1. Conflict Detection and Resolution
Notes: The complexity of air situations is bound to change so that it will be more difficult for the controllers to assess the situations in order to find potential problems. E.g. the removal of many of the procedures that are currently used for to control air traffic by ATC (say fixed routes) will most likely affect all of the task conducted by the controller.
The loss of the current existing organisation of traffic flows that is created through the use of more direct flight paths will potentially increase the complexity of air situation (although not necessarily the number of potential conflicts). By assigning each aircraft to a specific route selected from a finite and relatively small set of routes, today’s controller is significantly reducing the number of locations at which aircraft may come into conflict. In such a situation maintenance of situation awareness is much easier for the controller.
Automated Support To ATS Programme
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2. Today Short introduction to Automated Support to ATS Programme (ASA)
Medium Term Conflict Detection (MTCD)
Conflict Resolution Assistant
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3. Automated Support to ATS
Programme
ASA
EUROCONTROL developments in conflict probing and conflict resolution automation in the context of the European Air Traffic Management Programme (EATMP) have been reorganised recently under a new (sub)-programme called Automated Support to ATS (ASA).
ASA includes projects that address different aspects of ATS automation, such as sequencing and metering of arrivals and departures (similar to CTAS), conflict detection and resolution, airport surface movement management and safety assurance automation (Safety Nets, such as Short Term Conflict Alert, Minimum Safe Altitude Warning).
Programme will also address further developments of information processing (e.g. requirements for improved trajectory prediction and MET data). An important part of the ASA Programme is (re-) definition of controller roles, especially in the context of conflict resolution and multi-sector planning.
ASA Programme Strategy has been established recently and will be presented to the consultation process in November 1999.
The ASA Programme will run from 1999 to approximately 2008 with implementation dates from 2002 (e.g. arrival management) to 2015 (for conflict resolution requiring trajectory negotiation capability).
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4. Operational improvement
Expected improvements:
use of automated tools to assist the controller in planning and tactical decision making
redistribution of control tasks within sector teams or a control centre
transfer of some separation tasks to cockpit
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5. Implementation
Implementation dates do not always need to be identical throughout ECAC area
Two types of implementation must be exploited in the Strategy:
Initial Operation Capability (IOC) - to provide early benefits for the stakeholders. (perhaps in )
Full Operational Capability (FOC) - achieved when all of the ATM units expected to implement an improvement are able to do so. (around )
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6. Automation levels Initial automation Enhanced automation
controllers’ routine tasks that provide information for decision making
Enhanced automation
improves controllers’ problem detection and resolution activities
integration of information management to support decision making
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7. Automated Support to ATS
ASA Programme
Operational Requirements and Functional Specifications
Feasibility and Cost-Benefits
Algorithms, Demonstrators
ASA Programme will run from now to 2008.
Products will be validated operational requirements and functional specifications.
Cost-benefits analyses will be done in order to convince our customers - ECAC service providers and airlines using European airspace.
Functionality will be demonstrated in a series of demonstrators, prototypes (including operational trials) and simulations (mainly in the EEC, Brétigny, France)
Algorithms will be standardised where and as required in order to harmonise the the level of service provided throughout the ECAC area.
Work will be managed by the Agency and contracted to research institutes, national administrations and ATC industry.
Products will be available through the EATMP distribution, IPR will be with the Agency.
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8. ASA Functionality Arrival and Departure Management
Medium Term Conflict Detection
Conflict Resolution Assistant
Safety Nets
Short Term Conflict Alert
Minimum Safe Altitude Warning
Area Proximity Warning
Improved information management
Multi-Sector Planning
e.g. Traffic Load Smoother, Trajectory Editing
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9. Conflict detection and resolution
Is the core task of ATC
Facilitated now by strictly constraint procedures (e.g. fixed-route networks)
This will change with free routes/free flights concepts
A core part of the ATC task undertaken by controllers is the identification and resolution of potential future conflicts, carried out through planning and tactical controller roles. In most current ATC systems, the mechanism of identifying and resolving conflicts is driven by a process, which the controller follows in scanning a radar display and manipulating a collection of paper strips.
This process is facilitated by used of strictly constraint airspace procedures, which help the controllers in maintaining situation awareness and ability to detect potentially hazardous air situations.
The complexity of air situations and, hence, the controllers’ core task are bound to change so that it will be more difficult for the controllers to assess the situations in order to find potential problems. E.g. the removal of many of the procedures that are currently used to control air traffic by ATC (say fixed routes) will affect the entire task conducted by the controller. The loss of the currently existing organisation of traffic flows that is created through the use of more direct flight paths will potentially increase the complexity of air situation (although not necessarily the number of potential conflicts).
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10. Medium Term Conflict Detection MTCD
“I couldn't repair your brakes, so I made your horn louder.”
By assigning each aircraft to a specific route selected from a finite and relatively small set of routes, today’s controller is significantly reducing the number of locations at which aircraft may come into conflict. In such a situation maintenance of situation awareness is much easier for the controller.
A controller will be required to consider the possible conflicts that may occur in a region around an estimation of the route that the aircraft will follow in the evaluation and planning process. In this case, the controller experiences a considerable increase in the number of degrees of freedom that need to be managed. The level of difficulty of monitoring an air traffic situation will most likely increase for a similar reason. As is currently envisioned, future aircraft will have the flexibility to select their own routes of flight, and to modify that route at their discretion. Thus, it will be more difficult to predict the actions and intentions of aircraft. Controllers will have to monitor the flight path of each aircraft more closely to determine when an aircraft has decided to change course or speed.
Future ATC systems have the potential to improve this process with the introduction of computer-based assistance tools including trajectory prediction (TP), medium term conflict detection (MTCD), resolution advisory generation and advanced graphical HMI.
“I couldn't repair your brakes, so I made your horn louder.”
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11. EATCHIP Phase III MTCD
Is a planning tool and does not lend itself easily to tactical controller use although modification is possible
detection is only done on the planned trajectory (and all updates), tactical trajectory as a separate entity from the planned trajectory, was not considered
algorithms are based on geometric detection, uncertainty is modelled separately and taken into account within the MTCD
detection is done based on segments that are derived from the trajectory data
Amsterdam ACOD as a basis
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12. Some problems with trajectory
How to close an open trajectory?
intermediary Cleared Flight Level (climb and descent)
heading instructions
speed instructions
How to ensure that ATC clearances are in the system?
How to model uncertainty and transfer
Perhaps there is a need for two separate trajectories; planning trajectory and tactical trajectory?
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13. {Compilation of Pictures of MTCD simulation tools here
MTCD tools
{Compilation of Pictures of MTCD simulation tools here
Talk to Bob}
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14. EATCHIP 3 simulations Spring 97 Winter 1998/99 Phase 1 Phase 2 Phase 3
Create HMI baseline
Phase 2
SYSCO&Civil/Mil
Phase 3
MONA
MTCD
SNET
Phase 4
AMAN
EATCHIP III
Demonstrator
STD FS
OR/FS OR
Results
Review
Spring 97
Winter 1998/99
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15. EATCHIP-3 MTCD context
MTCD was built in EUROCONTROL HQs and ported into Brétigny simulation system using the SIM standard interface (CORBA environment).
MTCD includes the following major functions:
- ESCAPE/CORBA interface
- Conflict detection
- Virtual conflict detection (context aircraft)
- Uncertainty calculation
It was necessary to model uncertainty within MTCD since the trajectory prediction could not provide point-valued uncertainty data that is normally assumed for EACHIP compatible trajectory predictor.
The simulator has a separate ground and air flight data systems, therefore, the aircraft targets did not follow exactly the ground predictions, thus simulating somewhat the real-life situation of unpredictability.
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16. MTCD Simulations in Brétigny
November 1998
Problems with trajectory prediction and clarity of concept of operation
Controllers had some problems in accepting MTCD tools
December 1999
New trajectory predictor
New concept of operations
Display of context aircraft
New/updated HMI tools
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17. Conflict Resolution Assistant
CORA
The ASA Conflict Resolution Assistant (CORA) project proposes to define and develop Operational Requirements and prototype enhanced concepts for conflict resolution based on the introduction of further automation to assist the controllers in solving detected potential conflict situations.
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18. CORA Project One of ASA activities
Addresses all three levels of CORA functionality
Project Organisation
Operational Requirements and Data Processing Team (strategy)
ASA Programme Steering Group (action plans)
CORA Advisory Task Force(work plans and technical consultation)
Project runs from now until about 2008
“Whenever things sound easy, it turns out there's one part you didn't hear.” -Donald E. Westlake ...
Extensive consultation process will be needed
“Whenever things sound easy, it turns out there's one part you didn't hear.” -Donald E. Westlake ...
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19. Conflict resolution phases
CORA tools will have to provide assistance to controllers resolution of the following tasks:
Planning
Resolution implementation
Conflict monitoring and re-assessment
Conflict situation review
Conflict resolution has four main phases: Planning, Implementation, Monitoring, Review.
CORA will have to provide assistant in all these phases.
Depending on the level of automation provided, the controllers will be have plenty or little to do with the process. For instance using low level of automation provided by the entry level CORA, the controller will do most of the work involved in resolution whereas with the highest level of automation in CORA level 3, the controllers do not have be involved much in any of the processes.
The goal of CORA resolution is to provide a conflict-free trajectory for a pre-determined minimum horizon. Therefore, all the phases mentioned above are equally important.
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20. Resolution phases
In the planning phase, the controller determines the actions needed to resolve a conflict. This process results in instructions to pilots of altitude, heading, speed and/or route changes. Normally, the controller would also have to co-ordinate with other sectors/centres.
Once the plan is ready the controller implements the plan through the use communication facilities Also the system would have to be updated through data entry. After implementation, the controller must monitor the flight’s conformance to the planned resolution. The controller will also review the effectiveness of the resolution taking into account the traffic situation around the altered trajectories.
The process is being done and re-done for all of the detected conflicts continuously. This is where CORA benefits can be determined.
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21. CORA Performance levels
display of detailed and filtered conflict data,
provide what-if-probing and
input of the resolution as a new basis for the system trajectory
CORA-2
filtered resolution advisories in addition to the basic capability
CORA-3
use of trajectory negotiation capabilities (ground-ground and air-ground) for optimum resolutions and
implementation of the resolutions, decisions in the cockpit
The initial consultation process has mandated CORA requirement at basic and advanced levels. A very advanced level CORA is subject to further definition and agreement by the consultation process. Each level of CORA concept defines controller and system roles and a level of service provided by the computer support tools in the process of identifying and resolving conflicts.
The basic level CORA (Level 1) could be implemented around 2002, Level 2 around 2007 and Level 3 around 2012.
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22. Man/Machine task sharing
what-if-probing for the controller resolutions
CORA 1 :
controller creates resolutions
CORA provides data filtering on controller request, what-if-tools, trajectory manipulation and automatic system updates
CORA 2
CORA provides ranked advisories
controller selects form a list OR creates own resolutions
CORA 3:
automatic implementation of some resolutions
ground-ground and air-ground trajectory negotiation
Human role in conflict resolution will probably change in the course of automating this task. How much and how are still the questions to be answered, and it seems obvious to me that there is still a need for studies on this to find an acceptable baseline.
For CORA-2, like for CORA-1, the controller is still the decision maker.
In CORA-1 he was actively planning resolutions for detected and somehow filtered conflicts.
CORA-2 will provide a service for him planning alternative resolutions for controller selection and providing a fast way to input resolution as a basis for new trajectory for the flight.
In human factors as well as other aspects of CORA, the new concepts of operations such as free routes or even free flight, should be considered as appropriate. It is obvious that the current method of separating air traffic through the use of inflexible airway structure would be relaxed and a more flexible method of operations selected instead. This sets some constraints on the development of CORA but would also provide more airspace for manoeuvres. CORA should fully support this kinds of development.
The concept of operations and related roles of controllers and other actors are very much a part of the CORA project.
We should also discuss what added value would CORA-3 provide, perhaps pilot connection?
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23. Resolution context Trajectory Flight plan Uncertainty CORA constraints
Aircraft performance
Resolution itself has a context, that needs to be defined.
I already mentioned trajectory and conflict detection, uncertainty is very much related to these and must be addressed for resolution purposes during the CORA projects. Monitoring functionality for trajectory and detected conflicts needs to be analysed in order to determine whether there is a need to re-visit e.g. MONA functionality in light of the requirements imposed by CORA.
CORA resolutions will probably be constraint by various things like separation standards, flow restrictions, controller orders and other more permanent CORA constraints such as minimum manoeuvre requirements and allowed limits for manoeuvres, aircraft performance and weather will also be (an uncertain) factors in selection of conflicts resolutions.
All these need to be addressed and open questions around them solved.
Controller orders
Flow restrictions
Weather
Separation standards
Conflict detection
Resolution advisories
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24. CORA-2 advisory generation
Analyses the predicted conflict situations for a planned or tactical trajectory
Decides on the resolution strategy
who to move
how to move
when to move
Provides solutions for a conflict
Ranks the solutions based on their quality
Generates an advisory to the operator
appropriate centre/sector
The process of generating CORA advisories would probably look a bit like the following:
CORA would analyse the predicted conflicts for a given planned or tactical trajectory, decide on a strategy to follow in resolution with respect to whose trajectory should be modified, in what direction and when to solve the conflict(s) within a conflict-free horizon. CORA would then generate say 0-3 resolutions and present those for the appropriate actor (e.g. the controller 15 minutes down the trajectory) for him to validate the resolution (or select one of the proposals) and execute it as appropriate.
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25. Solutions Ranked in descending order based on their “goodness”
“Goodness” is based on criteria e.g. such as:
least track miles
least cost
least relative inconvenience, etc
Say 0-3 solutions per conflict
All solutions are based on minimum manoeuvre principle
Solutions presented for the controller would be ranked in a descending order based on their “goodness”. That would depend on the criteria that will have to be developed during the project, e.g. a solution based on the least accumulated extra track miles, least cost, least inconvenience (say the longest flight should be most stable) etc.
All the solutions must be based on the principle of minimum manoeuvre within the constraints imposed otherwise to CORA.
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26. Planning Horizons 0-5 min 5-20 min 20-x min Tools: Tools: Tools:
Implement resolutions planned and indicated by other actors
Resolve unresolved or new (i.e. unforeseen) conflicts
Monitor traffic situation
Manage the R/T communications
Implement control actions planned for this horizon
Plan actions to resolve those conflicts considered worth solving or that can be solved without ATC involvement later (4D aircraft, co-ordination)
Prepare resolutions for some conflicts (e.g. within high complexity situations)
Negotiate trajectory modifications with concerned flights and adjacent MSP areas through data-link
Balance traffic load between the sectors
Reduce traffic complexity to:
reduce number of potential conflicts,
reduce the number of required unplanned subsequent actions or
simplify subsequent actions
Optimise individual trajectories
Tools:
Conflict Probe / Linear prediction
Tactical conflict resolution
Context filtering
STCA, MSAW, APW
Outer Horizon:
extend from the middle planning horizon to the practical limit of the present trajectory prediction.
assumed that that limit would be of an order of 60 minutes (perhaps 60 minutes is not far enough)
actors include: CFMU planners, AO planners, ATC planners and pilots as planners.
includes complexity detection, traffic load smoothing and trajectory negotiation
Planning strategies are initially based on measurements of the complexity of air traffic situations rather than a need to resolve individual aircraft conflicts.
Typically uncertainties involved would be very large and difficult to predict.
However, resulting resolutions will include actions on individual aircraft (e.g. re-routing, re-planning of PEL/XFL etc.).
Middle Horizon:
extend from the inner planning horizon to the outer planning horizon.
assumed from 5 minutes to 30 minutes
accuracy of trajectory prediction dictates limits
actors include: ATC planners, AO planners and pilots.
includes medium-term conflict detection, conflict resolution assistance and trajectory negotiation
planning actions are based on the relative (probable) positions of the aircraft
uncertainties would be predictable and normally trajectory point-valued by the trajectory prediction functionality
Inner Horizon:
actions of tactical Air Traffic Control to prevent imminent losses of legal separation
and actions derived from the use of ground or airborne safety nets
upper limit of an order of 5 minutes (perhaps a maximum of 8 minutes or so)
Actors include: tactical ATCOs and pilots.
includes: tactical conflict detection, tactical conflict resolution, trajectory monitoring, trajectory negotiation, safety nets
look ahead within confines of one sector and its vicinity (sector area of interest)
planning actions based on tactical trajectories or the part of planned trajectories with small uncertainties
Tools:
Trajectory prediction
Traffic Load Smoother
Trajectory editing
Conflict resolution
Tools:
Conflict Probe / Trajectory prediction
Trajectory editing
Conflict resolution
0-5 min
5-20 min
20-x min
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27. Possible levels of automation
No assistance from the computer
Complete set of advisories (action alternatives)
A ‘filtered’ set of alternatives offered
Only one advisory is offered
Computer executes the suggestion if the controller approves it
Allows a restricted time (countdown) for the controller to veto before executing automatically
Computer executes automatically and always informs the controller
Computer executes automatically and informs controller if asked
Computer executes automatically and decides to inform controller
Computer decides and executes automatically ignoring the controller
NOTE: The above categorisation is not author’s original work (the American source cannot be identified due to lack of data).
The question of the level of automation needs to be solved in consultation with the user community (including airlines).
The above categorisation could be a starting point. The levels here are depicted from no automation to full automation and various levels have been defined between those.
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28. Possible levels of automation
Workload
Awareness
Faith
No assistance from the computer
Complete set of advisories (action alternatives)
A ‘filtered’ set of alternatives offered
Only one advisory is offered
Computer executes the suggestion if the controller approves it
Allows a restricted time (countdown) for the controller to veto before executing automatically
Computer executes automatically and always informs the controller
Computer executes automatically and informs controller if asked
Computer executes automatically and decides to inform controller
Computer decides and executes automatically ignoring the controller
The selected level of automation will effect various things, e.g.controller workload, controller’s situation awareness and level of acceptance by the controllers (I.e. in their faith in the basic concepts). Validation, demonstration and proof are key issues here.
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29. Some open questions (1) How far will we go and with what time-frame?
Level of automation
Implementation dates
Enhanced planning process –
How to transfer responsibility between tactical and planing controllers?
Provide CORA assistance also to tactical controller (VERA, same tool)?
What makes up the complexity of a conflict?
Number of aircraft? Context or resolution options? Or difficulty in delivery of solution?
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30. Some open questions (2)
How does the AOC/aircraft interact with CORA? Or do they?
Feedback aircraft capability, route preference and company/aircraft operating procedures to controller when taking problem/optimisation resolution decisions?
Is there a need for a core algorithm to assure fairness to all operators and service providers?
Or are individual flights monitored to ensure that they are fairly treated?
Gate to gate considerations?
CORA should ideally work from the departure planning phase providing, if possible, a basis for a conflict free trajectory that does not need holding in the air?
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31. Some open questions (3)
Is CORA Sector, Centre (I.e. multi-sector) or multi-Centre function?
System-wide optimisation – CORA without sector or centre constraints?
Impact of automated co-ordination between ground / ground and air / ground with the controller out of the loop?
How to take account of TP uncertainty?
Use the output of conflict algorithm to propose a default behaviour based on what a controller is doing (could be used to closed the trajectory e.g. radar heading with anticipation of return to navigation)?
System failure - what does this mean and how is it handled? Safeguards to cater for fallback - beware that we cannot limit the system to procedural fallback.
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32. Some open questions (4)
Controller needs to understand the system processes.
Skills will need to evolve or be modified
Define situation awareness
Modifying the controller’s skill-set is an issue to be addressed
Evolution towards single controller sectors (mixed planning and tactical tasks) with move towards supporting multi sector planning concept?
Airspace sector concept - a mix of actors operating in the same volume?
Is the one-controller one-airspace concept outlived its usefulness?
Issues in moving CORA to the cockpit - responsibility and certification?
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