Technical Aspects of Medium Term Conflict Detection

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Technical Aspects of Medium Term Conflict Detection

41TH ANNUAL CONFERENCE, Cancun, Mexico, 15-19 April 2002

WP No. 93

Technical Aspects of Medium Term Conflict Detection

Presented by SC1


1.1  At the 40th annual Conference in Geneva 2001, SC1 accepted the work item to review the technical aspects of medium term conflict detection.

1.2  There is a clear move to introduce more tools into the controller environment to aid conflict detection/resolution, and to manage arrivals and departures.

1.3  This paper will review such tools to identify specific problems and recommend policy or further research into specific areas.


2.1  Medium Term Conflict Detection (MTCD) is a planning tool with a typical detection horizon of 0 – 20 minutes for aircraft conflicts, 20 – 60 minutes for nominal route overlaps, and 0 – 60 minutes for special use airspace penetrations and descents below lowest usable flight level. MTCD is not a conflict alert tool. MTCD will assist the controller in monitoring the air situation continuously and provide conflict data to the controller through HMI.

2.2  This definition varies depending on the system parameters, which can be specified by the developer or the user (State).

2.3  MTCD tools accomplish this task ideally by using both planning data and actual radar data, although the data used depends on the sophistication of the system.

2.4  MTCD tools provide conflict detection (not conflict alert) and will have the potential to provide conflict resolution advice. The reliability of both is dependant on the quality or reliability of the data input available to the system. Any system in place must be supplied with incorruptible data to ensure the reliability of the results it will produce.

2.5  System data variables that affect the reliability of the system can include:

i. Poor or absent radar feed

ii. Status of special use airspace

iii. Flight data accuracy (equipment changes or route changes)

iv. Compatibility with adjacent systems

v. Human error inputs

vi. Deviations from expected trajectory

2.6  The systems perform better with the higher levels of information that would be provided by Mode S or data link information, but realistically must be able to perform adequately with a mixed equipment environment that is transparent to the controller.

2.7  Systems in adjacent units must be compatible and provide adequate data to the system to ensure reliable operations.

2.8  The accuracy of the conflict detection will be dependant on the accuracy of the information provided to it. Ground based trajectory projection that is not enhanced with airborne data (via data link) will result in greater buffers for conflict detection. This will create additional workload for the controller, as more conflicts will be detected than would be necessary for data link equipped aircraft.

2.9  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.

2.10  The level of automation of the system will dictate the level of involvement of the controller. A highly automated system could make resolution decisions for the controller, while a moderate system will require controller validation for all decisions.

2.11  Most systems involve enough controller validation that a planning position is required to operate the sector. Not all operations currently utilize a planning position, and it should not be required that a controller working traffic be expected to operate a planning system such as MTCD. The distraction of operating a separate system could affect the controller’s ability to effectively controller and monitor the present traffic.

2.12  MTCD incorporates several subsystems to produce the results it displays to the controller. It does not reveal how it obtained its results, and in advanced systems, the controller may have no way of verifying the validity of the results. Therefore the methodology of the MTCD should be incorporated in the training the controller receives.

2.13  The level of involvement of the controller in the decision making process will determine the controller’s reliance on the system. A highly automated system that provides limited information to the controller will increase the controller’s dependence on the system, and reduce the controller’s ability to control traffic without the system.

2.14  The controller must be able to validate the results provided by an MTCD system. Results that are communicated to a pilot or another controller through an automated means would take the control function away from the ATCO and create further issues regarding liability.

2.15  In an advanced system, continued performance training will be required to ensure the skills of the controller do not deteriorate to the point they are unable to perform without the automated tools.

2.16  Existing IFATCA policy on automation states:

“Automation must improve and enhance the data exchange for controllers. Automated systems must be fail-safe and provide accurate and incorruptible data. These systems must be built with an integrity factor to review and crosscheck the information being received. The Human Factors aspects of Automation must be fully considered when developing automated systems.

Automation must assist and support ATCOs in the execution of their duties.

The controller must remain the key element of the ATC system.

Total workload should not be increased without proof that the combined automated/human systems can operate safely at the levels of workload predicted, and to be able to satisfactorily manage normal and abnormal occurrences.

Automated tools or systems that support the control function must enable the controller to retain complete control of the control task in such a way so as to enable the controller to support timely interventions when situations occur that are outside the normal compass of the system design, or when abnormal situations occur which require noncompliance or variation to normal procedures.

Automation should be designed to enhance controller job satisfaction.

The legal aspects of a controller’s responsibilities must be clearly identified when working with automated systems.

A Controller shall not be held liable for incidents that may occur due to the use of inaccurate data if he is unable to check the integrity of the information received.

A Controller shall not be held liable for incidents in which a loss of separation occurs due to a resolution advisory issued by an automated system.”



3.1 Existing policy on automation covers Medium Term Conflict Detection.

3.2 Future developments in MTCD risk degrading controller’s confidence in operating the ATC system without the resolution advice it could provide. IFATCA must continue to monitor developments in this area to develop policy in the field of conflict resolution systems.

3.3 The issues surrounding MTCD and controller liability and controller competence (para 2.15 refers) should be forwarded to SCIV for review.


4.1 That this paper be accepted as information material.

Last Update: September 29, 2020  

March 13, 2020   723   Jean-Francois Lepage    2002    

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