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. (1) 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. Military RNAV equipment approval procedures, 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 VOR/DME/TACAN STATION REFERENCED AREA NAVIGATION ERROR TABLE (95% PROBABILITY)
DISTANCE ALONG TRACK FROM TANGENT POINT 0 5 10 15 20 25 30 35 40 60 70 80 90 100 110 120 130 150 200 19 2:2 2:9 2:3 3:% 9.3
4.0 6.0 7 4 16 11 12 2 3:6 3:3 85 › ⅜ 8 1 16 11 12 22 25 13 2 •0 2:5 3:3 1:6 12:
> l 2 12 2 13 182326 3:2 9:3 3:8 233 12:2 PERPENDICULAR DIST TO TANGENT POINT (ark) 13 1. 1:4 1:2 1:518 2:1 1:8 2:6 12:2 25 10 103 1 16 18 1:9 20 2:1 23 27 30 32 13 58 2:8 2} 29 1233 trk) 1:9 19 1:3 2:0 21 23 2:2 2:3 2:3 12:3 2:3 3:2 9 42 25 3:0 16:4 2:2 2:2 29 2:3 2:3 2:3 2:8 1:0 3: 3:% 4.J 2:% 9:2 12:3 40(x8 CEk) trk) 2:3 1:5 2:8 2:1 2:} 3:2 2:9 33 63 (x trk) 3:1 3:2 3: 2 3: 2 3: 3 3:3 2:1 2:3 6:5 7:1 8: 2 3:8 3:3 3.0 4:3 3:⅔ 2:2 2:2 2: 3 2: & 2:3 9:3 & :5 8:3 +½:3 (aig tik) trk) 3:8 3:6 3:2 5: 2 3:3 0 • 0 ₴: S *2:8 3:8 2. 0 3:8 3:} 3:7 5: 8 6:2 6:2 6:3 6:3 +2:3 100(18 EEK) trk) 3:2 62 312 2:3 3:5 2:3 2:3 5.0 6.0 63 71 2 12 3 199
6. 0 238 06 64 69 70 43 4:1 13 3 7:6 7:8 13 81 18 13:2 120(X8 ) 7:6 7:3 7:3 7:5 7:3 ·: S 6:0 6:1 8.2 8:8 19:2 +3:⅔ 130(18 k) 3:1 8:1 1 8:1 #: 1 8:1 8:2 0:2 8:6 3:9 3:8 140(1 ) #3 83 3 83 в:З 92 933 10:0 13:3 +50(X8 82) #3 99 99 913 914 96 9:7 10.2 1013 10:6 11:2
TO FIND THE CROSS-TRACK AND ALONG-TRACK ELECTRONIC ERROR ELEMENTS
SYSTEM ERROR (LESS PILOTAGE) AT A POINT, ENTER TABLE GROUND WITH PERPENDICULAR DISTANCE AND DISTANCE ALONG VOR 1.90 TRACK FROM TANGENT POINT, i.e., when the Perp Dist is DME 0.I NM 30 and the along-track dist is 50, the cross-track error AIRBORNE is + 3.3 NM and the along-track error is 2.5 NM. VOR 3.0° D ME 3% or 0.5 NM RNAV SYSTEM 0.5 NM Tangent Pt ALONG TRACK DIST PILOT ZERO TABLE 1 Page 15
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 (SIC) .
a. What the SIC applicant does:
Makes an application for STC at the FAA Regional Engineering and Manufacturing office. Early contact is wise, since scheduling may be critical. FAA evaluates the data submitted by the applicant (see Paragraph 1.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.
Makes available an aircraft (with the area navigation system installed) for ground inspection and flight test. The applicant 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 installation 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.
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AC 90-45А 2/21/75 Appendix B
(4) Any needed structural substantiation.
(5) Electrical schematics.
(6) Any needed flight manual revision or supplement, or placard drawings.
(7) Evidence of previously approved data.
c. What the Equipment Manufacturer Can Do.
Assist the STC applicant by supplying the data specified in Paragraphs 1.a. (3) and 1b.(1).
(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 satisfied.
2. APPROVAL OF TECHNICAL DATA BY FORM 337, Major Repair and Alteration (Airframe, powerplant, propeller or appliance) OMB 04-R060.1 (FOR USE UNDER INSTRUMENT 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 requirerents of Appendix A, Paragraphs
3.h. and 3.c. have been met.
b. Additional Data Which May be Required. If required for FAA Airworthiness evaluation by the FAA District Office approving the technical data, the applicant may also be required to furnish a copy of the equipment schematics, manufacturer's operating and installation instructions, fault analysis for installation, installation details and/or photographs, substantiation of structural changes, electrical schematics, and any appropriate proposed flight manual revision and/or placards.
Inspection of Aircraft. Make the aircraft available for data conformity inspection.
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Appendix C APPENDIX C. SOURCES OF NAVIGATION SYSTEM ERROR CENERAL. The establishment of relationships between navigation system accuracy and IFR aircraft separation criteria or route widths is a complex process. The first problem is to determine a reasonably achievable level of navigation system accuracy. This must be based not only on analysis of the measurable system error elements for state-ofthe-art equipment but also on a series of intangibles judged primarily on the basis of experience.
Current separation criteria, based on such analysis and experience, provide aircraft under IF control a hich degree of protection against collision with other aircraft or obstructions. These criteria take into account the measured accuracies of the VOR/DME ground facilities and airborne equipment and judgments as to how pilots actually fly their airplanes. Accumulating evidence shows that VOP/DMF information, when used with area navigation computing and display devices and presented properly to the pilot, offers the potential for an even more efficient utilization of the airspace while maintaining current standards of inflight safety.
CURRENT RELATIONSHIP BETWEEN NAVIGATION ACCURACY AND ROUTE WIDTH.
system of airways and routes used in the United States has widths 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 nautical mile route width out to a distance of 51 N from the facility and a widening of route protection on the + 4.5 degree basis beyond 5l miles.
CURRENT RELATIONSHIP BETWEEN VERTICAL NAVIGATION ACCURACY AND SEPARATION STANDARDS. The system of airways used in the United States allow for altimetry systems errors and atmospheric errors of various amounts dependent on mode of flight and altitude of the flight operations.
Altimeter standards for accuracy (TSO C 10h) requires certain demonstrations of accuracy over a wide range of conditions including temperature, vibration and pressure. These accuracies combined with the expected changes in atmospheric pressure over the distances used and pilotage factors do not exceed a value which would interfere with other IFR aircraft operating with 1000' vertical separation below 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 above, as well as below, this flight level. The accuracy requirements of the current altimeter standards are not stringent enough to meet this goal but the do import day vertical separation at all fishe levend are intended
4. SOURCES OF ERROR.
a. Horizontal Errors. The basic assumption is that four sources of Par 1 Page 1
Appendix C error - ground VOR and DME radiated signal, airborne VOR receiver equipment, area navigation equipment, and pilotage - contribute independent errors of such distribution that they may be combined in RSS fashion. This is the normal assumption used traditionally by the FAA and is required by the method recommended by ICAO Annex 10 for the determination of VOR system use accuracy (ICAO Annex 10, Second Fdition, April 1968, Attachment C to Part I, Paragraph 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 composite values including error contributions from various factors.
For example, "Errors in radiated signals" include propagation errors as well as errors in the transmitted signals arising from geographical siting and magnetic alignment of the ground station.
"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 "airborne VOR equipment error" can be correspondingly reduced. (NOTE: This factor is considered subsequently as one type of error compensation that may be afforded by area navigation equipment.) The errors for DME receivers 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.
"Area navigation equipment error" includes error components contributed by any input, output, or signal conversion equipment used, by any computing element employed, by the display as it presents either aircraft position or guidance commands
(e.g., course deviation or command heading), and by any course definition entry devices employed. For systems in which charts are incorporated as integral parts of the display, the "area navigation equipment error" necessarily includes charting errors to the extent that they actually result in errors in controlling the position of the aircraft relative to a desired path over the ground. To be consistent, in the case of symbolic displays not employing integral charts, any errors in waypoint definition directly attributable to errors in reference charts used in determining waypoint positions should be included as a component of "area navigation equipment error."
This type of error is virtually impossible to handle and in general practice highly accurate published waypoint locations are used to the greatest extent possible in setting up such systems to avoid such errors (and to reduce workload).
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Appendix C 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. Manual insertion errors are due to the human interface with the control and display units that affect the performance of an RNAV operation.
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 in track setting and in setting waypoint bearing information in some types of systems.
Blunder errors are gross errors in human judgment or attentiveness 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 error" 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, 1s linear in nature. A value of ‡ 2.0 N is typical for the enroute case and + 0.5 is typical for final approach operations.
"Manual" 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 waypoint.
The term "pilotage error" in the RNAV equipment error budget 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.
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Appendix C
5. COMBINING THE ERROK ELEMENTS. Based on the assumptions that the variable errors from the various sources are normally distributed and independent, they may be combined in RSS (root-sum-squares) fashion. Thus, the standard deviations obtained from the various contributing sources may be combined geometrically rather than arithmetically by taking the square root of the sum of their squares:
ó total = 7 612+022... +ón2 ERROR BUDGETING.
a • In optinizing a navigation system design, it is generally desirable to avoid having the error from one source much larger than those of combination, it from the other sources since, by the Ros method or 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 and display capability to the basic VOR/DME 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 Fligit Technical Error, may be traded provided the total system accuracy reflected in Appendix D, Tables 2, 3 and 4 are met.
(1) Assume that a company sells an airborne VOR system designed To un the in Pact 1y to fly within a + 4 NM route width to a distance of 51 iM from a ground facility on the basis of the following error oudget :
(2) Ground VOR Station Lrror Airborne VOR Equipment Error Ground DML Error Pilotage Error +1.9° @ 51 NM = 1.7 NM cross-track error +3.0° @ 51 NH = 2.7 NM cross-track error +0.1 N1 on radial = 0.0 NH cross-track error +2.5° @ 51 NM = 2.2 NM cross-track error
(3) The error elements combine to make:
Total Error = + 1.72 + 2.72 + 2.22 = + 3.80 Page 4 Par 5
Appendix C In designing a new system containing area navigation devices contributing an error element of +2 NM (equivalent to +2.3° at 51 NM), 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:
By picking off signals directly from the VOR receiver and using a digital course selector in the RNAV equipment 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 orientation 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. INSTRUMENT FLIGHT PROCEDURES 1• GENERAL. This appendix contains obstacle clearance requirements for RNAV instrument flight procedures. Section I provides guidelines which are applicable to all RNAV procedures. Section II discusses the concept of 3-D RNAV only. Obstacle clearance requirements will be included in the U. S. Standard for Terminal Instrument Procedures (TERPs).
a. Approval of RNAV procedures will be based on FAA capability to provide service, anticipated volume of traffic, and compatibility of the procedure with existing airways, routes, traffic and procedures.
b. All approved area navigation routings and procedures will be assured adequate signal coverage and frequency protection. Those approved for public use will be published in the United States government flight information publication enroute and terminal charts, FAR's and/or Airman's Information Manual (AIM).
Pilots should refer to AC 90-63, Air Traffic Control Procedures for Random Area Navigation Routes" to insure correct use of offairways routes.
d. RNAV routes which require VOR/DME inputs will be provided uninterrupted VOR/DME signal reception as opposed to Victor airways which may incorporate signal gap areas.
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 pronounceable 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 lateral course change is required at that point. It is used to simplify pilot workload. An ATD fix may be used in lieu of a missed approach waypoint when the runway waypoint is NOT the MAP. Changeover points on RNAV routes will be defined using distance from an established waypoint.
Terminal area routes are normally flown 'to' the waypoint, and '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' identifies the route as an RNAV route. For example, J 830 R indicates a high altitude RNAV route while V 762 R indicates a low altitude RNAV route. RNAV standard Par 1 Page 1
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:
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.
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:
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 which shall be expressed in statute miles and RVR which shall be expressed in feet.
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Appendix D
(4) Aircraft speeds in knots.
(5) Track angles shall be expressed in degrees.
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