01 - Introduction to RNAV.pdf
- 1. ICAO PBN Workshop Tanzania Introduction to RNAV
- 2. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 2 Outlines Introduction to RNAV • Introduction • Conventional vs RNAV • RNAV positioning • RNAV calculator
- 3. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 3 Introduction to RNAV System « Area navigation (RNAV). A method of navigation which permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self-contained navigation aids, or a combination of these. »
- 4. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 4 Copyright 2009 © Quovadis S.A.S. All rights reserved Visual References (Stars…) Instrument landing System: 1938 VOR (Airways): 1960s Introduction of 2D RNAV VOR/DME: 1975 GPS navigation: 1994 RNP: 1996 PBN ICAO mandate: 2016 Some history RNAV System - History
- 5. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 5 RNAV System - History • RNAV began in the US in the 1970’s and the certification/approval requirements followed evolutions of this concept and of its associated technologies. • AC 90-45 « Approval of area navigation systems for use in the US NAS » issued in 1969. • AC 90-45A issued in 1975 • 2D RNAV with vertical guidance for advisory • Positioning based on VOR/DME • AC 20-130 Approval of multi-sensor navigation system for use in the US NAS » issued in 1988. • Positioning based on VOR/DME, DME/DME and/or Inertial • AC 20-130A issued in 1995 addressing FMS and GPS systems. • AC 90-100A (RNAV for Enroute and Terminal area) and AC 90-101 (RNAV for specific approaches: RNP AR) issued in 2007 • …
- 6. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 6 Conventional navigation versus RNAV
- 7. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 7 • Defined based on old aircraft capabilities and use of conventional navigation means • Large protection areas and separation criteria to cope with limited accuracy of position estimation • Based on Ground Navigation Aids • Overfly • Relative position • Limited design flexibility • Leading to traffic saturation Conventional Routes 7 Ground NAVAIDs Eg: VOR/NDB Widely used but no more suitable due to traffic increase and high fuel cost
- 8. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 8 • RNAV stands for Area Navigation • RNAV : Capability to fly any desired flight path, defined by waypoints such as geographic fixes (LAT/LONG) and not necessarily by ground navaids RNAV Definition 8 Ground navaids Waypoint RNAV capability is linked to aircraft on-board equipments (RNAV systems) RNAV is a method of navigation allowing for the definition of more direct routes
- 9. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 9 RNAV advantage town NDB VOR/DME WPT runway VOR/DME
- 10. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 10 PBN Predictability 10 Four departure fixes KATL Before RNAV Departures
- 11. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 11 PBN Predictability 11 KATL After RNAV Departures Eight departure fixes
- 12. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 12 The RNAV system
- 13. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 13 RNAV system - Basic principle Sensor positioning RNAV Computer Path definition Defined in Navigation DataBase Human – Machine Interface (ex keyboard, ,…) Displays AP FD Annunciators …..
- 14. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 14 RNAV positioning • Determine the aircraft position (latitude and longitude) • The aircraft can determine its position on the following sensors: • GNSS • DME/DME • VOR/DME • Inertial Positioning sensor
- 15. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 15 1 5 Based on GPS constellation A constellation of 24 satellites* into 6 orbital planes Position calculated in the WGS84 reference system Actual accuracy within about ten meters * USA engagement on the minimal GPS constellation Positioning : GNSS Worldwide coverage Usable all phases of flight
- 16. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 16 Positioning : GNSS . 1 3 2 1 2 3 4 4 1. Measurement of the distance user – satellite from time information (satellite and user clocks) 2. GPS signal contains satellite position 3. Determination of the navigation solution by triangulation 4. Error calculation GPS user positioning accuracy (95% of time, global average) Annexe 10 – attachement D Horizontal position error 33 m (108 ft) SA ON – 13m (43 ft) SA OFF Vertical position error 73 m (240 ft) SA ON – 22m (72ft) SA OFF
- 17. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 17 Positioning : GNSS RAIM AAIM Stand-alone integrity control by the receiver Stand-alone integrity control by the aircraft Stand-alone GNSS receiver Multi-sensors system Multi-sensors system Based on the redundancy and the geometry of GPS satellites Based on the combination of GNSS signal with other sensors (example: inertial system) • GPS alone performance does not meet ICAO requirements for navigation • ABAS Autonomous Based Augmentation System is required to check integrity of the GPS data • Horizintal Alarm Limit (HAL) • 2 Nm (En route), 1 Nm (Terminal area) and 0.3 Nm (Final Approach) • Two techniques: • Accuracy (NSE) (on board – TSO C129 performance requirements) • 0.124 Nm (95%) in En-route and Terminal area • 0.056 Nm (95%) in Approach RAIM : Receiver Autonomous Integrity Monitoring AAIM : Aircraft Autonomous Integrity Monitoring
- 18. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. A need to trust “SIS” for safe operation 13/10/2014 This is checking integrity of SIS GPS or GLONASS Satellites may broadcast Erroneous signal for hours Distance errors Erroneous clock or ephemeris data Positioning errors Users needs To know quality of computed position To be warned if anything goes wrong
- 19. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. GNSS integrity monitoring 13/10/2014 GNSS integrity monitoring techniques aim at monitoring the quality of GNSS positioning Large variety of techniques: In an autonomous manner (ABAS) : Using the redundancy of GNSS measurements only (RAIM ) Using additional information from other sensors (AAIM) Using a ground station (GBAS) Using a network of ground stations (SBAS) All these systems can include Fault Detection (FD) or Fault Detection and Exclusion (FDE)
- 20. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. A need to trust “SIS” for safe operation 13/10/2014 GPS or GLONASS 4 satellites to determine 3D position and time Usually more satellite are available (6 to 12) RAIM uses 5 satellites for fault detection (FD) 6 satellites for fault detection and exclusion (FDE) RAIM provides integrity and warning RAIM RAIM on board function to guarantee integrity
- 21. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 21 Note that : for approach the GPS can be completed with • a satellite based augmentation signal SBAS (ex WAAS, EGNOS) • Increase precision and integrity => used for Approach with vertical guidance (part of PBN) • A ground based augmentation signal – GBAS • Used for precision approach (not part of PBN) Positioning : GNSS
- 22. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. • Position calculated (lat&long) from 2 DME distances • To have the accuracy performance within 1NM: • FMS constraints: Positioning : DME/DME DME1 (lat&long) DME2 (lat&long) θ 30°≤ θ ≤150° d 3NM < d <160NM •The DME is selected and tuned by the RNAV system •Scanning DME (with multiple chanel)
- 23. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 23 Positioning : RNAV Inertial • Autonomous Navigation • Positioning • Position determined through computations based on accelerometer and laser gyro sensed signals • IRU senses accelerations along and rotation about each of the three axis. • Inertial drift • 2Nm/hour • High drift rate the first ½ hour of navigation (8Nm/hour) • Alignment of IRS is required before the flight • IRS alignment consists of determining local vertical and initial position and angles. • with / without automatic radio updating of aircraft position • Inertial data can be used to update GPS data and provide an Hybrid GPIRS position (e.g Airbus aircraft).
- 24. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 24 Positioning : VOR/DME • Use of VOR/DME • Position computed from a DME distance and a VOR angle (bearing) • Accuracy • Depend on the distance from the station • The VOR/DME is selected and tuned by RNAV • Positioning not accurate enough (no future) VOR/DME 24
- 25. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 25 RNAV calculator • Compute a guidance to follow the required path • Based on the positioning • Based on a selected trajectory • Selected Trajectory – By the pilot – Flight Plan, route, procedure,… • Positioning can use one or several positions – Simple (ex GPS), – Hybridization (ex GPIRS), – IRS Radio update (ex IRS/DME), – Blended position (ex W1IRS+ W2 Radio+ W3 GPS)
- 26. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 26 RNAV computer and the coding cycle ARINC 424 : standardizes waypoints path terminators and routes « depiction » Translation of the route or the procedure from the paper chart into an electronic format
- 27. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 27 RNAV computer - ARINC 424 - Waypoints Two types of waypoints for two different trajectories : Fly-over waypoint Fly-by waypoint
- 28. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 28 Several different trajectories may exist to reach the same point According to the path terminator, the trajectory is more or less predictable Example of ARINC 424 path terminator DF: Direct to Fix CF: Course to Fix TF: Track to Fix
- 29. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 29 Other example of ARINC 424 path terminator • Transition with repeatability of the path Radius to Fix (RF leg) Fixed Radius Turn (FRT) For routes R will depend on the level of the transition RF leg can be used in terminal area and Approach
- 30. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 30 Examples of RNAV Avionics Architecture
- 31. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 31 RNAV architecture for General aviation example – Stand alone Display system slaved to the route to be flown Standalone RNAV system Remote annunciator and selection Flight Technical Error (FTE) NSE
- 32. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 32 RNAV architecture for air transport aircraft – Multisensors Sensors Sensors FMC 1 FMC 2 Displays Displays Flight Director/Autopi lot selection Display selection Display selection MCDU MCDU
- 33. © AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. Page 33 End of the presentation Thank you for your attention – Any question ?