T
Appendix 2
Public RNP AR Procedures Minimum Straight Segments between Turns and Decision Altitude GS = Category Speed + 15 kt Figure 3. Minimum Straight Path Before DA A2-7. Navigation Data Validation Program.
The aircraft’s onboard navigation database defines the RNP AR procedure path and RF in final DA Direction of Flight If there is a turn before or after the DA , Distance before or after DA computed from Distance ( NM ) = GS ( KT ) * T ( SEC )/ 3600 where Runway DER LTP Min Time = 50 s RF in miss Min Time = 10 s A2-20
Appendix 2 associated constraints, allowing for lateral and vertical guidance. In view of the reduced obstacle clearance associated with RNP AR procedures, the associated navigation database information warrants special attention and consideration. This paragraph provides guidance for validating RNP AR instrument approach data contained in aircraft navigation databases. The guidance in this paragraph applies in full to aircraft operators performing RNP AR instrument approach procedures, as well as to any other entity with which an operator may contract to provide navigation database validation services.
Note 1: Although an aircraft operator may contract with an outside entity to perform navigation database validation services, the operator is responsible for ensuring the aircraft navigation database contains RNP AR instrument approach procedures validated in accordance with this appendix.
Note 2: An aircraft operator’s application to conduct RNP AR procedures should specifically describe the extent and nature of the services provided by an outside entity contracted to perform navigation database validation services.
a. Database Management Process.
The operator must identify in writing the individual responsible for managing the overall onboard navigation database process. The process and procedures for accepting, verifying and loading navigation data into the aircraft must be established in writing and maintained under configuration control (e.g., formal control of revisions and updates to the process). The operator may not contract out this responsibility to a third party.
b. RNP AR Procedure Data Validation.
The operator must ensure an RNP AR instrument approach procedure contained in its database has been validated before flying that approach procedure in IMC. The validation process ensures the RNP AR procedure contained in the navigation database accurately reflects the intended procedure design parameters. Proper data validation includes the following:
(1) Accuracy Check.
Compare the RNP AR procedure in the navigation database with the government source data. The FAA Form 8260-series, specifically form 8260-3 and 8260-10, and other government source data defining the procedure, are available at the FAA Aviation System Standards website. Data for international procedures is available via the respective country’s aeronautical information publication (AIP). Any differences between the database and source data must be investigated. A list of the specific procedure data parameters that must be examined during this accuracy check, as well as the allowable differences between source data and that contained in the navigation database for each parameter can be found at the FAA’s Performance Based Flight Systems Branch (AFS-470) website located at:
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Appendix 2 http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/rnp/
(2) Flyability Check.
An initial flyability check is required for all non-part 97 U.S. RNP AR procedures, as well as all foreign RNP AR procedures the operator is authorized to fly. Validate the RNP AR instrument approach procedures in the navigation database to ensure they match the published instrument approach procedures using: the actual aircraft in visual meteorological conditions; a flight simulation training device (FSTD) approved for RNP AR; or an appropriately configured desktop/laptop computer. An FSTD or desktop/laptop computer must use software identical to that used by the aircraft (i.e., FMS software) and use an aerodynamic model of the aircraft's flight characteristics. A map display must be used in the aircraft, FSTD or computer to compare the database procedure with that published. This validation process requires flying the entire procedure and should confirm the path is flyable, does not contain any lateral or vertical discontinuities, and is consistent with the published procedure.
c. Data Updates.
(1) Before using an updated navigation database (e.g., 28 day update), the operator must ensure the RNP AR approach data contained in that update remains within the tolerances prescribed in paragraph A2-7.b(1) of this appendix, when compared to the government source data. If a data parameter is found to exceed prescribed tolerances , the operator should consult with the appropriate navigation data supplier to resolve the discrepancy prior to using the approach procedure. Discrepancies may be resolved by correcting the error within the current cycle, removal of the procedure from the database, or potentially through operational mitigations approved by the FAA until the procedure data can be corrected.
(2) The method by which an operator conducts this recurring data comparison is optional, subject to the approval of the principle operations inspector or flight standards district office. One acceptable method is to establish a reference database, sometimes referred to as a “golden database,” containing known validated approach data, and comparing data from subsequent navigation updates against this reference data. Some FMS suppliers provide automated tools that enable a quick comparison of data parameters between databases and alert to any changes or differences. Operators may also choose to compare the navigation data contained in the updated database directly against the government source data. Regardless of the method used, operators must assure the integrity of the validated navigation data at each update cycle.
Note: An operator should be particularly attentive to potential discrepancies when database updates coincide with a change to the data supplier’s packing software. This packing software is used to format the navigation data into code readable by aircraft avionics.
d. Data Suppliers.
As a minimum, data suppliers must have an LOA for processing navigation data in A2-22
Appendix 2 accordance with AC 20-153(latest revision). An LOA recognizes the data supplier as one whose data quality, integrity, and quality management practices are consistent with an acceptable process. The aircraft operator’s supplier (e.g., FMS manufacturer) must have a Type 2 LOA. Those entities providing data to the aircraft operator’s supplier likewise must possess either a Type 1 or Type 2 LOA.
e. Aircraft Modifications.
If a manufacturer modifies an aircraft system required for RNP AR operations
(e.g., software or hardware change), the operator must, before flying any RNP AR procedures in IMC, confirm the aircraft’s ability to fly RNP AR procedures as published, with the modified aircraft system(s). The operator should examine a number of RNP AR procedures in its navigation database for this flyability check. The criteria described in paragraph A2-7.b(2) of this appendix should be used to perform this check.
Note: The operator does not need to perform this additional confirmation if the manufacturer documents the modification has no effect on the navigation database, or path computation.
f. Recurrent Audits.
The processes identified in this paragraph for validating and updating RNP AR instrument approaches in navigation databases are subject to recurrent FAA audits. The operator’s processes, as well as those performed by any outside entity contracted to provide navigation database services, are subject to audit by the FAA. Additionally, operators are expected to conduct their own recurrent audits of entities with whom they contract to provide navigation database services described in this appendix.
A2-8. Installation Considerations for RNP AR.
a. Detailed Rationale.
The applicant should provide:
(1) RNP Certification Plan.
Provide detailed rationale in the RNP certification plan (or project specific certification plan) for the use of RNP. This rationale should include a detailed explanation as to how the assigned levels support the system safety assessment, as well as a detailed explanation of the system architecture, including any means used to mitigate hazards and failure conditions resulting from the use of RNP. Additionally, include a detailed explanation of the interfaces between the FD, the autopilot and other sensors, and avionics hardware/software required, as it relates to the computed commands used for RNP.
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Appendix 2
(2) Software Problem Reports.
Present clarification on how existing open software problem reports are resolved within the aircraft or other equipment that could directly or indirectly affect the RNP approval.
Open software problems or changes that could affect RNP operations should be addressed.
b. Failure Modes/Annunciation.
Identify any failure modes potentially affecting RNP capability. Verify annunciation of RNP failure modes exists. This verification should be compatible during manual flight and with the aircraft’s FGS to ensure unambiguous flight crew action(s). Verify that following failure modes, any pilot selected entries are retained or their cancellations annunciated (e.g., manual entry of RNP type, blackballed navaid, etc.). Typical failure modes include loss of electrical power, loss of signal reception, and RNP equipment failure (including degradation of navigation performance resulting in a loss of RNP containment integrity). The aircraft manufacturer should also verify that a visual alert within the flight crew’s primary field of view occurs with a loss of navigation capability and/or loss of RNP containment integrity.
An aural alert should accompany the visual alert.
c. Aircraft Manufacturer Installation Guidelines.
The aircraft manufacturer should comply with the following installation guidelines. Avionics manufacturers should note the following guidance to ensure their positioning and navigation equipment can support RNP operations.
(1) Each installation of RNP equipment requires an airplane flight manual containing the limitations and operating procedures applicable to the installed equipment. In addition, an RNP capabilities document for the system should be developed and submitted for FAA approval. The RNP capabilities document should be referenced in the airplane flight manual and made available to the operator upon request. The document will provide a description of the system, including assumed operating environment, the interface of the navigation function to the flight crew, the specific navigation capabilities of the system and potential application.
The intended use of the document will be to facilitate operational approval of the navigation capability for RNP operations. The flight manual or referenced capabilities document should contain at least the following information:
(a) A statement indicating the aircraft meets the requirements for RNP and demonstrated the established minimum RNP capabilities. This documentation should include:
the phase of flight (e.g., oceanic, enroute, terminal area, approach), mode of flight (e.g., manual, FD on or off, and/or autopilot on or off, and applicable lateral and vertical modes), minimum demonstrated RNP value, and sensor limitations, if any (e.g., GPS required). The phase of flight description should indicate what procedure design criteria the navigation performance is designed to support, as applicable.
(b) Any conditions or constraints on path steering performance (e.g., autopilot engaged, FD or manual control with CDI or map display, including lateral and vertical modes A2-24
Appendix 2 and/or CDI/map scaling requirements).
(c) The criteria used for the demonstration of the system, acceptable normal and non-normal procedures, the demonstrated configurations, type of facilities used, and any constraints or limitations necessary for safe operation.
(d) Define all the assumptions on systems external to the aircraft (e.g., signal in space performance, coverage, and survey accuracy). This includes GNSS-based limitations in the AFM(S)/RFM(S) for RNP AR APCH availability predictions at the destination, or checking NOTAMs. These predictions are consistent with the equipment performance described in chapter 5.
(i) A pre-departure RAIM prediction (FD or FDE as appropriate) is acceptable for GPS-based RNP AR operations that are limited to RNP AR 0.3 accuracy.
(ii) GPS/SBAS provides improved availability and enhanced accuracy during RNP AR operations. An RNP AR operation that is limited to RNP AR 0.3 accuracy based on GPS/SBAS only needs to confirm via NOTAM that there is no GPS/SBAS outage.
(iii) A pre-departure FDE RAIM prediction is acceptable for RNP AR operations limited to RNP AR 0.3 accuracy when outside of the GPS/SBAS coverage area or during a GPS/SBAS outage.
(iv) A pre-departure RNP prediction must be conducted prior to dispatch for accuracy values below RNP AR 0.3 (i.e., RNP AR < 0.3). If no RNP prediction capability is available (either external to the aircraft or within the navigation system), then the operator must not plan to use RNP AR < 0.3. Instead, the operator must plan to use RNP AR 0.3 if that line of minima exists for the procedure.
Note: The guidance on RNP prediction only applies to RNP AR operations conducted in the U.S. national airspace system. This does not apply to RNP AR operations in other ICAO States. When operating in another State’s airspace, operators must follow the RNP AR operational requirements for that State.
(2) If compliance to the continuity requirements has been shown through a combination of navigation sensors, the AFMS/RFMS should contain a statement that “Continuity of RNP navigation has been demonstrated only where the operational environment supports all of the following types of sensors: <insert type of sensors for which credit is being sought>.
d. Flight Technical Error (FTE).
The aircraft manufacturer should verify maintenance of FTE (95% of the flying time) during straight and curved path segments per Table 9. The FTE should be demonstrated in each phase of flight and each autopilot mode.
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Appendix 2
e. Interface to FGS.
Verify acceptable autopilot response to an RNP fault by simulating a representative fault consistent with the equipment architecture (e.g., pulling the circuit breaker) for the RNP equipment. The aircraft manufacturer should complete this test in each of the RNP and autopilot modes, as applicable.
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Appendix 3 Appendix 3. Advanced RNP Functions.
A3-1. Introduction.
a. ICAO document 9613 Performance Based Navigation (PBN) Manual, fourth edition, 2013 lists six advanced RNP functions. The six functions are:
• RF legs
• Parallel offsets
• Scalable RNP
• RNAV holding
• Fixed radius transitions (FRT)
• Time of arrival control (TOAC) Note: The PBN Manual includes Higher Continuity as an advanced RNP function. Higher continuity is not really a function, but a result of the hazard level associated with advance RNP functions affecting aircraft equipage (see paragraph A3-1.e).
b. The equipment must include RF legs, Parallel offsets, Scalable RNP, RNAV holding, and FRTs for advanced RNP recognition. The rationale for including all of these functions is for international harmonization. To include advanced RNP recognition, t he equipment, at a minimum, must meet the performance and functional criteria for RNP 2.0, RNP
1.0 and RNP APCH to LNAV minima.
(1) TSO-C115d implements RTCA/DO-283B which provides acceptable methods of implementing advanced RNP functions in RNP equipment consistent with the aircraft performance requirements found in RTCA/DO-236C, Chg 1.
(2) At present, the U.S. intends to implement only RF legs, Parallel offsets, and Scalable RNP which constitutes the U.S. definition of advanced RNP. RNAV holding, FRT, and TOAC are presently considered optional advanced RNP functions in the U.S.
(3) Other States may choose to implement a different subset of functions, or all six functions for their advanced RNP definition.
(4) At present, TOAC is a function for longer-term implementation and remains optional for all equipment due to uncertain equipment requirements and airspace implementation.
c. Equipment manufacturers may decide to only implement a select set of advanced RNP functions rather than implementing all functions for “advanced RNP” recognition.
Implementing selected functions means the equipment will have limitations for the functions not implemented. That is, aircraft using equipment with a reduced set of functions will not receive “advanced RNP” recognition. These aircraft will be restricted from airspace that requires functions not implemented in the equipment, or that requires “advanced RNP” A3-1
Appendix 3 recognition.
d. This appendix provides the additional equipment guidance unique to implementing advanced RNP functions. Equipment manufacturers that choose to include selected advanced RNP functions or “advanced RNP” recognition should provide an advanced RNP statement of capabilities document in the installation instructions/manual. Airworthiness approval holders must provide an AFM(S)/RFM(S) capabilities statement describing both the advanced RNP functions provided, and the advanced RNP functions not provided (if any).
Note: Advanced RNP functions may have aircraft-level integration dependencies necessary to implement the capability on the aircraft even though the avionics equipment itself includes the functions (see paragraph 12-7).
e. The continuity requirement for advanced RNP implementation is classified as a major failure condition that can be satisfied with dual independent equipage.
f. Manufacturers should refer to RTCA/DO-236C, Chg 1 and RTCA/DO-283B for requirements when implementing RF legs, parallel offsets, scalable RNP, RNAV holding, FRT, and TOAC. Equipment with advanced RNP functions previously approved to RTCA/DO 236B/-283A remains valid for those advanced RNP functions.
A3-2. Radius to Fix Leg Capability.
RF legs are an optional capability rather than a minimum requirement for RNP operations.
This capability can be used in the initial, intermediate, and missed approach segments of instrument approaches, RNP DPs and RNP STARS. Additional information on RF legs may be found in the Aeronautical Information Manual. For RNP systems incorporating RF leg capability, the systems must comply with the criteria in chapter 8 for RNP Approach, and chapter 9 for RNP 1.0 (terminal). Appendix 7 provides information on demonstrating RF leg capability. For RNP AR systems incorporating RF leg capability the RNP value can be less than 1.0., and RNP AR procedures may have RF legs intercept the final approach segment inside the final approach fix. RNP AR systems must comply with the criteria in appendix 2.
Note: In the U.S., RF legs will not intercept the final approach segment of an RNP approach inside the final approach fix. However, RF legs may do so for an RNP AR approach.
a. System Criteria.
(1) Path Definition.
Aircraft RNP lateral accuracy performance is evaluated around the path defined by the published procedure. RNP equipment should provide lateral guidance so aircraft remain within the lateral boundaries of the RF leg.
A3-2
--- Appendix 3
(2) Demonstration of Path Steering Performance.
The navigation system must have the capability to execute leg transitions and maintain tracks consistent with an RF leg between two fixes. There is no requirement for the aircraft to include a redundant navigation capability to perform RF legs should a loss of navigation occur during the RF leg. However, TC or STC applicants for RNP approval that include RF legs are encouraged to provide a redundant navigation capability on the aircraft that can maintain the RF leg track.
Note: The AFM/RFM or aircraft qualification guidance should document limitations if: 1) the aircraft cannot proceed “Direct-To” the initial fix defining an RF leg segment, 2) the aircraft cannot accept a radar vector (a heading assigned by ATC) to the middle of an RF leg segment for intercepting and completing the RF leg segment from that point while sustaining the desired level of performance.
(3) Flight Technical Error (FTE).
System documentation should support maintenance of FTE (95 percent of the flying time) during straight and curved path segments, for each phase of flight and each autopilot and/or FD mode requested. If using FTE values other than those listed in Table 9, the applicant must complete the demonstration in accordance with paragraph 17-2.
(4) Interface to FGS.
An acceptable autopilot and/or FD response to an RNP system failure or loss must be verified in each autopilot and FD mode, as applicable.
Note: If autopilot malfunction testing was performed for worst case failures, no further validation is required. In this case, the aircraft or equipment manufacturer must provide a statement of confirmation.
(5) Failure Modes/Annunciation.
System documentation should identify any failure modes potentially affecting RNP system RF Leg capability. Failure modes may include loss of electrical power, loss of signal reception, and RNP equipment failure, including navigation performance degradation, resulting in a loss of RNP containment integrity. The applicant should verify that a visible alert occurs within the flight crew’s primary field of view when loss of navigation capability and/or loss of integrity are experienced.
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Appendix 3
b. Functional Criteria.
(1) Autopilot and Flight Director.
Flight Standards requires using an autopilot or FD with at least “roll-steering” capability that is driven by the RNP system during RNP procedures with RF legs (see guidance in AC 90-105A). The autopilot/ FD must operate with suitable accuracy to track the lateral and, as appropriate, vertical paths required by a specific RNP procedure.
(2) Bank Angle.
The flight management computer, the FD system, and the autopilot must be capable of commanding a bank angle up to 30 degrees above 400 feet AGL. Aircraft with lower speeds will typically not achieve these bank angles in normal operations. For these aircraft it may be acceptable for the flight management computer, the FD system, and the autopilot to command bank angles less than 30 degrees consistent with their maximum airspeed provided the airworthiness applicant can demonstrate RF leg performance (see appendix 7).
For RNP AR applications, the flight management computer, FD system and autopilot must be capable of commanding a bank angle up to 8 degrees below 400 feet AGL.
Note: The specified bank angles comply with RTCA/DO-283B and RTCA/DO-236C, Chg 1. These are consistent with a common procedure design criteria that accommodates all aircraft categories; including those with the highest approach speeds.
(3) Electronic Map Display.
The aircraft should have an electronic map display depicting the RNP computed path of the selected procedure including RF legs. The map display should be capable of depicting the curved, RF leg segments without discontinuities on both active and inactive leg segments if a moving map display is included with or interfaced to the positioning and navigation equipment. Positioning and navigation equipment manufacturers should include a list of compatible moving map displays in the installation manual/instructions by part number, model, and/or software version as applicable to support RF leg capability.
(4) Maintaining LNAV in Missed Approach.
If abandoning a procedure while on an RF leg or initiating a go-around or missed approach (through activation of TOGA or other means), the flight guidance mode should remain in LNAV to enable deviation and positive course guidance display during an RF leg. If the aircraft does not provide this capability, crew procedures must be used that assure the aircraft will adhere to the specified flight path during the RF Leg segment.
Note 1: For missed approaches with an RF Leg, the flight crew must be able to couple the autopilot or FD to the RNP system (engage LNAV) by 500 feet AGL.
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Appendix 3 Note 2: For RNP AR, if the flight guidance does not remain in LNAV upon initiation of a go-around or missed approach, then the applicant and/or operator should define flight crew contingency procedures for maintaining compliance with the desired track and re-engaging LNAV as soon as possible. These contingency procedures should clearly address flight crew actions should a go-around or missed approach begin with the aircraft established on or having just completed an RF leg segment.
(5) Crew Workload Analysis.
The installation applicant should analyze the crew workload and determine acceptability when flying and monitoring track adherence in association with RF legs during all phases of flight, including those non-normal procedures that can be evaluated in flight.
c. System Approval - Eligibility Airworthiness Documents.
The flight manual or referenced document should contain the following information:
(1) A statement indicating the aircraft meets the criteria for RNP operations with RF legs and has demonstrated the established minimum capabilities for these operations. This documentation should include the phase of flight, mode of flight (e.g., FD on or off and/or autopilot on or off; and applicable lateral and vertical modes), minimum demonstrated RNP value, and sensor limitations, if any.
(2) Any conditions or constraints on path steering performance should be identified
(e.g., autopilot engaged, FD with map display, including lateral and vertical modes, and/or CDI/map scaling criteria). Use of manual control with CDI only is not allowed on RF legs.
(3) The applicant should identify the criteria used for the system demonstration, acceptable normal and non-normal procedures, the demonstrated configurations, type of facilities used, and any constraints or limitations necessary for safe operation.
A3-3. Parallel Offsets.
a. Parallel offsets can be used on route segments in enroute and terminal areas, and are intended to replicate all of the centerline route characteristics at the desired offset to the left or right of the centerline route. Parallel offsets are not intended for approach segments, arrivals, or departures. RTCA/DO-283B paragraph 2.2.1.2.7 provides detailed requirements for implementing parallel offsets in RNP equipment consistent with the aircraft performance requirements in RTCA/DO-236C Chg 1, paragraph 3.2.4.3.
Note: RTCA/DO-236C and RTCA/DO-283B requirements specify increments of 0.1 nm to support using parallel offsets for both terminal and enroute/oceanic A3-5