Future ATM Systems of the Next Century

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Future ATM Systems of the Next Century

35TH ANNUAL CONFERENCE, Tunis, Tunisia, 15-19 April 1996

WP No. 94A

Future ATM Systems of the Next Century


Future ATM Systems of the next century will be characterised by increased complexity with extensive use of highly automated sub-systems. Controllers operating such Systems will need a broad range of skills, with a different balance from those of today. “Tool use” skills, with a basic sequence of perception, goal recognition, detection and problem solving will remain, but new skills will be added to these.

As a result tilture ATM systems must be founded on a philosophy of human-machine interaction which permits the human to discharge their responsibilities fully and knowingly. Human-centred automation is one such philosophy which may enable high levels of system performance, with advanced automation combining with the human in the future ATM system.

Modern technology is providing the designers of Air Traffic Management systems with the facility to incorporate higher and higher levels of automation, both at the information processing level and in Human Machine Interface. Therefore acceptance of these principles and philosophies are imperative for successful transition from the manual control process of today to the designs envisaged for the future.

Notwithstanding the above People will continue to be the most important system element. Modern proven technology is increasingly making use of automation and advanced human machine interfaces.

Economic pressure will continue to be the crucial catalyst that drives the need for further automation as well as the need to increase safety levels in the face of continued traffic growth to meet capacity. The prime objective of the system users is to facilitate the demand for ATC system capacity, and for ATC to be less of a burden on the operation of aircraft. Recent investigations in the USA and abroad have indicated that Automation, operating within the constraints of the current ATC environment will be able to increase the number of operations that terminal facilities can sustain.

A recent report “Evaluation of the Capacity and Delay Benefits of Terminal ATC Automation” (Steven B Boswell Lincoln Lab. MIT 1993) states:

“in fiscal year 2000, the FAA forecasts approximately 8.25 million air carrier departures. Our forecast methodology predicts that with the contemporary ATC system air carriers will report 3.7 million hours of delay. A nominal 12% capacity gain is subsequently estimated for CTAS (Centre TRA CON Automated System) and this capacity improvement is predicted to reduce delays in fiscal year 2000 by 383 thousand hours, or by slightly more than 10% representing a saving to air carriers of almost $2billion”.


In general terms, the ideal benefits to be derived from the implementation of such systems include:

  • maximise productivity from controllers by automating routine tasks, allowing the controller to concentrate on the executive functions.
  • provide a longer planning horizon
  • minimise system operational costs
  • provide an ability to reconfigure systems to cater for changing operational and technical requirements
  • minimise potential errors through use of error checking systems inherent in the software and hardware packages
  • provide maximum redundancy with fail safe modes able to cope with failures
  • permit greater flexibility in routing for reduced environmental impact and less fuel consumption

Several issues arise over and above the philosophical issues:

  • Duty of Care and liability considerations – Automation places an intricate and complex set of technical layers between the controller and his traffic that can exclude the provision of raw information needed to carry out tasks safely. There exists therefore the risk of corrupt or incorrect information being presented to the controller. This is a system design issue, to what extent are the system designers, planners and engineers of that system responsible and share in the controllers duty of care.
  • Workload management – the number of degraded modes of operation is likely to become much greater as automation increases. While controllers are likely to be much more productive when the system is fully functional, how will workload be managed when the machine slows down. A critical phase of the operation is the transition from the fully automated to a manual or back up system.
  • System Validation – a comprehensive testing and validation program of future automated systems will be a costly and time consuming exercise, that must be thoroughly and rigorously conducted prior to commissioning.
  • All software should be correctly engineered and exhaustively tested on full fidelity simulators prior to introduction into operational service.

The potential for a high degree of automation in an advanced aviation system will permit the dynamic and flexible structuring of airspace sectorisation to facilitate the use of multiple flexible tracks , which will allow a global airspace structure able to provide for the full range of possible airborne equipage configuration and performance capabilities. The ATM system required to meet this objective must be sufficiently flexible to support dynamically restructured airspace configurations.

However, the automation of separation and flow functions could quickly progress beyond the point where the human can reasonably be expected to provide adequate manual backups or reversions In defining the role of the human in future systems the roles and relationships of those actors with the technical components of the system must be determined and supported with due regard to the capabilities of human cognition and information processing. They must address the question of technology and human integration, and the classical “replace the human with automated functions and technology” must be seen to be recognised for what it is, a fallacious and potentially limiting concept which inflicts instability and inflexibility in the ATM system such as to add the potential of making the system incapable of meeting the complete set of demands placed upon it.

There is a tendency to provide the human with decision and monitoring aids that it is believed will support the controller in ways that will alleviate the human of routine tasks. Such approaches risk the detachment of the human, or their exclusion from events and information that the human requires in order to support the basic cognitive functions of perception, judgement and attention. Decision aids have a major part to play in the future ATM environment. If the human is to be able to correct system errors, or intelligently make decisions, then such decision aids must facilitate such decision making and not become mental crutches. The risk of so doing will remove an essential ingredient of error tolerance resistance from the system operation. Monitoring aids must support the controller, but care must be exercised in their use, because certain routine actions are required by the human in order to maintain a mental picture of the operating environment – this supports the identification of errors by pilots and the technical systems themselves.

Any new system must be the result of effective participation by all stakeholders. For gains to be made in the future it must be recognised that aircraft operators will be required to invest heavily in aircraft based systems, and that pilots and controllers will have to operate the system. System designers and planners must ensure therefore that where automation is employed in system designs, that it is done so with meaningful and committed use of controllers and pilots, and that where controller tasks are to be redesigned, it is based upon a thorough understanding of the controllers functional responsibilities in the future system.

Due consideration should be given to the effects of a reduction of understanding or comprehension by the controller due to a change of man machine interface. Specifically this relates to the effects upon sensory perception, in that some of the unique and potentially beneficial properties might not be fully embodied in a new electronic system;

such as :

a) Touch associated with flight progress strip (FPS) manipulation: It has been claimed that the strips may embody important communicative purposes (Shapiro, Hughes, Rendall and Harper – 1991), that they are important external retrieval aids, and that they support cognitive processes in numerous additional ways.

b) Visual marking of FPS assists with ‘attention grab’ , which would be reduced with electronic FPS, where all strips would look much the same.

c) Cueing – manipulation of FPS assists with memory cueing, by arranging strips in a logical manner, offsetting strips, markings.

It may prove difficult to use the electronic equivalent of the strips as a memory aid or cue that is cognitively equivalent to a paper FPS. In this context, the automating of routine tasks must be conducted with due regard to the way that such routine tasks are used by the controller as stimuli and cues in maintaining mental model of the traffic situation. Denial of these cues and stimuli can lead to adverse effects on human performance.

Increased personnel productivity will only be achieved in such a complex and dynamic domain such as ATC through automation which works synergisticly with the human. In contrast to other elements of the system design, new technology will not be available in people, and considerable research must be accomplished to identify the education, psychological characteristics, selection criteria, training and other factors critical to successful human performance in joint systems.

The use of ATM automation will be most visible in the following areas :

  • Flow management – ATM automation will make it possible to formulate real time flow management strategies.
  • A more efficient picture can be computed with greater lead time, enabling the Flow Director to reduce the prevalence of gaps that otherwise develop in :
    • arriving traffic as it is organised into a final approach stream,
    • crossing traffic converging on an enroute intersection.
  • With increased spacing precision, controllers will be able to deliver final spacings that are more consistent and more reliable, and thus can deliver tighter spacings, that, on average, are nearer the minimum required for safe separation.
  • By identifying and organising arriving groups of differing performance and weight category aircraft, automation software can create a capacity advantage by explicitly accounting for complexity in the control task.
  • Tactical Control – ATM automation will allow direct negotiation between ATM and aircraft to enhance tactical control.
  • Data Link and voice channels, enhanced by automation aids, will be used for aircraft not capable of automated negotiation with ATM.
  • Segregated airspace for aircraft capable of complying with automated ATM (ADS) and others e.g. designating the more optimal routes (ADS) routes, would make for a more easily managed strategy, reducing the complexity of the separation problems that might arise in a tactical environment.
  • Oceanic operations – flexible oceanic ATM will accommodate user – preferred trajectories (DARPS and I or Free Flight.)
  • En-route and Terminal Area Operations – both flow management and tactical control will be enhanced for en-route and TMA operations.
  • Air ground Information Exchange will be improved by Controller Pilot Datalink Communications (CPDLC), and by the ability to access the aircraft flight management system.
  • Airport Operations – new ATM systems will support increased airport capacity.
  • Independent IFR parallel approaches.
  • Surface guidance and control systems to enhance airport surface movements.
  • Noise monitoring – flexibility in controlling the noise footprint of airport traffic operations will be increased.

In order that a full understanding can be obtained of the future control environment, the system design and the operating philosophies, there is a pressing need for increased use of full fidelity simulators. This will allow a wider and more deliberate testing of the possible system parameters, with error checking and system redundancy limits accurately predicted. Accuracy of system information is a vital component of separation standards. Where such changes are proposed, they must be validated in real time using system components as well as in simulators.

Simulator design should accurately replicate the functionality and performance of correctly engineered software and hardware. This design procedure must include maximum input from operational personnel with commensurate experience to the system being designed, i.e. the person who will eventually use the system must be exposed to the simulation tests, thereby giving confidence and total understanding of the operational system.

The control task today relies acutely on the mental model that the human builds of the traffic situation. Applied psychology is only now developing an understanding of the “Picture” , or situational awareness as it is now fashionably known. The use of automation, tools and decision aids must ensure that the ability of the human to build the necessary mental models is not compromised in any way, and that the essential attributes of the controllers task such as dynamic rescheduling of tasks, and multitasking is supported directly. The importance of this item is particularly relevant in the context of the human accepting a responsibility for system degradation or system failure.

The hardware and software designs should have inbuilt safeguards to immediately alert controllers to any such degradation of facility, both ground network and airborne, in a timely fashion to allow contingency procedures to be put in place. This should be based on the cognitive principle that humans do not make good routine monitors, thereby they need to be kept actively involved with assessment of the traffic picture and system operation functioning in order that they can discharge their responsibilities.

The next generation of controller must be selected on assessment of major competencies which highlight the adaptation to automated CNS/ATM system management and team work.

The main criteria for selection would include an individuals attributes in:

  • Managing change;
  • Coping with change and detail;
  • Adaptability;
  • Planning ability;
  • Team orientation;
  • Communicate skills;
  • Determination;
  • Decision making;
  • Initiating.

Some typical functions of an ATC automated system might include :

  • Generic Air Situation Display: A single electronic display to present the controller with an integrated picture of surveillance information derived from all available sources vis – radar, flight data processor, ADS, manual input.
  • Short term conflict alert: A safety net to detect separation errors.
  • Electronic flight strip manipulation: Processing of the information may have an automatic display of electronic strips in a logical sequence e.g. time, altitude, position etc.
  • Medium term conflict alert – look ahead function: To assist the controller in air traffic management and conflict management, the system may support a look ahead function detecting conflict and/or allowing future traffic patterns to be displayed at a higher speed, and/or at a nominal future time.
  • Flight plan route probe To assist the controller in maintaining a high level of situational awareness, the system may provide the display of controller selectable and definable route leader lines based on flight plan and alternative navigational input data. It is possible that this function may include FMS down/hiking for accurate trajectory prediction.
  • Danger area infringement warning: To assist the controller in maintaining a high level of situational awareness , the system may alert the controller to an impending infringement of active Danger Areas.
  • Flight plan conformance monitoring To assist the controller in maintaining a high level of situational awareness. This monitoring tool would provide warnings when the aircraft was detected to deviate, within certain tolerances, from the planned route.
  • Minimum safe altitude warning To assist the controller in maintaining a high level of situational awareness, the system may alert the controller to an impending inillingement of lower safe altitude.
  • Estimated time of passing: To assist the controller in Air Traffic management and conflict resolution, the system may support the rapid determination of the Estimated Time of Passing between selected aircraft.
  • Dynamic bearing and distance: To assist the controller in maintaining a high level of situational awareness, and to assist (horizontal) conflict assessment and resolution, the system may support the use of hookable bearing/distance ‘elastic bands’, which can be accurately attached between aircraft and a fixed point, between aircraft and aircraft or between fixed points, providing a dynamic display of position in relation to the ‘connected ‘ end.
  • Level filtering: To assist the controller in Air Traffic Management and future conflict detection, and to assist (vertical) conflict assessment and resolution, the system may support the use of controller selectable level filtering. A side view function may provide the ‘Elevation’ perspective of aircraft at any nominated time i.e. real time or projected.
  • Navigation tolerance: To assist (lateral) conflict assessment and resolution, the system may support the display of controller definable tolerances. These may be dynamically altered dependent upon the navigational parameters set appropriate to the flight, with manual override functionality available. Differing symbology dependent on source (ADS, RADAR) and limit (RNP, FOM) provide visual clues.
  • Angular difference between tracks: To assist controllers in Air Traffic Management and future conflict detection, the system may support the rapid determination of the angular difference between selected tracks. Where the track selection is by selection of two aircraft symbols, the system may identify relevant Lateral Separation Points (using known aircraft capabilities and Lat Sep. Tables) and graphically display the Area of Conflict on either side of the track intersection.
  • Design functionality: The design functionality of Systems detailed above may incorporate aural and visual alarms for out of conformance situations, urgent or emergency messages, and system (ground and airborne) degradation.

Implementation and transition to future automated systems needs to be a phased and coordinated process, with full consultation between participating States, and carefully monitored. The need for an evolutionary transition is critical to planning for the new automated systems.

Technology being developed needs to be moved out of the laboratory and into the field. Open architecture will assist the evolution process by allowing products to evolve and be added as technology and automation develops and matures. Timely implementation is imperative for both the service provider and the user.

Consideration of specific aspects of certain parts of the world in view of differing environments and operational conditions must be understood. To achieve a globally co-ordinated plan for implementation of any future automated systems, it is necessary to ensure the harmonisation of the implementation timescales within neighbouring FIR’s with the level of capability of such operationally compatible systems serving those FIR’s.

Training requirements associated with new technologies are an essential concern, as is the importance of human factors in future automated systems; an importance that will continuously increase with the level of automation in ATC applications, for which advanced simulator trainers should be designed and available for regular training.

It is not enough just to apply traditional training programmes to significantly new technology. Automated CNS/ATM systems are powerful tools for efficient ATC techniques, but can also become powerfill traps if they are given dominant priority over plain common sense.

Such transition will need to be done in a safe manner and with emphasis on qualified education and training to all those subjects to this dramatic change.

Proficiency at rapid reversion to basic controlling techniques must form part of a regular simulator training programme, while specific rating validation requirements may need to be considered.

Training programmes should be co-ordinated to ensure that the training provided by all States is standardised and consistent in quality.


Automation and the integration of air ground systems will result in changes to the basic controller activities, causing a new and dynamic interaction between controller and flight crew . There is a need for a significant emphasis to be placed on contingency procedures to be used in the event of system degradation.

Technology should not replace humans or replace the reasoning process but rather support the human to carry out their tasks more efficiently. Automation in some domains has removed the need for human operator to carry out manual skills -manipulation, decision making, judgement etc. , potentially reducing skill levels and expertise of established personnel, thereby weakening the knowledge base of new controllers. If the human is to retain responsibility for system safety this degradation must be avoided at all costs.

With the introduction of new CNS capabilities and increasingly capable ground and airborne automation, air traffic automated management changes over time are expected to be evolutionary rather than revolutionary.

System development must be harmonised to enable future technologies to be accommodated in a consistent manner throughout the world.

There should be continued research on this subject.

SC IV should be requested to examine IFATCA selection and training policy in the context of the introduction of automation in ATC systems.

Last Update: September 28, 2020  

December 25, 2019   778   Jean-Francois Lepage    1996    

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