1. Space Indexed Flight Guidance along Air Streams Mastura Ab Wahid, Hakim Bouadi, Felix Mora-Camino MAIA/ENAC, Toulouse SITRAER20141

2. 2 Outline Introduction Definition of Air Stream Air Stream Reference Track Flight Guidance Model Space Indexed Guidance Performance Nonlinear Inverse Control Law Standard Manoeuver within an Air Stream Traffic Management within an Air Stream Conclusion

3. SITRAER20143 The Air transportation traffic has known a sustained increase over the last decades leading to airspace near saturation in some large areas of developed and emerging countries. The global air traffic has doubled in size once every 15 years and it will continue to do so. The design of new navigation and guidance systems with improved accuracy for spatial and temporal trajectory tracking has turned possible free flight which has appeared as an appealing opportunity for airlines. However, in the case of high traffic density regions, the adoption of free flight should result, even through a 3D+T trajectory negotiation process with ATM, into an increasing number of conflicts which are solved by modifying these aircraft trajectories and losing flight efficiency. INTRODUCTION

4. SITRAER20144 Then, new concepts such as air corridors and time-based flow management ( TBFM ) are under development and early implementation in United States. TBFM should meters aircraft through speed adjustments with discrete metering points through all flight phases in order to monitor the level of traffic demand in airspace sectors and deliver traffic down to the runway in a smooth way. Here it is considered that in high traffic density regions, air traffic can be organized along main air streams using the full navigation and guidance capability of modern on-board systems so that a common spatial reference trajectory ( ASRT ) can be used by aircraft flying through a high density traffic space to maintain an accurate position within their assigned dynamic slot on a given lane. The adoption of such spatial reference will enforce the efficient use of the available time-space capacity along the air space and ease the on- board traffic separation task for an organized traffic along such fixed 3D reference. INTRODUCTION

5. SITRAER20145 An air stream is defined as a set of air lanes organized around and along a common 3D reference trajectory (air stream reference track- ASRT). There aircraft are supposed to adopt the reference speed and flight level of their assigned lane and are guided in a common space index basis to maintain their position in their assigned dynamic slot. Like classical airways, air streams propose a common space for aircraft adopting similar navigation and guidance objectives for a portion of their flights but they can join or quit the air stream at any stage. Contrarily to airways and airspace flow corridors, air streams have no nominal shape (width, height or radius). DEFINITION

6. SITRAER20146 In many situations, the central line of an airway or airspace flow corridor could be adopted as an ASRT, although air stream reference trajectories may present turns and may be changed according to different factors such as traffic demand and next day forecasted weather conditions. Aircraft with different performances or adopted cost indexes and speeds can be present in the same air stream but in different lanes. To be allowed in an air stream, aircraft equipment requirements are similar to that of airspace flow corridors: transportation aircraft must be equipped with required navigation performance (RNP), self-separation capability and on-board automated separation assurance. Self-separation on a lane is performed by dynamic position adjustments where the ADS-B technology can provide position and speed information. DEFINITION

7. SITRAER20147 Lane change manoeuvres within the air stream are performed without intervention of a central controller when an aircraft adopts a new reference airspeed. The on-board automated separation assurance system is supposed to incorporate different levels of protection against a collision, including conflict detection and resolution, where the last protection against a collision is the Traffic Collision Avoidance System (TCAS). In air streams, the pilots will remain responsible in insuring the safe separation with nearby aircraft by maintaining situational awareness, performing standard manoeuvers and reacting to conflict resolution advices. DEFINITION

8. SITRAER20148 Air Stream Reference Track

9. SITRAER20149 Air Stream Reference Track track

10. SITRAER201410 Flight Guidance Model Wind speed Air speed Angle of attack Sideslip angle Attitude angles

11. SITRAER201411 Euler equations Rotation matrix from B to L External forces Flight Guidance Model

12. SITRAER201412 Flight Guidance Model Aerodynamic forces Acceleration equations with Thrust dynamics

13. SITRAER201413 Flight Guidance Model Position equations Rotation matrix from L to E with

14. SITRAER201414 Desired 3D+T trajectory Space Indexed Guidance Performance Guidance errors

15. SITRAER201415 Space Indexed Guidance Performance with where are stable polynomials Space indexed nominal guidance errors dynamics

16. SITRAER201416 First space derivatives First space derivatives of time Nonlinear Inverse Control Law

17. SITRAER201417 Nominal guidance error dynamics Nonlinear Inverse Control Law Guidance dynamics

18. SITRAER201418 Nonlinear Inverse Control Law Nominal guidance error dynamics with inputs Theoretical flight guidance law

19. SITRAER201419 Standard Manoeuver within an Air Stream Lane shift

20. SITRAER201420 Standard Manoeuver within an Air Stream Speed evolution Fly over times

21. SITRAER201421 Standard Manoeuver within an Air Stream Space indexed reference trajectory

22. SITRAER201422 Standard Manoeuver within an Air Stream i Slot selection

23. SITRAER201423 Traffic Management within an Air Stream Case study

24. SITRAER201424 Traffic Management within an Air Stream Slot synchronization condition Conflict free conditions

25. SITRAER201425 Traffic Management within an Air Stream Greedy assignment algorithm

26. SITRAER201426 Traffic Management within an Air Stream Initial traffic configuration and goals

27. SITRAER201427 Traffic Management within an Air Stream First ranking of transient flights

28. SITRAER201428 Traffic Management within an Air Stream Final assignment and scheduling of transient flights

29. SITRAER201429 Conclusion In this study a new approach to traffic organization in dense areas compatible with the current performances of aeronautical communication, navigation and surveillance systems, has been proposed. The objective here has been to complement the free flight and traffic management through trajectory negotiation approaches, by introducing new high density traffic links organized in a way limiting traffic conflicts. Then in this paper it has been proposed to organize traffic in congested airspace along main air streams which are characterized by a central 3D track which acts as a common space indexed reference for the involved aircraft which follow lanes associated with different aircraft performances (preferred speeds and flight levels).

30. SITRAER201430 Guidance objectives have been expressed with respect to the common spatial reference offered by an ASRT and the synthesis of guidance control laws based on nonlinear inversion has been considered. Then the case of lane shift along a common air stream has been considered, leading to the complete characterization of the resulting trajectories. This allows to manage the traffic inside the airstream by predicting the duration of lane shift manoeuvers and using the common spatial reference to prevent conflicts. Conclusion

31. SITRAER201431 Conclusion Then the assignment of conflict free trajectories to transient flights inside the air stream can be performed using different techniques including heuristics. Preliminary concepts have been introduced in this paper to support this idea and many complementary studies should be developed to prove the effectiveness of the proposed approach.

32. SITRAER201432 Thank You very much for your attention