43RD ANNUAL CONFERENCE, Hong Kong, China (SAR), 22-26 March 2004
WP No. 90
Produce a Definition of Conflict Detection Tools
Presented by SC1
1.1. IFATCA policy exists for Automation, Short Term Conflict Alerts (STCA) and the Technical aspects of Medium Term Conflict Detection (MTCD) tools. The purpose of this paper is to produce a definition of Conflict Detection Tools (CDTs).
1.2. Traffic levels are forecast to continue to increase and Air Navigation Service Providers (ANSPs) and airspace users are pursuing higher levels of aviation safety as well as pushing for a reduction in delays and an increase in capacity. This strategy includes the introduction of automations or Controller Tools (CTs) such as CDTs to support decision-making functions within air traffic control.
1.3. It is hoped that the automation of various tasks (for example: planning, sequencing and separation) will decrease controller workload while extending both the controller’s abilities and their capacity for handling more traffic safely and expeditiously.
2.1. The thrust for automation in air traffic control comes from two main directions. Firstly, automation may curb or even prevent an increase in the number of fatal accidents especially those attributed directly to air traffic control. Secondly, automation may assist air traffic controllers cope with the continuing increase in traffic levels and worsening congestion at airports. Future plans for airspace uses include user preferred routes and levels (the flexibility to optimize flight paths is known as ‘free flight’) without compromising safety and efficiency. ANSPs and airspace users are pursuing higher levels of aviation safety as well as pushing for a reduction in delays and an increase in capacity.
2.2. CTs are automated functions of a developed Air Traffic Services (ATS) system that enhance a controller’s ability to meet the objectives of ATS. They provide information that assists a controller in making a decision, rather than dictating a course of action. CTs could ideally increase capacity and safety by alleviating the controllers’ decision-making workload.
2.3. CDTs are controller tools that are used in en-route and terminal airspace, as well as in towers for runways and manoeuvring areas. They are already in use in the guise of MTCD tools (which look ahead for approximately twenty minutes), STCA – when their parameters are set to announce potential infringements of separation minima – and Advanced Surface Movement Guidance and Control Systems (A- SMGCS). CDTs can either process data from a variety of sources (i.e. radar data, flight data, and Automatic Dependent Surveillance – Broadcast (ADS-B) data).
2.4. CDTs are computer based Controller Tools that identify conflicts and then provide system generated conflict advice to controllers. CDTs can either provide conflict detection continually or provide one-off probes (modelling to assess the potential conflicts on an intended action such as a reroute, level change or speed adjustment). CDTs can also provide conformance monitoring to ensure that aircraft conform to instructions issued to solve a detected conflict.
2.5. More advanced systems will provide conflict resolution suggestions and it is feasible, though perhaps undesirable, that future systems will combine with advanced datalink to automate separation. The controller must be able to validate the results provided by CDTs. Results communicated to a pilot or another controller without validation would take the control function away and will create issues regarding separation liability.
2.6. The ICAO Concept defines a conflict as “any situation involving an aircraft and a hazard in which the applicable separation minima may be compromised” and a hazard as “another aircraft, terrain, weather, wake turbulence, incompatible airspace activity and when the aircraft is on the ground, surface vehicles and other obstructions on apron and manoeuvring area”. CDTs could include separation provision from all these hazards and must adapt numerous different separation minima applicable to various airspace categories, hazards and airspace users.
2.7. CDTs are Controller Tools and should announce separation infringements in a timely manner while considering other potential hazards as far ahead as is practicable. This differs significantly from Conflict Detection Safety Nets (CDSNs), which provide last minute collision avoidance of imminent hazards, often requiring immediate avoiding action without considering other potential hazards. CDSNs were not part of this years’ work programme, and will not be addressed at the Hong Kong conference. However, the group of tools can be marked as a work item for the 2005 conference. SC1 may also need to review present IFATCA policy on STCA as these new definitions evolve.
2.8. Safety should be maintained or preferably enhanced by the introduction of CDTs. Small increases in traffic levels have the potential for exponential increases in incidents therefore improved safety needs to be the fundamental goal of automation.
2.9. CDTs should have interoperability across air navigation systems and communication and navigation systems. CDTs will be combined with other automations, especially tools for conflict resolution and traffic synchronization. Adjacent CDTs and interrelated tools will need seamless boundaries to provide for a uniform provision of ATS.
2.10. The presentation of CDTs must be user friendly and should not increase controller workload. The level of automation of the system will dictate the level of involvement of the controller; however, the distraction caused by interacting with the CDTs HMI could lessen the controller’s ability to control traffic effectively. If the controller interaction is excessive, provision of a planner position to support the tactical controller shall be considered.
2.11. Introduction of CDTs in towers could increase a heads-down culture. Tower controllers must be mindful that automation may bring about increased distraction from heads up visual separation.
2.12. The sophistication of CTs depends on the accuracy of the available data. The most basic forms are velocity vectors (radar based forecast of the expected track of an aircraft) or short route probes (flight data system based indicators that display an aircraft’s route and forecast position) which are aids to conflict detection. CDTs will detect potential conflicts and point out the aircraft or hazards involved to the controller in whose airspace the confliction occurs (i.e. while in the announced state), leaving the controller to interpret, prioritize and resolve the conflict.
2.13. CDTs could cause a reduction in a controller’s situational awareness, whilst still enabling the controller to handle the traffic safely and efficiently. This is because they automate some of the tasks currently undertaken manually by the controller, for example: the detection, interpretation, prioritization and presentation of potential conflicts. The introduction of CDTs could result in a change of the controller’s role from being active: by recognizing potential conflicts and providing solutions, to being passive: by monitoring the system. In an automated system, continued performance training will be required to ensure the skills of the controller do not deteriorate to the point where they are unable to perform without the automated tools.
2.14. CDTs should avoid spurious or false alerts. The accuracy of the conflict detection will be dependant on the accuracy of the information provided. The criteria for determining a conflict must be broad enough to ensure all conflicts are detected, yet narrow enough to ensure the controller is not overloaded with information about conflicts that do not really exist.
2.15. CDTs require excellent redundancy, however if the system integrity degrades it should automatically alert all users and should have the capability to transfer automated functions to the controller in an uncomplicated and safe way. During degraded modes (operations when CDTs are being upgraded and are fully or partially unavailable), clearly defined operating procedures must exist. Regular degraded modes refresher training should be provided.
2.16. Introduction of CDTs must be as per IFATCA policy, in particular automation/human factors and training.
3.1. CDTs are Controller Tools that identify conflicts and provide system generated conflict advice to controllers. They can either provide conflict detection continually or provide one-off probes (modelling to assess the potential conflicts on an intended action such as a reroute, level change or speed adjustment). CDTs can also provide conformance monitoring to ensure that aircraft conform to instructions issued to solve a detected conflict.
3.2. CDSNs were not part of this years’ work programme, and will therefore not be addressed at the Hong Kong conference. This item should be put on the work programme of SC1.
3.3. Tower controllers must be mindful of the added distraction from visual separation which automation may attract.
It is recommended that:
4.1 Conflict Detection Tools (CDTs) are computer based Controller Tools that identify conflicts and then provide system generated conflict advice to controllers.
4.2 CDTs can provide conformance monitoring to ensure that aircraft comply with instructions issued to resolve a detected conflict.
4.3 Responsibility and legal implications should be fully addressed before implementation of CDTs.
4.4 During degraded modes, clearly defined operational procedures must exist.
4.5 Nuisance and false alerts must be kept to an absolute minimum.
WP 02-158 ATC Separation Monitoring Tool (ASMT).
WP 03- 87 (Conflict Detection Tools).
WP 03-88 Review of Policy on Ground Based Safety Nets.
WP 98-98 Short Term Conflict Alert.
WP 02-93 Technical Aspects of MTCD Introduction.
AN-Conf/11 WP/34 The role of collision avoidance in future ATM systems.
AN-Conf/11 WP/93 Conflict Management by IFATCA.
Manual on Advanced-Surface Movement Guidance and Control Systems.
ICAO ATM Operational Concept Document.
EATCHIP Medium Term Conflict Detection Part 1.
A Review of Conflict Detection and Resolution Modelling Methods.
Last Update: September 29, 2020