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Direction des Services de Navigation Aérienne (DSNA), the French air navigation service provider


As part of the Single European Sky (SES) initiative led by the European Commission, the French Air Navigation Service Provider (ANSP) DSNA is involved in different multi-year programmes, which aim to modernise the entire Air Traffic Management (ATM) system in France. Europe’s ATM modernisation will result in less fragmented airspace, more interoperability between ANSPs and increased performance. Although the sharp drop in air traffic caused by the pandemic now questions this growth in the short and mid- term, there is still a pressing need for greater resilience of ATM in the future. Aviation evolutions also come with massive environmental challenges and SES includes important objectives in terms of sustainability, through reduction of greenhouse gas emissions and optimisation of flight paths.

In line with SES objectives, the 4-FLIGHT programme is the centrepiece of the modernisation of the French ATM system for en-route centres. It will provide operational staff with innovative tools to handle traffic safely, efficiently and maximising environmental considerations. Key components and developments of the new system are decision support tools for air traffic controllers, 4D trajectories and an electronic strip environment.

Role of Egis

Since the start of the 4-FLIGHT programme ten years ago, Egis has been providing technical assistance to DSNA’s technical and innovation department (DTI). We help them define operational needs, design system architecture, assess safety and Human Factors performance, build training programmes for operational staff, as well as test and run operational validation of 4-FLIGHT prior to deployment.

DSNA selected our team for their solid functional and technical knowledge of ATM systems (CAUTRA, COFLIGHT and 4-FLIGHT components, interfaces with different systems including French Defence, EUROCONTROL, and foreign ACC systems). They also value Our Service Oriented Architecture (SOA) engineering system method and our ability to work with multiple stakeholders and partners in France and across Europe.

Defining and validating operational needs

Egis supported DSNA with:

  • Developing the 4-FLIGHT operational concept, detailing operational needs for control working positions or technical operations (systems settings, maintenance or supervision, quality of service) with Aix, Reims and Paris area control centres (ACC);
  • Definition and operational validation of the 4-FLIGHT system, contribution to ACC technical staff training and to operational procedures development (operations manual for maintenance);
  • Detailing 4-FLIGHT operational needs related to Defence control centres, 4-FLIGHT system integration in the CAUTRA system, and migration of On Line Data Interchange (OLDI) for operational French sites;
  • Designing the change management process;
  • Preparation, data collection and delivery reports for several operational evaluations on the 4-FLIGHT programme in Paris, Aix and Reims ACCs;
  • Definition of working methods on the 4-FLIGHT system, training sessions, and taking Human Factors into account in the 4-FLIGHT safety studies;
  • Design review for Short-Term Conflict Alert (STCA) for 4-FLIGHT.

System definition and integration

Egis contributed to the definition and integration studies of 4-FLIGHT, with particular attention to transition and interoperability with the existing CAUTRA system in en-route control centres. Through these activities we could identify the necessary adaptations (modifications, configuration) of both CAUTRA components and the 4-FLIGHT system, as well as potential system restrictions leading to changes in air traffic controllers’ working methods, in coordination with operational staff.

Before 4-FLIGHT is deployed at the five ACCs, air traffic management in France will rely on two systems: partially 4-FLIGHT and the current CAUTRA system. To make this work, CAUTRA also requires technological developments and adaptations.

We assisted with:

  • Supporting the definition of the versions of 4-FLIGHT to meet the operational needs identified at Aix, Reims and Athis-Mons ACCs;
  • Defining the logical system architecture, including system specification and contribution to safety cases;
  • A set of integration studies that covered flight plans, surveillance and safety nets data, dynamic environment data, arrival and departure management (AMAN/DMAN), integration with radar sources and meteorological data sources, technical supervision, system operation and maintenance, integration with French central systems (aeronautical data provider, archives, fees, etc.);
  • Transition study from the legacy CAUTRA system to the 4-FLIGHT integrated system through identification of successive transition steps, including operational tests called programmed operational uses (UOPs) at the ACC centres. 4-FLIGHT was first used as a stand-alone system, without being interfaced with CAUTRA and then progressively tested in a “target” system architecture with the system gradually used for longer periods of time and increasing traffic volumes.
  • Building a reference database of the new 4-FLIGHT system integrated within CAUTRA.

Operational readiness and validation

The operational readiness scope covered a wide spectrum of components.

We assisted with:

  • Defining test environments (simulation tools, test architecture);
  • Defining test cases and associated scenarios;
  • Implementing test architectures and effectively running tests;
  • Integrating 4-FLIGHT into its final environment within the deployment architecture of ACCs, ensuring interoperability with existing software;
  • Assisting ACCs with conducting the programmed operational uses (UOPs);
  • Defining the versions of 4-FLIGHT to meet the operational needs identified at Aix, Reims and Athis-Mons ACCs;
  • Training and raising awareness of air traffic controllers in Aix, Paris and Reims about the complete configuration of a complex system. Training was adapted to:
  • Standard users who discover a new system because of constraints inherent to their activities and who work on a limited range of tasks;
  • Advanced users who are familiar with some of the details of the system they work on, expect specific functionalities and settings to be developed and know the system’s limitations
  • Monitoring progress of 4-FLIGHT operational configuration work with each of the stakeholders involved in data and system settings (supplier, ACC operators and technical/functional experts).

Through collaborative work, we facilitated workshops that gave the ANSP the opportunity to see what the configuration would look like and how it would work when integrated with the operational system.

How configuration workshops worked


Since 2017, successful programmed operational uses (UOPs) have been taking place with real traffic in safe mode. The first 4-FLIGHT UOPs took place in a context of low traffic, at night, without interface with the adjacent ACCs. UOPs are fundamental steps towards system implementation, like flight tests for a new aircraft. These exercises require several months of preparation and are a milestone in the life of the project. Their success testifies to the great professionalism of the 4-FLIGHT teams.

In 2020, over 640 flights were controlled using 4-FLIGHT at Reims ACC over 3 days, also testing airspace mapping management, controller shifts and technical supervision. The controllers from Aix-en-Provence controlled more than 400 flights and tested connections with the nearer control centres in France (Athis-Mons and Bordeaux) and abroad (Geneva, Barcelona/Palma, Milan and Rome) and datalink instructions.

The next implementation phases of 4-FLIGHT will be gradual. They will be run progressively at each ACC to take into account the importance of the change of the new ATM system and its impacts. Full implementations are planned running up to 2025 for Reims, Aix-en-Provence, Paris, Brest and Bordeaux.

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Julien Pratx

Julien Pratx

Director, Design & Project Management

+33 (0)5 62 24 56 00