ERATO – electronic environment

Published on Friday 7 January 2022

Modernization of Air traffic management in France

ERATO (En-Route Air Traffic Organizer) designed by DSNA is a set of modern tools for air traffic controllers. They integrate innovative functions providing helpful assistance in conflict resolution in an electronic environment.

ERATO is much more than simply a Mid-Term Conflict Detection (MTCD) tool : the system also includes parameter simulation (“What if ” concept) and monitoring alert (MONA) tools.

Live trials in France and real-time simulations in Italy have demonstrated significant benefits that ERATO can bring in terms of safety and capacity.

700 ATCOs from Brest, Bordeaux and Brindisi ACCs will use ERATO at the end of 2015; then, the system will be deployed in the other 3 Italian ACCs.

ERATO will be gradually integrated in DSNA and ENAV’s new generation ATM system, the 4-Flight programme.

2 years after the Electronic Environment En Route Air Traffic Organize (EEE) transition in Brest ACC

After 2 full years of operational use in Brest ACC, has the EEE implementation benefitted your operations?

E.E.E stands for Electronic Environment En Route Air Traffic Organizer. The deployment of this new generation Air Traffic Management (ATM) system was completed in Brest ACC the 18th December 2015.
ERATO is a server that provides a set of cooperative tools embedded in a whole operational concept. Based on trajectory prediction and on human heuristics*, ERATO is able to display a filtered air situation that contains all the aircraft that should be considered by the air traffic controller. This represents a helpful assistance for conflict detection.
Besides the Electronic Environment (E.E.) itself displays updated information on the radar image and provides new helpful functions for conflict resolution.

*human heuristics can be considered as any strategies derived from previous experiences with similar problems.

EEE in Brest ACC improved safety

Since its implementation in Brest ACC, EEE has significantly contributed to the reduction of Separation Minima Infringements (SMI). This major safety achievement must be particularly emphasized as Brest ACC has faced a 14% traffic growth in the first 9 months of 2017 compared with the same period in 2015.
A SMI occurs between airborne aircraft whenever the minimum separation standards (i.e. 5NM or 1000ft for France) are breached.

Crédits : Tous droits réservés - DGAC

Let’s focus now on the E.E.ERATO tools that contributed to these results.

The SEP tool

This new ATC tool helps reducing the SMI with root cause: “conflict between aircraft detected but insufficiently resolved”.
It provides Air Traffic COntrollers (ATCOs) with the minimum distance in time between two aircraft. Not only the minimum distance is displayed but also when it will be reached. Air traffic controllers do not need to estimate this distance anymore, making conflict resolution safer and quicker.

Crédits : Tous droits réservés - DGAC

On the radar screen, this minimum distance will appear in 3 different colors, each of which providing guidance on the ATM action to be issued: no action needed, monitoring the separation in time, initiate action to provide a compliant separation (i.e. 5NM minimum between 2 aircraft at the same level). Additionally, this tool helps ATCOs integrate the wind effect for their conflict resolutions.

EEE helps oceanic clearances’ compliance

EEE integrates an alarm that triggers when one of the elements contained in the oceanic clearance (exit beacon, time on the beacon, level) is different with the flown profile. Since January 2016 and the implementation of EEE in Brest, no new cases of oceanic clearance non-compliance have been reported, making the transition to the oceanic airspace safer.

EEE allows the identification of horizontal or vertical flight trajectory deviations

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The MONitoring Aids (MONA) allows the detection of deviations compared with the assigned clearance respectfully in the horizontal or vertical plan. These safety support tools are independent from onboard systems and rely on flight trajectories as tracked and processed by the radar surveillance system.

In the first semester of 2018, Datalink will be enriched by the possibility for the controller to display on the radar screen specific downlink aircraft parameters into the label of each controlled aircraft. These parameters are the magnetic heading, the indicated air speed, the Mach number and the Selected Flight Level (SFL). They are obtained with enhanced Mode S surveillance. In addition, an alarm will trigger if the pilot selects in its Flight Management System (FMS) a different value than its Cleared Flight Level (CFL). A reduction of level bust events is expected.

Here is an example:
RYR1DG is cleared from Fligh Level (FL) 400 to FL380. The aircrew accidentally inserts FL370 into his FMS.

Crédits : Tous droits réservés - DGAC

Maintaining the highest level of safety with the change management process

DSNA change management process includes:

  • the preparation of the following system transitions
    • working methods workshops,
    • safety assessment focused on appropriate Human/Machine coupling, triggering safety requirements on the human operator (knowledge and Working Methods),
    • assessment of the training time needed on the simulator and real time traffic training before considering capacity increases,
    • training simulations with human factor focus,
    • operational evaluations before system deployment, in order to get an appropriate trust level in terms of safety.


  • the safety assurance process:
    • the continuous assessment of the safety performance following the implementation of an ATM system such as EEE
    • post change analysis built on detailed and systematic ATC feedbacks and event reporting, showing the differences between what had been taught during training and what has been developed in real time ATM
      • How well have the working methods been appropriated?
      • How to better adapt ATCO’s skills in the medium term? How did ATC evolve when managing unusual situations, such as adverse weather events and multiple route deviations?
      • How differently do ATCOs tackle the real time traffic increase on a sector? How to adjust consequently surveillance and regulation rates of control sectors used by FMP unit?

The final objectives are to

  • continue working on the identification of safety improvements in relation with major technological steps
  • adjust the working methods in a continuous assessment of the safety performance
  • make the best use of the feedbacks of such a major ATM system transition to prepare the following ones.

EEE in Brest ACC improved ATM performance

Since 2015, the number of managed aircraft in Brest ACC has significantly increased, +14% in 2017 compared with 2015. Not only EEE has allowed absorbing this constant rise, but it has also helped containing Brest ACC Air Traffic Flow Management (ATFM) delays. It is a major achievement considering that generally ATFM delays are subject to exponential increases when facing double-digit traffic growth.

More aircraft have been safely managed

With the intensification of the SW Axis demand (holiday traffic flows from northern Europe to/from Spain and the Canary Islands), Brest has seen its traffic jump by 8.82% since the beginning of year 2017 compared with the same period in 2016. When comparing with the traffic before the implementation of EEE, the increase is even more impressive.

Traffic regulation rates have significantly improved

When ATFCM measures such as rerouting & FL scenarios, STAM (Short Term ATFCM Measures), MCP (Mandatory Cherry Picking), or Collaborative Advanced Planning have failed to contain the traffic demand within the capacity of a concerned control sector (or a grouping of sectors), ATC have to apply traffic regulations to flatten out traffic peaks, so the airspace continues to be safely managed.
For more information please read the section "DSNA Collaborative Advanced Planning" on the Air traffic flow management page.

The regulation rate of a control sector is defined according to its capacity. It is also assessed and modified in real time, taking into account the traffic complexity, the weather conditions and all external events that may have an effect on the maximum number of aircraft managed within an hour.
Since the implementation of EEE in Brest ACC, we have noticed that regulation rates applied are higher for nearly most of the controlled sectors (i.e. either elementary sectors or combined). Moreover, the cumulative duration of the regulations on the most penalizing sectors has been reduced by more than 60%

Average regulation rates (i.e. managed aircraft per hour) and evolution


  Number of aircraft managed in the hour Evolution
Control sectors 2015 2017 2015 v. 2017
MZUpper   41,24 43,31 5,02%
NU 33,72 39,8 18,03%
MZSI 39,44 42,21 7,04%
QXSI 35,75 36,48 2,04%
JSH 35,52 38,78 9,17%
A 37,09 44,92 21,11%
G 35,47 44,02 24,09%
VKW 33,32 36,03 8,14%
VKWS 32,58 39,45 21,07%
VKWU 30,8 39,09 26,91%


Control sectors can either be isolated or combined (i.e. grouped with another).

The ATFM delay per controlled flight has reduced

Crédits : Tous droits réservés - DGAC

ATFM delays have been cut down by 10% compared with 2015. The peak of 2016 includes the effects of the EEE transition.
ATFM delays may have various causes such as the lack of airspace capacity (C), rerouting actions (R), lack of staff (S), ATC equipment failures (T), airspace management with the military (M) and special events such as sporting events or ATM system implementations (P). Read More on traffic regulation coding.

For more information about trafic regulation coding please read the section "Air navigation delays in minutes" on the page Performance of Air Traffic Management.

The implementation of EEE in Brest ACC resulted in less traffic regulations needed, for less time generating less ATFM delays for the airlines. Combined with staffing measures as well as innovative ATFCM measures, EEE has had a very positive effect on the delay reduction in summer 2017, while improving safety figures.

Assessing the consistency of traffic regulations and control sectors capacities is a constant process. Based on the feedback from summer 2017, Brest ACC continues to adjust its monitoring and regulation rates upwards, taking into account in real time the configuration of the various traffic flows.


EEE has proven beneficial for the airspace users flying over the west part of France considering the current traffic growth context. But for lasting performance, all air transport actors must aim at improving traffic predictability. Accurate traffic counts in control sectors subject to high traffic demand are a major challenge we can meet by a better understanding of the issues at stake. Traffic volatility causes disruption in the current air traffic management solutions ANSPs promote. Flight plan adherence is the only way forward.

For more information please read the page Air traffic flow management.

EEE transition in Brest ACC

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Depuis l'été 2016, les contrôleurs aériens du CRNA Ouest disposent d'un environnement de travail moderne et performant, avec une interface électronique stripless.

EEE transition and customer consultation

Brest ACC was the first French ACC to transition to a fully electronic environment and new ATC tools designed to improve decision making while ensuring the highest safety levels. Unfortunately, Brest ACC was confronted with significant technical issues soon after the system transition. These failures postponed the forecasted increase of capacities creating high level of disruption in the network.

Taking into account the customer feedback from the Brest ACC transition, the Bordeaux ACC transition was dealt with much earlier, together with increased coordination and collaboration with all involved stakeholders. Therefore, ATFM delays and induced additional costs for airinbes were reduced, and a quick return to normal operations was observed.

The Bordeaux EEE transition was recognized by the community as setting a great example of a well mastered ATM system transition, with contained level of disruption and a quick recovery of capacity.


Brest ACC transition – customer feedback

Bordeaux ACC transition – lessons learnt
  • Lack of coordination in delivering a collaborative contingency plan.


  • Anticipated customer information required.


  • No insight as when the capacity offer would improve.
  • NM associated earlier and improved coordination with adjacent ANSP.


  • DSNA/NM consultation meetings with all involved stakeholders for defining the appropriate set of mitigation solutions.


  • Coordinated plan with the AOs to mitigate the impact, contain ATFM delays and reduce additional costs.


  • Release of a clear capacity increase plan integrating well identified appropriation time periods for ATCOs.



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