Air-Ground Integration

1. Air-Ground Integration Ed Bailey, Airborne Project Leader & Ian Wilson, PATs Project Leader

2. The Aim : • What is air-ground integration • How was it done • How should it have been done • How it worked in practice - technical story of a flight

3. PHARE Objective: • “The objective of PHARE is to organise, co-ordinate and conduct on a collaborative basis, experiments and trials aiming at proving and demonstrating the feasibility and merits of a future air ground integrated air traffic management system in all phases of flight.”

4. PHARE Air/Ground Integration • Integration in PHARE was limited to Trajectory Negotiation • Trajectory Negotiation did not involve ‘exchange of trajectories’ or ‘Remote Procedure Calls’ • Simply Trajectory Negotiation was: • Trajectory from the aircraft • Constraints from the ground • Equivalent to:“Here is my intent - is it safe, if not, make it safe”

5. Application Level View

6. Aircraft downlinks User Preferred Trajectory Ground checks trajectory for conflicts adding constraints if necessary to deconflict and to sequence departure and arrival, then uplinks the constraints to the aircraft Aircraft modifies User Preferred Trajectory and downlinks it to the ground Ground checks the new User Preferred Trajectory for conflicts, broken constraints and infringements and if none uplinks deviation parameters to the aircraft Aircraft generates trajectory and downlinks ‘Accept’ Ideal Trajectory Negotiation

7. Problem areas - Is the first downlink really the User Preferred Trajectory ? What ‘ground checks’ are really needed ? Does the controller need to see a trajectory that has no conflicts ? Is there a need to co-ordinate sector-sector on trajectory changes and what is the place of Letters of Agreement ? Delay during checks causes asynchronous work for controller Its NOT that simple

8. User Preferred Trajectory ? • Ideally Blue Sky trajectory • But it includes known ATC restrictions such as Flight Levels and posslibly routings • If the user does not get the request the alternative may be very different

9. Ground Checks • Negotiation Manager Software checks for • Conflicts caused in current and neighbour sectors • Constraints not met • Changes in entry exit conditions at sector boundaries • Conflicts must be checked, but the other checks may be unnecessary • Forcing co-ordination not appreciated • Time delay means controller may need to multi-task

10. Controller display • Does a trajectory without problems need to be displayed ? • Depends on: • Trust in system • Method of controller working - with tools it is not strictly necessary • The ‘Big Picture’ - is it still required by controllers with automated support ?

11. Shortened Procedures • Standard Trajectory Negotiation may be too long in some circumstances. • Shortened procedures: • From Air - Pre-Emptive Negotiation • From Ground - Formal Clearance

12. Pre-Emptive Negotiation • The aircraft is doing something therefore the ground is told not asked. • Sequence: • Trajectory sent to ground • Deviation parameters and accept • Equivalent to: “Here is what I am flying - is it safe ? If not, make it safe.”

13. Formal Clearance • The ground requires an aircraft to do something now therefore the aircraft is told not asked. • Sequence: • Set of constraints and deviation parameters are sent to the aircraft • The aircraft generates a trajectory and flies it when the pilot accepts • Equivalent to: “Fly this trajectory.”

14. Flight Planning to 40 Mins • Nominal values to process the information • Trajectory Predictor Generates Initial Trajectory into Flight Data Base • Flight Database distribution • Conflict Probe on Trajectory • Initial Arrival and Departure sequencing commences

15. Air Trajectory Prediction • The Trajectory is generated for the entire flight. • SID and STAR (plus any procedural routings) are used for initial constraints. • Trajectory is in 3 main ‘Phases’: • Climb, • Cruise, • Descent.

16. Ground Trajectory Prediction • For ‘what-if’ modelling of all flights, by the controller and by the sequencing tools. • For provision of advisories to the Tactical Controller to pass to non-equipped aircraft. • Non-equipped - either without Datalink or with a less capable FMS.

17. Aircraft Log In to Datalink • Aircraft Provides trajectory based on aircraft data. • Get Meteo data • Derive vertical profile and 3D plus relative times • Pilot checks then ‘Negotiate’s • First Trajectory Negotiation to Ground • Ground sequences the flight and constraints passed for push-back and take-off

18. Take Off • DAP or trajectory indicating Take Off • Trajectory now certain • Re-negotiate Trajectory if required • New contract if required

19. Diagrammatic View of Planning and Control Authority

20. Post Take-off Planning • ‘Next’ Planner plans and deconflicts (using CP, CT, PS, TP, NM) • Tactical controller monitors (using FPM and CT, PS, TP, NM if change required) • Multi-Sector Planner 30 minutes away - checks loadings on the sectors (Using TLS and TP, NM if change required)

21. Control by Pictures - Air

22. Control by Pictures - Ground

23. Airborne Route Amendments • Pilot amends route on AHMI • Aircraft generates trajectory based on aircraft data. • Constraints provided from the ground for en-route deconfliction and Arrival • Aircraft recomputes trajectory to meet constraints and datalinks down • Checked and Agreed with ground

24. Automated Holds - Stacks • Long lookahead to avoid holds… • If hold required trajectory predictors in the EFMS and on the ground create one • If there are other aircraft in the hold a Stack Manager process on the ground provides descent constraints.

25. Arrivals • Sequencing continual while aircraft are en-route with sequence arrival times defined • Changes of Time of Arrival only ‘negotiated’ when change exceeds parameter time • Automated sequencing frozen prior to descent

26. Automated Approaches • Expedite and Retard using trombones or approach fans • Aircraft uses the area of the trombone or fan to amend its trajectory to achieve accuracies within 5 seconds at the approach gate • Always misunderstood by controllers

27. Problems - Communications • Datalink • Slow, very low bandwidth • Trajectory Information Structure • System • Some single threaded - resulted in unworkable delay • If multi-threaded, controller also has to ‘multi-thread’

28. Achievement of Concept • PHARE integrated the aircraft and ground systems • The aircraft generates the trajectory held in the ground flight database • The aircraft is only ‘constrained’ if required to avoid conflict • Similar control by pictures approach both in the air and on the ground • Data-Link with sufficient bandwidth is essential for full benefit

29. Air-Ground Integration Ed Bailey, Airborne Project Leader & Ian Wilson, PATs Project Leader