Chapter 8. Equipmen t Performance - RNP Approach.
8-1. Introduction.
This chapter provides guidance on the perform ance and functional requirements for systems used to conduct RNP approach operations, which are designated under part 97 as RNAV (GPS) or GPS and categorized as RNP APCH in ICAO. The baro-VNAV equipment performance applicable to RNP approaches is specified in chapter 10. Baro-VNAV systems are optional capabilities that are not a minimum requirement to fly RNAV (GPS) or GPS approaches using the LNAV line of minima.
8-2. Aircraft and System Requirements.
The notes below apply to the entire paragraph.
a. Aircraft with approval to conduct R NAV (GPS) or GPS approaches meet the performance and functional requirements in this AC for RNP instrument approaches without RF legs.
b. Aircraft with a statement of compliance with the criteria in this AC in their airplane flight manual (AFM)/rotorcraft flight manual, AFMS/RFMS, pilot operating handbook (POH), or the operating manual for their avionics meet the performance and functional requirements for RNP instrument approaches. This presumes compliance with the operational guidance in AC
90-105.
c. Aircraft with a statement from the manufacturer documenting compliance with the criteria in this AC meet the performance and functional requirements for RNP instrument approaches. These statements should include the airworthiness basis for compliance.
Compliance with the sensor requirements will have to be determined by the equipment or aircraft manufacturer while compliance with the functional requirements in this chapter and chapter 14 may be determined by the manufacturer or by inspection by the operator, but must presume compliance with operational guidance in AC 90-105.
d. GPS stand-alone systems should be approved in accordance with TSO-C146(AR) Class 1, 2, or 3 or have an existing TSO-C129(AR) Class A1 approval (see 8-2.f note 2) and meet the applicable functionality and performance requirements of chapter 5, this chapter, and chapter 9. These systems should be installed for instrument flight rules (IFR) use in accordance with this AC.
e. GPS sensors used in multi-sensor system equipment (e.g., FMS) should be approved in accordance with TSO-C196(AR), or TSO-C145(AR) Class 1, 2, or 3 or have an existing TSO-C129(AR) Class B1, C1, B3, C3 approval (see 8-2.f note 2) and meet the performance and functionality requirements of chapter 5, this chapter, and chapter 9. These systems should be installed for IFR use in accordance with this AC.
f. Multi-sensor systems should be approved in accordance with TSO-C115b (or later revision), but may also have incomplete system TSO-C146(AR) Class Gamma approval (see paragraph 3-2.e) or an existing incomplete system TSO-C129(AR) Class A approval (see note 47
2). Those system s using GPS equipment should comply with the applicable GPS equipment chapters and chapters 6, 11-13, 15, 18-19, and 21 of this AC. These systems should also meet the performance and functionality requirements in this chapter.
Note 1: GPS equipment approved to TSO-C129(AR) must meet the system functions specified in this chapter. In addition, integrity should be provided by RAIM. It is recommended that GPS receivers include the pseudo-range step detection and health word checking functions if those functions were not specifically required for TSO approval (see appendix 1 for additional information).
Note 2: TSO-C129a has been cancelled so it is not possible to receive a new incomplete system TSO-C129a TSOA. But equipment with an existing TSO-C129a TSOA may still be produced and installed.
Note 3: Multi-sensor systems that use DME/DME or DME/DME/IRU as the only means of RNP compliance are not authorized to conduct RNP approaches. However, operators still retain the option to develop special RNP approaches using these systems.
8-3. Performance and Functional Requirements for RNP Systems.
a. Accuracy.
(1) The aircraft must com ply with RTCA/DO-236B, Minimum Aviation System Performance Standards: Required Navigation Performance for Area Navigation, dated October 28, 2003, paragraph 2.1.1.
(2) During operations on the initial and intermediate segments and for the missed approach of a RNP approach procedure, the lateral TSE must be within ±1 NM for at least 95 percent of the total flight time. The along-track error must also be within ±1 NM for at least 95 percent of the total flight time.
(3) During operations on the final approach segment, the lateral TSE must be within ±0.3 NM for at least 95 percent of the total flight time. The along-track error must also be within ±0.3 NM for at least 95 percent of the total flight time.
(4) To satisfy the accuracy requirement, the FTE should not exceed 0.5 NM on the initial, intermediate and missed approach segments of an RNP approach procedure. The FTE should not exceed 0.25 NM on the final approach segment of the approach.
Note 1: This requirement is considered satisfied as long as the TSE for each segment is not exceeded where the navigation system provides for RNP performance monitoring and alerting and where the integration of 48
operational modes and configuration s account for accuracy and FTE.
Note 2: Using a deviation indicator with 1 NM full-scale deflection on the initial, intermediate and missed approach segments and 0.3 NM full-scale deflection on the final approach segment is an acceptable means of compliance.
b. Integrity.
Malfunction of the aircraft navigation equipment that causes the TSE to exceed 2 times the RNP value without annunciation is classified as a Major failure condition under airworthiness regulations (i.e., 10-5 per hour).
c. Continuity.
Loss of function is classified as a minor failure condition if the operator can revert to a different navigation system and safely proceed to a suitable airport.
d. Performance Monitoring and Alerting.
During operations on the initial, intermediate, and the missed approach segments, the RNP System or the RNP system and pilot in combination must provide an alert if the accuracy requirement is not met or if the probability that the lateral TSE exceeds 2 NM is greater than 10-5. During operations on the final approach segment, the RNP system or the RNP system and pilot in combination must provide an alert if the accuracy requirement is not met or if the probability that the lateral TSE exceeds 0.6 NM is greater than 10-5.
e. Signal in Space.
During operations on the initial, intermediate, and missed approach segments, the aircraft navigation equipment must provide an alert if the probability of signal-in-space errors causing a lateral position error greater than 2 NM exceeds 10-7 per hour. During operations on the final approach segment, the aircraft navigation equipment must provide an alert if the probability of signal-in-space errors causing a navigation system error greater than 0.6 NM exceeds 10-7 per hour.
Note: There are no RNP requirements for the missed approach if it is based on conventional means (VOR, DME, and NDB) or on dead reckoning.
f. Path Definition.
Aircraft performance is evaluated around the path defined by the published procedure and RTCA/DO-236B, paragraph 3.2.5.4.1.
Note: The guidance in this paragraph provides equivalent performance to the intent in AC 90-105 for basic RNP 49
approach. AC 90-105 references R TCA/DO-236B, paragraph 3.2.5.4.2, Fixed-Radius Transitions, which is more closely associated with RNP Advanced Features in appendix 3.
g. Functional Requirements for Navigation Displays.
(1) The following navigation displays and functions are required, as installed in accordance with this AC or equivalent system installation advisory material. Navigation data, including a TO/FROM indication and a failure indicator, must be displayed on a lateral deviation display (course deviation indicator (CDI), electronic horizontal situation indicator (EHSI)) and/or a navigation map display. These must be used as primary flight instruments for aircraft navigation, for maneuver anticipation, and for failure/status/integrity indication.
Note: Unlike traditional, ground-based instrument procedures, some navigation computers construct RNP procedures by navigating to each procedure defined waypoint. This is referred to as “TO/TO navigation”. See paragraph 8-3.g(2) for guidance on RNP systems with navigation computers using TO/TO navigation algorithms.
(2) RNP systems using TO/TO navigation algorithms do not require a navigation display with a TO/FROM indication during RNP instrument procedures. Displays supporting TO/TO navigation computers can fully comply with all RNP-related requirements in this AC without a TO/FROM indication. At a minimum, the navigation display supporting a TO/TO RNP system should display the active waypoint and active waypoint name.
(a) If an aircraft’s sensor suite intends to support traditional navigation using ground-based navigation aids (such as executing a VOR-DME instrument approach procedure), then the aircraft and avionics manufacturers must ensure the aircraft installation properly accommodates these traditional, ground-based instrument flight procedures. A TO/FROM indication is essential to qualify the aircraft for these traditional procedures because they may rely on navigation to and from a navigation aid, an ad hoc fix assigned by air traffic control, or a defined fix.
(b) Additionally, a TO/FROM indication is necessary when the RNP system uses GNSS substitution for the ground-based navigation aid(s) defining a traditional instrument procedure.
(3) A non-numeric lateral deviation display (for example, CDI, EHSI), with a TO/FROM indication and a failure annunciation, used as primary flight instruments for aircraft navigation, for maneuver anticipation, and for failure/status/integrity indication, should have the following attributes:
Note: see paragraph 8-3.g(2) for TO/TO navigation computer displays.
(a) The displays m ust be visible to the pilot and located in the primary field of view.
(b) The lateral deviation display scaling should agree with any alerting and annunciation limits, if implemented.
(c) The lateral deviation display must have a full-scale deflection suitable for the current phase of flight and must be based on the TSE requirement. Scaling of ± 1 NM for the initial, intermediate, and missed approach segments and ±0.3 NM for the final segment is acceptable.
(d) 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 approach values.
(e) The lateral deviation display must be automatically slaved to the RNP computed path. It is recommended that the course selector of the deviation display be automatically slewed to the RNP computed path.
Note: This does not apply for installations where an electronic map display contains a graphical display of the flight path and path deviation.
(f) As an alternate means, a navigation map display must provide equivalent functionality to a lateral deviation display with appropriate map scales (scaling may be set manually by the pilot). To be approved as an alternative means, the navigation map display must be shown to meet the TSE requirements and be located in the primary field of view.
h. System Capabilities.
The following system capabilities are required as a minimum:
(1) The capability to continuously display to the pilot flying, on the primary flight instruments for aircraft navigation (primary navigation display), the RNP computed desired path and aircraft position relative to the path. For operations where the required minimum flightcrew is two pilots, a means for the pilot not flying (pilot monitoring) must also be provided to verify the desired path and the aircraft position relative to the path.
(2) 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. The stored resolution of the data must be sufficient to achieve the required track keeping accuracy. The database must be protected against pilot modification of the stored data.
(3) The means to display the navigation data validity period to the pilot.
(4) 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 to be 51
flown.
(5) Capability to load from the database into the RNP system the whole approach to be flown. The approach must be loaded from the database, into the RNP system, by its name.
(6) The means to display the following items, either in the pilot’s primary field of view, or on a readily accessible display page:
(a) Distance between flight plan waypoints;
(b) Distance to go to the waypoint selected by the pilot;
(c) Along track distances between waypoints;
(d) Active navigation sensor type;
(e) The identification of the active (To) waypoint;
(f) The ground speed or time to the active (To) waypoint; and
(g) The distance and bearing to the active (To) waypoint.
(7) The capability to execute a “Direct to” function.
(8) The capability for automatic leg sequencing with display to the pilots.
(9) The capability to execute RNP instrument approach procedures extracted from the onboard database including the capability to execute fly-over and fly-by turns.
(10) The capability to automatically execute leg transitions and maintain tracks consistent with the following ARINC 424 path terminators, or their equivalent:
(a) Initial Fix (IF).
(b) Track to Fix (TF).
(c) Direct to Fix (DF).
Note 1: Path terminators are defined in ARINC Specification 424, and their application is described in more detail in RTCA/DO-236B and RTCA/ DO-201A, Standards for Aeronautical Information, dated April 19, 2000.
Note 2: Numeric values for tracks must be automatically loaded from the RNP system database.
(11) The capability to display an indication of the RNP system failure in the pilot’s primary field of view.
(12) The capability to indicate to the crew when the navigation system error (NSE) alert limit is exceeded (alert provided by the “onboard performance monitoring and alerting function”).
i. Flight Director/Autopilot.
It is recommended that the flight director (FD) and/or autopilot remain coupled for RNP approaches. If the lateral TSE cannot be demonstrated without these systems, then coupling becomes mandatory. In this instance, operating guidance must indicate that coupling to the FD and/or automatic pilot from the RNP system is mandatory for approaches.
j. Database Integrity.
The navigation database suppliers must comply with RTCA/DO-200A. A Type 2 Letter of Acceptance (LOA), issued by the appropriate regulatory authority, demonstrates compliance with this requirement. Type 2 LOAs issued prior to this AC are considered compliant.
8-4. System Eligibility and Approval for RNP Operations.
a. Introduction.
The original equipm ent manufacturer (OEM) or the holder of installation approval for the aircraft (e.g., STC holder), must demonstrate compliance with the appropriate provisions of this AC to the FAA and the approval can be documented in manufacturer documentation
(e.g., Service Letters, etc.). AFM/RFM entries are not required provided the FAA accepts the manufacturer’s documentation.
b. Eligibility for RNP Instrument Approach Operations.
Systems meeting the requirements in paragraph 8-2 are eligible for RNP instrument approach operations. Aircraft qualified by any revision of AC 90-101 for RNP AR are considered qualified for RNP approach operations without further examination.
c. System Eligibility for RNP Approach Operations.
(1) LNAV line of minima qualification.
(a) Stand-alone systems meeting TSO-C129(AR) Class A1 or TSO-C146(AR) Class 1, 2, or 3 meet the aircraft qualification requirements for RNP instrument approach operations using the LNAV line of minima provided the systems and IFR installations were performed in accordance with this AC.
(b) Multi-sensor systems using TSO-C129(AR) Class B1, B3, C1, or C3 sensors; TSO-C196(AR) sensors; TSO-C145(AR) Class 1, 2, or 3 sensors; or, TSO-C161a 53
sensors us ing GBAS positioning service meet the aircraft qualification requirements for RNP instrument approach operations using the LNAV line of minima, provided the installations are in accordance with this AC and the associated FMS complies with TSO-C115b (or later revision).
Note 1: Multi-sensor systems may also have incomplete system TSO-C129(AR) Class A or TSO-C146(AR) Class Gamma approvals (see paragraph 3-2.e).
Note 2: TSO-C129a has been cancelled so it is not possible to receive a new incomplete system TSO-C129a TSOA. But equipment with an existing TSO-C129a TSOA may still be produced and installed.
(2) LNAV/VNAV line of minima qualification.
(a) Stand-alone TSO-C146(AR) Class 2 or 3 systems meet the aircraft qualification requirements for RNP instrument approach operations using the LNAV/VNAV line of minima provided that the installations are in accordance with this AC. Systems meeting TSO-C129(AR) Class A1 with baro-VNAV can be used for RNP approaches using the LNAV/VNAV line of minima if the criteria in chapters 13 and 15 are met and the systems are installed in accordance with this AC.
(b) Multi-sensor systems using TSO-C145(AR) Class 2 or 3 sensors meet the aircraft qualification requirements for RNP instrument approach operations using the LNAV/VNAV line of minima provided that the installations are in accordance with this AC and the associated FMS complies with TSO-C115b (or later revision).
Note 1: Multi-sensor systems may also have incomplete system TSO-C129(AR) Class A or TSO-C146(AR) Class Gamma approvals (see paragraph 3-2.e).
Note 2: TSO-C129a has been cancelled so it is not possible to receive a new incomplete system TSO-C129a TSOA. But equipment with an existing TSO-C129a TSOA may still be produced and installed.
(c) Multi-sensor systems using TSO-C129(AR) Class B1, B3, C1, or C3 sensors with baro-VNAV; TSO-C196(AR) sensors with baro-VNAV; or, TSO-C161a sensors using the GBAS positioning service with baro-VNAV can be used for RNP approaches using the LNAV/VNAV line of minima if the criteria in chapters 13 and 15 are met and the systems are installed in accordance with this AC. The associated FMS must comply with TSO-C115b (or later revision).
Note 1: Multi-sensor systems may also have incomplete system TSO-C129(AR) Class A or TSO-C146(AR) Class Gamma approvals (see paragraph 3-2.e).
55 Note 2: TSO-C129a has been cancelled so it is not possible to receive a new incomplete system TSO-C129a TSOA. But equipment with an existing TSO-C129a TSOA may still be produced and installed.
Chapter 9. Equipment Performa nce - RNP Terminal.
9-1. Introduction.
This chapter provides guidance on the perform ance and functional requirements for RNP 1 operations in the terminal area. RNP Terminal terminology is used in the AC 90-105, appendix 2 title, and is synonymous with RNP 1. The equipment can be used to conduct RNP instrument departure procedures (including RNP ODPs and SIDs) and RNP STARs within the United States NAS where domestic air traffic control procedures are applied.
9-2. Aircraft and System Requirements for RNP Terminal Operations.
a. Aircraf t with a statement of compliance with the criteria in this AC in their AFM/RFM, AFMS/RFMS, POH, or the operating manual for their avionics meet the performance and functional requirements for RNP terminal operations. This presumes compliance with the operational guidance in AC 90-105.
b. Aircraft with a statement from the manufacturer documenting compliance with the criteria in this AC meet the performance and functional requirements for RNP terminal operations. These statements should include the airworthiness basis for compliance.
Compliance with the sensor requirements will have to be determined by the equipment or aircraft manufacturer while compliance with the functional requirements in this chapter may be determined by the manufacturer or by inspection by the operator, but must presume compliance with operational guidance in AC 90-105.
c. GPS stand-alone equipment should be approved in accordance with TSO-C146(AR) Class 1, 2, or 3 or have an existing TSO-C129(AR) Class A1 approval (see 9-2.e note) and meet the applicable performance and functional requirements of chapter 5 and this chapter. These systems should be installed for IFR use in accordance with this AC.
d. GPS sensors used in multi-sensor system equipment (e.g., FMS) should be approved in accordance with TSO-C196(AR), or TSO-C145(AR) Class 1, 2, or 3 or have an existing TSO-C129(AR) Class B or C approval (see 9-2.e note) and meet the applicable performance and functional requirements of chapter 5 and this chapter. These systems should be installed for IFR use in accordance with this AC.
e. Multi-sensor systems should be approved in accordance with TSO-C115b (or later revision), but may also have incomplete system TSO-C146(AR) Class Gamma approvals (see paragraph 3-2.e) or an existing incomplete system TSO-C129(AR) Class A approval (see note).
Those systems using GPS equipment should comply with the applicable GPS equipment chapters and chapters 6, 11-13, 15, 18, 19, and 21 of this AC. These systems should also meet the performance and functionality requirements in this chapter.
Note: TSO-C129a has been cancelled so it is not possible to receive a new incomplete system TSO-C129a TSOA.
But equipment with an existing TSO-C129a TSOA may still be produced and installed.
f. Aircraft/equipm ent with approval under AC 90-100A (or later revision) to use GPS is approved under this AC for RNP 1 operations.
g. RNP aircraft with P-RNAV approval based on GPS capability meet the functional requirements of this AC for RNP 1 operations, such as RNP DPs, RNP SIDs, and RNP STARS.
Note 1: RNP 1 operations are based on GPS positioning and, if adequate coverage is available, DME/DME/IRU.
Positioning data from other types of navigation sensors may be integrated with the GPS data provided it does not cause position errors exceeding the TSE budget.
Otherwise, means should be provided to deselect the other navigation sensor types.
Note 2: TSO-C145(AR) or TSO-C146(AR) equipment may also be authorized to conduct RNP operations in United States airspace where domestic air traffic control procedures are applied (Class I Navigation operations) without an airworthiness limitation for other navigation equipment on the aircraft. This authorization includes operations outside the navigational service volume of ICAO standard ground-based NAVAIDs.
9-3. System Performance Monitoring and Alerting.
a. Accuracy.
(1) The aircraft must com ply with RTCA/DO-236B, paragraph 2.1.1.
(2) During operations in airspace or on routes designated as RNP 1, the lateral TSE must be within ±1 NM for at least 95 percent of the total flight time. The along-track error must also be within ±1 NM for at least 95 percent of the total flight time. To satisfy the accuracy requirement, the 95 percent, FTE should not exceed 0.5 NM (see chapter 16).
Note: Using a lateral deviation indicator with 1 NM full-scale deflection is an acceptable means of compliance.
Using an autopilot or FD is also an acceptable means of compliance, but roll stabilization systems do not qualify.
b. Integrity.
Malfunction of the aircraft navigation equipment that causes the TSE to exceed 2 times the RNP value without annunciation is classified as a major failure condition under airworthiness regulations (i.e., 10-5 per hour).
c. Continuity.
Loss of func tion is classified as a minor failure condition if the operator can revert to a different navigation system and proceed to a suitable airport.
d. Performance Monitoring and Alerting.
The RNP system, or the RNP system and pilot in combination, must provide an alert if the accuracy requirement is not met, or if the probability that the lateral TSE exceeds 2 NM is greater than 10-5 for RNP 1 operations.
e. Path Definition.
RNP systems should provide lateral guidance so aircraft remain within the lateral boundaries of the fly-by transition area as defined in RTCA/DO-236B, paragraph 3.2.5.4.1.
f. Signal-in-Space.
If using GPS, the aircraft navigation equipment must provide an alert if the probability of signal-in-space errors causing a lateral position error greater than 2 NM exceeds 10-7 per hour for RNP 1 operations.
g. Functional Requirements of Navigation Data Displays.
(1) If using this AC as the means of compliance, then the following navigation displays and functions are required and must be installed in accordance with this AC.
(2) Navigation data, including a TO/FROM indication and a failure indicator, must be displayed on a lateral deviation display (CDI, EHSI) and/or a navigation map display.
These must be used as primary flight instruments for aircraft navigation, for maneuver anticipation, and for failure/status/integrity indication. A non-numeric lateral deviation display (for example, CDI, EHSI), with a TO/FROM indication and a failure annunciation, used as primary flight instruments for aircraft navigation, for maneuver anticipation, and for failure/status/integrity indication, should have the following attributes:
Note: See paragraph 8-3.g(2) for TO/TO navigation computer displays.
(a) The displays must be visible to the pilot and located in the primary field of view when looking forward along the flight path.
(b) The lateral deviation display scaling must agree with any alerting and annunciation limits, if implemented.
(c) The lateral deviation display must have a full-scale deflection suitable for the current phase of flight and must be based on the required total system accuracy.