiency in the system, as required by Section 121.40l(c).

e. The training program conforms with the above and is approved by a representative of the Administrator.

*Travel Clubs will conform to the applicable parts of the above training program.

2. OPERATIONS MANUAL. Revisions to the operations manual should be provided outlining all procedures and emphas izing the methods for preflight and inflight test and step-by-step operation of the area navigation equipment.

The manual should contain procedures for continuing the flight with partial or complete area navigation equipment failure.

3. MINIMUM EQUIPMENT LIST (MEL). For those components of the area navigation equipment required for area navi gation operations, MEL revisions will be needed and operations specifications will so specify. The MEL should permit single system operation in dual s ystem installation s .

4. AUTHORIZATION. The operations s pecifications will contain the authoriza­ tion to use an area navigation system and identify the airborne equipment.

Par l ~el

### Page 62

Appendix F

5. APPROACH HINIMUMS. For the initial six months -of RNAV operations, approach minimums may be approved with an additional margin of 200 feet and 1/2 mile above the MDA and visibility minimums published on the standard instrument approach procedure. At the end of that period, the minimums published on the standard instrument approach procedure may be approved on a permanent basis if the operational reliability has been satisfactorily demonstrated during the initial six month period.

Page 2 Par 5

### Page 63

I N N -....

~ -1.1\ O£PA .. TM(i.NT 0,. TRANSPORT4TIO ....

FEDERAL AVIATIDM ADMINISTRATIDM OPERATIONS SPECIFICATIONS. EN ROUTE FLIGHT PROCEDURES Fonn Approved Budget Bureou No. 04-ROBJ. I

**ROUTE OR ROUTE SEGMENT VIA**

NAME OF AIR CARRIER ABC Airlines, Inc.

FAA fo"" S.C00-1 1:)-6at OPERATION AUTHORIZED TYPE OF AIRCR.AFT AUTHORIZED SPECIAL REQUIR! ..!NTS ~--~O~A~Y---4---N~I~GH~T~~DC-9

V~" IFA V FR … B-707

MOCA MEA MAA OTHER TYPl NAVIGATION!

Note: Both pilot1 wil be ~V RNAV qualified i acco dane wit app1 oved trainilng pr grams exc pt t at wren naviga~ion s be it g pe form d under the supervi ion o an ppr o ed Rli!AV­ qualified c eck p lot, the ilotE perfot"'ing uch s\perv sed avigetion need c nly h ve sac is fa tori y conpleted the a~~rove< RNAV grou d sc ool curri<~lum.

I " 'here a navigator or special coc kpit aavigation and rquipmeat is rr.o uire d , "o s""cify; ie NRvigator, Cockpit IOopplu- Loran), <Inertial> • . RNAV ,­

### Page 64

Appendix G APPENDIX G. GENERAL AVIATION

1. TRAINING PROGRAM. The operator should become thoroughly familiar with the operation of his area navigation equipment before he uses this equipment in an IFR environment. A recommended training program should:

a. Encompass all phases of the operation of the area navigation system.

b. Cover the theory of operation, setting procedures. familiarization, detection of malfunctions. preflight and inflight testing and cross­ checking methods.

c. Include procedures for continuing the flight with partial or complete area navigation equipment failure.

d. Provide that each operator of area navigation equipment will complete a sufficient number of simulated IFR approaches, missed approaches, departures and en route operations to ensure that he is competent to operate the equipment.

2. APPROACH MINIMUMS. The accuracy of RNAV equipment which meets only the minimum operational characteristics is such that a straight-in landing cannot always be assured. Therefore, general aviation pilots should not use lower than circling minimums unless they insure their RNAV systems are capable of consistently placing their aircraft within the final approach alignment tolerance.

The lowest minimums that may be authorized for operations that meet the above performance are those published on the standard instrument approach procedure.

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Appendix H APPENDIX H. AIR TAXI

**1. AIR TAXIS USING SMALL AIRCRAFT.**

a. TRAINING PROGRAM. This type operator should outline the training program he plans to establish in compliance with the tr-aining re­ quirements of his operations specifications. A training program is acceptable if:

(1) It encompasses all phases of the operation and fully covers all responsibilities of flight crewmembers and maintenance personnel.

(2) Its technical content, for pilots, covers:

(a) Theory and procedures, limitations, detection of malfunctions, preflight and inflight testing, cross-checking methods, etc., relating to the operation; and,

(b) An operational explanation of all systems, a review of navigation and flight planning.

(3) Its recurrent training program includes area navigation training.

(4) Each pilot assigned as an operating crewmember completes as many trips over a 'route or area (either in actual operation or, in part, in an approved simulator or approved procedural trainer or training device) under the supervision of an instructor or a check airman, as may be necessary to:

(a) Ensure his qualification in the system; and ,

(b) Enable certification of his proficiency in the system, as required by Section 135.131 .

b. OPERATIONS MANUAL. Revisions to the operations manual should be provided outlining all procedures and emphasizing the methods for preflight and inflight test and step-by-step operation of the area navigation equipment. The manual should contain procedures for continuing the flight navigation with partial or complete area navigation equipment failure.

c. AUTHORIZATION. The operations specifications will contain the authorization to use an area navigation system and identify the airborne equipment .

2. APPROACH lHNll1UMS. For the initial six months of RNAV operations, approach minimums may be approved with an additional margin of 200 feet and 1/2 mile above the MDA and visibility minimums published on the standard instrument approach procedure. At the end of that period, the minimums published on the standard instrument approach procedure may be approved on a permanent basis if the operational reliability has been satisfactorily demonstrated during the intial six-month period.

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I Appendix APPENDIX I. COMPUTATION OF CROSS-TRACK AND ALONG-TRACK ERROR COMPONENTS.

**1. TRACK ERROR.**

The track error table is developed by combinin g the appropriate cross­ track and along-track error vector derived from VOR, DME, RNAV equip­ ment and pilotage error values. The value printed out in the table is the larger of the two possible vectors (left or right, fore or aft).

The mathematics used in these computations for distance greater than five miles are shown in subsequent paragraphs.

NOTE: This appendix is presented for information pur poses and for use by manufacturers who wish to develop tables f or certification of equipment.

**2. CROSS-TRACK.**

a. Definitions.

= Distance from facility to the tangent point.

= Distance from aircraft to the tangent point.

D = Distance from facility to the aircraft.

{) = The angle formed by the tangent point, facility and the aircraft (facilitv at Vortex).

= Ground VOR error.

)3 = Airborne VOR error.

2l = Vet.2 + /) DGE = DME ground error.

DAE = DME air error X %or YNM whichever is greater.

DTE = + VE = Cross track comPOnent of errors due to C( and jJ .

DE = Cross track component of errors due to DAE and DGE.

Pilot = Pilot error.

Comp. = Computer error.

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### Page 67

e = arctan D = Appendix I VOR Component (VE)b .

0 D2 Dl -jol2 + Dz2 VE = o1 - D Cos ( 9 + r) cc. DME Component (DE) DTE

n.::::2:..---------~~,_,______ .... ~ -::;J ~DE DE= DTE Cos e Page 2 Par 2

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Appendix I

d. Total expected cross-track error (95%) probability All cross-track components are combined by the "roo"t-sum-square" method as follows:

2cross-track error = + J' VE + DE2 + Comp2 + Pilot 2

**3. ALONG-TRACK.**

a. Definitions = Distance from facility to tangent point.

o1 D2 = Distance from aircraft to the tangent point.

D = Distance from aircraft to the facility.

e = The angle formed by the tangent point, facility and the aircraft (facility at Vortex).

0: = Ground VOR error.

jJ = Airborne VOR error.

'f = t/~'"2 + 132 ~ DGE = Ground DME error.

DAE DME air error X % or'{ NM whichever is greater.

= DTE ~~~2-·= AvE = Along-track component of errors due to ~ and jJ .

AoE = Along-track component of errors due to DAE and DGE.

Pilot = Pilot error.

Comp. = Computer error.

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### Page 69

AC 90-45A 2/21/75Appendix I

b. VOR Component (AVE) D2 arctan­0 - 1 ~= sin < e -r) D , s·D2 = D ~n ce - 7)

c. DME Component (AoE) Page 4 Par 3

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Appendix I ADE Sin 8 ::: -:-=­DTE ::: DTE Sin 9

d. Total expected along-track error (95%) probability.

All along-track components are combined by the "root sum square 11 method.

2 2 "1 2Comp + P1. otAlong-track error =YAVE + Par 3 Page 5

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Appendix J APPENDIX J. COMPUTATION OF GEODESIC INFORMATION

1. METHOD. Mathematical formulas used for geodetic computat_ions are de­ rived from a procedure developed by Sodano (U.S. Army Engineer; Geodesy, Intelligence and Mapping Research and Development Agency; Fort Belvoir, Virginia.) The method provides very good direct and inverse compu­ tational compatibility; it is used by the FAA for all Route development.

NOTE: This appendix is presented for information purposes and for use by manufacturers who wish to compare airborne computational processes.

All angles are expressed in degrees and distances in Nautical Miles.

**2. COMPUTATION OF A GEODESIC LINE GIVEN TWO GEODETIC POINTS.**

Given: B1 , L1 Geodesic Lat., Long. of P1 B2 , L2 Geodesic Lat., Long. of P2 And F = 3.3901 X 10- 3 A0 = 3443.95594 (Semimajor Axis of the Earth) Required:

Al2: Azimuth of Geodesic from pl to p2 A21: Azimuth of Geodesic from p2 to pl S: Geodesic Length Compute S (Geodesic Length in Nautical Miles):

s = (1-F) A s0 1 Par 1 Page 1

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Appendix J 2 S1 ;:: \j_J + (F +F) [':VC2-M) + [X (2A-M~)] 2 2+ 1!~ [s 'f!2 (M-1) [A + CXcot 18n-\jl] + cx.2 0 [SA (M0-A)+(l-20 )] + ex Yl] \I/ - _][_ A T 1:5._X - 180 rc an ~ 2 2 2 M = (X - Sin L Cos /31 Cos 2 /32 cxz 2 2CX.. ;:: [ Sin L Cos /3 + (Sin j3 Cos jJl - Sin /]1 Cos }J2 Cos L)2] 112 2 2 1/J ~ = Sin /31 Sin /3 + Cos /31 Cos /]2 Cos L2 [::

if IL' I s 180 ° L = + 360 I~: I if I L'l > 180 ° L = 11 - Lz A= Sin Sin/3 1 j32 jJi ;:: Arc Tan [ (1-F) Tan Bil for i = 1, 2 Compute A12 (Az imuth of Geodesic from P1 to P2) o· if 1 -~ o Al2 = [ 6 + 180 ° if L " 0 Where:

Arc Tan ! + 180° if Ar c Tan ~ < 0 cf= Arc Tan 2; ~ >if Arc Tan 0b Page 2 Par 2

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Appendix J a Sin H Cos /32 b = Sin j32 Cos fJ 1 - Cos H Sin fJ1 Cos /32 H 180 [Sin L Cos (X/31 Cos fJz]=rr ------L--=--.L..-..:::... + L + MF2\II 2 - AF2 [ 2 w2J [cx.0 -s':Y+ 4 \j/2 cor 1aU':l! ]X = r (F+F ) 2[X ex + 2 I 4 Compute A21 in degrees (Azi muth P2 to P1) if 1-:= o if L ::::> 0 Where :

c[:180, + Arc Tan J if Arc Tan d < 0 v = Arc Tan £. if Arc Tan .£. > 0 d d c = Sin H Cos /31 d Sin /J Cos ;0 Cos H - Sin j] Cos j3 2 1 1 2 Par 2 Page 3

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AC 90-45A 2/21/75Appendix J Computation of the Geodetic Description of a True Bearing and Distance From A Given Geodetic Point.

Given: B1 Geodesic Latitude of a P1 L1 Geodesic Longitude of a P1 S Geodesic Length A12 Azimuth of Geodesic from P1 to P2 And:

F = 3.3901 X 10-3 A0 = 3443.95594 Required: B2 Geodesic Latitude of P2 L2 Geodesic Longitude of P2 A21 Azimuth of Geodesic from P2 to P1 Compute B2 Geodesic Latitude B2 [ /J2]Tan= Arc Tan 1-F 'Where:

Sin jJ1 Cos p + Cos /31 Cos A12 Sin pTan fJ2 = r.Leos2 f3 + (Cos j) Cos f3 1 Cos A12 - Sin fJ 1 Sin p )2'1j 172 0 f\ = r 90AlE2 s· MlE2 '(2 180 s· 2 ) + 225 A2E2 s· 2r jJ - rr Ln r - -8- r - 7( ~n r 4f( 1 2 m 22r - 2340 Sin 2r - 16r Cos2 r + ~ Cos2 r Sin 2r][ Tf J l 2 AM E [ + 1 1 2 1080 Sin r + 4r Cos r - 90 °Cos r Sin 2rl 16 IT IT J = h [sin 2 jJ1 Cos r + Cos fJ1 Cos A12 Sin /31 Sin r] A1 r = -~1::.:8:;.;:0'-"S'---- T( (1-F)A 0 Page 4 Par 2

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AC 90-45A2/21/75 Appendix J ~ h (1 - Cos2 j3 )M1 0 h = 1 + E; Sin 2 /31 fJ1 = Arc Tan [ (1-F) Tan B1] Cos fJo = Cos /31 Sin A12 -2 E = (1-F) -12 Compute L (Geodesic Longitude)2 360 L~ ~ 180 rL~ - IL21 if IL;l Lz ;::

< ~2 180if IL;j Lc Otherwise Compute Geodesic Azimuth A21 in degrees if Sin A 0> 12= ~~~1 + 180 °) A2l if Sin A12 <. 0A21 Par 2 Page 5

### Page 76

Appendix J A+ 180° if N-< 0If / =A21 A if !>on- A = Arc Tan ~where -90 ° -c:: A "$ 90° (Principle Arc Tan) N = Cos j30 D = Cos }31 Cos A Cos {J - Sin p1 Sin P12 Page 6 Pa.::- 2

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