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 RNAV system baseline performance capable of supporting RNAV 1 and RNAV 2 routes, as well as RNAV 1 departure procedures (DP) 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 Very High Frequency Omni-Directional Range (VOR), Non-Directional Beacon (NDB), Localizer (LOC), or Attitude and Heading Reference System (AHRS). There is no requirement to use VOR, NDB, LOC, or AHRS 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 inertial navigation systems (INS) coasting. This equation assumes the airborne equipment satisfies the accuracy requirements of Technical Standard Order (TSO)-C66c, Distance Measuring Equipment (DME) Operating within the Radio Frequency Range of 960-1215 Megahertz.
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 nautical miles (NM) per 15 minutes.
e. Additional Flight Management System (FMS) Capabilities.
Appendix 2
(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.
(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 (FTE) for DME/DME/Inertial (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 course deviation indicator (CDI), electronic horizontal-situation indicator (EHSI) 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, EHSI), 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 Area Navigation (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 omni bearing selection (OBS) or horizontal situation indicator (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, subparagraph 1a(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.
Appendix 3
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 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 departure procedure (DP) or Standard Terminal Arrival (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 nautical mile (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 flyover and flyby 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:
Appendix 3
• Initial Fix (IF).
• Course to Fix (CF).
• 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, Minimum Aviation System Performance Standard: Required Navigation Performance for Area Navigation, and DO-201A, Standards for Aeronautical Information.
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 Obstacle Departure Procedures (ODP) 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., Flight Management System (FMS) manufacturer) must have a Type 2 LOA. Discrepancies that invalidate a procedure must be reported to the database supplier and
Appendix 3 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.
15. It is recommended RNAV systems provide lateral guidance so aircraft remain within the lateral boundaries of the flyby transition area as defined in DO-236B, section 3.2.5.4.1.
Advisory Circular Feedback Form If you find an error in this AC, have recommendations for improving it, or have suggestions for new items/subjects to be added, you may let us know by contacting the Flight Technologies and Procedures Division (AFS-400) at 9-AWA-AFS400-Coord@faa.gov or the Flight Standards Directives Management Officer at 9-AWA-AFB-120-Directives@faa.gov.
Subject: AC 90-100A CHG 2, U.S. Terminal and En Route Area Navigation (RNAV) Operations Date: _____________________ Please check all appropriate line items:
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