Appendix 1
a. Airplane Manufacturer (Type Certificate (TC) Holders Incorporating FMS and DME/DME Positioning). The manufacturer should review the available data for the integrated navigation system, and obtain additional data as appropriate, to determine compliance with the criteria in this AC. Those manufacturers who have achieved compliance with the criteria should provide this information by letter to their customers. Manufacturers are also requested to provide a copy of this letter to AFS-400, to facilitate making this information available to all operators.
b. Equipment Manufacturers (Typically Separate Technical Standard Order (TSO) DME and FMS Holders).
(1) DME Sensor. The only requirement in this appendix that needs to be considered for a DME sensor is the accuracy requirement. DME sensors have been demonstrated to a variety of performance requirements per TSO-C66, Distance Measuring Equipment (DME) Operating within the Radio Frequency Range of 960-1215 Megahertz.
(a) TSO-C66 performance standards have evolved as follows:
(i) TSO-C66: (August 1960) RTCA/DO99.
(ii) TSO-C66a: (September 1965) RTCA/DO151, accuracy requirement as total error with 0.1 NM attributed to ground facility, airborne equipment accuracy of 0.5 NM or 3 percent of distance, whichever is greater, with a maximum of 3 NM.
(iii) TSO-C66b: (November 1978) RTCA/DO151a, accuracy requirement as total error with 0.1 NM attributed to ground facility, airborne equipment accuracy of 0.5 NM or 1 percent of distance, whichever is greater, with a maximum of 3 NM.
(iv) TSO-C66c: (September 1985) RTCA/DO189, accuracy requirement as total error for the airborne equipment of 0.17 NM or 0.25 percent of distance, whichever is greater.
(b) The accuracy required by TSO-C66c is adequate to support the criteria in this appendix, and DME equipment manufacturers under these versions of the TSO do not need to further evaluate their equipment for RNAV 1 and RNAV 2 operations. DME sensor manufacturers may use the following process to establish more accurate performance than originally credited.
(i) Determining Achieved Accuracy. Rather than relying on original demonstrated performance, the applicant may elect to review the original TSO or TC/STC test data to determine the demonstrated accuracy and/or make any appropriate changes to qualification tests to determine achieved accuracy.
NOTE: When conducting accuracy analysis, the DME signal-in-space error can be assumed to be 0.1 NM 95 percent (both inside and outside the published service volume). If demonstrating accuracy under bench or flight test conditions the actual accuracy of the bench equipment or ground facility should be considered.
Appendix 1
(ii) Accomplishing New Testing. New testing should be performed under the same conditions used to demonstrate compliance with the original TSO-C66 standard.
(iii) Manufacturers who have demonstrated more accurate DME performance should state the demonstrated accuracy in a letter to their customers. Manufacturers are also requested to provide a copy of this letter to AFS-400 to facilitate making the information available to all operators.
(2) Multi-Sensor Systems (FMS). The manufacturer should review the available data for the integrated navigation system, and obtain additional data as appropriate, to determine compliance with the criteria in this appendix. Manufacturers who have determined compliance should state such in a letter to their customers, along with any operational limitations (for example, if the pilot is expected to manually inhibit the use of facilities which are listed by NOTAM as unavailable). The manufacturer’s certification may limit the compliance to specific DME systems, or may reference any DME qualified to the accuracy requirements of TSO-C66c.
Manufacturers should also provide a copy of this letter to AFS-400.
(a) FMS accuracy is dependent on a number of factors, including latency effects, the selection of DME facilities, the method of combining information from multiple DMEs, and the effects of other sensors used to determine a position. For FMSs using two (or more) DMEs at the same time and limiting the DME include angle to between 30 and 150°, the accuracy requirement can be met if the DME sensors meet the accuracy requirements of TSO-C66c. For FMSs without these characteristics, the accuracy should be evaluated under poor DME geometry scenarios and should consider the demonstrated DME sensor accuracy. Poor geometry scenarios may include angles at the limits specified earlier, with or without additional DME facilities available outside those conditions.
(b) Identify those conditions that would result in failure to meet the accuracy requirement, and the means to preclude those identified conditions.
Appendix 2 APPENDIX 2. CRITERIA FOR APPROVAL OF BASELINE AREA NAVIGATION (RNAV) SYSTEMS USING DISTANCE MEASURING EQUIPMENT (DME) AND
INERTIAL REFERENCE UNIT (IRU)
1. PURPOSE. This appendix defines a minimum DME/DME/IRU (D/D/I) RNAV system baseline performance capable of supporting RNAV 1 and RNAV 2 routes, as well as RNAV 1 departure procedures (DPs) and Standard Terminal Arrivals (STAR). For routes and procedures designed using this performance standard, the FAA will decide if adequate DME coverage is available using FAA computer modeling and flight inspection assets. This assessment of DME coverage will also determine if an Expanded Service Volume (ESV) is necessary for select DME facilities.
2. MINIMUM REQUIREMENTS FOR DME/DME/IRU RNAV SYSTEM.
a. The Minimum Requirements of Appendix 1 Apply and Are Not Repeated in Appendix 2, Except Where Additional Performance Is Required. The performance confirmation process in appendix 1, paragraph 4, applies to appendix 2.
b. No Requirement to Use VOR, NDB, LOC, or AHRS. There is no requirement to use VOR (VHF omni-range), NDB (non-directional beacon), LOC (localizer), or AHRS (attitude heading reference system) during normal operation of the DME/DME/IRU RNAV system.
c. Position Estimation Error (PEE). Given any two DME facilities satisfying the criteria in appendix 1, subparagraphs 2b, 2c, and 2d, and any combination of other valid DME facilities not meeting that criteria, the 95 percent PEE must be better than or equal to the value obtained using the equation referenced in Appendix 1, subparagraph 2f.
NOTE: In order to take full advantage of the inertial coasting capability during gaps in DME/DME coverage, it is necessary to define the best possible baseline for the DME/DME performance at the beginning of the coverage gap. This baseline needs to take into account the DME geometry and performance at that time to provide as much margin as possible, thereby allowing the most time for INS coasting. This equation assumes the airborne equipment satisfies the accuracy requirements of TSO-C66c.
d. Inertial Performance.
(1) Inertial system performance must satisfy the criteria of 14 CFR part 121 appendix G.
NOTE: Based on an evaluation of IRU performance, the growth in position error after reverting to IRU can be expected to be less than 2 NM per 15 minutes.
e. Additional FMS Capabilities.
(1) Automatic position updating from the DME/DME solution is required.
NOTE: Operators/pilots should contact manufacturers to discern if any annunciation of inertial coasting is suppressed following loss of radio updating.
Appendix 2
(2) Must be able to accept a position update immediately prior to takeoff.
(3) Must exclude VORs greater than 40 NM from the aircraft.
f. Minimum Performance Standard for each Route or Procedure. The total system error must be less than or equal to 1.0 NM (95 percent) throughout the route. In order to maximize the amount of IRU coasting allowed, the flight technical error for D/D/I aircraft on terminal procedures should be limited to 0.5 NM (95 percent).
NOTE: The FAA assures that systems meeting the D/D/I RNAV minimum performance standard satisfy this requirement on all identified routes and procedures, and these RNAV systems do not require further evaluation. Systems seeking approval using different RNAV system characteristics or performance must demonstrate this performance for each published route or procedure.
Appendix 3 APPENDIX 3. NAVIGATION DISPLAYS AND FUNCTIONS
1. Navigation data, including a to/from indication and a failure indicator, must be displayed on a lateral deviation display such as CDI, (E)HSI and/or a navigation map display. These shall be used as primary flight instruments for the navigation of the aircraft, for maneuver anticipation and for failure/status/integrity indication. They shall meet the following requirements:
a. Non-numeric lateral deviation display (for example, CDI, (E)HSI), with a To/From indication and a failure annunciation, for use as primary flight instruments for navigation of the aircraft, for maneuver anticipation, and for failure/status/integrity indication, with the following five attributes:
(1) The displays shall be visible to the pilot and located in the primary field of view (± 15 degrees from pilot’s normal line of sight) when looking forward along the flight path.
(2) The lateral deviation scaling should agree with any alerting and annunciation limits, if implemented.
(3) The lateral deviation display must also have a full-scale deflection suitable for the current phase of flight and must be based on the required total system accuracy.
(4) The display scaling may be set automatically by default logic or set to a value obtained from a navigation database. The full-scale deflection value must be known or must be available for display to the pilot commensurate with en route or terminal values.
(5) The lateral deviation display must be automatically slaved to the RNAV computed path. The course selector to the deviation display should be automatically slewed to the RNAV computed path or the pilot must adjust the OBS or HSI selected course to the computed desired track.
NOTE: The normal function of stand-alone GNSS equipment meets this requirement.
b. If using a navigation map display, it should give equivalent functionality to a lateral deviation display as described above, (appendix 3, paragraph 1.a. (1-5)), readily visible to the pilot, with appropriate map scales (scaling may be set manually by the pilot).
2. The following system functions are required as a minimum within RNAV equipment:
a. The capability to continuously display to the pilot flying, on the primary flight instruments for navigation of the aircraft (primary navigation display), the RNAV computed desired path and aircraft position relative to the path.
b. For operations where the required flightcrew is two pilots, means for both pilots to verify the desired path and the aircraft position relative to the path.
c. A navigation database, containing current navigation data officially promulgated for civil aviation, which can be updated in accordance with the Aeronautical Information Regulation and
Appendix 3 Control (AIRAC) cycle and from which terminal airspace procedures can be retrieved and loaded into the RNAV system. The stored resolution of the data must be sufficient to achieve the required total system error. The database must be protected against pilot modification of the stored data.
d. The means to display the validity period of the navigation data to the pilot.
3. The means to retrieve and display data stored in the navigation database relating to individual waypoints and navigation aids, to enable the pilot to verify the route/procedure to be flown.
4. The entire RNAV segment of the DP or STAR to be flown must be extracted from the navigation database. In this document, the RNAV segment begins at the first occurrence of a named waypoint, track, or course and ends at the last occurrence of a named waypoint, track, or course. Heading legs, prior to the first named waypoint or after the last named waypoint of a procedure, are not part of the RNAV segment and do not have to be loaded from the database.
Similarly, direct-to-fix legs prior to the first named waypoint of a procedure are not part of the RNAV segment. While not required, the ability to extract the entire RNAV procedure, including heading and direct-to-fix legs, from the database is a recommended function.
5. The means to display the following items, either in the pilot’s primary field of view, or on a readily accessible page on a multipurpose control and display unit (MCDU).
a. The active navigation sensor type.
b. The identification of the active (To) waypoint.
c. The ground speed or time to the active (To) waypoint.
d. The distance and bearing to the active (To) waypoint.
6. Where the MCDU is used to support accuracy checks by the pilot, the capability of displaying lateral deviation with a resolution of at least 0.1 NM.
7. The capability for the navigation system to execute a “Direct to” function.
8. The capability for automatic leg sequencing with display of sequencing to the pilot.
9. The capability to execute procedures extracted from the onboard database including the capability to execute fly-over and fly-by turns.
10. The capability to execute leg transitions and maintain tracks consistent with the following ARINC 424 path terminators:
a. The aircraft must have the capability to automatically execute leg transitions and maintain tracks consistent with the following ARINC 424 path terminators, or their equivalent:
• Initial Fix (IF)
• Course to a Fix (CF)
Appendix 3
• Direct to Fix (DF)
• Track to Fix (TF) NOTE 1: Path terminators are defined in ARINC Specification 424, and their application is described in more detail in RTCA documents DO-236B and DO-201A.
NOTE 2: Numeric values for courses and tracks must be automatically loaded from the RNAV system database. However, automatic CF capability is not required for approval to fly: (1) all RNAV routes covered by this AC as these are constructed using TF path terminators, or (2) those ODPs using a DF or TF path terminator for the first segment.
b. The aircraft must have the capability to automatically execute leg transitions consistent with VA, VM and VI ARINC 424 path terminators, or must be able to be manually flown on a heading to intercept a course or to go direct to another fix after reaching a procedure-specified altitude.
c. The aircraft must have the capability to automatically execute leg transitions consistent with CA and FM ARINC 424 path terminators or the RNAV system must permit the pilot to readily designate a waypoint and select a desired course to or from a designated waypoint.
11. The capability to load a named RNAV route into an RNAV system from the database is a recommended function. However, if all or part of the RNAV route (not DP or STAR) is entered through the manual entry of fixes from the navigation database, a TF leg type must be used to define the path between a manually entered by name fix and the preceding and following fixes.
12. The capability to display an indication of the RNAV system failure, including the associated sensors, in the pilot’s primary field of view.
13. For multi-sensor systems, capability for automatic reversion to an alternate RNAV sensor if the primary RNAV sensor fails.
NOTE: This does not preclude providing a means for manual navigation source selection.
14. Database Integrity. The navigation database should be obtained from a database supplier holding an FAA Letter of Acceptance (LOA) in accordance with AC 20-153. This LOA provides recognition of a data supplier’s compliance with the data quality, integrity and quality management practices of RTCA DO-200A, Standards for Processing Aeronautical Data. The operator’s supplier (e.g., FMS manufacturer) must have a Type 2 LOA. Discrepancies that invalidate a procedure must be reported to the database supplier and affected procedures must be prohibited by an operator’s notice to its flightcrew. Aircraft operators should consider the need to conduct ongoing checks of the operational navigation databases in order to meet existing quality system requirements.
NOTE: AC 20-153 contains procedures for database LOAs.
Appendix 3
15. It is recommended RNAV systems provide lateral guidance so aircraft remain within the lateral boundaries of the fly-by transition area as defined in DO-236B, section 3.2.5.4.1.