U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Approval Guidance for RNP Procedures with AR Date: 2/23/11 Initiated by: AFS-400 AC No: 90-101A Change:
1. PURPOSE. This advisory circular (AC) provides airworthiness and operational approval guidance material for aircraft operators conducting Title 14 of the Code of Federal Regulations (14 CFR) part 97 Area Navigation (RNAV) Required Navigation Performance (RNP) instrument approach procedures (IAP) with Authorization Required (AR), charted as “RNAV (RNP) RWY XX.” Hereafter, refer to these procedures as “RNP AR” within this AC. Operational approvals obtained under the guidelines of this AC also apply to existing RNAV (RNP) IAP with special aircraft and aircrew authorization required (SAAAR). As current RNAV (RNP) SAAAR instrument approach charts are revised or amended, they will be updated to reflect AR.
a. Method of Compliance. This AC provides a method of compliance with public RNP AR IAP requirements. In lieu of following this method without deviation, operators may elect to follow an alternative method, provided the alternative method is acceptable to the Federal Aviation Administration (FAA).
b. Language. This AC uses mandatory terms such as “must” only in the sense of ensuring applicability of these particular methods of compliance when using the acceptable means of compliance described herein. This AC does not change, add, or delete regulatory requirements or authorize deviations from regulatory requirements.
2. DEFINITIONS.
a. Area Navigation (RNAV). A method of navigation, which permits aircraft operation on any desired flightpath within the coverage of ground- or space-based Navigational Aids (NAVAID), within the limits of the capability of self-contained aids, or a combination of these.
b. Estimate of Position Uncertainty (EPU). A measure based on a defined scale in nautical miles (NM), which conveys the current position estimation performance, also known as Actual Navigation Performance (ANP) and Estimate of Position Error (EPE) in certain aircraft.
The EPU is not an estimate of the actual error, but a defined statistical indication.
c. Flight Management System (FMS). An integrated system, consisting of airborne sensor, receiver, and computer with both navigation and aircraft performance databases, which provides performance and RNAV guidance to a display and automatic flight control system (AFCS).
d. Global Positioning System (GPS). GPS is a U.S. satellite-based radio navigation system that provides a positioning service anywhere in the world. The definition of the service provided by GPS for civil use is in the GPS Standard Positioning System (SPS) Signal Specification. GPS
Page 2 Par 2 is the U.S. core Global Navigation Satellite System (GNSS) satellite constellation providing space-based positioning, velocity, and time. GPS is composed of space, control, and user elements.
e. Global Navigation Satellite System (GNSS). GNSS is a generic term for a worldwide position, velocity, and time determination system, which includes one or more satellite constellations, aircraft receivers, and system integrity monitoring. GNSS includes GPS, Satellite-Based Augmentation Systems (SBAS) such as the Wide Area Augmentation System (WAAS), Ground-Based Augmentation Systems (GBAS) such as the Local Area Augmentation System (LAAS), Global Orbiting Navigation Satellite System (GLONASS), GALILEO, and any other satellite navigation system approved for civil use. GNSS can be augmented as necessary to support the RNP for the actual phase of operation.
f. Primary Optimum Field of View (FOV). For the purpose of this AC, the primary optimum FOV is within 15 degrees of the pilot’s primary line of sight.
g. Radius to a Fix (RF) Leg. An RF leg is defined as a constant radius circular path, around a defined turn center, that starts and terminates at a fix. An RF leg may be published as part of a procedure.
h. Receiver Autonomous Integrity Monitoring (RAIM). An algorithm that verifies the integrity of the position output using GPS measurements or GPS measurements and barometric aiding.
i. Required Navigation Performance (RNP). RNP is a statement of the 95 percent navigation accuracy performance that meets a specified value for a particular phase of flight or flight segment and incorporates associated onboard performance-monitoring and alerting features to notify the pilot when the RNP for a particular phase or segment of a flight is not being met.
j. Required Navigation Performance (RNP) Value. The RNP value designates the lateral performance requirement in NM increments associated with a procedure. Examples of RNP values are RNP 0.3 and RNP 0.15.
3. RELATED READING MATERIAL (current editions).
a. Where You Can Find ACs/Orders/Notices. You can find this AC at http://www.faa.gov/regulations_policies/advisory_circulars and Orders/Notices at https://employees.faa.gov/tools_resources/orders_notices. Inspectors can also access this AC through the Flight Standards Information Management System (FSIMS) at http://fsims.avs.faa.gov (see the link to http://rgl.faa.gov). Operators and the public may find this information at http://fsims.faa.gov (see the link to http://rgl.faa.gov).
(1) Order 8400.12, Required Navigation Performance 10 (RNP 10) Operational Authorization;
(2) Order 8260.52, United States Standard for Required Navigation Performance (RNP) Approach Procedures with Special Aircraft and Aircrew Authorization Required (SAAAR);
Par 3 Page 3
(3) AC 20-138, Airworthiness Approval of Positioning and Navigation Systems;
(4) AC 20-153, Acceptance of Data Processes and Associated Navigation Databases;
(5) AC 25.1309-1, System Design and Analysis;
(6) AC 25-15, Approval of Flight Management Systems in Transport Category Airplanes;
(7) AC 120-29, Criteria for Approval of Category I and Category II Weather Minima for Approach; and
(8) AC 120-91, Airport Obstacle Analysis.
b. RTCA, Inc., Documents. Obtain copies of the following RTCA documents from RTCA, Inc., 1828 L Street, NW, Suite 805, Washington, DC 20036, or purchased online at http://www.rtca.org:
(1) RTCA/DO-178B, Software Considerations in Airborne Systems and Equipment Certification;
(2) RTCA/DO-187, Minimum Operational Performance Standards for Airborne Area Navigation Equipment Using Multi-Sensor Inputs;
(3) RTCA/DO-189, Minimum Operational Performance Standards for Airborne Distance Measuring Equipment (DME) Operating within the Radio Frequency Range of 960-1215 MHz;
(4) RTCA/DO-200A, Standards for Processing Aeronautical Data;
(5) RTCA/DO-201A, Standards for Aeronautical Information;
(6) RTCA/DO-208, Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS);
(7) RTCA/DO-229D, Minimum Operational Performance Standards for Global Positioning System/Wide Area Augmentation System Airborne Equipment;
(8) RTCA/DO-236B, Minimum Aviation System Performance Standards: Required Navigation Performance for Area Navigation; and
(9) RTCA/DO-283A, Minimum Operational Performance Standards for Required Navigation Performance for Area Navigation.
c. FAA Technical Standard Orders (TSO). Obtain copies of the following TSOs from the U.S. Department of Transportation, Publications Department, Ardmore East Business Center, 3341Q 75th Avenue, Landover, MD 20785:
(1) TSO-C115b, Airborne Area Navigation Equipment Using Multi-Sensor Inputs;
Page 4 Par 3
(2) TSO-C129a, Airborne Supplemental Navigation Equipment Using the Global Positioning System (GPS);
(3) TSO-C145c, Airborne Navigation Sensors Using the Global Positioning System (GPS) Augmented by the Satellite Based Augmentation System; and
(4) TSO-C146c, Stand-Alone Airborne Navigation Equipment Using the Global Positioning System Augmented By The Satellite Based Augmentation System.
4. BACKGROUND. RNP AR approaches provide an unprecedented level of flexibility in construction of approach procedures. These operations are RNAV procedures with a specified level of performance and capability. RNP AR approach procedures build upon the performance-based National Airspace System (NAS) concept. When RNP approaches replace visual or Nonprecision Approaches (NPA) safety is enhanced and efficiency improves through more repeatable and optimum flightpaths. A predefined aircraft capability and navigation system are the basis for conventional obstacle evaluation areas for ground-based NAVAIDs. The RNP AR criteria design is flexible in order to adapt to unique operational requirements, which can include avoiding terrain or obstacles, de-conflicting airspace, or resolving environmental constraints. This allows for approach-specific performance requirements.
a. AR. RNP AR approaches include unique capabilities that require special aircraft and aircrew authorization similar to Category (CAT) II/III instrument landing system (ILS) operations. All RNP AR approaches have reduced lateral obstacle evaluation areas and vertical obstacle clearance surfaces predicated on the aircraft and aircrew performance requirements of this AC. In addition, selected procedures may require the capability to fly an RF leg and/or a missed approach, which requires RNP less than 1.0. Appendix 2 of this AC identifies specific aircraft requirements that apply to these capabilities.
b. Navigation Performance Monitoring. A critical component of RNP is the ability of the aircraft navigation system to monitor its achieved performance and to identify for the pilot whether the performance meets set standards during an operation.
5. APPROVAL.
a. Overview. Operators may receive operational approval to conduct RNP AR IAPs through operations specifications (OpSpecs), management specifications (MSpecs), or letters of authorization (LOA), as appropriate to the operator. Operators should comply with the requirements in Appendices 2 through 6. Appendix 7 describes information operators should submit when seeking approval for RNP AR operations. It contains a checklist to use as a guide in preparing the application, as well as an approval process flowchart. Prior to application, operators and manufacturers should review all performance requirements. Installation of equipment by itself does not guarantee final approval for use.
NOTE: Operational approvals issued under the guidance of AC 90-101 also apply to RNP AR approach procedures.
b. Aircraft Qualification and Initial Acceptance of Recommended Operational Documentation.
Par 5 Page 5
(1) Aircraft Qualification Documentation. Aircraft manufacturers should develop aircraft qualification documentation showing compliance with Appendix 2. This documentation identifies the optional capabilities (e.g., RF legs and RNP missed approaches), the RNP capability of each aircraft configuration, and the navigation system characteristics that may require operational mitigations to meet the requirements of this AC. This documentation should also define the recommended RNP maintenance procedures.
(2) RNP AR Operational Documentation. Aircraft manufacturers are strongly encouraged to develop RNP AR operational documentation. This documentation would provide operators of their aircraft with recommended procedures/practices for: Navigation Database (NDB) validation, flying RNP AR instrument approaches, pilot/dispatcher RNP AR training, and an RNP monitoring program, all in accordance with the requirements of Appendices 3 through 6 of this AC. The operator’s use of manufacturer-developed and FAA-accepted operational documentation would likely facilitate the operational approval process.
(3) FAA Acceptance.
(a) For new aircraft, approval of the aircraft qualification documentation can be part of an aircraft certification project and reflected in the Aircraft Flight Manual (AFM) and related documents. The Aircraft Evaluation Group (AEG) may also receive the RNP AR operational documentation and coordinate with the Flight Technologies and Procedures Division (AFS-400) for final acceptance.
(b) For existing aircraft, the aircraft manufacturer should submit the aircraft qualification and RNP AR operational documentation to AFS-400. AFS-400 will coordinate with other FAA offices and may accept the package as appropriate for RNP AR operations. AFS-400 will document acceptance in a letter to the aircraft manufacturer.
c. Operator Approval. Title 14 CFR part 91, 91 subpart K (part 91K), 121, 125, or 135 operators should provide their Flight Standards District Office (FSDO)/certificate-holding district office (CHDO) with the information listed in Appendix 7, reflecting compliance with the requirements of Appendices 2 through 6. Aircraft qualification and operational documentation provided by the aircraft manufacturer and accepted by the FAA will facilitate the operator’s preparation of the items listed in Appendix 7. The FSDO/CHDO will coordinate with FAA headquarters (HQ) in accordance with Appendix 7, Figure 2, RNP AR Application Flow.
Once the operator has satisfied the requirements of this AC, or equivalent, the FSDO/CHDO issues OpSpecs, MSpecs, or an LOA authorizing RNP AR approach procedures.
(1) Interim Authorization. Ordinarily, operators will have authorization to conduct RNP AR approaches using minima associated with RNP 0.3, for a period of 90 days and until the operator has accumulated 100 AR approaches in each aircraft type. For approach procedures with no line of minima associated with RNP 0.3, you must fly the procedure in visual meteorological conditions (VMC).
NOTE: Operators experienced with equivalent RNP approaches may receive credit toward the interim authorization requirements.
NOTE: Experienced RNP AR operators operating new or upgraded aircraft types/systems, derivative types, or different aircraft types with identical crew
Page 6 Par 5 interface and procedures may use reduced interim authorization periods
(e.g., less than 90 days and 100 approaches) as determined by the CHDO/FSDO.
NOTE: In unique situations where the completion of 100 successful approaches could take operators an unreasonably long period of time due to factors such as a small number of aircraft in the fleet, limited opportunity to use runways having appropriate procedures, etc., consideration of a reduction in the required number of approaches will be on a case-by-case basis. The FSDO/CHDO will coordinate with FAA HQ in consideration of an operator’s request for reduced interim authorization requirements.
(2) Final Authorization. The CHDO/FSDO will issue OpSpecs, MSpecs, or LOA authorizing use of lowest applicable minima after operators satisfactorily complete their interim authorization period and upon the CHDO/FSDO review of reports from the operator’s RNP monitoring program.
(3) Aircraft Modification. If any aircraft system required for RNP AR is modified
(e.g., software or hardware change/revision), the operator must obtain the manufacturers’ updated aircraft qualification and operational documentation confirming continued suitability for RNP AR approach operations. AFS-400 and either AFS-200 or AFS-800, must approve the operator’s use of the aircraft with modifications for RNP AR operations. The FSDO/CHDO should coordinate with AFS-470 to facilitate processing of the operator’s request for operational approval with the changed/revised equipment.
ORIGINAL SIGNED by /s/ John McGraw for
John M. Allen Director, Flight Standards Service
Appendix 1 APPENDIX 1. RNP AR IAPs
1. Introduction. Federal Aviation Administration (FAA) Order 8260.52, United States Standard for Required Navigation Performance (RNP) Approach Procedures with Special Aircraft and Aircrew Authorization Required (SAAAR), defines the procedure design criteria for RNP Authorization Required (AR) approaches. This appendix provides a summary of the key characteristics of RNP AR approach procedures. Sample, illustrative approach charts are shown in Figures 1 and 2.
2. Characteristics of RNP AR Approaches.
a. RNP Value. Each published line of minima has an associated RNP value. For example, Figure 2 shows both RNP 0.3 and RNP 0.15 lines of minima. Each operator’s RNP AR authorization documents a minimum RNP value, and this value may vary depending on aircraft configuration or operational procedures (e.g., use of flight director (FD) with or without autopilot). RNP AR approaches will have an RNP value of RNP 0.3 or less.
b. Procedures with Radius to a Fix (RF) Legs. Some RNP AR approaches include RF legs. The instrument approach charts will indicate requirements for RF legs in the notes section or at the applicable initial approach fix (IAF). Figures 1 and 2 provide examples of procedures with an RF leg segment (e.g., between SKYCO and CATMI).
c. Missed Approaches Requiring Less Than RNP 1.0. At certain locations, the airspace or obstacle environment may require RNP capability of less than 1.0 during a missed approach.
Operation on these approaches typically requires redundant equipment. This requirement ensures that no single point of failure can cause loss of RNP capability. Figure 2 provides an example of a missed approach requiring RNP less than 1.0. The notes section of the chart indicates this requirement.
d. Non-Standard Speeds or Climb Gradients. Normally, RNP AR approach procedure design relies on standard approach speeds and climb gradients including on the Missed Approach Segment (MAS). The approach procedure will indicate any exceptions to these standards, and the operator must ensure it can comply with any published restrictions before conducting these approach operations. Figure 2 provides an example of a non-standard climb gradient and speed restrictions.
e. Temperature Limits.
(1) The RNP AR approach chart will identify outside air temperature limits applicable to operators using barometric vertical navigation (baro-VNAV). Cold temperatures reduce the effective glide path angle while high temperatures increase the effective glide path angle without cockpit indication of the variation. Figures 1 and 2 provide examples of temperature limits.
NOTE: Temperature affects the aircraft’s altitude indications. The effect is similar to high and low pressure changes, although not as significant. When temperature is higher than the International Standard Atmosphere (ISA), the aircraft will be higher than the indicated altitude. When temperature is lower than standard, the aircraft will be lower than indicated on the
Appendix 1 altimeter. For additional information, refer to the Altimeter Errors paragraph in chapter 7 of the Aeronautical Information Manual (AIM).
(2) Operators using baro-VNAV in an aircraft with an airworthiness approval for automatic temperature compensation, or in an aircraft using an alternate means for vertical guidance (e.g., Satellite-Based Augmentation Systems (SBAS)), may disregard the temperature limits (high temperature limit still applies if the system only compensates for low temperature).
f. Aircraft Size. Aircraft size may determine the minimums for an RNP AR approach procedure. Large aircraft may require higher minimums due to gear height and/or wingspan.
Approach charts will annotate any applicable aircraft size restrictions when appropriate. Figure 1 provides an example of an aircraft size restriction.
Appendix 1 FIGURE 1. EXAMPLE OF RNP AR APPROACH PROCEDURES WITH A RADIUS TO
A FIX LEG SEGMENT ANYTOWN, USA AL-330 (FAA) APP CRS Rwy Idg 8000 RNAV (RNP) Y RWY 28R THRE 26 281° Apt Elev 30 ANYTOWN (ANY) T GPS required. Procedure NA for aircraft with wingspan greater than 136 feet. MALSR MISSED APPROACH: Climb on track A For uncompensated Baro-VNAV systems, Procedure NA below -5°C (23°F) or above 40°C (104°F). 281° to FIKOG and hold.
ATIS ANYTOWN APP CON ANYTOWN TOWER GND CON CINC DEL ARR 128,35 269,9 DEP 120,625 239,25 124,35 299,2 118,7 257,8 Rwy 10L-28R 123,775 251,125 Rwys 3-21, 10R-28L 121.9 348,6 120.125 318.1 ASA RW 28 25 N (RF REQD) (IAF) (RNP 0.15 5900 -PROTOTYPE NOT
DEMGE FOR NAVIGATION (IAF) **/ 280° 4 NM BATTLEGROUND (RNP 0.15) (RF REQD) BTG 0-1500 (4.3) 103° LARIE A ·50o 1700 A FIKOG 000 SKYKO 1300 251° (IAB ELEV 30 Ramy 2 1 18g 6321 RW28R 281% (2.3) 1800 FATIG 200 KIAS. 1000 ROVRE DMIVZ DIKKE CATMI (IF) (5.6) 257° 3600 261°+ 281° CATMI W 2040 DMIZ DIKKE = 251°-1800 THRE 26 FIKOG ©9%‡ • 281°- +251 1300 RW28R 1300 A96‡ 130+ GP 3.00° TCH 65
- 2.3 NM- RW28R 281ª to CATEGORY D RNP 0.15 276/40 250(300-34) RNP 0.3 346-1 320(400-1) REIL Rwys 3 and 21 TDZ/CL Rwy 10R AUTHORIZATION REQUIRED MIRL Rwy 3-21 HIRL Rwys 101-28R and 10R-28L
ANYTOWN, USA ANYTOWN (ANY) Orig 00000 45°35 N-12236W RNAV (RNP) Y RWY 28R Page 3
Appendix 1 FIGURE 2. EXAMPLE OF RNP AR APPROACH PROCEDURES WITH A RADIUS TO
A FIX LEG SEGMENT WITH A MISSED APPROACH REQUIRING RNP LESS THAN 1.0 ANYTOWN, USA AL-330 (FAA) APP CRS 281° Rwy lag THRE Apt Elev 8000 30 26 RNAV (RNP) Z RWY 28R ANYTOWN (ANY) GPS required. RF required. Missed approach requires T RNP less than 1.0. For uncompensated Baro-VNAY systems, MALSR MISSED APPROACH: Climb on Procedure NA below -5°C (23°F) or above 40°C (104°F) A * Requires Missed Approach Climb Gradient of 380 ft/NM to 4000'.
** Requires Missed Approach Climb Gradient of 425 it/NM to 4000* *** Requires Missed Approach Climb Gradient of 360 It/NM to 4000' and hold.
ARR 128,35 269,9 ATS ANYTOWN APP CON Rwy 10L-28R ANYTOWN TOWER Rwys 3-21, 10R-28L GND CON CINC DEL DEP 120,625 239,25 124,35 299,2 118,7 257,8 123,775 251,125 121,9 348,6 120.125 318.1 NASA RIN 28 25 NA (RNP 0.15 (LAF) KRATR 5900]
- DEMGE PROTOTYPE NOT 4 NM FOR NAVIGATION / 2800 8 (IAF) 100% (RNP 0.15) C4500
BATTLEGROUND BTG 1Q3.
LARIE 4500 WODYU 000 SKYKO 1300 HAMIT 251° ELEV 30 twy 3 lag 6321 RW28R + 281 (2.3) 1800 FATIG 200 KIAS. 1000 ROVRE twy 21 Idg 6321 DMIYZ DIKKE CATMI (IF) (5.6) 257°. 3600 261° 281° 4000 011° BTG CATMI † DMIYZ DIKKE 1251°-1800 THRE 291_ 26 HAMIT WODYU • 281° - +251° 1300 RW28R 1300 A961 GP 3.00° TCH 65 52 NM - - 2.3 NM - - 23 NM - 281° to CATEGORY RW28R * RNP 0.15 276/40 250(300-⅞) ** RNP 0.3 346-1 320(400-1) ***RNP 0.15 426-1 400(500-1) RNP 0.3 486-14 460(500-11) REIL Rwys 3 and 21 TDZ/CL Rwy 10R MIRL Rwy 3-21 AUTHORIZATION REQUIRED HIRL Rwys 10L-2BR and 10R-28L
ANYTOWN, USA ANYTOWN (ANY) Orig 00000 45°35 N-122-36W RNAV (RNP) Z RWY 28R Page 4
Appendix 2
Page 1 APPENDIX 2. AIRCRAFT QUALIFICATION
1. Introduction. This appendix describes the performance and functional criteria for aircraft to qualify for RNP AR approaches. Applicants may establish compliance with this appendix as part of a type certification or Supplemental Type Certification (STC) and document this in the Aircraft Flight Manual Supplement (AFMS). The type-certificate holder of a previously certified aircraft can document compliance with these aircraft qualification criteria without a new airworthiness project (e.g., without an Aircraft Flight Manual (AFM) change), and should advise the appropriate Aircraft Certification Office (ACO) of any new performance not covered by the original airworthiness approval. The AFM or other aircraft qualification evidence should address: the required modes of operation to fly an RNP AR approach, the normal and abnormal flightcrew operating procedures, responses to failure alerts and annunciations, and any other operating limitations. In addition to the specific RNP AR guidance in this document, the aircraft must comply with the current edition of AC 20-138, Airworthiness Approval of Positioning and Navigation Systems.
2. Performance Requirements. This paragraph defines the general performance requirements for aircraft qualification. Paragraphs 3, 4, and 5 provide guidance material on an acceptable means of satisfying these requirements.
a. Path Definition. The published instrument approach procedure (IAP) and section 3.2 of RTCA/DO-236B define the path the aircraft must use to evaluate performance. The aircraft’s navigation system will also define all vertical paths in the Final Approach Segment (FAS) by a Flight Path Angle (FPA) (RTCA/DO-236B, Section 3.2.8.4.3) as a trajectory to a fix and altitude.
b. Lateral Accuracy. The aircraft must comply with section 2.1.1 of RTCA/DO-236B.
c. Vertical Accuracy. The vertical system error includes altimetry system error (assuming the temperature and lapse rates of the International Standard Atmosphere (ISA)), the effect of along-track error, system computation error, data resolution error, and Flight Technical Error (FTE). The 99.7 percent of system error in the vertical direction must be less than the following (in feet):
() ( )() () () () () ()( ) 22 22 28 36076115 1 225 60 75 88 10 65 10 50.. t a n t a n . .R N P hh hhθθ Δ Δ −−⋅+ + + − ⋅ + + ⋅ + +
NOTE: Where θ is the vertical navigation (VNAV) path angle, h is the height of the local altimetry reporting station and Δh is the height of the aircraft above the reporting station.
d. Airspace Containment. The FAA publishes RNP AR approaches as performance-based approaches. As such, they do not inherently require any specific technology or procedure but instead require a level of performance.
(1) Primary Means of Compliance. This AC provides a detailed acceptable means of compliance for aircraft using an Area Navigation (RNAV) system relying primarily on Global
Appendix 2
Page 2 Navigation Satellite System (GNSS) and a VNAV system relying on barometric altimetry or Satellite-Based Augmentation Systems (SBAS). Paragraphs 3, 4, and 5, in conjunction with guidance described in Appendices 3 and 4, describe an acceptable means of achieving the required navigation performance. Aircraft and operations complying with these paragraphs provide the requisite airspace containment.
(2) Other Systems or Alternative Means of Compliance (AMOC). For other systems or AMOC, the probability of the aircraft exiting the lateral and vertical extent of the obstacle clearance volume (see FAA Order 8260.52, United States Standard for Required Navigation Performance (RNP) Approach Procedures with Special Aircraft and Aircrew Authorization Required (SAAAR)), must not exceed 10-7 per approach, including the missed approach. An operator may satisfy this requirement through an operational safety assessment applying:
appropriate quantitative, numerical methods; qualitative operational and procedural considerations and mitigations; or an appropriate combination of both quantitative and qualitative methods.
NOTE: If the aircraft does not remain within the obstacle clearance volume after annunciating the system’s failure, then this requirement applies to the total probability of excursion outside the obstacle clearance volume. This includes events caused by latent conditions (integrity) and by detected conditions (continuity). When ensuring the aircraft does not exit the obstacle clearance volume, an analysis of the aircraft performance should consider the monitor limit of the alert, the latency of the alert, the crew reaction time, and any aircraft response to the alert. The requirement applies to a single approach, considering the exposure time of the operation and the Navigational Aid (NAVAID) geometry and navigation performance available for each published approach.
NOTE: This containment requirement derives from the operational requirement. This requirement is notably different from the containment requirement specified in RTCA/DO-236B. The requirement in RTCA/DO-236B facilitates airspace design and does not directly equate to obstacle clearance.
e. System Monitoring. The critical components of RNP AR approach procedure implementation are the RNP requirements of the approach and the ability of the aircraft navigation system to both monitor navigation performance and alert the pilot when RNP requirements are not being met.
3. RNP AR General Requirements.
NOTE: RTCA/DO-236B provides additional information concerning many of the required functions for RNP AR aircraft qualification.
a. Position Estimation. The navigation system must estimate the aircraft’s position. This section identifies unique issues for the navigation sensors within the context of RNP AR instrument approaches.