2 Learning Objectives Organisation of PBN Manual Vol II Vol II Part A, GeneralPBN concept reviewNavigation performanceSystem performance error componentsRole and application of on-board performance monitoring and alertingUse of navigation specificationsRelationship with existing criteriaVol II Parts B and CSummary
3 Organisation of PBN Manual, Volume II Part A: GeneralPart B: Implementing RNAV (including RNAV Specifications)Part C: Implementing RNP (including RNP Specifications)Attachment A: Barometric VNAV
4 PBN Concept Review 3 2 1 NAVIGATION APPLICATION NAVAID NAVIGATION SPECIFICATION2NAVAIDINFRASTRUCTURE1As you know, a Navigation Application is the application of a navigation specification and associated navaid infrastructure to ATS routes, instrument approach procedures and/or defined airspace volume.In simple terms a Navigation Specification describes in detail the requirements for an Area Navigation (RNAV) System for operation along a specific ATS route or procedure.
5 PBN Concept Review Requirements placed on the RNAV system Performance required for accuracy, integrity, continuity and availabilityFunctions available to achieve required performanceNavigation sensors to achieve required performanceFlight crew procedures to achieve required performanceRNP specifications require on-board performance monitoring and alerting…RNAV specifications do not
6 Navigation Performance System performance error componentsLateral navigation errorsLongitudinal navigation errorsOn-board performance monitoring and alertingRoleApplication
7 System Performance Error Components (1) Lateral navigation errors (95%)3 main errors: PDE, NSE and FTEThe inability to achieve the required lateral navigation accuracy may be due to navigation errors related to aircraft tracking and positioning.The three main errors in the context of on-board performance monitoring and alerting are Path Definition Error (PDE), Flight Technical Error (FTE), and Navigation System Error (NSE).The distribution of these errors are assumed to be independent, zero-mean and Gaussian. Therefore, the distribution of Total System Error (TSE) is also Gaussian with a standarddeviation equal to the Root Sum Square (RSS) of the standard deviations of these three errors.PDE occurs when the path defined in the RNAV system does not correspond to the desired path i.e. the path expected to be flown over the ground. Use of an RNAV system for navigation presupposes that a defined path representing the intended track is loaded into the navigation database.NSE refers to the difference between the aircraft’s estimated position and actual position.Note. – NSE is sometimes referred to as Positioning Estimation Error (PEE)FTE relates to the air crew or autopilot’s ability to follow the defined path or track, including any display error (e.g., CDI centering error). FTE can be monitored by the autopilot or air crew procedures and the extent to which these procedures need to be supported by other means depends, for example, on the phase of flight and the type of operations. Such monitoring support could be provided by a map display.Note. – FTE is sometimes referred to as Path Steering Error (PSE)
8 System Performance Error Components (2) Longitudinal navigation errors (95%)Along-track navigation errors (NSE)No FTE in longitudinal dimensionNo current navigation specifications require 4-D controlThe accuracy requirement of RNAV and RNP specifications are defined for the lateral and along-track dimensions i.e., NSE is considered as a radial error and PDE is considered negligible.There is no declared FTE in the longitudinal dimension. It is really a time differential.Note: The on-board performance monitoring and alerting requirements of RNP specifications are defined for the lateral dimension. However, because NSE is considered as a radial error, the on-board performance monitoring and alerting is effectively provided in all directions.Longitudinal performance implies navigation against a position along the track (e.g., 4-D control).At the present time, there are no Navigation Specifications requiring 4-D control.
9 Role of On-board Performance Monitoring and Alerting (1) The PBN concept uses “on-board performance monitoring and alerting” instead of “containment”The associated ICAO terms were previously containment area, contained airspace, containment value, containment distance, obstacle clearance containmentReplaced by the navigation accuracy of TSEThe PBN concept uses “on-board performance monitoring and alerting” instead of “containment”Avoids confusion between existing uses of “containment” in various documents by different areas of expertiseFor example:a) Containment has referred to the region within which the aircraft will remain 95% of the time. The associated terms have been containment value and containment distance and the related airspace protection on either side of a RNAV ATS route.b) Within PANS-OPS material, containment has referred to the region used to define the obstacle clearance, and the aircraft is expected to remain within or above that surface (regardless of alerting) with very high probability.c) Within the industry standards of RTCA/DO-236() and EUROCAE/ED-75, containment referred to the region that the aircraft will remain when there is no alert ( probability). The associated terms are containment limit, containment integrity, containment continuity, and containment region.
10 Role of On-board Performance Monitoring and Alerting (2) Allows the flight crew to determine whether the RNP system satisfies the navigation performance required in the navigation specificationDependent on system architectureRelates to both lateral and longitudinal navigation performance
11 Role of On-board Performance Monitoring and Alerting (3) “On-board” means the performance monitoring and alerting is on-board the aircraft“Monitoring” relates to NSE and FTEPDE is constrained through database integrity and functional requirements on the defined path“Monitoring” refers to the monitoring of the aircraft’s performance; ability to determine positioning error and/or to follow the desired path“Alerting” is related to monitoringFlight crew alerted if navigation system not performing to requirement“On-board” means the performance monitoring and alerting is on board the aircraft and not elsewhere (e.g., using a ground-based route adherence monitor or ATC surveillance)“Monitoring” relates to FTE and NSEPDE is constrained through database integrity and functional requirements on the defined path, and is considered negligible.“Monitoring” refers to the monitoring of the aircraft’s performance as regards its ability to determine positioning error and/or to follow the desired path.
12 Application of On-board Performance Monitoring and Alerting (1) Aircraft (or aircraft and pilot in combination)Required to monitor TSEProvides an alert if accuracy requirement is not met, or if probability that TSE exceeds 2x accuracy value is larger than 10-5Net effect of RNP navigation specifications is to bound TSE distributionPDE negligible; FTE known; NSE variesRecall error components:PDEFTENSESince PDE is assumed to be negligible, reduced to FTE and NSE.FTE is assumed to be a function of a given flight control mode (e.g., Manual, or Flight Director, or Autopilot).However, NSE distribution varies over time due to changing characteristics, most notably fromSelected NAV sensorsRelative geometry (GNSS, DME)
13 Application of On-board Performance Monitoring and Alerting (2) RNP navigation specifications provide assurance that TSE is suitable for the operationAircraftTSE remains ≤ required accuracy for 95% of flight time; andProbability TSE for each aircraft exceeds specified TSE (2xRNP) without annunciation is < 10-5Performance monitoring is not error monitoringTypically, the 10-5 TSE requirement provides the greater restriction on performance.For example, any system with Normal distribution of XTKE, the 10-5 monitoring requirement constrains the standard deviation to be 2 x (accuracy value) / 4.45 = accuracy value / 2.23, while the 95% requirement would have allowed the standard deviation to be as large as the accuracy value / 1.96.While these characteristics define the minimum requirements that must be met, they do not define the actual TSE distribution.Actual TSE distribution may be expected to be typically better than the requirement, but there must be evidence on the actual performance if a lower TSE value is to be used.There can be significant variability in how individual errors are managedSome systems monitor actual XTKE and ATKE individually, while others monitor the radial NSE to simplify the monitoring and eliminate dependency on aircraft track (e.g., based on typical elliptical 2-D error distributions)Some systems include FTE in the monitor, by taking current value of FTE as a bias on the TSE distributionFor Basic GNSS systems, the accuracy and 10-5 requirements are met as a by-product of the ABAS requirements, defined in equipment standards, and the FTE distribution for the standardized CDI displays.Performance monitoring is not error monitoringPerformance monitoring alert issued with the system cannot guarantee, with sufficient integrity, that the position meets the accuracy requirement.When such an alert is issued, probable reason is loss of capability to validate the position data (insufficient satellites).For such a situation, most likely position of aircraft is what is shown on display. Likelihood of TSE exceeding twice accuracy value just prior to alert is approximately 10-5However, cannot assume that simply because there is no alert, the TSE is less than twice the accuracy value.Example: Aircraft accounting for FTE based on fixed error distribution. If FTE grows large, no alert is issued by the system even when the TSE is many times larger than the accuracy value.For this reason, operational procedures to monitor FTE are important.
14 Application of On-board Performance Monitoring and Alerting (3) Safety assessmentPerformance monitoring and alerting for RNP 4, Basic-RNP 1 and RNP APCH does not obviate need for safety assessmentsCannot assume appropriate route spacing is 4xRNPNavigation database errors not covered by nav specsRNP AR APCHAdditional requirements to more tightly control each error sourceRisk EvaluationsCannot assume appropriate route spacing is 4xRNP, because:Collision risk depends on probability of loss of separation in dimension under consideration, and the exposure to that loss of separation.Exposure may be evaluated over time (i.e., to conduct an instrument approach), or over the number of risk events (e.g., number of aircraft that will be passed in an hour).RNP AR APCHRequirements can be tighter and a number of additional requirements are applied to more tightly monitor or control each error source.2 ways to determine obstacle clearance through analysis1. Derive obstacle clearance from TLS, given predetermined aircraft requirements and operational mitigations2. Derive aircraft requirements and operational mitigations from TLS, given predefined obstacle clearance criteria.Methodology applied for RNP AR used this second method.RNP AR APCH operations was first established to have a total width of 4x the accuracy value (+/- 2x accuracy value centered on the path), after which the aircraft requirements and operational mitigations were then developed to satisfy the TLS.
15 Use of Navigation Specifications Use and scope of navigation specifications by flight phaseRelationship with existing criteriaVol II, Parts B and C organisationNavigation specification template
16 Use and Scope of Navigation Specification by Flight Phase PBN Manual includes airworthiness, operational and training guidanceNAVIGATION SPECIFICATIONFLIGHT PHASEEn Route Oceanic / RemoteEn Route ContinentalARRAPPROACHDEPInitialIntermedFinalMissedRNAV 10 (RNP 10)10RNAV 55*5RNAV 22RNAV 111bRNP 44 Basic-RNP 11a,c1a1a,bRNP APCH0.3RNP AR APCHNotes: The numbers given in the table refer to the 95% accuracy requirements (NM)RNP 2 and Advanced-RNP 1 are expected to be included in a future revision of the PBN Manual;1a means that the navigation application is limited to use on STARs and SIDs only;1b means that the area of application can only be used after the initial climb of a missed approach phase1c means that beyond 30 NM from the airport reference point (ARP), the accuracy value for alerting becomes 2 NM* Means Above MSATHIS IS A REVIEWIncorporate existing operations as practicalRNAV 10 (designated and authorized as RNP-10)B-RNAV renamed as RNAV 5RNP APCH includes existing RNAV(GNSS) approachesAdditional guidance on barometric VNAVHarmonized European and US RNAVVolume II, Part B, Chapter 3: RNAV-1 and RNAV-2Considered limited terminal arrival/departure ATS surveillanceVolume II, Part C, Chapter 3: Basic RNP-1
17 Use and Scope of Navigation Specifications ICAO navigation specifications do not address all airspace requirements (e.g., comm, surv) necessary for operation in a particular airspace, route or areaThese will be listed in the AIP and ICAO Regional Supplementary ProceduresIncumbent upon States to undertake a safety assessment in accordance with provisions outlined in Annex 11 and PANS-ATM, Chapter 2ICAO PBN Manual provides a standardized set of criteria, but is not a stand-alone certification documentExamples: RNP 4, RNAV 1, RNP AR APCH
18 Navigation Specifications and the Approval Process Navigation specifications are used by States as basis for aircraft certification and operational approvalA navigation specification does not in itself constitute regulatory guidance materialAircraft approved by State of manufactureOperators approved in accordance with their National Operating RulesCompliance with one navigation specification does not guarantee compliance with anotherNavigation specification do not in itself constitute regulatory guidance material against which the aircraft or operator will be approvedFor example, with RNAV 2/ RNAV 1, there is still a need to have an approval process. This could be either through a dedicated approval document or through recognition that existingregional RNAV implementation certification documents (TGL No. 10 and AC ) can be applied with the necessary differences, to satisfy the objectives set out in the PBN Navigation Specification. Compliance should be determined against each relevant Navigation Specification.
19 Relationship with Existing Criteria Not re-inventing the wheelTaking existing criteria e.g., Orders, ACs, AMC, and TGL etc.A more logical structureCommon format and contentMore complete to enable uniform implementation
20 Common Organisation of Volume II, Parts B and C Where “X” represents the chapter number:X.1 IntroductionX.2 ANSP ConsiderationsX.3 Navigation SpecificationX.4 ReferencesX.1 IntroductionBackgroundPurposeX.2 ANSP ConsiderationsNavaid Infrastructure ConsiderationsCommunication and ATS Surveillance ConsiderationsObstacle Clearance and Horizontal SeparationAdditional ConsiderationsPublicationController TrainingStatus MonitoringATS System MonitoringX.3 Navigation SpecificationApproval ProcessAircraft EligibilityOperational ApprovalDescription of aircraft equipment, training documentation, operations manuals and checklists, minimum equipment list considerationsAircraft RequirementsOperating ProceduresPilot Knowledge and TrainingNavigation DatabaseOversight of OperatorsX.4 References
21 Air Navigation Service Provider Considerations Navigation infrastructureSufficient for proposed operation, including reversionary modesCommunication and ATS surveillanceDetermine reliance on radarObstacle clearance and route spacingReferences PANS-OPSPublicationIncorporation into AIP, and reference to ICAO Annex 15
22 Air Navigation Service Provider Considerations ControllerCore training and training specific to the Nav SpecStatus monitoringNavaid infrastructure monitoringATS System monitoring
23 Overview of Specific Navigation Services D/D/IRURNP AR APCHRNP APCHRNP-1RNP-4RNAV-1RNAV-5RNP-10D/VORD/DIRUGNSS
24 Navigation Specification BackgroundApproval processAircraft requirementsOperating proceduresPilot knowledge and trainingNavigation databaseOversight of operators
25 Approval Process Aircraft Eligibility Operational Approval Can be based on Aircraft Flight Manual or supplemental informationOperational ApprovalOperating proceduresFlight crew trainingControl of navigation database process, where requiredApproval obtained in accordance with State operating rules
26 Aircraft Requirements Performance RequirementsAccuracy, Integrity, Continuity, GNSS signal-in-spacePerformance monitoring and alertingOnly applicable for RNP systemsCriteria for Specific Navigation ServicesDefines allowable systems and required performanceFunctional requirementsJust as important as performanceNavigation database requirements
27 Operating Procedures Pre-flight planning General operating procedures Performance expectations (deviation from path)Pilot has critical role in performance monitoringContingency procedures
28 Pilot Knowledge and Training Lists training tasks considered important, which may already be part of operator’s training programSystem-specific information on how navigation system functions is vital to success
29 SummaryPBN Concept = navigation specification + navaid infrastructure + navigation applicationNavigation performanceSystem performance error componentsOn board performance monitoring and alertingUse of navigation specificationsNavigation Specification provides implementation guidance for PBN operations -- not a stand-alone certification documentRelationship with existing criteriaCommon organisation of Vol II Parts B and CANSP considerations, navigation specification