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Functional Requirement Identification Development of Methodology

European Union
Complete with results
Project Acronym
STRIA Roadmaps
Network and traffic management systems (NTM)
Infrastructure (INF)
Transport mode
Airborne icon
Transport policies
Societal/Economic issues


Background & Policy context

There are plans to implement the European ATM system (EATMS) starting from 2005. Therefore, the need to specify adequate CNS (control, navigation and surveillance) infrastructure and the best cost/effectiveness ratio is now a reality. A new approach is needed to define the requirements for CNS infrastructure to support the ATM system. Analysing the impact of C, N or S equipment or sub-systems on the overall ATM system and its performance is becoming harder because of a more complex integration, involving not only technical but also functional and geographical issues.


The objectives of the FRIENDLY project were to:

  • establish a methodology, within a moving and modular technical environment, for the identification and validation of CNS functional requirements, which allow the overall ATM system, supported by the CNS infrastructure, to achieve its expected performance level;
  • analyse the use of simulation facilities to support this methodology.

The aim is to achieve greater cost-effectiveness, as a build-and-try approach could involve expensive backtracking in case of inadequacies becoming apparent after implementation.


Parent Programmes
Institution Type
Public institution
Institution Name
European Commission; Directorate-General for Energy and Transport (DG TREN; formerly DG VII)
Type of funding
Public (EU)


The FRIENDLY project has provided a methodology aimed at defining validated CNS functional requirements, combining a top-down analysis for the identification of functional requirements with a bottom-up general procedure for validating them.

The approach used to produce the CNS functional requirements provides, tractability to the original User Requirements, takes into account any envisaged operational concept, and covers three specific viewpoints of the ATM system: operational, technological and architectural.

The approach used to validate these functional requirements has the following features:

  • it uses available knowledge and expertise, with traceability in order to allow feedback (i.e. validation);
  • it uses simulation facilities for local validation and justification allowing modification at the local level;
  • it assesses the performance of the whole system taking into account the complex interactions between C, N and S elements;
  • it takes maximum advantage of the existing knowledge CNS elements incorporated into a macroscopic numerical model;
  • it involves simulation facilities to assess the performance levels and characteristics of known subsystems in order to improve the macroscopic numerical model.

The project has shown the crucial need, when using this methodology, for a starting point comprising an Operational Concept together with clear missions and objectives, consistent with the requirements specified or expressed by the users. Moreover, there is still a need for automated tools to implement this methodology, in particular its validation aspect based upon macroscopic numerical models. Recommendations have been drawn which will help the production and validation of real-world CNS functional requirements.

Policy implications

The project has prepared for future work concerning the design of the CNS functional requirements for EATMS. The full capability of the methodology will then be used for the benefits of the EC, Eurocontrol and all actors of the ATM and CNS domain. The methodology has to continue to evolve, taking into account the contributions of the ATM community, in order, in the next few years, to reach the same level of maturity as the rest of EATMS. The methodology is also a very important tool for improving the definition of EATMS because it is based upon system engineering techniques (closing the loop between design and validation), that provide a formalised communication, and thinking discipline for this process.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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